Princeton Applied Research EG G AM 1 Manual 201985173552...EG&G PRINCETON APPLIED RESEARCH P. O. Box 2565 Princeton, NJ 08540 Phone: 609/452·2111 TELEX: 84 3409 WARRANTY EG&G PRINCETON

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MOEL 113LOW- NOISE

PREAMPLIFIER

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SHOULD YOUR EQUIPMENT REQUIRE SERVICE WARRANTY

A. Contact the factory (609/452-2111) or your local factory EG&G PRINCETON APPLIED RESEARCH warrants each in-representative to discuss the problem. In many cases it strument of its manufacture to be free from defects in material Qwill be possible to expedite servicing by localizing the and workmanship. Obligations under this Warranty shall beproblem to a particular plug-in circuit board. limited to replacing, repairing or giving credit for the purchase

price, at our option, of any instrument returned, freightB. If it is necessary to send any equipment back to the fac- prepaid, to our factory within ONE year of delivery to the

tory, we need the following information. original purchaser, provided prior authorization for such returnhas been given by our authorized representative.

(1) Model number and serial number.This Warranty shall not apply to any instrument which our in-

(2) Your name (instrument user). spection shall disclose to our satisfaction, has become defec-tive or unworkable due to abuse, mishandling, misuse, acci-

(3) Your address. dent, alteration, negligence, improper installation or othercauses beyond our control. Instruments manufactured by

(4) Address to which instrument should be returned. others, and included In or supplied with our equipment, are notcovered by this Warranty but carry the original manufacturer’s

(5) Your telephone number and extension. warranty which is extended to our customers and may be morerestrictive. Certain subassemblies, accessories or com-

(6) Symptoms (in detail, including control settings). ponents may be specifically excluded from this Warranty, inwhich case such exclusions are listed in the Instruction

(7) Your purchase order numberfor repair charges (does Manual supplied with each instrument.not apply to repairs in warranty).

We reserve the right to make changes in design at any time(8) Shipping instructions (if you wish to authorize ship- without incurring anyobligation to install same on units

ment by any method other than normal surface previously purchased. 1transportation).

THERE ARE NO WARRANTIES WHICH EXTEND BEYOND THEC. U.S. CUSTOMERS—Ship the equipment being returned DESCRIPTION HEREIN. THIS WARRANTY IS IN LIEU OF, AND

to: EXCLUDES ANY AND ALL OTHER WARRANTIES OR REPRE-SENTATIONS, EXPRESSED, IMPLIED OR STATUTORY, IN-

EG&G PRINCETON APPLIED RESEARCH CLUDING MERCHANTABILITY AND FITNESS, AS WELL AS7 Roszel Road ANY AND ALL OTHER OBLIGATIONS OR LIABILITIES OF(Off Alexander Road, East of Route 1) EG&G PRINCETON APPLIED RESEARCH, INC_UDING, BUTPrinceton, New Jersey NOT LIMITED TO, SPECIAL OR CONSEQUENTIAL DAMAGES.

NO PERSON, FIRM OR CORPORATION IS AUTHORIZED TOD. CUSTOMERS OUTSIDE OF U.S.A.—To avoid delay in ASSUME FOR EG&G PRINCETON APPLIED RESEARCH ANY D

customs clearance of equipment being returned, please ADDITIONAL OBLIGATION OR LIABILITY NO“ EXPRESSLYcontact the factory or the nearest factory distributor for PROVIDED FOR HEREIN EXCEPT IN WRITING DULY EXE-complete shipping information. CUTED BY AN OFFICER OF EG&G PRINCETON APPLIED

RESEARCH.E. Address correspondence to:

EG&G PRINCETON APPLIED RESEARCHP. O. Box 2565Princeton, NJ 08540

Phone: 609/452-2111TELEX: 84 3409

3

SHOULD YOUR EQUIPMENT REQUIRE SERVICE

A. Contact the factory (609/452·2111) or your local factory representative to discuss the problem. In many cases it will be possible to expedite servicing by localizing the problem to a particular plug·in circuit board.

B. If it is necessary to send any equipment back to the fac· tory, we need the following information.

(1) Model number and serial number.

(2) Your name (instrument user).

(3) Your address.

(4) Address to which instrument should be returned.

(5) Your telephone number and extension.

(6) Symptoms (in detail, including control settings).

(7) Your purchase order number for repair charges (does not apply to repairs in warranty).

(8) Shipping instructions (if you wish to authorize ship· ment by any method other than normal surface transportat ion).

C. U.S. CUSTOMERS-Ship the equipment being returned to:

EG&G PRINCETON APPLIED RESEARCH 7 Roszel Road (Off Alexander Road, East of Route 1) Princeton, New Jersey

D. CUSTOMERS OUTSIDE OF U.SA-To avoid delay in customs clearance of equipment being returned, please contact the factory or the nearest factory distributor for complete shipping information.

E. Address correspondence to:

EG&G PRINCETON APPLIED RESEARCH P. O. Box 2565 Princeton, NJ 08540

Phone: 609/452·2111 TELEX: 84 3409

WARRANTY

EG&G PRINCETON APPLIED RESEARCH warrants each in-strument of its manufacture to be free from defects in material ~ and workmanship. Obligations under this Warranty shall be limited to replacing, repairing or giving credit for the purchase price, at our option, of any instrument returned, freight prepaid, to olJr factory within ONE year of delivery to the original purchaser, provided prior authorization for such return has been given by our authorized representative.

This Warranty shall not apply to any instrument which our in· spection shall disclose to our satisfaction, has become defec· tive or unworkable due to abuse, mishandling, misuse, acci· dent, alteration, negligence, improper installation or other causes beyond our control. Instruments manufactured by others, and included in or supplied with our equipment, are not covered by this Warranty but carry the original manufacturer's warranty which is extended to our customers and may be more restrictive. Certain subassemblies, accessories or com-ponents may be specifically excluded from this Warranty, in which case such exclusions are listed in the Instruction Manual supplied with each instrument.

We reserve the right to make changes in design at any time without incurring any obligation to install same on units previously purchased.

THERE ARE NO WARRANTIES WHICH EXTEND BEYOND THE DESCRIPTION HEREIN. THIS WARRANTY IS IN LIEU OF, AND EXCLUDES ANY AND All OTHER WARRANTIES OR REPRE· SENTATIONS, EXPRESSED, IMPLIED OR STATUTORY, IN· ClUDING MERCHANTABILITY AND FITNESS, AS WELL AS ANY AND ALL OTHER OBLIGATIONS OR LIABILITIES OF EG&G PRINCETON APPLIED RESEARCH, INCLUDING, BUT NOT LIMITED TO, SPECIAL OR CONSEQUENTIAL DAMAGES. NO PERSON, FIRM OR CORPORATION IS AUTHORIZED TO ASSUME FOR EG&G PRINCETON APPLIED RESEARCH ANY ~ ADDITIONAL OBLIGATION OR LIABILITY NOT EXPRESSLY PROVIDED FOR HEREIN EXCEPT IN WRITING DULY EXE-CUTED BY AN OFFICER OF EG&G PRINCETON APPLIED RESEARCH.

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TABLE OF CONTENTS

r Section Page

CHARACTERISTICS 1-1 1:1 Introduction 1-1 1.2 Specifications 1-1

II INITIAL CHECKS 11-1 2.1 Introduction 11·1 2.2 Equipment Needed 11·1 2.3 Procedure 11-1

III OPERATING INSTRUCTIONS 111-1 3.1 I ntrodu cti on 111-1 3.2 Noise and Source Resistance 111-1 3.3 Grounding 111-2 3.4 Signal Voltage and Gain 3.5 Dc Zero Adjustment 111-2 3.6 Overload Fast Recovery 111-3 3.7 Low-Pass/High·Pass Filters 111-3 3.8 Single-Ended/Differential Operation 111-3 3.9 Common-Mode Rejection and Dc Zero Adjustments 111-4 3.10 Maximum Input Signal Consistent with Linear Operation 111-4 3.11 Battery Operation, Test, and Charging 111·5 3.12 Rack Mounting 111-5 3.13 Using a Signal Input Transformer 111·6 3.14 Use of the Model 113 in Bio-Medical Applications 111-12

,...,.. IV . CIRCUIT DESCRIPTION IV-l 4.' Block Diagram Discussion IV-l

4.1A Input Coupling Circuit IV-1 4.1B Ground·Loop Suppression IV-1 4.1C Gain Determination IV-1 4.10 Rolloff Filter Circuit IV-' 4.1 E Overload Fast-Recovery Circuit IV-2 4.1 F Power Supply IV-2

4.2 Circuit Descriptions IV-2 4.2A Differential Preamplifier (A 1) IV-2 4.2B Output Amplifier (A2) IV-3 4.2C Power Supply Circuit IV-3 4.2D Battery Test Circuit IV-3

V ALIGNMENT PROCEDURE V-l 5.1 Introduction V-l 5.2 Preliminary V·l 5.3 Equipment Needed V·1 5.4 A2 FET Gate Source Zero Adj. V·1 5.5 Common-Mode Rejection Adj. V-l 5.6 Gain Calibration V-' 5.7 Low Frequency Rolloff Compensation V-2 5.8 High Frequency Rolloff Compensation V·2 5.9 Battery Test Calibrate V-2

VI TROUB LESHOOTI NG VI-l 6.1 Introduction VI-l 6.2 Procedure VI·' ,.. 6.3 Printed Circuit Soldering VI·l

\,,~ VII SCHEMATICS V 11-'

Number ' Page

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-'0-'1

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VI-1

-'2A-'28

FIGURES

ypical Recovery Time vs Low Frequency Rolloff . . . '_P Filter Normalized Amplitude Transfer Curve . . .HP Filter Normalized Amplitude Transfer Curve . . ._P/HP Filter Normalized Phase Transfer Curve . . .Typical Common Mode Rejection Characteristics . . . . . . . . . . .Vlaximum Differential Input to Model 113 . . . . . . . . . . . . . . .Vlodifying the AM-1 Transformer for Use with the Model 113 Preamplifier . . .Frequency Response of Typical Model AM-1 Transformer . . . . . . . . .Noise Figure Contours for Typical Model AM-1 Transformer . . . . . . .Schematic of Model AM-1 Transformer (Unmodified) . . . ' .Photographs of Model AM-1 Transformer . . . . . . . . .Frequency Response of Typical Model AM-2 Transformer . . . .Noise Figure Contours for Typical Model AM-2 Transformer . . .Model AM-2 Schematic, Turns Ratio 1:100 . . . . . . . . .Phot0ofModelAM-2 ................ .Frequency Response of Typical Model 190 Transformer . .Noise Figure Contours for Typical Model 190-113 System . . .

Ground-Loop Current Path . . IVSolder Removal byWicking . . VI1

..Vl1

Typical Noise Figure Contours for the Model 113 . . ll 1 , Dll-3II4II4ll-4II4

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Model190Schematic ............... ..lll-10Photograph of Model 190 Transformer . . . . Ill-10B-H Curve & Waveform . . . . . . . . . Ill-10Degaussing Waveforms . . . . . Ill-11

Number

1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9A 1-98 1-10 1-11 1-12A 1-128 1-13 1-14 1-15 1-16

11-17 11-18 11-19 11-20 V-l

VI-l

FIGURES

Typical Noise Figure Contours for the Model 113 Typical Recovery Time vs Low Frequency Rolloff LP Filter Normalized Amplitude Transfer Curve HP Filter Normalized Amplitude Transfer Curve LP/HP Filter Normalized Phase Transfer Curve Typical Common Mode Rejection Characteristics Maximum Differential Input to Model 113 Modifying the AM-l Transformer for Use with the Model 113 Preamplifier Frequency Response of Typical Model AM-l Transformer . Noise Figure Contours for Typical Model AM-l Transformer Schematic of Model AM-l Transformer (Unmodified) Photographs of Model AM-l Transformer ....... . Frequency Response of Typical Model AM-2 Transformer . Noise Figure Contours for Typical Model AM-2 Transformer Model AM-2 Schematic, Turns Ratio 1: 100 ..... Photo of Model AM-2 . . . . . . . . . . . . . . . Frequency Response of Typical Model 190 Transformer Noise Figure Contours for Typical Model 190-113 System Model 190 Schematic . . . . . . . Photograph of Model 190 Transformer B-H Curve & Waveform Degaussing Waveforms . . Ground-Loop Current Path Solder Removal by Wicking

• Page

111-' ~. 1-3 1-4 1-4 1-4

I 1-4 I 1-5 I 1-6 I 1-6 I 1-6 111-7 111·7 111-8 111-8 111-8 111-9 111-9 111-9

111-10 111-10 111-10 111-11 IV-l VI-l

. VI-l

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POWER CORD WHEN CHANGING THE LINE with normal heart functioning. However, recentVOLTAGE SETTING. Depend'ng on the switch research has shown that dangerexists at far lowerposition, either “115” or “230” (both are printed on current levels than was previously suspected. Asthe switch) will be visible to the operator. For a consequence of this increased awareness, andoperation from a line voltage of nominally 115 V after a careful analysis of the Model 113 design,ac, the switch should be set so that “115” shows. EG&G Princeton Applied Research CorporationFor operation from a line voltage of nominally feelsthat it cannot recommend the Model 113for230 V ac, “23O” should show. use in applications involving human subjects or

patients. In certain situations involving specificconditions of grounding, internal component

E. LINE FUSE failure, or excessive common-mode input, theThe Model 113 line fuse is located inside the in- high input impedance of the Model 113 could failstrument. To check or replace the fuse, it is first and potentially dangerous currents could flownecessary to remove the top cover and also the through the subject.shield mounted on the inside of the rear panel.The fuse should be a slow-blow type rated at However, the reader should not get the impres-either 1/16 A (115 V Operation) or 1/32 A (230 V sion that the Model 113 is in any wayadangerousoperation). The voltage rating should be 125 V or instrument to use in ordinary applications. Thosehigher in the Case 01 115 V Operation and 250 V or characteristics that necessitate the advisoryhiélherththe eeee Qt 230V0DeFeti0i1-9h|YeBU$$ against the instrument’s use in bio-medical ap-MDL OF equh/eteht thee Sheuld be USed- plications with humans are common to most other

preamplifiers as well. In fact, with its low internalwA|=tNiN(;i supply voltages, capability for internal battery

TO AVOID THE POSSIBILITY o|= A SAFETY HAZ- power with epinpieie independence of the ep line.ARD FRQM E|_ECTR|CA|_ SHQCK wi-ii(3i-i (3QUi_|3 and extremely high input impedance under normalREsui_T |N INJURY OR DEATH, |)|$(;()Ni\|EcT operating conditions, the Model 113 is probablyTHE PQWER CORD BEFQRE REM()V|NG QR |i\|- one of the safest preamplifiers available for$"i'Ai_i_|N(3 A FU$E_ i3E(;Ati$E QF Ti-ii; PQTEN- general use. For all practical purposes, it can beT|A|_ HAZARD, Ti-ii; FUSE Si-|()U|_[) BE CHECKED considered to be completely harmless. The maxi-AND/OR CHANGED BY A QUALIFIED SERVICE mum internei Supply vpitepee eppiied tp the em-"|'E(3i-i|\ii(3iAN ()Ni_Y_ plifiers are only i 12 V. Even these low voltages

can only appear at the input under very specificA prooeoure for geinino eooeee to the fuse operating conditions, and then generallyforonlyafollows. few milliseconds. A person inadvertently touching

the input under these conditions would, in(1) Remove the top oover_ it is eeoureo by e general, not even be aware that there was any

single screw on the bottom surface ofthetop- Vettege there at ett ehd hY he etfeteh Qt the im-oover “tip” et the reer of the inetrument_ with agination could the operator of the instrument bethe screw removed, the cover simply slides ie9eTded ee hethg ih ehY dehgehback to where it can be freed from the instru-ment_ The preamplifier can be used in biological appli-

cations involving animal subjects. However, if the(2) Remove the shield attached to the inside of eppiieeiipn ie pne in whieh ekin reeieienee is

the rear panel. This shield is secured by a dreetivredueed prbvpeeeed.tne pperetprie advis-einoie eorew at its oenter_ with the ehieio ed to observe the following recommendations ifremoveo, the iuee hoioer, iooeteo oireotiy unnecessary risk to the experimental animal istoabove the Line Voltage Selector switch, he evetdetibecomes accessible. 1

(1) Turn the amplifier power on BEFORE making(3) After oheokino eno, it eppropriete, ohenging any connections to the experimental animal.

the fuse, remount the shield and top coverbefore plugging in the line cord and operating (2) set the thput Ceuhtthg ewttehee 01 the Medetthe inetrument_ 113 to GND before making any connections to

the experimental animal. Do not transfer fromthe GND settings until after the connectionsare completed.

F. USE OF THE MODEL 113 IN 1BIO-MEDICAL APPLICATIONS (3) Do not turn the power switch on or off while

In the past few years, safety in bio-medical ap- the instrument is connected to the experi-plications has been a matter of growing concern mental animal.to both the users and suppliers of electronicsequipment. It has long been known that electrical It may prove helpful to consider the reason forcurrents passing through the heart can interfere these precautions. By understanding them, the

3

—_---up

POWER CORD WHEN CHANGING THE LINE VOLTAGE SETTING. Depending on the switch position, either "115" or "230" (both are printed on the switch) will be visible to the operator. For operation from a line voltage of nominally 115 V ac, the switch should be set so that "115" shows. For operation from a line voltage of nominally 230 V ac, "230" should show.

E. LINE FUSE The Model 113 line fuse is located inside the in-strument. To check or replace the fuse, it is first necessary to remove the top cover and also the shield mounted on the inside of the rear panel. The fuse should be a slow-blow type rated at either 1/16 A (115 V operation) or 1/32 A (230 V operation). The voltage rating should be 125 V or higher in the case of 115 V operation and 250 V or higher in the case of 230 V operation. Only a BUSS MDL or equivalent fuse should be used.

WARNING! TO AVOID THE POSSIBILITY OF A SAFETY HAZ-ARD FROM ELECTRICAL SHOCK WHICH COULD RESULT IN INJURY OR DEATH, DISCONNECT THE POWER CORD BEFORE REMOVING OR IN-STALLING A FUSE. BECAUSE OF THE POTEN-TIAL HAZARD, THE FUSE SHOULD BE CHECKED ANDIOR CHANGED BY A QUALIFIED SERVICE TECHNICIAN ONLY.

A procedure for gaining access to the fuse follows.

(1) Remove the top cover. It is secured by a Single screw on the bottom surface of the top-cover "lip" at the rear of the instrument. With the screw removed, the cover simply slides back to where it can be freed from the instru-ment.

(2) Remove the shield attached to the inside of the rear panel. This shield is secured by a Single screw at its center. With the shield removed, the fuse holder, located directly above the Line Voltage Selector switch, becomes accessible.

(3) After checking and, if appropriate, changing the fuse, remount the shield and top cover before plugging in the line cord and operating the instrument.

F. USE OF THE MODEL 113 IN BIO·MEDICAL APPLICATIONS

In the past few years, safety in bio-medical ap-plications has been a matter of growing concern to both the users and suppliers of electronics equipment. It has long been known that electrical currents passing through the heart can interfere

with normal heart functioning. However, recent research has shown that danger exists at far lower current levels than was previously suspected. As a consequence of this increased awareness, and after a careful analysis of the Model 113 deSign, EG&G Princeton Applied Research Corporation feels that it cannot recommend the Model 113 for use in applications involving human subjects or patients. In certain situations involving specific conditions of grounding, internal component failure, or excessive common-mode input, the high input impedance of the Model 113 could fail and potentially dangerous currents could flow through the subject.

However, the reader should not get the impres-sion that the Model 113 is in any way a dangerous instrument to use in ordinary applications. Those characteristics that necessitate the adviSOry against the instrument's use in bio-medical ap-plications with humans are common to most other preamplifiers as well. In fact, with its low internal supply voltages, capability for internal battery power with complete independence of the ac line, and extremely high input impedance under normal operating conditions, the Model 113 is probably one of the safest preamplifiers available for general use. For all practical purposes, it can be considered to be completely harmless. The maxi-mum internal supply voltages applied to the am-plifiers are only ± 12 V. Even these low voltages can only appear at the input under very specific operating conditions, and then generally for only a few milliseconds. A person inadvertently touching the input under these conditions would, in general, not even be aware that there was any voltage there at all and by no stretch of the im-agination could the operator of the instrument be regarded as being in any danger.

The preamplifier can be used in biological appli-cations involving animal subjects. However, if the application is one in which skin resistance is greatly reduced or bypassed, the operator is advis-ed to observe the following recommendations if unnecessary risk to the experimental animal is to be avoided.

(1) Turn the amplifier power on BEFORE making any connections to the experimental animal.

(2) Set the Input Coupling switches of the Model 113 to GND before making any connections to the experimental animal. Do not transfer from the GND settings until after the connections are completed.

(3) Do not turn the power switch on or off while the instrument is connected to the experi-mental animal.

It may prove helpful to consider the reason for these precautions. By understanding them, the

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operator may be better able to safely carry out electrical monitoring of experimental animals, not only where the input amplifier is the Model 113, but where other preamplifiers are used as well.

(1) Turn-On Transients

When the amplifier is first turned on, all cir-cuits do not instantly assume their quiescent operating state. Instead, a finite time is re-quired for the common-mode loop amplifier to set the input stages to their proper operat-ing point. During this interval (which varies from a few milliseconds to a second or more depending on the source impedance), the source-gate junction of one input transistor or the other is forward-biased. In this state, the transistor does not exhibit a high im-pedance, but instead appears as a low im-pedance from the input of the instrument to the output of the common-mode amplifier.

(2) Power Transformer

The power transformer in the Model 113 is of very high quality and is unlikely to fail during the life of the instrument. Nevertheless, the possibility of such a failure, however remote, must be considered. Should a short develop, and if the instrument were being used with in-complete or improper ground returns (com-mon in many buildings and installations), a dangerous situation would exist.

(3) Internal Component Failure

The input transistors of the Model 113 are junction-type field-effect transistors. Al-though they exhibit an extremely high input resistance when properly biased, their resis-tance can drop to a few ohms if their operat-ing current or bias is out of the normal operat-ing range sufficiently to give a simple forward biased diode junction from the gate to either the source or the drain. There are several possible internal component failures which, though unlikely, could bring about this condi-tion. Should it occur, the input of the ampli-fier would be connected through a low im-pedance directly to the instrument's power supply.

(4) Excessive Common-Mode Input

As stated in the specifications, the common-mode input limit of the Model 113 is 1 V rms. Higher levels "turn on" low conduction paths at the input of the preamplifier to protect the input circuits, and thereby lower the input im-pedance.

Again, it should be emphasized that, even though EG&G Princeton Applied Research Corporation does not recommend the Model 113 for use with human subjects, its use in all other applications is recommended without reservation.

G. VENTILATION With a power consumption of only 5 watts when operated from the ac line, and even less when bat-tery operated, the Model 113 does not have any special ventilation requirements. It can be operated on a bench or in a rack (rack mounting kits can be purchased from the factory), the only constraint being that the ambient temperature be in the range of 15°C to 45 °C.

H. DEFECTS AND ABNORMAL STRESSES

Whenever it is likely that the protection provided by the connection to earth ground has been im-paired, the apparatus shall be made inoperative and secured against any unintended operation. The protection is likely to be impaired if, for exam-ple, the apparatus:

(1) Shows visible damage,

(2) Fails to perform the intended measurements,

(3) Has been subjected to prolonged storage under unfavorable conditions,

(4) Has been subjected to severe transport stresses.

Such apparatus should not be used until its safety has been verified by qualified service personnel.

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SECTION I

CHARACTERISTICS

1.1 INTRODUCTION

The Model 113 Low-Noise Preamplifier provides high gain, low noise amplification of wideband signals from dc to 300 kHz. Adjustable high and low frequency rolloffs allow the bandwidth to be reduced. Two inputs, with individual coupling switches, allow either differential or single-ended operation. Calibrated gain is switch selectable from x10 to X104 in a 1·2-5 sequence, and an uncalibrated gain vernier provides x1 to x2.5 range expansion.

The unit may be powered either from the ac line or from its own batteries. The nickel-cadmium batteries recharge automatically during line operation.

Other features include an overload fast-recovery switch, special circuitry that reduces the effects of ground-loop currents, front-panel dc zeroing and common mode rejec-tion screwdriver controls, and battery test provisions.

The Model 113 is well suited for use as a preamplifier for other Princeton Applied Research signal processing instru-ments.

1.2 SPECIFICATIONS

(1) INPUTS

Two channels, each with a three position switch to provide for ac or dc coupled, single-ended or differen-tial operation. I nput connectors are BNC type.

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(2) INPUT IMPEDANCE

(a) Ac coupled: through 0.1 J.1F, shunted to ground with 100 megohms and 15 pF in parallel.

(b) Dc coupled: 1 gigohm, shunted by 15 pF.

(3) MAXIMUM INPUT WITHOUT DAMAGE

(a) Dc coupled: Common-Mode, ±10 V; Differen-tial, ±7.5 V.

(b) Ac coupled: coupling capacitors can withstand 200 V. Transients which pass through coupling capacitors cannot exceed dc coupled operation limits.

(4) MAXIMUM INPUT SIGNAL CONSISTENT WITH LINEAR OPERATION (see Subsection 3.10)

(a) Common mode: 1 V rms.

(b) Differential mode (gains of 10 to 100): ±500 mY.

(c) Differential mode (gains of 200 through 10 k): ±50 mY.

(5) COMMON MODE REJECTION (11) OUTPUT VOLTAGE

FREQUENCY FOR GAIN > 200 FOR GAIN < 200 10 volts pk-pk ahead of 600 ohms.

dc to 100 Hz 120 dB (min) 100 dB (min) (12) OUTPUT IMPEDANCE1 kHz 100 dB 80 dB

10 kHz 80 dB 60 dB 600 ohms.100 kHz 60 dB 40 dB

(13) OVERLOAD RECOVERY

(6) GA|N Resets immediately with spring-loaded front-paneltoggle. See Figure Ill-2 for characteristic recovery

x10 to x104 calibrated gain settings. Accuracy of data-calibrated gains is i2% when gain vernier is in the (14) P()\/\/ER REQU|RE|\/|E|\|TScalibrate position. Gain vernier provides uncalibratedgain F8099 eXl3>an$i0n 01 LID ‘£0 X2-5(fT\ilmUm)- (a) Rechargeable nickel-cadmium batteries provide

approximately 30 hours operation bet\/veen(7) FREQUENCY RESPONSE charges. A front-panel, three-position, spring-

loaded toggle switch and test lamp permit test ofRolloff frequencies are switch selectable. Front panel each of the -[W0 in-[ema| bat-(erie5_switch markings indicate 3 dB point of 6 dB/octaverolloff curve. Rolloffs are selectable as follows: (b) AC |ine Operation; 195-125 \/ ac or 210-259 \/

ac, 50-60 Hz, 5 watts. Internal batteries will(8) I-OW FFBQUBHCVI d¢ P050100 and 0-03 HZ ‘E0 I recharge automatically while unit is connected to

kHz positions in 1-3-10 sequence. ac power line_

(b) High Frequency: 3 Hz to 300 kHz in 1-3-10 (15) DIMENSIONSsequence.

8.6" W x 4.1" H x11.3" D (21.8 cm x 10.4 cm x 28.7(8) NOISE cm).

At 10 Hz with a 2 megohm source impedance, noise (16) WEIGHTfigure is 0.3 dB maximum. At 1 kHz with a 1 megohmsource impedance, noise figure is 0.2 dB maximum. 4 pounds (1.8 kg).See Section Ill for further discussion and noise figurecontours. (17) ACCESSORIES

(9) DC DRIFT If the source impedance is less than 100 ohms, bestlow-noise performance will be obtained if a Model

(a) Referred to input (dc coupling): maximum 10 AM-1, AM-2, or 190 input transformer is used. Both‘I-IV/QC Or I688 than 10 /1V/24 hours at constant the AM-1 and the AM-2 have 1:100 turns ratios. Theambient temperature. A front panel screwdriver AM-1 has a 3 dB bandwidth Qf fr()m 1 kHz to 10 kHzcontrol provides for dc Zeroing. at 10 ohms source impedance, and the AM-2 has a

bandwidth of from 1 kHz to 150 kHz with a 1 ohm(bl Referred to Output: less than 1 mv/CC’ or less source. The Model 190 has a 1:10:100 turns ratio. The

than 1 mv/24 hours at Constant ambmnt tern‘ three dB bandwidth is from 0.25 Hz to 500 Hz with aperatum 1 ohm source. See Section lll for further details

regarding these transformers.

(10) DISTORTION Flanges are available for mounting on a single unit ortwo units side by side in a 19" relay rack. See

Typicaldistortion is less than 0.01%. Subsection III-12 for the part numbers of theseflanges.

I-2

(5) COMMON MODE REJECTION

FREQUENCY

dc to 100 Hz 1 kHz

10 kHz 100 kHz

(6) GAIN

FOR GAIN> 200

120 dB (min) 100 dB BOdB 60 dB

FOR GAIN < 200

100 dB (min) BO dB 60 dB 40 dB

x10 to X104 calibrated gain settings. Accuracy of calibrated gains is ±2% when gain vernier is in the calibrate position. Gain vernier provides uncalibrated gain range expansion of up to x2.5 (minimum).

(7) FREQUENCY RESPONSE

Rolloff frequencies are switch selectable. Front panel switch markings indicate ~ dB point of 6 dB/octave roll off curve. Rolloffs are selectable as follows:

(a) Low Frequency: dc position and 0.03 Hz to kHz positions in 1-3-10 sequence.

(b) High Frequency: 3 Hz to 300 kHz in 1-3-10 sequence.

(B) NOISE

At 10 Hz with a 2 megohm source impedance, noise figure is 0_3 dB maximum_ At 1 kHz with a 1 megohm source impedance, noise figure is 0.2 dB maximum_ See Section III for further discussion and noise figure contours.

(9) DC DRIFT

(a) Referred to input (dc coupling): maximum 10 "IlV/C or less than 10 IlV/24 hours at constant ambient temperature. A front panel screwdriver control provides for dc zeroing.

(b) Referred to output: less than 1 mV/C, or less than 1 mV/24 hours at constant ambient tem-perature.

(10) DISTORTION

Typical distortion is less than 0.01%.

1-2

(11) OUTPUT VOLTAGE

10 volts pk-pk ahead of 600 ohms.

(12) OUTPUT IMPEDANCE

600 ohms.

(13) OVERLOAD RECOVERY

Resets immediately with spring-loaded front-panel toggle. See Figure 111-2 for characteristic recovery data.

(14) POWER REQUIREMENTS

(a) Rechargeable nickel-cadmium batteries provide approximately 30 hours operation between charges. A front-panel, three-position, spring-loaded toggle switch and test lamp permit test of each of the two internal batteries.

(b) Ac line operation: 105-125 V ac or 210-250 V ac, 50-60 Hz, 5 watts. I nternal batteries will recharge automatically while unit is connected to ac power line.

(15) DIMENSIONS

B.6" W x 4.1" H x 11.3" D (21.B cm x 10.4 cm x 2B.7 cm).

(16) WEIGHT

4 pounds (1.B kg).

(17) ACCESSORIES

If the source impedance is less than 100 ohms, best low-noise performance will be obtained if a Model AM-1, AM-2, or 190 input transformer is used. Both the AM-1 and the AM-2 have 1: 100 turns ratios. The AM-1 has a 3 dB bandwidth of from 1 kHz to 10 kHz at 10 ohms source impedance, and the AM-2 has a bandwidth of from 1 kHz to 150 kHz with a 1 ohm source. The Model 190 has a 1: 1 0: 1 00 turns ratio. The three dB bandwidth is from 0.25 Hz to 500 Hz with a 1 ohm source. See Section III for further details regarding these transformers.

Flanges are available for mounting on a single unit or two units side by side in a 19" relay rack. See Subsection 111-12 for the part numbers of these flanges.

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S)lO3H3 'lVl.l.lNIll NOLLOHS

SECTION II

INITIAL CHECKS

2.1 INTRODUCTION

The following procedure is provided to facilitate initial performance checking of the Model 113. In general, the procedure should be performed after inspecting the instru-ment for shipping damage (any noted to be reported to the carrier and to Princeton Applied Research Corporation), but before using it experimentally. Should any difficulty be encountered in carrying out these checks, contact the factory or one of its representatives.

2.2 EQUIPMENT NEEDED

(1) General purpose laboratory oscilloscope.

(2) Signal generator capable of providing a 1 V pk-pk sinewave at 1 Hz, 100 Hz, and 1 kHz.

2.3 PROCEDURE

(1) Make sure the rear-panel slide switch is in the position indicating the line voltage to be used (115 V ac or 220 Vac).

(2) Plug the line cord into the rear of the instrument and into the power receptacle.

(3) Press the power switch so that it remains depressed.

(4) Push the spring-loaded battery test toggle to the left, then push it to the right. The green indicator should light for both positions.

(5) Make the following initial control settings:

(a) Gain: x10; Cal.: fully counterclockwise (turn until the switch "clicks").

11-1

(b) Coupling: A input AC, B input GND.

(c) Low Frequency Rolloff control: 1 Hz.

(d) High Frequency Rolloff control: 1 kHz.

(6) Connect the oscilloscope to the output BNC jack_

(7) Set the signal generator to 1 Hz, 1 V pk-pk, and connect it to the A input BNC jack. (Use the oscilloscope to make the signal generator amplitude settings, to obtain consistency between input settings and output readings.)

(8) Monitor the output; the output level should be 7 V pk-pk.

(9) Set the signal generator to 100 Hz, 1 V pk-pk. Monitor the output; the output level should be ten times the input level.

(10) Set the signal generator to 1 kHz, 1 V pk-pk. Monitor the output; the output level should be 7 V pk-pk.

(11) Press the OVL recovery button; the output should decrease to a low level, typically 50 mV. However, the absolute signal amplitude can vary considerably from unit to unit.

(12) Return the power switch to the OFF (out) position.

This completes the initial checks. If the instrument per-formed as indicated, one can be reasonably sure that it is operating properly.

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SNOl.I.3H.I.SNl 9NI.l.V!:l3dOIII NOLLOHS

SECTION III OPERATING INSTRUCTIONS

3.1 INTRODUCTION

To obtain optimum performance from the Model 113, care must be exercised in selecting the signal source impedance, in selecting the bandwidth, and in ground loop considera-tions, all of which are discussed below.

Fundamentally, the instrument is powered as required either from the self-contained batteries or from the ac line, and the signal to be ampl ified is applied to the input connector(s); the amplified signal is available at the output jack through a resistance of 600 ohms.

NOTE: Before operating from ac line power, make sure the rear-panel switch is in the position indicating the line voltage to be used, and be sure the proper size line fuse is installed (1/16 A for 115 V operation or 1/32 A for 230 V operation). Operating from too high a line voltage will blow the line fuse and possibly damage the power transformer and circuit components.

3.2 NOISE AND SOURCE RESISTANCE

Best amplifier performance is often regarded to be realized under those conditions where it least decreases the overall signal-to-noise ratio. In many instances the thermal noise generated by the signal source resistance is the dominant factor in determining the input signal-to-noise ratio. In this respect, amplifier noise performance can be specified by the amount of noise the amplifier adds to the amplified source thermal noise; expressed in decibels, this is called the "Noise Figure":

(1) Noise Figure =

20 I total rms noise voltage at the ampl ifier output 0910 gain x source thermal noise voltage (rms) dB

where the Source Thermal Noise = V4KTRl'lf volts rms = E, and

K = Boltzmann's constant, 1.38 x 10-23 joules/K T = absolute temperature in kelvins M = equivalent noise bandwidth in Hz R = source resistance in ohms (differential source

resistance for Model 113; if used single-ended, set the coupling selector for th.e unused input to ground, and regard this part of input resistance to be zero).

The total output noise may be converted to an equivalent input noise by dividing by the amplifier gain. The noise figure, expressed in these terms, becomes:

(2) Noise Figure =

20 I total rms noise voltage referred to amp. input dB 0910 source thermal noise voltage (rms)

II 1-1

Each ampl ifier has its own characteristic noise figure, wh ich varies as a function of frequency and source resistance. These figures are obtained experimentally, and plotted

graphically. Figure 111-1 is a typical set of noise figure contours for the Model 113.

30dB

--'_---l, 10 -1 10- 1 00 IO~ ~ IO~

FREQUfNr i .N Hz

Figure 111-1. TYPICAL NOISE FIGURE CONTOURS

FOR THE MODEL 113

In using these contours, the total equivalent rms input noise is usually the quantity of interest. This can be obtained from the graph and equation (3):

(3) Total equivalent rms input noise voltage = source thermal noise x antilog NF/20 volts rms

The equivalent noise bandwidth used in determining the source thermal noise is a function of the external circuitry and/or the amplifier bandwidth. When operating dc coupled (LF rolloff to DC), the equivalent noise bandwidth of the M113 is simply the HF rolloff frequency multiplied by 1T/2. If the LF rolloff frequency setting is other than dc, the equivalent noise bandwidth is given by the formula:

where: uted by the transformers, the results obtained using atransformer hardly resemble the ideal theoretical results as

f2 is the setting of the HF Rolloff Control, and to use noise figure contours and amplitude transfer curvesENB is the equivalent noise bandwidth in Hz, predicted in the example. When ug a transformer, it is best Qft is the setting of the LF Rolloff Control. obtained empirically for the individual transformer. Sub

section 3.11 contains such data for the transformers.

If the two frequency settings are far apart, the equivalentnoise bandwidth to a close approximation is simply 1r/2 33 GROUNDiNGtimes the HF rolloff frequency. '

_ The Model 113 is specifically desi ned to have a hi h de reeSup.hOSe_ one _ihtehded tO_ Operate the Modei its ih of immunity to the effects of gtiound-loop curretnts. itfhecon unction with t h . . - . .tm ted t 50 in expegmeh t att htisehts ahsoutlge signal ground side of the input connectors is connected to. p a _ O .0 ms’ ah Suppose i‘ 'S_ h_OWh t at t e chassis ground through a 10 ohm resistor. To maintaininformation re u edf th d b l . . . . .q ir rom e experiment is situate e ow

_ _ ground-loop immunity, avoid shorting the input grounds to3 S.ihCe. tits soutge tthetmet)hotgsegorhttiisutihe te_tt_he chassis ground at the amplifier end of the cables. To furtherbo ad _dOtirie. is, eheh deg Oh, ahh W|i_Ft 'nt ti amp iliet reduce the effects of ground-loop currents, use an input

an Wt is minimize ysettihet e to O Cohtto to cable that is short and has a high conductivity outerdc and the HF toiiott ‘?°"‘F'°' to 3 kH,Z' DC Coupling is used‘ conductor. (For a discussion of the circuit desi n with9h : . . . .T e source thetmai noise ih this Case is respect to grounding considerations, see Section IV).

E =\/4x1.38 >< 10-” X 2.9x 102x 50>< 3 X103X1.57= 6 i X to-s V rms CAUTION: The power rating of the 10 ohm resistor is %

i watt. Avoid excessive ground-to-ground current to avoidFrom Figure lll-1, the noise figure for the Model 113 at a burning out this reststtmcenter frequency of 1500 Hz and a source resistance of 50ohms is 18 dB. Substituting these values into equation (3): when the Signet is aepned to the input via a transformer,

totai equivaient input noise operate the amplifier single-ended. That is, place one inputZ 61 X to-s X ibis/20 selector to the ground position, and connect the trans-

eieev former to the other input (ac couple); connect onetransformer lead to the outer shell of the BNC connector

Occasionally the dc component is not required, so that the and eenneet the other transformer ieed to the Centerhest heise Dettetmehee eeh he 8Chie\/ed With the help 0t eh conductor of the connector. Connecting this way avoids theinput transformer. This is possible by taking advantage of nrebiem Qt etatie energe bui|d-up at tne inputs due te nothe property of a transformer to multiply the source greund return_resistance by the square of the turns ratio and the voltageby the ratio. With atransformer inserted between the signal 3_4 $|G|\|AL \/()|_TAGE AND GAINsource and the amplifier input we can increase the effectivesource resistance to a value that reduces the noise figure toless than 0.05 dB. From Figure lll-1, the source resistance With the Vetiehie 9eih eehttei ih the eeiihtated hesitiehshould be about 1 megohm. The transformer turns ratio, ieewii the hesitieh et the geih Seieetet eeetiteteiy Sets thetor this inibedanee inerease, is W: t40_ -|-herntai gain to the indicated level. Intermediate levels of gain maysource noise at the amplifier input is equal to the noise be ehteihed ieV use et the tiheeiibteteei Vetiehie Qeihgenerated by the 50 bhrn sbtiree inuitibiied by the turns control. If it is desired to accurately set an intermediateratio. With a noise figure near zero, the total equivalent rms ievei et geihl ephiy eh ihhtit Sighei to the ethpiitiet ihptitinput nbise is aisb edtiai to the nbise generated by the 50 and, using an ac voltmeter, proportionally adjust the outputdhrn sbtiree nitiitibiied by the turns ratio! I 70 tiv rrns_ signal level to a corresponding value between the levels ofAlthough the numerical value of equivalent input noise is the two tixed geih 5ettih95 hteeketihg the desired 9aih-much larger than before, the signal-to-noise ratio isisub-stantially increased. This can be seen by considering all ofthe transformed source signal voltage as appearing at the The maximum Output that the aihphtiet Cah provide is toamplifier input terminals, because the Model 113 input t/hits pea_k'tO'heak (through 600 Ohms ihto ah Opeh Circuit)"teeietenee is mueh ieteet than the 1 meeehm etesenteei by For maximum input voltages, refer to the specifications andthe transformer; the signal-to-noise ratio is equal to the to Suhsectioh 3'i0'maximum possible value: esig/E x antilog NF/20) E esie/E.In this example the transformer increases the signal-to-noiseratio by a factor of 8.

3.5 DC ZERO ADJUSTMENTPrinceton Applied Research Corporation manufacturestransformers for use in low level, low frequency applica- The dc zero adjustment may need to be touched Cip as thetions. Characteristics and details regarding the use of some Qeih is ehehgeti ih Dettietliet, it the ediustmeht is titst madeof these transformers are discussed in Subsection 3.11. Wheh 0Detetih9 at e i0W Qeih, t0ii0Wed ietet hV ttehstet teBecause the transformers have so much influence in high-Qeih Opetetiehi it is impetteht that the de Zero bedetermining bandwidth, and because of the noise contrib- Cheeked, ahd, it heeessetV. teedlusted as required-

lll-2

where:

ENB is the equivalent noise bandwidth in Hz, f2 is the setting of the HF Rolloff Control, and fl is the setting of the LF Rolloff Control.

If the two frequency settings are far apart, the equivalent noise bandwidth to a close approximation is simply 1T/2 times the HF rolloff frequency.

Suppose one intended to operate the Model 113 in conjunction with an experiment that presents a source impedance of 50 ohms, and suppose it is known that the information required from the experiment is situated below 1 kHz. Since the source thermal noise contributing to the total noise is dependent on bandwidth, the amplifier bandwidth is minimized by setting the LF rolloff control to dc and the HF rolloff cuntrol to 3 kHz. Dc coupling is used. The source thermal noise in this case is:

E =)4 x 1.38 x 10 23 x 2.9 x 10 2 X 50 x 3 x 10 3 x 1.57

= 6.1 x 10-8 V rms

From Figure 111-1, the noise figure for the Model 113 at a center frequency of 1500 Hz and a source resistance of 50 ohms is 18 dB. Substituting these values into equation (3):

total equivalent rms input noise = 6.1 X 10-8 X 101 8 / 20 = 0.5 pV rms

Occasionally the dc component is not required, so that the best noise performance can be achieved with the help of an input transformer. This is possible by taking advantage of th e property of a transforme r to multi ply the sou rce resistance by the square of the turns ratio and the voltage by the ratio. With a transformer inserted between the signal source and the amplifier input we can increase the effective source resistance to a val ue that reduces the noise figure to less than 0.05 dB. From Figure 111-1, the source resistance should be about 1 megohm. The transformer turns ratio, for this impedance increase, is VR2/R 1 = 140. Thermal source noise at the amplifier input is equal to the noise generated by the 50 ohm source multiplied by the turns ratio. With a noise figure near zero, the total equivalent rms input noise is also equal to the noise generated by the 50 ohm source multiplied by the turns ratio, = 70 pV rms. Although the numerical value of equivalent input noise is much larger than before, the signal-to-noise ratio is sub-stantially increased. This can be seen by considering all of the transformed source signal voltage as appearing at the amplifier input terminals, because the Model 113 input resistance is much larger than the 1 megohm presented by the transformer; the signal-to-noise ratio is equal to the maxi~um possible value: esig/E x antilog N F /20) .::= esig/E. In thiS example the transformer increases the signal-to-noise ratio by a factor of 8.

Princeton Applied Research Corporation manufactures transformers for use in low level, low frequency applica-

tions. Characteristics and details regarding the use of some of these transformers are discussed in Subsection 3.11. Because the transformers have so much influence in determining bandwidth, and because of the noise contrib-

111-2

uted by the transformers, the results obtained using a transformer hardly resemble the ideal theoretical results as predicted in the example. When ug a transformer, it is best to use noise figure contours and amplitude transfer curves obtained empirically for the individual transformer. Sub-section 3.11 contains such data for the transformers.

3.3 GROUNDING

The Model 113 is specifically designed to have a high degree of immunity to the effects of ground-loop currents. The signal ground side of the input connectors is connected to chassis ground through a 10 ohm resistor. To maintain ground-loop immunity, avoid shorting the input grounds to chassis ground at the ampl ifier end of the cables. To further reduce the effects of ground-loop currents, use an input cable that is short and has a high conductivity outer conductor. (For a discussion of the circuit design with respect to grounding considerations, see Section IV).

CAUTION: The power rating of the 10 ohm resistor is 'h watt. Avoid excessive ground-to-ground current to avoid burning out this resistor.

When the signal is applied to the input via a transformer, operate the ampl ifier single-ended. That is, place one input selector to the ground position, and connect the trans-former to the other input (ac couple); connect one transformer lead to the outer shell of the BNC connector and connect the other transformer lead to the center conductor of the connector. Connecting this way avoids the problem of static charge build-up at the inputs due to no ground return.

3.4 SIGNAL VOLTAGE AND GAIN

With the variable gain control in the calibrated position (ccw), the position of the gain selector accurately sets the gain to the indicated level. Intermediate levels of gain may be obtained by use of the uncalibrated variable gain control. If it is desired to accurately set an intermediate level of gain, apply an input signal to the amplifier input and, using an ac voltmeter, proportionally adjust the output signal level to a corresponding value between the levels of the two fixed gain settings bracketing the desired gain.

The maximum output that the amplifier can provide is 10 volts peak-to-peak (through 600 ohms into an open circuit). For maximum input Voltages, refer to the specifications and to Subsection 3.10.

3.5 DC ZERO ADJUSTMENT

The dc zero adjustment may need to be touched up as the gain is changed. In particular, if the adjustment is first made when operating at a low gain, followed later by transfer to high-gain operation, it is important that the dc zero be checked, and, if necessary, readjusted as required.

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.? -—O€

I I A

P

4

+

30.-------------,--------------,-------------,---------------

Recovery Time = time required for the output to settle to within 1 volt of steady state value.

25~--------------~--------------_r--------------~

Overload ~ sufficient input to saturate the output stage of the first amplifier.

20

-: (.)

Data taken with the input coupling switch in the dc position.

In the ac coupling position, a 0.1 J.lF capacitor in' series with a 100 megohm resistor is added (RC ~ 10 seconds).

ILl (/)

GAIN X 2K - X 10

Minimum Recovery Time is available when the input coupling is dc and the Low Frequency Rolloff switch set at dc.

ILl 15 ::f

t= >-a:: ILl > 8 ILl a:: 10

5

The OV L pushbutton provides immediate recovery in all modes.

Absolute Maximum I nput Voltage (differ· ential or common mode):

ac coupling ~ 115 V, 60 Hz dc coupling ~ ±20 V

.01 .03 0.1 0.3 1.0 LOW FREQUENCY ROLL-OFF SETTING (Hz)

Figure 111-2. TYPICAL RECOVERY TIME VS LOW FREQUENCY ROLLOFF

3.6 OVERLOAD FAST RECOVERY

If the input signal exceeds the level indicated in the specifications (Section I). the amplifier will saturate and remain disabled until coupling and filter capacitors dis· charge (see the recovery time data, Figure 111-2). Pressing the spring·loaded overload recovery toggle causes fast discharge of the capacitors so that normal operation can be resumed immediately.

3.7 LOW-PASS/HIGH-PASS FILTERS

Series low·pass and high·pass filters are incorporated to provide bandpass characteristics. Minimizing the bandwidth minimizes the source thermal noise. In addition, the filters can be used to eliminate unwanted signals (such as dc, high frequency, or 60 Hz pickup). The following figures are normalized amplitude and phase transfer characteristics.

If one or both Coupling switches are set to the AC Coupling position, the LF ROLLOFF switch should not be left in the DC p.osition. If it is left in the DC position, output voltage

111-3

offsets resulting from the input offset current (100 pA max) may occur. At high gains, the offset could exceed full scale.

3.8 SINGLE-ENDED/DIFFERENTIAL OPERATION

The amplifier may be operated differentially or single· ended. For single·ended operation, simply place the unused input coupling switch to the ground position, and place the signal·input switch to ac or de coupling as desired.

For differential operation, place both coupling switches in ac or dc positions or one in dc and the other in ac, as appropriate. The output voltage is equal to the gain times the difference of the voltages at the A and B inputs.

Remember that the two signal grounds (tied together internally) are connected to chassis ground through a 10 ohm resistor. For maximum ground-loop rejection, avoid shorting the signal ground to chassis ground.

I 1 ITo do zero adjustment, place both coupling switches inthe ground position, set the L.F. Rolloff switch to DC, +80 . -and set the gain switch to the position to be used. Then ~adjust the front-panel zero potentiometer for 0 V at the +10 i iii" '*°output. l ix |

+60 i V i i '30

3.9 DC ZERQ ADJUSTMENT l I

.. i 1/

l.O

O6F Eout

O

I O

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' (READ LEFT DEGREE SCALE) (READ RIGHT DEGREE SCALE)0,3 i_--'"|i1—---in tom. Pans: = ALGEBRAIC suu or HF a LF PHASE ANGLESlllllii _\-

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IIII::::-III

——II

l0.0

L.__i____________ ____.Figure Ill-3. LP FILTER NORMALIZED AMPLITUDE

"TRANSFER CURVE

i i Figure Ill-5. LP/HP FILTER NORMALIZED

PHASE TRANSFER CURVE

.._......... "-—-——_————-1--It T '—IIIIl—II_II§l!—II-IIIII I40 as . . ._ _-IIIII_---IIII|._---IIIII » ,_IIIIl:-I_IIIIlilI_IIIII_IIIIl——I_IIIIl—I§:!lIIlI00 l3OdB _

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S

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IIIIIIIII

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ll|l|IIIIl|l|iIII::'-all —‘ Figure Ill-6. TYPICAL COMMON MODEn|||IIIInuiIw.--nunIlll||IIIIIll||I'IIIl|l|| REJECTI ON CH ARACTE R ISTICSI-=iiIiIII===iIiIl—.‘-iiiiii:°~8 IIIIIIIIIIIIIIIIMIIIIIIun 'IIIInu||IIIIIln|rII-InnuIIIIIIIIIIIIIIIIIIIIIIll|||IIIIn|||IIIIIllnII-cumO 6 IIIIIIIIIIIIIIIIIIIIIIlln

i i II=::::::II=:'§::i--'E 9”’ IIIIIll||IIII,:|lE in Hp IIIIl||||IIIIAll

0,, IIIIIIIIIIIIIAIIIgggg 3.10 MAXIMUM INPUT SIGNAL CONSISTENT:::: WITH LINEAR OPERATIONnuIIIIiii! - - - -nu When speaking of the maximum input that can be applied,

a distinction must be made between common mode signal,::: that signal which is common to and identical at both the A"' and B inputs, and differential signal, that signal which exists'°° between the in ut th t ' th t' m ed t n 'n utT__' '- ps, ais,ais easur aoeip

U3“ with respect to the other. A perfect amplifier responds notat all to common mode signal, that is, if both the A and Binputs are driven by the same large signal, no trace of that

Figure |||_4_ HP HL-I-ER NQRMAUZED signal should appear at the output. The signal at the outputAMPLITUDE TRANSFER cunvE should result from the differential input signal only. Real

Ill-4

; l

3.9 DC ZERO ADJUSTMENT

To do zero adjustment, place both coupling switches in the ground position, set the L.F. Rolloff switch to DC, and set the gain switch to the position to be used. Then adj ust the front-panel zero potentiometer for 0 V at the output.

TOTAL GAIN

0.6

~ ~LP

0.4 f:=--

0.2

o 0.1

GAIN x jEout I x ~ E ,n L P [E;;;I HP

1.0 10.0

figure 111-3. LP FILTER NORMALIZED AMPLITUDE TRANSFER CURVE

0.8

0.6

I~ E in IHP 0.4

0.2

o .01 0.1 1.0

Figure 111-4. HP FILTER NORMALIZED AMPLITUDE TRANSFER CURVE

100

10.0

111-4

140 dB

130 dB

120 dB

IIOdB

IOOdS

90dB

80 dB

..i.." _f f LF3dB fHF3dB

(READ LEFT DEGREE SCALE) (READ RIGHT DEGREE SCALE)

TOTAL PHASE = 4LGEBRA'C StM CF HF 6 LF PHASE ANGLES

Figure 111-5. LP/HP FILTER NORMALIZED PHASE TRANSFER CURVE

......

'" " c- - -"\t-,. "\

r\.

~ .-r-- .. -

-

~ r\. I--- [1] " '-;- . '0 2 10 10' 2 10 FREQUENCY IN H l

Figure 111-6. TYPICAL COMMON MODE REJECTION CHARACTERISTICS

3.10 MAXIMUM INPUT SIGNAL CONSISTENT WITH LINEAR OPERATION

When speaking of the maximum input that can be applied, a distinction must be made between common mode signal, that signal which is common to and identical at both the A and B inputs, and differential signal, that signal which exists between the inputs, that is, that is measured at one input with respect to the other. A perfect amplifier responds not at all to common mode signal, that is, if both the A and B inputs are driven by the same large signal, no trace of that signal should appear at the output. The signal at the output should result from the differential input signal only. Real

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amplifiers, including the Model 113, do not exhibit com-plete immunity to common mode signals_ However, as

stated in the COMMON MODE REJECTION specification the immunity, though finite, is very great indeed. Thi~ immunity only holds for common mode signals of 1 V rms or less. With higher common mode signals, input circuits become non-linear and a very great degradation in common mode signal rejection occurs. This is the meaning of the Common Mode Maximum Input Signal specification.

To appreciate the meaning of the Differential Mode Maximum Input Signal specifications, it is necessary to distinguish between attenuated differential input signal and unattenuated differential signal. Attenuated input signals are those at a frequency wh ich is attenuated by either the High Pass Filter or the Low Pass Filter_ The frequencies affected by these filters depend on the setting of the corresponding Front-panel switches. Unattenuated signals are those at a frequency which is unaffected by the filters. The maximum output capability of the Model 113 is 10 V pk-pk. Clearly, for an unattenuated signal, the maximum differential input one can apply is 10IG V pk-pk, where G is the selected gain. At frequencies where the filters begin to have some effect, greater differential input signals can be applied. The further one moves into the region of filter influence, going either higher or lower in frequency, the larger the differential input signal can be. However, a limit is reached where any further increase in· input signal, regardless of frequency, will cause non-linear operation and performance degradation_ This limit, which is a function of the Gain switch setting, is given by the two Differential Mode Maximum input signal specifications. For gains of 10 to 100, the absolute maximum one can apply is 1 V pk-pk. For gains of 200 to 10,000, the absolute maximum differential signal one can apply is 100 mV pk-pk. It should be clear that if the frequency component of interest is not being maxima!ly attenuated by the High Pass or Low Pass Filter, the maximum input will be lower. Figure 111-7 illustrates these relationships.

c:

> oK ... I

LOW FREQ. ROLLOFF

LIMIT FOR UNATT£NUATED SIGNALS (GAIN' 100) AS

DETERMINED BYiG

~ 10mV~--------~~~~-L------------~

Figure 111-7_ MAXIMUM DIFFERENTIAL INPUT TO MODEL 113

111-5

3.11 BATTERY OPERATION TEST AND CHARGI NG' ,

The Model 113 has rechargeable batteries good for up to 30 hours of operation when fully charged. I f they are not fully charged, or if the Model 113 is driving a load having an impedance of less than 10 kS1, a shorter operating period will result. To operate from battery power, set the Power switch to ON, but do not plug in the line cord. When the period of battery powered operation is completed, be sure to set the switch to OF F to prevent running down the batteries.

To check the batteries, push the spring-loaded test switch to the left and to the right. If the green indicator lights, the corresponding battery is charged. If it remains out, the batteries need charging. Battery charging takes place when-ever the Power switch is set to OF F with the I ine cord plugged in. Beginning from the fully discharged state, it takes anywhere from 24 to 36 hours to fully recharge the batteries. I n general, one should follow each period of battery operation with a charging period of equal or greater duration.

NOTE: When the power switch is set to ON with the line cord plugged in, the batteries "trickle charge" at a rate very much lower thal1 that obtained with the switch set to OFF. For this reason, it is better to charge with the switch set to OFF.

The batteries used in the Model 113, should they require replacement, can be ordered from Princeton Applied Research Corporation. The part number is 4000-0016-04 Specification #710311 A. '

When the batteries are being recharged (instrument plugged in but with Power switch in OFF position), there is no time limit, that is, there is no possibility of overcharge with subsequent battery damage due to the charging being maintained for to

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Princeton Applied Research EG G AM 1 Manual 201985173552...EG&G PRINCETON APPLIED RESEARCH P. O. Box 2565 Princeton, NJ 08540 Phone: 609/452·2111 TELEX: 84 3409 WARRANTY EG&G PRINCETON