HP-150-1500-Manual-Low-Level-Preamp-Chopper 电路图.pdf

LOW LEVEL PREAMPLIFIER MODELS 150-1500, 150-1500A iM-150-1500-1 INSTRUCTION MANUAL HEWLETT _ PACKARD Cb SANBORN DIVISION RadioFans.CN 收音机爱 好者资料库 INSTRUCTION MANUAL TABLE OF CONTENTS Paragraph Page 1 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2 Tabulation of Characteristics . . . . . . . . . . . . . . 1 3 Front Panel Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4 Operation: Basic Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5 Connecting the Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 Checking for Stray Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 8 Standardizing (Model 150-1500) . . . . . . . . 5 9 Voltage Recording without Zero Suppression . . . . . . . . . . . . . . . . . . . 5 10 Current Recording without Zero Suppression . . . . . . . . . . . . . . . . . . . . 5 11 Voltage Recording with Zero Suppression (Model 150-1500) . . . 6 12 Current Recording with Zero Suppression (Model 150-1500) . 6 13 Operation as a Null Indicator (Model 150-1500) -. . . . . . 7 14 Reducing Stray Potentials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 15 Checking the Damping Control Adjustment . . . . . 8 16 Adjusting the Hum Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 17 Removing and Replacing Preamplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 18 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 19 Functional Description of Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 The name SANBORN is registered in the U.S. Patent Office. RadioFans.CN 收音机爱 好者资料库 HP Archive This vintage Hewlett Packard document was preserved and distributed by Please visit us on the web ! Prepared by on-line curator: Tony Gerbic For FREE Distribution Only * RadioFans.CN 收音机爱 好者资料库 SANBORN LOW LEVEL PREAMPLIFIER MODELS 150-1500, 150-1500A INSTRUCTION MANUAL SANBORN LOW LEVEL PREAMPLIFIER Mode Is 150- 1500 and 150-1500A 1. FUNCTIONAL DESCRIPTION The Sanborn Low Level Preamplifier is a chopper type of amplifier for measuring slowly varying direcr voltages, or measuring slowly varying curreocs by adding an exrernal shunt resistor. These signals may be read in circuits removed from ground by as much as 300 volts DC. Model 150-1500 includes a ZERO SUPPRESSION circuit, which is omitted in Model 150-1500A. This manual applies to the Preamplifier which uses an improved chopper circuit, identified by the HUM control on the Croor panel, starring wich serial no. 200. 110 100 z 90 0 ;: u 80 u. w 0 70 j 60 g so z 0 CL VI 40 30 a: w CL 20 10 0 0.5 -r- r-I-. t-, r-. / I I y I I I INPlT SIGNAi I I I O m.tt< I . 2 10 20 so 100 FREQUENCY IN CYCLES PER SECOND Figure 1. Combined Response Choracteristics of Sanborn Low Level Preamplifier, Driver Amplifier, ancl Galvanometer. 2. TABULATION OF CHARACTERISTICS SENSITIVITY FREQUENCY RANGE RISE TIME 100 microvolts per centimeter co 0.1 volt per centimeter, in ten steps with panel-mounted ATTENUATOR. With external 100 ohm resiscor, measures LO microampere per centimeter co 1.0 milli- ampere per cenrimecer. Three decibels down ac 15 cycles. See fig. 1. 0.03 seconds. Defined as rime required to reach final deflection, as measured by besc straight line approximation to che initial rise of the response co unit step input. See fig. 1. INSTRUCTION MANUAL 2. TABULATION OF CHARACTERISTICS (Cont.) INPUT IMPEDANCE SOURCE IMPEDANCE DRIFT OVERLOAD ATTENUATOR ERROR CALIBRATION ZERO SUPPRE5.510N RIPPLE 3. FRONT PANEL CONTROLS POSITION SENSITIVITY HUM CAL 200 MICROVOLT INPUT STANDARD SUPPRESSION RANGE ZERO SUPPRESSION 5300 ohms with Model 150-1500, 4400 ohms with Model 150- l500A. Input looks into transformer primary, incermittemly shorted 120 times per second by chopper. (Input is insulated from chassis ; may be grounded externally as required). Up to 500 ohms, looking back into s ignal circuit. 0.1 mm/br. plus 1.0 microvolt/ hr., after 30 minutes warmup. Will tolerate accidental momentary overload up co 5 voles (10 times maximum raced signal). Higher voltages may damage the chopper. Mose probable error: 13 Maximum possible error: 23 lncernal, 200 microvolts. Accuracy: !43 (Model 150-1500), il.03 (Model 150-1500A) (Model 150-1500 only)IOO mv.and 10 mv. ranges, concrollcd by 1000 division dial. 100 mv. range is accurate to 1.0 mv., and the 10 mv. range is accurate to 0.05 mv. Approximately 13 of the signal, at twice line frequency. This locking control provides for adjustment of the stylus position. Clockwise rotation moves the stylus up-scale. This locking control adjusts the gain of the Preamplifier, to permit calibration. This screwdriver adjustment, available through an access hole in the panel, is used to adjust the recording for minimum line- frequency component on the recording. This buccon applies a 200 microvolt calibration signal to the Preamplifier input circuit. This connector is used to connect the signal to the Preamplifier. This locking control (Model 150-1500 only) provides an accurate pre-operational adjustment of the zero suppression volcage. This switch (Model 150-1500 only) selects either standard operation, wichouc zero suppression, or operation with zero sup- pression up co cbe full-scale suppression limits marked on the panel. This ten-turn precision control, with a dial which reads from zero to 1000, (Model 150-1500) is use<l co suppress DC voltages up to 100 millivolts . 2 SANBORN LOW LEVEL PREAMPLIFIER MODELS 150- 1500, 150-1500A 3 3. FRONT PANEL CONTROLS (Cont.) OUT / IN ATTENUATOR This swicch (MoJel 150-1500) makes the :cero suppression facilities available or nor, as required. This mulci-posicion :.wirch accenuaces the inpuc signal by any one of chc faccors marked on che panel. 4. OPERATION: BASIC PROCEDURES There is a sequence of five basic procedures co follow when curoing on the Sanborn Low Level Preamplifier and making a recording: CONNECTING CHECKING FOR STRAY POTENTIALS CALIBlA TION STANDARDIZING OPEHATION 5. CONNECTING THE SIGNAL This includes che warmup perioJ, and connecting rhe inpur s ignal(para- graph 5.) This helps avoid measurement errors when recording at high sensitivicy (paragraph 6.) This uses an accurace incernal circuit (paragraph 7.) Required in Model 150-1500 only, for maximum zero suppression accuracy (paragraph 8.) Five cypes of operation are available (paragraphs 9 through l3). Apply power and allow 30 minutes warmup for maximum stability. Connect the s ignal to the INPUT socket on che panel, or to the conneccor 204 or )304 at chc Driver Amplifier rear, as shown in figure 2. J204 or J304 Figure 2. Input Connections to Low Level Preamplifier. INSTRUCTION MANUAL 5. CONNECTING THE SIGNAL (Cont.) A positive pocenrial at terminal A with respect co terminal B (or of pin 1 with respect to pin 3) gives an up-scale deflection of the stylus. hen measuring current, shunt the input terminals with a wire wound resistance of a material which has a low thermal potential with respect to copper, such as manganin. A value of 100 ohms gives a rated sensitivity of 1.0 microampere per centimeter. Values up co 500 ohms may be used for greater sensitivity, depending on the individual circuit. If ZERO SUPPRESSION is co be used, leave the ZERO SUPPRESSION OUT / IN switch at IN during warm up. 6. CHECKING FOR STRAY POTENTIALS When measuring exccemely low voltages or currents, stray potentials in the external circuit may prevent full use of the Preamplifiers abilities. These potentials appear on the record as a signal which may be difficult co distinguish from the value being measured, and can cause a baseline shift when the ATTENUATOR is turned. To check for stray potentials, proceed as follows: 1. Short terminals A and n, sec the ZERO SUPPRESSION OUT/ IN switch to OUT, advance the ATTENUATOR co XI , press the CAL button intermittently, and adjust the SENSITIVITY control for two centimeters of stylus deflection. 2. Connect the external circuit and set the signal to zero. Wait until the entire external circuit is at thermal equilibrium with its surroundings. The temperature of the circuit and its physical layout should be rhe same as for the intended measurements, with all possible sources of AC coupling or heat (transformers, soldering irons, etc.), kept at a distance during these checks and .luring the measurements. 3. Turn the ATTENUATOR from OFF co XI and back again. If the resulting stylus deflection is negligible over the range of ATT ENUATOH steps needed for the measurements, stray potentials may be ignored. 4. If the stylus deflection is too large to be ignored, see paragraph 14 for suggestions on eliminating some of the causes. 5. To check the Preamplifier itself for stray potentials, short the INPUT terminals and repeat the preceding test. The stylus deflection will be approximately Yimillimeter or less between the OFF and the XI positions of the ATTENUATOR. 7. CALIBRATION Calibrate the P reamplifier with the external circuit connected and the signal at zero, or with the external circuit replaced by the impedance it presents to the Preamplifier. The source impedance equally attenuates both the calibration voltage and the open circuit signal voltage. The recording is tl1erefore in terms of the equivalent open circuit signal voltage. 1. With the external circuit (or representative impedance) connected, set the ZERO SUPPRESSION OUT/ IN switch (Model 150-I500 only) co OUT. SeL the ATTENUATOR to OFF and adjust che POSITION control for a convenienc baseline. 2. Advance the ATTENUATOR ro XI and intermittently press the CAL button. Adjust the SENSI- TIVITY control for two centimecers of stylus deflection as the button is pressed. Return the ATTENUATOR ot OFF. 4 SANBORN LOW LEVEL PREAMPLIFIER MODELS 150-1500, 150-1500A 5 7. CALIBRATION (Cont.) 3. For voltage measurements, the instrument is now calibrated co a basic sensitivity of 100 microvolts per centimeter at X 1, 200 microvolts per cemimecer at X2, 500 microvolts per centimeter at XS, ecc. The recording is in terms of the equivalent open circuit signal voltage of cbe source. 4. For current measurements (with LOO ohm external resistance), the instrumenc is now calibrated to a baic sensitivity of LO microamperc per centimeter ac Xl, 2.0 microamperes per centimeter at X2, 5.0 microamperes per centimeter at X5, ecc. The recording is in terms of the voltage drop across the external resistor alone. 8. STANDARDIZING (Model 150-1500 only) Standardization insures an accurate zero suppression voltage, and is not required when recording without zero suppression. I. Set the ATTENUATOR co OFF and the ZERO SUPPRESSION OUT /IN switch co IN. Allow 30 minutes warmup for the zero suppression cells to polarize, if this has not already been done. 2. Remove the connector from the INPUT socket or the connector at the Driver Amplifier rear, set the SUPPRESSION RANGE swicch to STD, and cum the ZERO SUP PRE ION control to zero. 3. Set the stylus to mid-scale wich the POSITION concrol. 4. Sec the ATTENUATOll co STD and return che stylus to midscale with the STANDARD control. S. Re-connect 1he signal. 9. VOLTAGE RECORDING WITHOUT ZERO SUPPRESSION Check the pre-operational seeps (see paragraph 4) and set che ZERO SUPPRESSION OUT/ IN switch co OUT. Ignore che controls (present on Model 150-1500 only) marked ZERO SUPPRESSION, SUP- PRESSION RANGE, and STANDARD. To record, advance the ATTENUATOR for a convenient scylus deflection. Read the equivalent open circuit signal voltage from the record at 100 microvolts per centimeter of stylus deflection when chc ATTENUATOR is at XI, 200 microvolts per cencimeter when che ATTENUATOR is at X2, 500 microvolts per centimeter when the ATTENUATOR is at X5, etc., or by using the formula: microvolts -(100) X (ATTENUATOR setting) X (centimeters of deflection) 10. CURRENT RECORDING WITHOUT ZERO SUPPRESSION 01eck the pre-operation steps (paragraph 4), and set the ZERO SUPPRESSION OUT / IN switch to OUT. Ignore the controls (present on Model 150-1500 only) marked ZERO SUPPRESSION, SUPPRESSION RANGE, and STANDARD. Be sure chat che external resistor is of a material having a low thermal potential with respect to copper, such as manetanin. Read the current through the external (100 ohm) resistor directly from che record at one microampere per centimeter of stylus Jefleccion when the ATTENuATOR is at Xl, two microamperes per cencimeter when che ATTENUATOR is at X2, five microamperes per cencimecer when the ATTENUATOR IS at XS, ecc., or by using the formula: microampeces 0 (ATTENUATOH setting) X (centimeters deflection) INSTRUCTION MANUAL 11. VOLT AGE RECORDING WITH ZERO SUPPRESSION (Model 150-1500 only) L After calibration and standardizing, set the SUPPRESSION RANGE control for che range and direction of suppression. Sec the ZERO SUPPRESSlON OUT / IN switch co IN. Remember that a positive signal at terminal A with respect to terminal B results in an up-scale deflection. SUPPRESSION RANGJ: +100 mv. +IO mv. -10 mv. -100 mv. omi:CTION OF SUPPRESSION down -scale down-scale up-scale up-scale SENSITIVITY OF ZERO SUPPRESSION CONTROL 100 microvolts/ division 10 microvolts/ divis ion 10 microvolts/ division 100 microvolts/ division 2. There are cwoways to use the ZERO SUPPRESSION control: a. Sec the ZERO SUPPRESSION control co the voltage to be suppressed, advance the ATTEN- UATOR for a convenient deflection, and s tare recording. b. Alternate method: Advance the ZERO SUPPRESSION control and the ATTENUATOR together and start recording when there is a convenient deflection (When the RANGE switch is at 100 mv., ATTENUATOR sectings lower than XlO are not recommended; these settings are too critical with no improvement in accuracy). 3. When interpreting the final recording, voltage is foun<l as the algebraic sum of two components (assuming calibration at 100 microvolts / cm.): a. The component actually shown on the record,from the formula microvolts (100) X (ATTENUATOR setting) X (centimeters of deflection) b. The component from the ZERO SUPPRESS/ON control at either 10 or 100 microvolts per dial