My measurement devices


3. V,A meters

digital devices


Dual slope integration: (Control unit, counter, integrator, source of Vref).
- Input: Vin. Linear growth by integration Vo → Vx for digital counted fixed time t1.
- Input: switch Vin → Vref.
- Input: Vref. Linear fall by integration down Vx → Vo for time t2, measured by counting.   Vin = Vref * t2 / t1.

Nice design:  Soar ME-550.
Another beauties: chocolate,   pudding.
How it works:
Measurements of resistance, capacitance, frequency, current, voltage and rectification, auto power off in KT9901, KT9902 multimeters.
Some simple digital multimeters and their solutions for decimal point displaying.

Voltcraft VC920
Bought: May 2013 at Voelkner.

Voltcraft VC 920 calibrated
9V(block), 8mA. For measuring voltage, current both DC/AC, resistance, capacity, frequency till 400 MHz, temperature.
Works with 2 switchable accuracies. At 4V measuring range the better accuracy is ± 0.08 % + 10 dgt.
The accuracy is hold for temperature 23°C±5°C and rel. humidity less then 75%.
What does it mean, if I measure an 1.5 AA battery element and read from display 1.4074 V ?

0.08% from 1.4074 is aproximatelly 0.00113. The measured value is therefore between 1.40627 and 1.40853 V.
Last 10 digits place the displayd value from 1.4064 V till 1.4084 V.

If we take in account both, then the measured value is 1.407 V ± 0.002 V.
For orientation by the next measured values, if we take 1407 mV as reference value, then ±1 % is ±0.014 - from 1.393 V to 1.421 V.

At each of the following devices the displayed value after measuring the same element is written.
In most cases the displayed values are not far from the value 1.407 V measured with the VC 920.

Voltcraft VC140
9V(block). Lowcost multimeter.
Measured element: 1.397 V (-0.010).

Norma Normameter MP12
9V(block), < 1mA. Norma MCC1 or MCC2(ADC,...), NEC D7514G(CPU with dsp,kbd interf.), AD636JH(RMS→DC), TLC271, 93C46PC(EEPROM).
Probably same as Siemens B1021.
Measured element: 1.407 V (+0.000).

Norma Normameter MP13
9V(block), < 1mA. Norma custom IC MCC2(ADC,...), NEC D7514G(CPU with dsp,kbd interf.), AD636JH(RMS→DC), TLC372CP(comp), 93C46PC(EEPROM), 2*271C(OA), HEF4104(volt.transl.).
Probably same as Siemens B1022.
Measured element: 1.408 V (+0.001).

Norma Normameter MP14
9V(block), < 1mA. custom IC Norma MCC2(ADC,...), NEC D7514G(CPU with dsp,kbd interf.), AD636JH(RMS→DC), TLC372CP(comp), 93C46PC(EEPROM), 2*271C(OA), HEF4104(volt.transl.).
Probably same as Siemens B1023.
Measured element: 1.433 V (+0.026).

Norma Normameter MP11
9V(block), custom IC Norma MCC1 or MCC2(ADC,...), NEC D7514G(CPU with dsp,kbd interf.), 93C46PC(EEPROM), 2*271C(OA).
Probably same as Siemens B1020.

Siemens B1022
9V(block), 1mA. Custom IC Norma MCC1, NEC D7514G.

Probably same as Norma MP13 or Norma MP14.

7KB 9102-8CA: Surface-plunger-feeler up to 600°C.
Measured element: 1.406 V (-0.001).

BY 1933A
9V(block). For measuring V, mA DC/AC, 10A, Ohm, diode test, transistor test.
Measured element: 1.409 V (+0.002).

Peertronic ADM-10B
3V(2*AA). Measures V, mA DC/AC, 10A, Ohm, diode test.
Measured element: 1.417 V (+0.010).

9V(block), 1.5V button for clock.
V, mA DC/AC, 20A, Ω, Capacitance, diode test. IC: ICL7106
. Measured element: 1.402 V (-0.005).

Monacor DMT-4500
9V(block), 1.1 mA.
IC: CIC806E(ICL7126), 3 x LM358, JRC062D, 2 x 4030 (4 x excl.OR).
Made in Taiwan 1987.
Measured element: 1.395 V (-0.012).

9V(block), 0.4mA. IC: ICL7136. Made in Taiwan.
Measured element: 1.388 V (-0.019).

9V(block), 0.2mA. IC: ICL7136.
Measured element: 1.436 V (+0.029).

Keithley 130
9V(block). V, mA DC/AC, 10A, Ω, input imp. 10 Mω.
Measured element: 1.407 V (+0.000).

Keithley 136
9V(block), 6mA. V, mA DC/AC, 10A, Ω, input resistance on 200 mV and 2V > 1000 MΩ, else 10 MΩ.
Measured element: 1.408 V (+0.001).

Fluke 21
9V(block), 0.3mA. Made in USA.
Measured element: 1.407 V (+0.000).

Beckman Circuitmate DM25
9V(block), 3.5mA.
IC: 7106,
LM358 (Dual opAmp), 4070(Quad Exclusive-OR Gate),...
Beckman Industrial Corporation.
A Subsidiary of Emerson Electric Co. Brea, CA, 92621, Made in Taiwan. Prod.year ~1983.
Measured element: 1.405 V (-0.002).

Beckman Industrial DM25 XL
9V(block), 0.2mA.
IC: 7106,
4*TL062(low power dual J-FET OA), 4521(24-stage frequency divider and oscillator),...
Beckman Industrial Corporation.
An Affiliate of Emerson Electric Co. Instrumentation Products Division San Diego, California.
Made in Taiwan.
Measured element: 1.409 V (+0.002).

Beckman Circuitmate DM25L
9V(block), 2.2mA.
AD IC: 7106. Basic DC accuracy: 0.8%.
Beckman Industrial Corporation.
Made in Taiwan. Prod.year 1985.
Measured element: 1.406 V (-0.001).

Soar ME-550
3V(2*AA), 1 mA. IC:M5230. No manual range setting.
Measured element: 1.413 V (+0.006).

Soar 3430
9V(block), 7mA. Plug for external power supply.
Measured element: 1.411 V (+0.004).

Soar 3255
3V(2*AAA), 1 mA. IC: M6306.
Same or similar as Yokogawa 7534-03 and Hewlett Packard E2378A.
Measured element: 1.407 V (-0.000).

Soar 4055
3V(2*AAA), <1 mA. IC: M6266.
Measured element: 1.406 V (-0.001).

Soar 3520
3V(2*AA), <1 mA, IC: M5230. Smaller device, no manual range setting.
Measured element: 1.408 V (+0.001).

Soar 4030B
3V(2*AAA), 0.5 mA, DC V accuracy 0.3% + 1d. After 1 hour auto power off. Booklet printed in 1989.
Measured element: 1.407 V (-0.000).

ISHII DM 3350 Instrument Works Ltd, Yamanashi.
3V(2*AA), 1mA.
Measured element: 1.396 V (-0.011).

ISHII DM 4351 Instrument Works Ltd, Yamanashi.
3V(2*AA), 1mA, same device is Hioki 3216.
Measured element: 1.409 V (+0.002).

Hioki 3216
3V(2*AA), 1mA, same device is Ishii Instrument Works DM 4351.
Measured element: 1.407 V (+0.000).

Hioki 3230
9V(block), 3mA. Prod.year 1985.
Measured element: 1.405 V (-0.002).

Hioki 3231
3V(2*AA), 1mA. Prod.year 1988.
Measured element: 1.415 V (+0.008).

Sinometer DT9907C
9V(block), 6mA.
Measured element: 1.418 V (+0.011).

Metex M-4650CR
9V(block), 5mA.
Measured element: 1.409 V (+0.002).

Metex M80
9V(block), 2mA. IC: 7149.
Measured element: 1.405 V (-0.002).

Chauvin & Arnoux C.A 5220 G
3V(2*AA). V-A-Ω-Hz-n/µF multimeter, input impedance 10MΩ or 270kΩ,
frequency only till 200kHz, capacitance 1pF-40µF, 3V-2*AA.
Measured element: 1.408 V (+0.001).

Metrix MX 44
9V, cca 1mA. V-A-Ω, capacity multimeter. DC V accuracy 0.3% + 1d. Auto power off after cca 30 min.
Measured element: 1.407 V (+0.000).

Hewlett Packard E2378A    sent to Metama UG.(DE)
3V(2*AAA), 1 mA. IC: M6306. The same, but not rugged case E2377A.
Same or similar Yokogawa 7534-03 and Soar 3255.
Measured element: 1.406 V (-0.001).

Beha 93-3000
9V(block), 1 mA. IC: TC818ACBQ.
Current range and voltage dividers resistors accuracy: 0.25%.
Measured element: 1.406 V (-0.001).

Dwi 07977
9V(block), 5mA.
IC: 7106, 2*opamp 2904D, 2*JFETopamp 062D and 2 other ICs.
Measured element: 1.404 V (-0.003).

9V(block), 2mA. Digital-analog, input imp. 10 MΩ, V,A-DC/AC, Ω, nF,µF.
Battery test: 1.5V with 15Ω ca 100mA; 9V with 900Ω ca 10mA.
KTI - Founded in 1996, Ketai Instrument (Kunshan) Co., Ltd. in China.
Measured element: 1.409 V (+0.002).

DM620 multimeter - data logger
Produced by: SMTech, Korea.
3.7V(Li-ion 1400 mAh), 30mA. Loading current: 100mA. Basic accuracy: 0.05%
Mini USB, loading from 5V source or from PC-USB. PC-soft for controlling and data transfer.
IC's: D78FQ546, FS9704B-GC.
Measured element: 1.407 V (+0.000).

DMT 7000 Monacor ?
9V(block), <3 mA.
IC: CIC5136,      3*14070: quad XOR,   4*LM358: 2 of them only for Capacity meas.
741: with 1 LM358 only for 200Ω scope - zero adjust,
TC4528: dual monost.multivibrator + 4011: quad NAND - both only for frequency measurement.
Measured element: 1.423 V (+0.016), setting the trimmer 1.407 V (+0.000)

After adjusting the trimmer (at the picture in red circle) also at the 20V scope the accuracy was 1%. At 200mA current, resistance and capacitance scopes the accuracy was about 1%. For capacitance there is also a trimmer (at the picture in green circle). For both frequency scopes there are 2 trimmers (at the picture in blue circle). These scopes were not tested. Also the AC scopes were not tested.

In this device there is a 741 for zero adjusting on the 200Ω scale. (Also in KT9901 and KT9902). But here is a half of LM358 placed before 741. By all these OAs is the "-" input directly connected to output. (voltage followers). This LM358, where the second half of the OA is umused was defect. Also by KT9901 and KT9902 the 741 was defect. My suspicion is, that this directly connected "-" to output caused these defects.

KT 8801 Two color mutations.
Made in Taiwan 1989.   9V(block), 2mA.
IC: CIC5106,
4011:quad NAND, 4*14070:quad XOR, 14528: dual monost.multivibrator, JRC 062D, 3*LM358.

Measured element: 1.415 V (+0.008).

9V(block), 7mA. IC: UM7106
Made in Taiwan 1992.
Measured element: 1.422 V (+0.015).

How it works

KT 9901

9V(block), 5mA. U, I, R with continuity check, C, diode, tr.hfe, auto power off.
Made in Taiwan 1993.   Measured element: 1.409 V (+0.002).

IC: UM7106R (R: 7106 with left-right reversed !),
uA741: setting "0" at 200 Ω range,
1/2 062D as comparator for beeper, 1/2 062D AC to DC converter for U, I, C measurements,
2*LM358 for measuring C,
MC14060 for auto power off.
The accuracy of divider resistors is 0.5% (green strip).

KT 9902

9V(block), 5mA, U, I, R with continuity check, frequency until 2 MHz, temperature, diode, tr.hfe, auto power off.
Made in Taiwan 1992.   Measured element: 1.411 V (+0.004).

IC: UM7106R (R: 7106 with left-right reversed !),
uA741 setting "0" at 200 Ω range,
1/2 062D as comparator for beeper, 1/2 062D AC to DC converter for U, I, C measurements,
7555 - CMOS timer 555 with improved performance as frequency to voltage converter,
TC4049 - inverting hex buffer/converter as input signal amplifier for frequency measurement,
HEF4518 - dual BCD counter as divider by 10 and 100 for frequency measurement,
MC14060 for auto power off.

83X multimeters based on IC 7106

Small, simple, cheap, but usefull. Exists in many similar variants produced by several manufacturers from eighties till now also under different names.

DT-830B and DT-832
9V(block), 0.7 mA resp. 1.8 mA, input imp. 10 MΩ, V,A-DC, V-AC only 200 and 750V, Ω, trans.hFE.
Accuracy at V DC: ±0.5 %, ± 2 digits.
DT-832 has also continuity test buzzer and 50Hz square output.
Measured element DT-832: 1.402 V (-0.005).

Main divider at DT-832: 0.01(10A), 0.99, 9 and 100, 900, 9k, 90k, 358k+542k = 900k.

Accuracy: color strip or letter(used in circuit diagrams)
0.1 %0.25 %0.5 %1 %2 %5 %10 %20 %
purplebluegreenbrownredgoldsilverno strip
... ....

DT-830B: all divider resistors 0.25%, last two resistors 342+547=989k.
DT-832: all divider resistors with 0.25% accuracy, but last two resistors 0.5%.

Decimal points at DT-830B model:
I don't see any transistors, which should be used to invert the BP signal for showing the decimal point.
It works with an RC member M62;20n, which integrates the BP square signal. The scope traces are against COM.

Decimal points and HV displaying for 1000V DC and 750V AC at DT-832 model:
Battery V+ or ca 2.7V DC against COM for DP20, DP200 dec. points and HV indication.
It's the simplest way for displaying decimal points.

Another 830B concept:
Accuracy: Range setting resistors in this device have 0.5% accuracy.
Decimal points with phase inverting NPN transistors S9014.
Blue track - BP against COM, yellow track - collector of DP200 phase inverting transistor.
1. decimal point displayed (reversed phase),
2. decimal point not displayed (in phase).

9V(block), IC: 7106 ?, HD4011BP, HD14070BP, JRC 062D.
Divider resistors accuracy: green strip 0.5%.
Measured element: no valid, parts of PCB burned out.

9V(block), 3 mA, IC: 7106 ?, 2 x LM324.
Divider resistors accuracy: brown strip 1%.
Measured element: 1.429 V (+0.022).

Wavetek DM78     seems to be same as Beckman Circuitmate DM78.
2 x 1,5V LR44 button.
Measurig only voltage DC/AC, ohms with buzzer and diode. Hard to open for battery change.
Measured element: 1.407 V (+0.0).

process calibrators - meters

Burster 4409, Escort 2030, Keysight U1401B, Gossen Metrahit 28C

Burster 4409 process calibrator
9V(block), 4mA for M,
M/S: 12V external(8*1.5) or adapter.
M 70mA, M/S 85mA.
Measured element: 1.408 V (+0.001).

Seem same: Extech CMM-15, Escort 2000.

Output works only with the 12V external supply. The 9V battery is needed also if the 12V external power supply is connected.

Constant Voltage Output:
-1.5V till +1.5V, -15V till +15V, max.25mA (min.40 Ω at 1V).  0.03%+3dig.  Resolution: 0.1mV.
Constant Current Output:
Range: 0 till ±25mA, max. 12V (max.12 kΩ at 1mA).  0.03%+5 dig.  Resolution: 1µA. Maximum input voltage: 30 V.
Square Wave Generator Output:
frequency: 0.5 till 4800 kHz in 28 steps, puls width: 256 values in ms (1/256*frequency),
amplitude: 4 values +5V, ±5V, +15V, ±15V, duty cycle: 256 values 0.39% to 99.6%.

Scan Output: click opens in a new window

Offers 16 steps where each step can be programmed for 1.Amplitude and   2.Time interval 0...99s.
The programmed step values can be CONTinuous repeated, or in one CYCLE,
or only one STEP a time manualy by pushing the output button.

Ramp Output: click opens in a new window Offers start-end and end-start ramp.
Setting: 1.Amplitude    2.Resolution steps 0-999 with 0.33s duration of each step.
The start and end amplitude and resolution steps are adjustable for both ramps separately. We can run CONT or CYCLE.
For output there is a special yellow cable with a diod inside.
MAX133CQH: click opens in a new window
DMM IC is used as 3¾ AD converter. It has 4 bit multiplexed address/data bus (ADD-AD3.)
It performs autoranging with help of external resistors. These SMD resistors are on the PCB beneath of the MAX133CQH.
On the pin 18 there is a 10MΩ input resistor realised as 5 pieces of 200kΩ serial conected resistors and
1.1MΩ, 101kΩ, 10kΩ and 1kΩ resistors on the pins 19-22.
On the PCB we can also see 3 pairs of 8050 transistors with shortened BCs where BEs are used as antiparallel connected paired diods.
There are also a lot of TL062 opamps and some Sharp PC817 optocouplers.

Escort 2030 Process Calibrator/Meter.
8 NiMH AA size acc, 14V ext.power jack.
switch: M: 40mA,  M/S: 150mA,  accu charge: 600mA.
Measured element: 1.407 V (+0.000).
Probably same devices are
Extech CMM-17, Agilent U1401A(B), Keysight U1401A(B).

Usage and parameters of both devices Burster 4409 and Escort 2030 are similar, Escort 2030 has more options settable at startup.
The construction is also similar.
Escort uses 8 AA accumulators with a possibility to load them inside the device, or external power supply.

Both devices have a special problem (feature ?).
Measuring 0 till approx. 4.5V using Volt autorange is only possible with manual setting to the range nn.nnn.
On the n.nnnn range for instance measuring 1.5 V gives Burster a bad value and Escort no value.
This problem was solved with calibration of the specified range.

Keysight U1401B Multi-Function Calibrator/Meter.
8 NiMH AA size acc, 24V ext.power jack.
switch: M: 80mA,  M/S: 170mA,  accu charge: ?
Measured element: 1.406 V (-0.001).
Probably same devices are
Escort 2030, Extech CMM-17, Agilent U1401A(B).

All other functions - scan and ramp setting and operation are same as for the devices above. (Escort 2030 and Burster 4409).

In all these calibrators there is a yellow cable with a power diode inside for sourcing circuits with power supply.

Keysight U5481B IR serial to USB cable.
With downloaded software for transfering and displaying data and control in both directions. It works for some other Agilent / Keysight devices and also for similar devices (Escort 2030) with same IR connectivity.

I have also made some own software for controlling the U5481, can also write into DMM EEPROM and run it in SCAN or RAMP mode from Win PC or Rapberry Pi.

Gossen Metrawatt Metrahit 28C   Sent to J thru Hamburg to 7hk_xdia0rd9.
Dimensions 84 mm x 195 mm x 35 mm Weight approx. 420 gr. with batteries.
3 x 1.5V AA or external 4.2V-5V/500mA-600mA (switches batteries off).
Measured element: 1.407 V (+0.000).

1 main and 2 auxilary digital displays.
The "-" holes of DMM and CAL are internaly connected.
Memory for aprox. 3000 values, but read out only using a PC.
Info menu shows battery voltage, data memory occupation, current time and other infos.

Working in output mode as simulator / calibrator:
Voltage output: 0...300 mV, 0...3 V, 0...10 V and 0...15 V. The resistance of the load circuit should be > 1kΩ.
Current output works as I source or I sink.
Resistance can be simulated by means of 2 or 4-wire connection within the following ranges: 2-wire: 5...2000Ω, 4-wire: 0...2000Ω.
Zero balancing at the U: 300mV, 3V DC, R: 300Ω, 3kΩ, by pressing the ESC|FUNC and MAN|AUTO keys simultaneously.
Output square: 0...15V and max. 1kHz into resistance > 1kΩ.

Interval sequence: click opens in a new window All simulator functions except for Hz can be adjusted as output quantities.

The number of steps can be set within a range of 1...99,9.
The interval duration per step t1 can be selected from within a range of 1 second to 60 minutes.
The sequences can be run manually or automatically.
Step jumps can be selected manually (Auto = no) with the up/down keys, or automatically (Auto = yes) with time per step.

Ramp: click opens in a new window Output: U, I sink, I source, R, temp.

A lower Start and an upper End range limit can be selected for each output quantity.
Rise time t1, decay time t3 and dwell time t2 at the upper and lower range limits are adjustable from 0 seconds...60 minutes.

Ramp parameters example: Output quantity: U (0...15 V range)
Start = 2 V, End = 10 V, t1 = 5 s, t2 = 8 s, t3 = 5 s, repeat = Yes (yes for periodic ramp).

No external voltage may be put on the output except in resistance simulation mode and current sink mode - maximal 27V.
In dual mode the input and output must be electrically isolated except of case, where voltage output holes and voltage measuring are directly connected.
Only absolute values and timestamps can be stored. Memory content can be read out only using a PC. Max. output current at square wave is 18mA.

Haven Minical MK2
6V 3.2Ah lead-acid Battery, cca 350mA, loaded in device.
Input voltage 0-20V, Output voltage 0-10V,
input/output current 0-200mA
Accuracy ±0.025%.
Measured element: 1.407 V (+0.000).

pen like meters

Ireland meter 7321 also as Voltcraft VC999 or Peaktech 1080.
9V(block), 2.5mA, auto power off. V DC/AC, mA, Ω.
Measured element: 1.409 V (+0.002).

Soar 3100
3V(2 x LR44 button), V DC/AC, Ω.
Measured element: 1.410 V (+0.003).

Voltcraft 90S
3V(2 x LR44 button). V DC/AC, mA, Ω, diode, logic L/H, data hold.

3V(2*AAA), auto power off. V DC/AC, Ω, non-contact AC voltage detector with regulated sensitivity.
Measured element: 1.418 V (+0.011).

table top meters

Metra Blansko NR 50
Old lab. digital volt-amperemeter NR 50 with bull eyes digits.

A-V meter Norma D2210 A-V meter Norma D2210 A-V meter Norma D2210

Norma Austria - D2210
Loader for 4 "C" akkus 4.8V, current consumption of D2210 is nearly 250 mA.
IC's: LD211ACJ, LD210CJ, 4511, 555, LM308N*2, LM748.
It is the same device as Siemens VMG 3.

A-V meter Siemens VMG 3 A-V meter Siemens_VMG 3 A-V meter Siemens_VMG 3 A-V meter Siemens_VMG 3

Siemens - VMG 3
Loader for 4 "C" akkus 4.8V, current consumption of VMG 3 is nearly 250 mA. Instead of akku unit box it is possible to use the net adapter box, see 2. and 3. picture.
It is the same device as Norma D2210.

A-V meter Siemens VMG 3 inside A-V meter Siemens_VMG 3 inside A-V meter Siemens_VMG 3 inside A-V meter Siemens_VMG 3 inside

Siemens - VMG 3 - inside.

Multimeter HP 3476A Multimeter HP 3476A Multimeter HP 3476A Multimeter HP 3476A Multimeter HP 3476A

Hewlett Packard    sent to Ralf D.(Berlin)
Digital Multimeter 3476A.

Multimeter ICD 600D
V, mA DC/AC, Ohm, 9V-E(block).


3. V,A meters