Image from the 1995 Radio Shack catalog
4,000 count Auto-Ranging Digital Multimeter with Bar Graph and Hold.
Specifications
Note: minimum of shown range is the smallest "count" digit appearing in the lowest range.
% is mid-range accuracy, count adder not shown)
DCV 100μV - 1000V (input impedance 10MΩ), 1%
ACV 100μV - 750V (true RMS), filters DC on AC setting, 60Hz-1kHz 3%, 30-5kHz 5%
DCA 1nA - 400 mA (0.5A fuse); 10A (unfused), 2%
ACA 1nA - 400 mA (0.5A fuse); 10A (unfused), 4%
Resistance: 0.1Ω - 20MΩ, 1%
Capacitance: 1 pF - 400 μF, 2%
Diode: 2VDC, nominal current 0.5mA @0.6V
Transistor hfe: 0 - 39.99K; Emitter current ~0.5A, V(C-E) ~1-3V
Continuity threshold: 50 ohms
Temperature (probe) -50C to 150C, +/-2C, 10kΩ thermistor +/-1C
dBm +/- 60 dBm (input impedance 1 MΩ)
Frequency measured 1 Hz - 2 MHz, 3%. No duty cycle.
Low battery warning: 3.8V (uses 6 AA cells)
CPU fuse: 63 mA
Measurements of Intrinsic Parameters, Paul T., 2024
Test Lead Resistance (with hook clips) 36.3 mΩ Red, 36.4Ω Black
Resistance during DC current measurement 17 mΩ 10A range; 1.524 Ω in mA range.
Resistance range test current 0.92 mA
Diode test V(open circuit) = 2.587V, A(closed circuit) = 0.59 mA
Beeper: 95.7 dBA, 12 inches away, aimed at unit. 6 kHz pure tone from piezo speaker. (Label covering hole removed)
Verification Testing against standards, Paul T., 2024
Voltages:
0.180VDC calibrated power supply = 1.816mV (0.9% high)
1.800VDC calibrated power supply = 1.807V (0.4% high)
10.00000VDC transfer standard calibrator = 10.00V (NOTE: recently set the device adjustment potentiometers to this standard)
18.000VDC calibrated power supply = 17.98V (0.1% low)
Mains AC (USA) 122.5AC = 120.9V (1.3% low)
Current DC:
15mA process calibrator = 15.33 mA (2.2% high)
0.150A power supply = 150.5 mA (0.3% high)
1.500A power supply = 1.542 A (2.8% high)
Resistances:
Compared to Keithley 4-wire measurements of precision resistors
0.09913 Ω = 0.1 Ω (0.9% high)
0.99280 Ω = 0.9 Ω (9.3% low)
9.99110 Ω = 9.9 Ω (0.9% low)
100.0012 Ω = 99.6 Ω (0.4% low)
0.998775 kΩ = 1.000 kΩ (0.12% high)
9.999935 kΩ = 10.00 kΩ (0%)
100.0170 kΩ = 100.1 kΩ (0.1% high)
0.995375 MΩ = 0.994 MΩ (0.1% low)
10.11300 MΩ = 10.20 MΩ (0.9% high)
Capacitance:
* = starting reading of 150 pF manually subtracted from result
(REL is not a feature of the meter)
31 pF = 30 pF* (3.2% low) [mica]
209 pF = 220 pF* (5.3% high) [ceramic disc]
684 pF = 684 pF* (0%) [mica]
2.014 nF = 2.025 nF* (0.5% high) [poly]
7.980 nF = 8.14 nF* (2.0% high) [poly]
10.06 nF = 10.22 nF* (1.6% high) [poly]
32.20 nF = 32.42 nF* (0.7% high) [poly]
128.4 nF = 129 nF* (0.5% high) [poly]
1.021 μF = 1.072 μF (5.0% high) [MLCC]
10.17 μF = 9.94 μF (2.3% low) [tantalum]
99.2 μF = 96.4 μF (2.8% low) [tantalum]
1,004 μF = OL (MAX is 400 μF) [electrolytic]
6,560 μF = OL (MAX is 400 μF) [electrolytic]
21,770 μF = OL (MAX is 400 μF) [electrolytic]
Diodes:
Reference values are average of all other devices I track
Schottky 0.18V = 0.168 V
Silicon 0.59V = 0.551 V
Red LED 1.78V = 1.764 V
Orange LED 1.84V = 1.830 V
Yellow LED 1.86V = 1.855 V
Green LED 1.89V = 1.881 V
Blue LED 2.59V = OL
White LED 2.62V = OL
UV LED 2.91V = OL
3.3V Zener = OL
Transistor:
2N3904 (300 max) = 278 hfe after correct identification for NPN and EBC
Temperature:
Verified operation, but not Tested for accuracy.
Frequency:
I was able to verify from 10 Hz to the max I could generate.