Esr meter

ESR meter

This device measures impedance at 100 kHz in assumption it's resistive¹, basically an AC ohmmeter. Not for laboratory measurements, but for troubleshooting. The main usage is to find dried out electrolytic capacitors in aged electronics. Also may be used for continuity testing in a circuit containing inductors or transformers (it may be hard to distinguish a short from a winding at DC), or for finding shorted windings.

Some specs:

• Test signal: 100 kHz 50 mVpp 10 Ω sine wave
• Range: 0–99.99 Ω with non-linear resolution (the highest near zero)
• Measurement time: 1/16 s (average of 64 samples)
• Protection: two anti-parallel SM4007 diodes
• Power supply: a single cell Li-ion/Li-Po battery, charge from Micro-USB at 300 mA

Usage

To switch the meter on or off, press the button. After 3 minutes of inactivity the meter switched off automatically.

On startup, the meter performs a self-test. Keep the terminals open. During the test, the meter turns on all the segments on the display, then shows an error if any:

• E.F.LO: low fuel (battery voltage < 3.3 V);
• E.rEF: something wrong with voltage references or ADC;
• E.Prb: something wrong with the test signal (or the terminals aren't open).

When the test is passed, the meter shows the current battery level in percents as F <level>.

During normal operation the meter continuously shows the measured impedance in Ω, or -OL- if it's more than 99.99 Ω.

Note that inductance of test leads matters at 100 kHz. You should connect capacitors directly to the binding post, or use leads as short as possible.

License

Unless otherwise noted, this work is licensed under Creative Commons Zero 1.0.

Footnotes

1. The readings corresponds to a resistance that gives the same amplitude drop of the test signal as the device under test. ↩