Regards, Jay_Diddy_B aka JohnĬwalex and the group, The circuit board and the front panel were made with a LPKF Protomat C60. Current consumption is 26mA, that is about 25 hours of use. Here is a view of the inside of the ESR meter: And the Outside: If you build this, remember to discharge capacitors before using. The meter scale was printed on Photo paper to be attached to the meter. Artwork for a new meter scale was drawn using Corel Draw. The meter deflection was measure using some low value resistor. The circuit was made from the above design and the components attached: The meter circuit was hooked up. From the LTspice model, I made the OrCad schematic: And then the board layout, I used SMD parts, but thru hole parts could also be used.

This good because it gives an expanded scale. This is the result of the LTspice modelling, it shows how the meter deflection changes with ESR. The design started with modelling the circuit in LTspice: The building blocks are labelled. The new design was generated in KICAD version 5.00 The maximum voltage on the capacitor under test is 100mV. 10th Anniversary Edition I shared a modified version the ESR meter in this message: Two additional transistors are used to detect if the resistance of the capacitor being tested is less than 25 All the other features remain the same. OA91 or similar Ge diode should also work. Use small signal Schottky diodes such as 1N5711, common diodes like BAT54 have too much capacitance. The diodes in the meter circuit will effect the meter scale. The design should work with any general purpose transistors. The circuit should also work directly from 3 or 4 AA batteries without the regulator. When I was kid, radio manufacturers would sell transistor radios based on the number of transistor in them. ESR meter do not need to be precise, it most instances a bad capacitor will have any ESR many times that of a good one.

For Capacitors larger than a few uF this is approximately equal to the ESR. Strictly speaking this ESR meter does not measure ESR, it measures the impedance of the capacitor under test at 100kHz. I have decided to share my ESR meter design with the group. Hi Forum Members, There seem to be as many ESR meter designs as people who use them.

Transistor tester diagram