Capacitor datasheets do not specifically list ESR ratings because the rating is dependent on the test frequency. This extremely simple command-line program will calculate an ESR value given the tangent of loss angle listed for the part, the test frequency in hertz, and the value in microfarads. I've chosen to normalize on microfarads because all of the capacitors I'm testing for this project are in that range.
Here's an example that makes the following assumptions:
- Nichicon UFG capacitor
- 100 uF value
- 10V voltage rating
- 120 hertz test frequency (set your ESR meter to this as well!)
First, check the datasheet to find the tangent of loss angle for the part. In this case, the value was 0.19. Next, run the command-line program with the test frequency and value in uF:
esr 0.19 120 100
ESR: 2.519953
The resulting ESR value is printed to the terminal.
Tom R. Dial dialtr at gmail dot com