The sausage paws are playing with the pots. Turns out the power supply is not good enough for our purposes.
I decided to build the ESR meter I talked about a post or two ago, I must say it wasn’t as simple as I thought it would be, mainly due to several mistakes and problems I encountered, thankfully though one of the authors of the ESR meter gave me a hand troubleshooting the circuit, so I was able to finish that stage of the project.
Now that it’s functional, I’ve been working on the enclosure!
I decided to build a benchtop unit and later-on a portable one, mainly because I don’t need a portable ESR meter right now and I had the enclosure, transformer, etc. all assembled already.
There were some placement issues with the potentiometers, I actually added a feedback gain pot, and a backlight for the analog meter with it’s own “brightness” pot — So in total I’ve got 4 pots, if we count the voltage offset and zero ones.
However not everything is working as planned, turns out the TL082 likes to work at much higher voltages, so I’ll have to replace the transformer as well as the regulator.
Quick mockup of the enclosure, seems like everything is fitting! -- Of course we're missing a connector and the main switch, but we're getting there.
During the test phase I’ve been using 12V input without problem, the final setup uses 10V, but that’s not enough. Not even setting the feedback gain to 2x of the original is enough to get full deflection, 12V is required.
So I’ll have to find a suitable transformer of similar proportions to the one I already have installed — otherwise I’ll have to drill new holes, build a new support, etc. NOT fun!
I suspect the actual impedance transformer on the meter circuit itself is probably the culprit here, but I’m not willing to change that again.
Hopefully I’ll get this done in the next few days, stay tuned!
[...] with the ESR project, I’d like to enumerate the various issues I encountered during layout design, fabrication and [...]