Tag Archives: DIY


PIC-based ESR meter

My homebrew ESR meter spots a cap that is less than desirable. If anyone is interested I have my .asm code I am happy to share. The board is an Olimex prototyping development kit I got from ‘microcontrollershop’. It’s all assembler .. No C version and no desire to work on this anymore. The electrical aspects are documented in the code to some degree (enough that *I* could rebuild it…) I don’t have any plans for a kit. If you want the code you’ll have to agree that you’re building this project for yourself with no re-distribution. I don’t trust my code enough to be considered for some sort of commercial use.



Variable Frequency Drive Shortcut

I’ve had a project sitting on the back burner for quite a lot of time, really an embarrassing amount of time. It’s been a good 3 or 4 years since I started a yet unfinished variable frequency (speed) drive. I plan to drive a 3 phase AC motor for another project later to be reviled. I’ve had some trials both successful and magnificent failures but I decided to skip that whole learning to build a proper motor drive set when I came across a user York chiller compressor driver. The pin out wasn’t difficult to reverse engineer and went even more quick as I had a basic schematic of the interconnections of the York boards on a PDF I found online. Shown in the photo is the drive board. This is about 80% of my work taken care of for me all for the low price of a few bucks. I don’t know if you’ll be able to find yourself a drive board I just got lucky. I suspect if you can find an old used variable frequency drive you can just borrow it’s guts. If you like this board perhaps you can search by part number. It’s the 031- number found in the middle of the PCB. The connector was found through @digikey :

A100434CT-ND    CONN PIN 16-20AWG MINI-U M-N-L2
A100435CT-ND    CONN SCKT 16-20AWG MINI-U M-N-L2

I ordered both sides of the connector for testing and my own interface board. Note: I haven’t received this parts so I haven’t absolutely verified these are correct but the pin keys and measurements against specifications appeared correct.


VFD IGBT and driver board.
VFD IGBT and driver board.

I realize I could have used “XYZ development kit”, and I could have also dedicated more time to this project but my time is worth something and I have a chronic issue with being cheap.


A plumbers version of a blown fuse?


While installing my DIY boiler I found I didn’t get all the water out of my heating hot water lines the first time around.