Last week, I finally got a few parts I was waiting for. Namely the insulating pads that allow me to connect the MOSFET to the heatsink without making the entire case the drain! So with that, assembly is complete. Just need a label for the front which I can do at a later date if ever I make it to Staples to buy adhesive transparency sheets.
Properly mounted MOSFET. Note the pad under it, and the nylon bushing isolating the screw
No, that’s not a euphemism.
Recently, I purchased a new multimeter, the now widely used UNI-T UT61E, which as far as cheap chinese multimeters go is pretty darn good. After watching various teardowns and tests courtesy of Mr. Martin Lorton, I was actually reasonably impressed with the functionality and accuracy of the meter and really wanted one to replace my Mastech “shitty piece of shit” meter which I’ve grown to loathe over the years. Most annoyingly, it had stopped displaying decimal points almost entirely. An internal inspection revealed it to be the switch contacts not quite making contact on the volts ranges (which is… the most important range!). This led to some almost-accidents as I had to guess where that decimal point would be. Is it 2V? 20V? 200V? Bugger this, time to upgrade and get a decent meter. Not that I won’t use the Mastech still, always good to have two meters, and the Mastech measures temperature which the UT61E doesn’t.
It’s been a week of tweaking and assembly, mostly. This is both the part I love the most, and dread the most. On the one hand, it’s awesome to see the project come together and not just be a dangerous collection of bits on my bench. On the other hand – drilling into aluminium is such a chore!
Anyway, here it is thus far:
Front panel view, not perfect, needs labelling, but good enough!
As I said in my last post. I am mostly happy at how the Loaded Dummy performs, but with the caveat of some inaccurate voltmeter measurements.
After some more tuning and testing, I’ve identified two issues that leave the project just shy of my expectations. Neither are deal breakers, but are enough to make me want to investigate further and see if I could improve if not solve them.
Bit of a rats maze, but she works! All the bits are built.
For the past week and change, ever since getting my boards from the fab in the post, I’ve been assembling and testing and fiddling with my dummy load project. I outlined a few beginners mistakes in my last mention, and since, I’ve disovered a few more! Don’t worry, it still works fine enough and I’m still generally pleased with it. I’m even laughing at the absurdity of the bugs I’ve found.
Anyway, here’s the state of it now:
All the bits waving in the breeze, but she works!