Tag Archive for dummy load

Dummy Action

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

Properly mounted MOSFET. Note the pad under it, and the nylon bushing isolating the screw


Read more

Dummy Assembly

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!

Front panel view, not perfect, needs labelling, but good enough!


Read more

Dummy Calibration Questions

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.

Bit of a rats maze, but she works! All the bits are built.


Read more

Loaded Dummy Dumbness

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!

All the bits waving in the breeze, but she works!


Read more

Loaded Dummy is here!

Hurray! I got my PCBs via DHL this morning. So happy to receive them and hold in my hand my first professionally made PCB.

loaded_dummy_pcb_front
Read more

Panel Pooper

Institutionalized Dumpster Dive

Over the weekend, I had occasion (in other words I made an occasion) to visit A1 parts and surplus in Etobicoke. I have mentioned it before as a candyland for the junk enthusiast and this is essentially correct. Despite its remote location, it is well worth the visit, just be prepared to dig and expect no help from the rather cantankerous guy at the counter. Total comic book guy for the electronics store which I find endearing rather than offensive. Anyway, if you ever end up there, be prepared to wade through tons of unsorted junk, find a few gems, and score a few surplus deals.

Read more

Lipstick on a Dummy

Or how I just love to overcomplicate things

Lights, buttons knobs and dials have always fascinated me. In fact, it says so in my baby book pretty much exactly. I think that was genesis of my love for technology, electronics, sci-fi and general science and nerdom. After all, what could be cooker then “techy shit” as gmunk puts it?

With every project I do, I tend to dream up ways of making the interface and functionality as flexible (read: complicated) as possible. I want to feel like I’m flying the frickin’ Enterprise when I do my thing.

Read more

Dummy load acquires stability

Just a quick test and a quick solution

Had a few minutes to just check up on why the load would change when the voltage does. A simple test of trying a higher voltage power supply seemed to do the trick. Stayed within 10mA of where it should, and probably did better than that, but my multimeter can’t measure that. The new power supply is a 200mA 12V wall wort which is very unregulated. I measure 16V off the bugger with no load. Makes me wonder if what is printed on the box is merely a suggestion. Still, nice to have the headroom. Now the opamps have enough swing to really kick that MOSFET into regulating the current flow reliably.

Read more

Dummy load get’s a tune up and another test

Improvements and fine tuning

As mentioned in my last post on the dummy load, though I am very pleased with the results, there is always room for some fine tuning and improvement. Also, some parts needed to be bought. First off, here’s a revised version of the schematic:

dummy-load-v14_thumb
Read more

Encouraging results

Some quick tests work out quite well

Had a tiny pocket of time with which to test a few things with my aforementioned dummy load I just build. In looking through my collection of junked wall wort power supplies I found a low power one, a 9V 210mA. I wanted to check and see if the voltage headroom for the opamp would be worse. As it turns out, the stated 9V is actually 11.3ishV but whatever. I knew the supply would only need to deliver a few milliamps so I ventured to see how much exactly.

Read more