.:madworm:.'s photos

They are used as reverse polarity protection. These tiny SOT23 parts (AO3401) are really quite beefy. They exhibit about 50mOhm (logic level drive) and can take up to 4A each. The most they will have to tolerate on this board is 2.5A each. I got these on ebay. A pack of 50pcs is about 12$ including shipping.

Left-over PCBs might be found here .

It WILL NOT WORK with ceramic capacitors...

Vishay 534

V0.1 board assembled. It works OK once all the bugfixes have been applied to it. Left-over PCBs might be found here .

Believe it or not, but I couldn't find a battery holder with usable CAD drawings.

V0.1 board assembled. It works OK once all the bugfixes have been applied to it. Left-over PCBs might be found here .

I wonder what they did. Probably made sure it is non-explosive and has 0% cocaine in it.

Trying to take over the world.

Trying to take over the world.

I had to add these two (back-to-back) to get the thing to run stably. I don't know if it is the dummy load or the DUT that starts to oscillate...

I got the boards today. Left-over PCBs might be found here .

I got the boards today. Left-over PCBs might be found here .

My first 10x10cm boards from Elecfreaks .

No metal parts except the legs. I've already managed to kill 2 of these MOSFETs (IRLIZ34N). One of them died due to overheating. Now I'll switch to one that comes in the standard TO-220 package, which has better heat transfer (IRL3803).

It will be used for adjusting current. Unfortunately I couldn't get a metric version of this thing. Now I have to deal with a 1/4-in shaft. Yuck. The range of available knobs for non-6.0mm-shafts is rather limited.

A dummy load. Peak current is 5A. That is currently (hahaha) limited by using only 5V as the reference voltage for the opamp. LTSpice simulations (with a different opamp) showed possible oscillations at a set-current of above 2A. I had to add another BW-limiting capacitor to the opamp that drives the MOSFETs. If I'm lucky the real thing won't need it. If it does I'll have to bodge it. I won't immediately order the V0.2 PCB for that. I only need one working board for personal usage.

A dummy load. Peak current is 5A. That is currently (hahaha) limited by using only 5V as the reference voltage for the opamp. LTSpice simulations (with a different opamp) showed possible oscillations at a set-current of above 2A. I had to add another BW-limiting capacitor to the opamp that drives the MOSFETs. If I'm lucky the real thing won't need it. If it does I'll have to bodge it. I won't immediately order the V0.2 PCB for that. I only need one working board for personal usage. • BOM • schematic