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| Inside the new Korad KA3305P linear PSU |
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| Salas:
Probably doable, but to avoid the hassle maybe there is some old receiver around? Connecting on one channel's rails fuses after disconnecting its own PSU, no big reservoir capacitors aid to the bench PSU ;), and some cement resistors combo 5-10 Ohm 50W dummy load hanging off its speaker output posts should run the test without needing a loudspeaker driven to some earsplitting SPL. |
| torch:
The old receiver is a tube powered floor model radio. Most of the energy goes into heating the tubes -- not really very dynamic. Everything else is pretty low-powered around here. I'll see if I can figure something out. |
| mos6502:
A bunch of old car headlight bulbs should do the trick. Wire them in parallel/serial as needed. Just keep in mind they're non-linear and will draw about 10 times the normal current for a few milliseconds while they heat up. |
| torch:
The car headlights won't be very dynamic to do the ripple test that Salas asked for. Funny you should mention light bulbs though. I had a half-dozen new-in-box H3 bulbs that I bought on clearance for $1 or two each a few years ago. On my first attempt to load test I hooked them up to the Korad and they drew a heck of a current, but no light output. What the heck? I checked and rechecked connections before I discovered that every one of them was shorted out. I think the wires on each are pinched by the metal housings. No wonder they were on clearance. |
| mos6502:
--- Quote from: torch on September 05, 2015, 09:40:32 pm ---The car headlights won't be very dynamic to do the ripple test that Salas asked for. --- End quote --- Of course, you have to switch them on and off using your IGBTs. The good old NE555 should do the trick. 50Hz would be a good frequency. This will keep the bulbs hot so their resistance should remain fairly constant. --- Quote from: torch on September 05, 2015, 09:40:32 pm ---Funny you should mention light bulbs though. I had a half-dozen new-in-box H3 bulbs that I bought on clearance for $1 or two each a few years ago. On my first attempt to load test I hooked them up to the Korad and they drew a heck of a current, but no light output. What the heck? I checked and rechecked connections before I discovered that every one of them was shorted out. I think the wires on each are pinched by the metal housings. No wonder they were on clearance. --- End quote --- You're better off collecting a bunch at a junkyard. You can usually get them for free. And you'll know most of them will be working. Oh, and also take the bulb sockets while you're there. |
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