AC Adapter problem.

[eccerr0r]

Re: AC Adapter problem.

I was looking at some of my old multimeters that actually have less than 5V FS (and they're ANALOG!)
My VTVM has a 1.5V full scale AC range, and it uses two diodes... VACUUM tube diodes... to do half bridge rectification (6AL5). I would have thought vacuum tube voltage drops would be quite high.
My old analog VOM has a 2.5V full scale AC range. Its scale is kind of compressed near the left end, and uses two Germanium diodes (which have less voltage drop than silicon).

I guess this is moot anyway, you can't detect millivolts with these meters anyway.

[true_blue]

Re: AC Adapter problem.

I tried out the AC ripple test on another supply and it showed 41mv so guess it does work even on cheap multimeters. Got mine (VC99+) from Aidatek.com

I was wondering also.. how does one put a power adapter supply under max load to test it fully? I was thinking.. a 60w DC lightbulb at 12v would draw 5amps right? So if I have a 12v 5amp PSU then it should max it out and then I can get a accurate measurement of the voltage. But is there an easier way?

Cheers.. sorry if my question is nooby!

[budm]

Re: AC Adapter problem.

" 60w DC lightbulb at 12v would draw 5amps right?"
The hot resistance of the lamp is 2.40 Ohms, the cold resistance will be about 0.16 Ohms, your power supply may not be able to handle the surge current and may go into shutdown.

[true_blue]

Re: AC Adapter problem.

Ok thanks.. so which is a better way to test a PSU under load?

Cheers!

" 60w DC lightbulb at 12v would draw 5amps right?"
The hot resistance of the lamp is 2.40 Ohms, the cold resistance will be about 0.16 Ohms, your power supply may not be able to handle the surge current and may go into shutdown.