Check power supply

Thread Starter

simo_x

Joined Dec 23, 2010
200
Hi all, I have to check, without any measuring instrument (voltmeter and ampermeter) if a power source can supply 13,2 Vcc and at the same time 5,5A & 50A.

I was thinking about using 2 schottky (with little voltage drop) for a 12V - 65W bulb (5,5A) but I don0t know what use for the 50A..
However, I am trying to find a way for it.. Do you have some idea??
 

Georacer

Joined Nov 25, 2009
5,182
I would say zener diodes and current division networks and LEDs. One circuit for each ampere rating.
Then again, power isn't really my thing.
 

Wendy

Joined Mar 24, 2008
23,429
Dealing with a bad power supply I have found a oscope to be critical. This is because a meter (such as a DVM) can not see if the power supply has dropouts, where the voltage goes from the regulated level to ground and back in a narrow pulse. HP power supplies were very bad about this.

You can cobble together an electronic load, using a power BJT transistor on a heat sink in a constant current mode to make a easily programmable current sink.
 

Thread Starter

simo_x

Joined Dec 23, 2010
200
You can cobble together an electronic load, using a power BJT transistor on a heat sink in a constant current mode to make a easily programmable current sink.
I am not so expert about transistors.. How to deal with it???
Could I use two thyristors?
 
Last edited:

Wendy

Joined Mar 24, 2008
23,429
No, thyristors will stay on once they conduct. You need a basic constant current sink. Power transistors of the BJT variety are easy to thermally heat sink, they have many package styles such as the TO3 (google it) that are meant to make it easy.

I have a half way designed project for an electronic load, I'm working on getting an adequate chassis for it.

Electronic Loads

I find it unusual you have not studied basic BJT transistors, but have studied TRIACs. I highly recommend you put the hours in understanding transistors, as they are not going away, and have a lot of uses left in them still.

A much simpler version than what the link shows is possible.
 

Wendy

Joined Mar 24, 2008
23,429
I went ahead and drew up some simplified versions. The transistors will get extremely hot, at 1A R2 will barely heat up (and the transistors might scorch wood). The second drawing is slightly better, but both are constant current sinks, vary the voltage into them collector to ground and the current shouldn't change much. R1 adjusts the current setting.

 
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