[AMRadio] Voltage regulator

Brett gazdzinski brett.gazdzinski at verizonbusiness.com
Sat Mar 18 20:17:38 EST 2006

If its just relays, you can just add say a 5 ohm resistor
on the output.
measure the voltage with the relays pulled in, load/no load
voltage will vary a lot...

Or, if its DC, reduce the filter cap a lot, you don't need
filtering for relays, and the size of the cap has a big impact
on the loaded voltage you get out.

Or, add choke input,

Or, half wave rectify the thing, gives half the voltage output
(use a big cap), 8 and 18 volts may pull the relays in fine.

The three term regulators are mostly good for 1.5 amps,
there are adjustable ones and fixed ones, I don't think the fixed ones
have any additional parts...input, output, ground?


> This last week I built a 12 volt and 24 volt power supply in 
> one small box 
> to power various relays around the shack.
> Well, the 12 volt turned out to be 16 volts, and the 24 volt 
> is 36 volts. 
> Even loaded the voltage is high.
> I've done quite a bit of Googling on the subject of 
> three-terminal voltage 
> regulators, but have found nothing that had actual component 
> values that 
> would be pertinent to my needs.
> Also saw a three-terminal using a pass-transistor. Again, no actual 
> component values.
> I'd like to be able to get the voltages down to more nearly 
> what I need so 
> that I don't burn out a relay.  Perhaps 14 volts and 26 to 28 
> volts, at an 
> amp or so.
> My knowledge of solid-state devices is close to zero.
> Anyone have some ideas?
> 73, Barrie, W7ALW 
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