[time-nuts] +12 Volts 1A (plus a bit) supply?

[Bob Stewart]

Hi Hal and other responders,

I believe that the OCXO uses an ON-OFF type of regulation.  So, no, it doesn't use 1A all the time.  Maybe I should just put an ammeter in the line and see what kind of duty cycle it has after it's at temperature.


I tried a 7812 regulator with a small dissipator on it.  It goes into overheat mode almost immediately and the output voltage starts quickly doing down.  The case does have provisions for a single TO-3 transistor conducting heat to the back of the case with no radiating fins.  I had briefly considered using a zener and a 2N3055.

I think that instead of worrying this to death, I'm just going to use a brick to get it together, and then if something comes up later that I like, I'll put that in.  I did like the looks of that PT5102 but it's at end of life, and 1A is right at it's limit.  I've given some consideration to seeing whether I can pull a few turns off the transformer secondary, as well.


Bob - AE6RV



----- Original Message -----
> From: Hal Murray <hmurray at megapathdsl.net>
> To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Cc: hmurray at megapathdsl.net
> Sent: Thursday, June 27, 2013 2:24 PM
> Subject: Re: [time-nuts] +12 Volts 1A (plus a bit) supply?
> 
> 
> bob at evoria.net said:
>>  The transformer gives me about 20 volts DC out.  Dropping 8 volts at 1 amp
>>  is just a lot of power to void with a resistor.  I'd like to avoid 
> having
>>  that much waste heat in the unit.
> 
> Does it really take 1A after it's warmed up?