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

[Bob Camp]

Hi

I think you will find that the TBolt pulls about 750 ma at turn on off of the +12V supply.

Bob

On Jun 27, 2013, at 8:37 PM, Bob Stewart <bob at evoria.net> wrote:

> Thanks for the correction Bob.  I don't know what made me think it was an on/off oven.  The OC-050 datasheet gives a drain of 12 watts in warmup and 4 watts in run mode, so I went with that in the post I just made, calculating the loads, etc.
> 
> Bob
> 
> 
> 
> 
> ----- Original Message -----
>> From: Bob Camp <lists at rtty.us>
>> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>> Cc: 
>> Sent: Thursday, June 27, 2013 7:27 PM
>> Subject: Re: [time-nuts] +12 Volts 1A (plus a bit) supply?
>> 
>> Hi
>> 
>> The OCXO in the TBolt has a linear controller. It drops back to about 150 to 250 
>> ma on the +12 line after warmup. It's been at least 40 years since I saw an 
>> on/off oven control in production ….
>> 
>> Remember that the +12 feeds the oscillator circuit. The more crud on the 12 
>> volts, the worse the phase noise of the output. A linear regulator is a good 
>> idea.
>> 
>> Bob
>> 
>> On Jun 27, 2013, at 3:49 PM, Bob Stewart <bob at evoria.net> wrote:
>> 
>>> 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?
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