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

[Don Latham]

Use the buck/boost knurdle to lower the voltage, followed by a low noise
linear regulator. Quiet and efficient...
Don

Bob Camp
> 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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-- 
"Neither the voice of authority nor the weight of reason and argument
are as significant as experiment, for thence comes quiet to the mind."
De Erroribus Medicorum, R. Bacon, 13th century.
"If you don't know what it is, don't poke it."
Ghost in the Shell


Dr. Don Latham AJ7LL
Six Mile Systems LLP
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Skype: buffler2
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