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

[Adrian]

That's not really excessive voltage.
Given you have measured the 20V DC (average rectified voltage) at 
nominal wall voltage. then you should take some -10 percent tolerance 
into account. Another 3 V will be consumed by the regulator, and the 
remaining 3V are probably just right to cover the ripple on the 
unregulated side. You may use a smaller capacitor, just large enough for 
not getting below the minimum regulator input voltage at the lowest 
momentary voltage across the cap when your wall voltage is at its low 
spec side...

Adrian


Bob Stewart schrieb:
> 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.  I do have an old power brick, but I was hoping there was some small switching board that people had had good luck with.  Maybe the brick is the best option.
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> Bob
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>> ________________________________
>> From: Chris Albertson <albertson.chris at gmail.com>
>> To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com>
>> Sent: Thursday, June 27, 2013 1:32 PM
>> Subject: Re: [time-nuts] +12 Volts 1A (plus a bit) supply?
>>
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>> You mean you have to many volts for a 12V regulator to drop>  That's easy to fix, use a resister in series.  Make the resister par of an RC filter and cleaner power in the process.
>>
>>
>> I use a plug-in power brink from an old notebook computer.  I think mine outputs 15V and then this gets dropped to 12V and 5V with a RC filter and regulators.
>>
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