[time-nuts] newbie question Thunderbolt supply

ew ewkehren at aol.com
Mon Aug 27 10:48:29 UTC 2012

Starting with 3.4 W used by the Tbolt my battery version burns 4.4 W.  Using a switcher do generate 7 V   4.8 W and running the 7805 directly from 14.5 V 6.2.W. I use like you an IC temp sensor, two stage op amp driving a fan holding the backplate temp constant and total power goes up to 7.6 W since the oven has to work harder. T bolt, switchers and all regulators are on the other side of the 3/32" Alu plate. The AC switcher is not included in the power numbers. but is also on the plate. Plate is held at 40 C.
I am looking for a way to more closely couple the Tbolt circuit board to the back plate and am looking for the material switchers use between semiconductor and cooling plate Any one know where I can buy it in sheet form?
Bert Kehren

-----Original Message-----
From: Chris Albertson <albertson.chris at gmail.com>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Sun, Aug 26, 2012 12:31 pm
Subject: Re: [time-nuts] newbie question Thunderbolt supply

On Sun, Aug 26, 2012 at 3:46 AM, <EWKehren at aol.com> wrote:
> Having played with several solutions I found the best is a 12 V 1 A
 switcher with the output voltage increased to 15 V, check the capacitors
 and if
 necessary replace with 25 V. I laid out a PC board that has a TC7662A
 inverter  followed by a 79L12.  Also on the board is a 7812 followed by a
 Putting them in series gives me good thermal distribution. ....

ne of the advantages of generating waste heat like that is that you can
ut the heat to good use.  I build a temperature controlled fan.  It is
ery simple a temperature sensor IC connects to an opamp that drives a
ower transistor that drives a 12V fan.
As for the power supply.  I used a filter that does not drop any volts and
 can't see any RF on the DC using my old 365 Tek scope or by using a more
ensitive RF power meter.

hris Albertson
edondo Beach, California
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