[time-nuts] newbie question Thunderbolt supply

Ed Palmer ed_palmer at sasktel.net
Mon Aug 27 12:35:16 EDT 2012


There are thermal pads that are thermally conductive.  You typically see 
them in laptops and, oddly, optical drives.  They're usually one or two 
mm thick and very soft and squishy.  Pull the bottom plate off any 
full-size optical drive and you'll probably find one or two pieces.  I 
see lots of them on the auction site, but I have no personal experience 
with those.  It looks like there's at least one or two that are 
available in large pieces and I saw thicknesses from 0.4mm up to 4.0mm.

I wouldn't expect these to move heat nearly as well as a thin layer of 
thermal grease (which is itself a thermal insulator), but for some 
applications it works and is the only practical solution.

Ed

On 8/27/2012 10:12 AM, Bob Camp wrote:
> Hi
>
> The pad stuff is normally an insulator. It's not very stable, so there may
> be better alternatives.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of EWKehren at aol.com
> Sent: Monday, August 27, 2012 10:44 AM
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] newbie question Thunderbolt supply
>
> There are components and traces.
> Bert
>   
>   
> In a message dated 8/27/2012 10:10:45 A.M. Eastern Daylight Time,
> jsternmd at att.net writes:
>
> Are  these thermal pads temp conductive or insulative?  If you want  heat
> dissipation why not use the readily available thermal grease used  for
> semiconductor mounting? Cheap and not really messy if applied  correctly
>
> jerry
>
> -----Original Message-----
> From:  time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of  EWKehren at aol.com
> Sent: Monday, August 27, 2012 9:38 AM
> To:  time-nuts at febo.com
> Subject: Re: [time-nuts] newbie question Thunderbolt  supply
>
> Thank you. Will look for it here under thermal  pad.
> Bert
>
>
> In a message dated 8/27/2012 8:08:30 A.M. Eastern  Daylight Time,
> azelio.boriani at screen.it writes:
>
> Here in  Europe  Farnell has the 3M thermal pad in sheets (105x150mm)...
>
> On Mon,   Aug 27, 2012 at 12:48 PM, ew <ewkehren at aol.com>   wrote:
>
>> Chris
>> 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
>>   7805.
>>   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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