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"Heat Sink Putty" ?

  • Thread starter (PeteCresswell)
  • Start date
P

(PeteCresswell)

Jan 1, 1970
0
Any such thing?

I'll have a little bridge rectifier and voltage regulator serving
a bicycle hub alternator (6v 4w) and want to use the bike frame
as the heat sink.

My thought was that, if there's such a thing as heat-conductive
putty, I'd just embed the two components in some of it and stick
it to a frame tube.
 
W

William Sommerwerck

Jan 1, 1970
0
I've never heard of putty. Silicone grease is common, of course.
 
E

Eeyore

Jan 1, 1970
0
(PeteCresswell) said:
Any such thing?

I'll have a little bridge rectifier and voltage regulator serving
a bicycle hub alternator (6v 4w) and want to use the bike frame
as the heat sink.

My thought was that, if there's such a thing as heat-conductive
putty, I'd just embed the two components in some of it and stick
it to a frame tube.

Aluminium powder mixed with epoxy might work.

Graham
 
T

Trevor Wilson

Jan 1, 1970
0
(PeteCresswell) said:
Any such thing?

I'll have a little bridge rectifier and voltage regulator serving
a bicycle hub alternator (6v 4w) and want to use the bike frame
as the heat sink.

My thought was that, if there's such a thing as heat-conductive
putty, I'd just embed the two components in some of it and stick
it to a frame tube.

**Do you need heat sinking? 4 Watts is not much power. You could use a 6 Amp
bridge, which can dissipate quite a bit of power, before requiring any heat
sink. If you do need it, then use silicon glue (the stuff used for
guttering, kitchens, bathrooms, etc). It remains flexible and will transfer
reasonable heat to the frame. I seriously doubt that you need it though.

Trevor Wilson
 
S

Smitty Two

Jan 1, 1970
0
Eeyore said:
Aluminium powder mixed with epoxy might work.

Graham

Don't they make thermally conductive epoxy? OP might not want anything
electrically conductive.
 
G

GregS

Jan 1, 1970
0
Any such thing?

I'll have a little bridge rectifier and voltage regulator serving
a bicycle hub alternator (6v 4w) and want to use the bike frame
as the heat sink.

My thought was that, if there's such a thing as heat-conductive
putty, I'd just embed the two components in some of it and stick
it to a frame tube.

Thermal epoxy is better than regular epoxy but the conductivity
is very poor compared to copper, and copper is poor compared to diamond.
Might try the suggestion of adding metal filings to regular epoxy putty.
Thermal epoxy is not really putty.

greg
 
G

GregS

Jan 1, 1970
0
Thermal epoxy is better than regular epoxy but the conductivity
is very poor compared to copper, and copper is poor compared to diamond.
Might try the suggestion of adding metal filings to regular epoxy putty.
Thermal epoxy is not really putty.

The thermal epoxy I am currently using on a project is a lot thicker than
regular epoxy. Its Omega Bond 101.

greg
 
P

PeterD

Jan 1, 1970
0
Don't they make thermally conductive epoxy? OP might not want anything
electrically conductive.

Then use zinc oxide with epoxy, that should not be conductive... But
regardless, nothing will work very well, IMHO...
 
G

GregS

Jan 1, 1970
0
Then use zinc oxide with epoxy, that should not be conductive... But
regardless, nothing will work very well, IMHO...

Seems like there are atachments to the frame for accesories, and if they
are aluminum, it will make a great way to do it. Curved surface aluminum
block.

greg
 
J

Jim Yanik

Jan 1, 1970
0
[email protected] (GregS) wrote in
Thermal epoxy is better than regular epoxy but the conductivity
is very poor compared to copper, and copper is poor compared to
diamond. Might try the suggestion of adding metal filings to regular
epoxy putty. Thermal epoxy is not really putty.

greg

whatcha need is diamond-filled epoxy..... :cool:

you can buy very finely powdered copper at craft stores.
by the time you get enough copper or other filler mixed in the epoxy,it IS
the consistency of putty..... ;-)

better to machine an aluminum mount to mate closely with the bike tubing
and coat it with thermal paste,mount the circuit to the Al. plate. with
thermal paste.

Or use a switcher-type regulator for lower heat dissipation.
 
J

Jim Yanik

Jan 1, 1970
0
W

whit3rd

Jan 1, 1970
0
I'll have a little bridge rectifier and voltage regulator serving
a bicycle hub alternator (6v 4w) and want to use the bike frame
as the heat sink.    

If there's a brazed boss in some convenient spot, you can screw a
block of aluminum to that (or even a 1" square plate). The rectifier
won't need conduction cooling at these power levels, so it's just
the (three terminal TO-220?) regulator or pass transistor that gets
warm.

Generator mount bracket or headlamp bracket are good candidates.
If they get warm, it sinks to the frame quick enough.
 
E

Eeyore

Jan 1, 1970
0
Smitty said:
Don't they make thermally conductive epoxy? OP might not want anything
electrically conductive.

Bridge tectifiers usually have isolated cases anyway.

Trevor's idea is good though. Use a larger bridge than actually needed
(they're not expensive) and it'll happilly dissipate the heat without
additional cooling.

Graham
 
P

(PeteCresswell)

Jan 1, 1970
0
Per Trevor Wilson:
**Do you need heat sinking? 4 Watts is not much power. You could use a 6 Amp
bridge, which can dissipate quite a bit of power, before requiring any heat
sink.

I just checked the specs on the one I ordered. 25 amps/50v.

Sounds like my dinky little hub alternator will barely warm it
up. So much for the heat sink requirement....
 
J

Jimmie D

Jan 1, 1970
0
(PeteCresswell) said:
Any such thing?

I'll have a little bridge rectifier and voltage regulator serving
a bicycle hub alternator (6v 4w) and want to use the bike frame
as the heat sink.

My thought was that, if there's such a thing as heat-conductive
putty, I'd just embed the two components in some of it and stick
it to a frame tube.

There is an epoxy but it doesnt work like you want.It must be applied thinly
and used to conduct heat to a heatsink.
Just get a really big rectifier. I have a 5 amp power supply that uses a 20
amp bridge and its bolted to a piece of wood.

Jimmie
 
P

(PeteCresswell)

Jan 1, 1970
0
Per Jimmie D:
Just get a really big rectifier. I have a 5 amp power supply that uses a 20
amp bridge and its bolted to a piece of wood.

That's what I (inadvertently) did. 25 amp/50 volt to handle
about 1 amp/20 volts max.
 
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