The numbers don't seem to bear out these insulators:
https://www.tindie.com/products/Protofabtt/mylar-05mil-thermal-pads-to220--to247218-to-3/
I get about 3R thermal resistance based on the known thermal resistance of mylar at 0.5mil. Any differing results?
https://www.tindie.com/products/Protofabtt/mylar-05mil-thermal-pads-to220--to247218-to-3/
I get about 3R thermal resistance based on the known thermal resistance of mylar at 0.5mil. Any differing results?
Actually I think I made a mistake. The thermal conductivity of Mylar at 300K is 0.0008W/cmK. So for a TO-247 which has optimistically 5cm^2 of surface area, and a film thickness of 0.5mil (why make it thicker than needed?),
1/(0.0008*5/.00127)=0.3175C/W
That is assuming the metallization is not on the transistor side.
For them to work well though the transistor and the heatsink has to be flatter than 0.0005" across it's surface to achieve flush contact with the film without crushed spots with reduced breakdown voltage. So maybe not really practical, especially not without grease.
1/(0.0008*5/.00127)=0.3175C/W
That is assuming the metallization is not on the transistor side.
For them to work well though the transistor and the heatsink has to be flatter than 0.0005" across it's surface to achieve flush contact with the film without crushed spots with reduced breakdown voltage. So maybe not really practical, especially not without grease.
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The Sky is the Limit: Russian Girl Takes Most Extreme Shots Ever
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Pardon the near-on-topic post, but I just saw this "Coaxial Speaker!"
Vintage Kawai Technics 10" Speaker Coax Coaxial for Organ Piano Bass Guitar | eBay
Vintage Kawai Technics 10" Speaker Coax Coaxial for Organ Piano Bass Guitar | eBay
wonder how much, a few hundred would cost ...
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some women are more exciting than others -
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Couple Climbs The HIGHEST CONSTRUCTION SITE IN THE WORLD 640M - YouTube
https://youtu.be/tlEyZDPaqiw
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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An externally hosted image should be here but it was not working when we last tested it.
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I have an old Makita power drill. The cooling fan broke and the variable speed is stuck at high. I took the controller apart and the sliding resistive element is missing. I don't know if it's possible to replace it with something or what resistance it would need to be but I believe I found the applicable patent:
https://patentimages.storage.googleapis.com/pages/US3327196-2.png
Makita 6406 3/8" Variable Speed Reversible Drill Parts | Tool Parts Direct
Maybe I could cut up a linear potentiometer?
The capacitor is 47nF and the SCR is marked 35-275.
https://patentimages.storage.googleapis.com/pages/US3327196-2.png
Makita 6406 3/8" Variable Speed Reversible Drill Parts | Tool Parts Direct
Maybe I could cut up a linear potentiometer?
The capacitor is 47nF and the SCR is marked 35-275.
Having a very good handsaw and understanding how to use it matters greatly. Some practice doesn't hurt either.
A lot of cutting that isn't very nice comes from a lack of knowledge on how to use the handsaw. I've seen amazing work with what people consider crude saws (large), that are sharp.
A lot of cutting that isn't very nice comes from a lack of knowledge on how to use the handsaw. I've seen amazing work with what people consider crude saws (large), that are sharp.
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Thanks guys. A well set up hand saw and some sharp chisels.
I was lucky enough to spend a couple years here- Woodworking school, furniture making classes in Boston MA » Full-time Programs » Education » North Bennet Street School I visited the school when a friend was attending and knew I had to go. It was a stretch financially... My wife had just finished grad school and we had our first child coming. Glad I did it.
Check out the violin making program. That is truly the coolest.
I was lucky enough to spend a couple years here- Woodworking school, furniture making classes in Boston MA » Full-time Programs » Education » North Bennet Street School I visited the school when a friend was attending and knew I had to go. It was a stretch financially... My wife had just finished grad school and we had our first child coming. Glad I did it.
Check out the violin making program. That is truly the coolest.