I haven't built up an LM4780 amp in a while, and was wondering what people are currently using to isolate the chip.
Previously, I bought some big sheets of insulator material and cut them for the strange sized package, but would rather find something made for this task, vs buying a big sheet.
What are others using?
--
Brian
Previously, I bought some big sheets of insulator material and cut them for the strange sized package, but would rather find something made for this task, vs buying a big sheet.
What are others using?
--
Brian
I bought a sheet of non-pressure sensitive Kapton (polyimide) on eBay for about $5 and I cut out appropriate-sized pieces and use it like mica insulators, with grease. It's nice to work with since it just cuts like a thin plastic (which it is) with scissors.
..Todd
..Todd
taj said:
I've got similar stuff but I'm flummoxed as to how to make a hole in it. Cutting is easy - the hole is not.
What are you using?
I go bare onto the heatsink for open chassis amps.
For closed chassis, I use Mica insulators used for TO3 transistors. There is no other option available here. Scissors are used to shape the pads, and a small needle makes enough of an ingress for the bolt to spear through. I also divide the insulator: One can easily yield three. Thermal transfer is excellent this way.
We have suppliers who deliver custom shapes for bulk orders, and of good Indian Mica. They tend to be very thick however. I am sure other grades exist, but those are not commercially available. Splitting the mica works fine, but requires a new insulators if taken apart, as it is pretty fragile like that.
For closed chassis, I use Mica insulators used for TO3 transistors. There is no other option available here. Scissors are used to shape the pads, and a small needle makes enough of an ingress for the bolt to spear through. I also divide the insulator: One can easily yield three. Thermal transfer is excellent this way.
We have suppliers who deliver custom shapes for bulk orders, and of good Indian Mica. They tend to be very thick however. I am sure other grades exist, but those are not commercially available. Splitting the mica works fine, but requires a new insulators if taken apart, as it is pretty fragile like that.
MJL21193 said:
aaa this is very very easy ....the only thing you need to do is to go in a belt shop there you can see the tool they use to make holes in leather belts .... you may buy one of them and they are really nice to use ...( comes with a various holes ) and also very very cheap
regards
sakis
That tool does not always work well, a lot depends on quality and sharpness of the tubes:
You can make aluminum template and drill the holes through (a wooden base required); that produces most accurate and clean holes.
An externally hosted image should be here but it was not working when we last tested it.
You can make aluminum template and drill the holes through (a wooden base required); that produces most accurate and clean holes.
If I had one of those hole punches, I couldn't find it in any case.
Here's a simple scheme... Find a piece of tubing who's ID matches the size of the hole you want. Grind the edges so it's sharp on one end... bevel them to form a knife edge. Add a hammer to the equation.
Can't find a piece of tube? Drill a hole axially into a piece of steel... doesn't have to be very deep. Sharpen.
Can't find a drill or piece of steel?
Consider golf or horseback riding.
Here's a simple scheme... Find a piece of tubing who's ID matches the size of the hole you want. Grind the edges so it's sharp on one end... bevel them to form a knife edge. Add a hammer to the equation.
Can't find a piece of tube? Drill a hole axially into a piece of steel... doesn't have to be very deep. Sharpen.
Can't find a drill or piece of steel?
Consider golf or horseback riding.
Or, use a razor to cut a X shape at the bolt hole. When you thread the bolt, the flaps just fold out.
AndrewT said:
That's exactly what I did. I used these:
K10-105
The two holes just barely imping upon the top corners, and they worked quite well.
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