Im building a power supply from a L78S05, have it on the bread board all scoped up with a nice smooth output. I have two different types of heat sinks for the to-220 and another for the rectifier. From here on out, you will very quickly understand, I am as green as I can be...
The pins on both heat sinks are too big to fit in the perf board. Is drilling the perf board holes out a little more normal practice ?
Do I ground the heat sinks to offer additional shielding? There will be two, and Im not sure if there be any benefit to having them on opposite sides of the small board so that any rf is grounded by the heat sinks (as shields) while in an aluminum chassis. My gut is telling me it should be tied to ground on the secondary's center tap and that's all of the shielding I should need. But I also want to run the mains earth ground to that chassis. I want to make this a quiet and safe as I can, but all of the pieces of everything I have been learning wont quite fit together (yet)..
The pins on both heat sinks are too big to fit in the perf board. Is drilling the perf board holes out a little more normal practice ?
Do I ground the heat sinks to offer additional shielding? There will be two, and Im not sure if there be any benefit to having them on opposite sides of the small board so that any rf is grounded by the heat sinks (as shields) while in an aluminum chassis. My gut is telling me it should be tied to ground on the secondary's center tap and that's all of the shielding I should need. But I also want to run the mains earth ground to that chassis. I want to make this a quiet and safe as I can, but all of the pieces of everything I have been learning wont quite fit together (yet)..
I bought a small hardened steel PCB cutter from Maplin before it closed down to enlarge the very same type of holes .
For some strange reason on the web they only talk about using a drill , if that is all that is left then use a Dremel , I have two , easy to hold .
Usually the mains earth is terminated to a metal chassis near its input which would be the power supply input socket , I said "usually " some people have other ideas.
Yes earth the heatsinks at the ground/centre tap unless a metal chassis has already earthed it ?
All you have to worry about by enlarging the holes for the heatsinks is if the holes are near the edge of the PCB.
Got it ! -
Rapid 34-0600 Stripboard Cutter | Rapid Online
For some strange reason on the web they only talk about using a drill , if that is all that is left then use a Dremel , I have two , easy to hold .
Usually the mains earth is terminated to a metal chassis near its input which would be the power supply input socket , I said "usually " some people have other ideas.
Yes earth the heatsinks at the ground/centre tap unless a metal chassis has already earthed it ?
All you have to worry about by enlarging the holes for the heatsinks is if the holes are near the edge of the PCB.
Got it ! -
Rapid 34-0600 Stripboard Cutter | Rapid Online
Awesome.. after I posted I realized that there were not too many other options, and found a drill bit that was perfect, had at it and done.. But TY for responding and reassuring me I had the right idea... Reading and reading isn't the same as doing lol....
Check if the heatsink is insulated or at ground potential before you consider grounding it.
For most devices the heatsink tab is also joined to one of the device terminals.
If the heatsink is at a high potential, attach a warning label.
Use insulated mounting hardware if necessary.
Using perf board, ensure the heatsink tabs do not short your circuit - cut tracks as required.
That's from personal experience - I used software to lay out the board but didn't have a footprint for the heatsink and overlooked that it shorted the circuit!
For most devices the heatsink tab is also joined to one of the device terminals.
If the heatsink is at a high potential, attach a warning label.
Use insulated mounting hardware if necessary.
Using perf board, ensure the heatsink tabs do not short your circuit - cut tracks as required.
That's from personal experience - I used software to lay out the board but didn't have a footprint for the heatsink and overlooked that it shorted the circuit!
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