The 7812 is for the heaters? It'll be fine. If you're building the power supply in a metal chassis, it can usually just be bolted to the chassis. I have some MC29300 which would work better IMHO. I also have some heatsinks that should do the trick. I have LR8, too, and they don't require a heatsink.
Thanks for the Input guys. Koda yes the 7812 is for the heaters.
You can see the schematic on post 20 of this thread.
I haven't decided if I'm going to use a board of some sort to mount these components any advice?
I still have a piece of Vero board i can use. Eli thanks for the link on the heat sink type device. Any advice regarding selecting Capacitors?
You can see the schematic on post 20 of this thread.
I haven't decided if I'm going to use a board of some sort to mount these components any advice?
I still have a piece of Vero board i can use. Eli thanks for the link on the heat sink type device. Any advice regarding selecting Capacitors?
> schematic lists a 25vdc. Is it OK to put a 400v part or more?
Have you checked size and price??
4,700uFd @ 400V seems to be $40-$80 and as big as a can of soup (76x115mm).
4,700uFd @ 25V seems to be $2-$5 and can be size of a thumb, 16x40mm. (1/64th the volume)
While I do believe in using an 8-inch tree-trunk where a 3-inch post would do the job, I would not use a 24-inch trunk. (I have a couple laying around.) If nothing else it takes-up good space for no great advantage.
There is also an old-tech's belief that a way over-volted Electrolytic which never gets anywhere near rated voltage will "decay" and lose uFd value. There is a documented case from ~~1960 where this happened in a production run. That may be a fluke and caps have got much better. We routinely use 50V in 1.5V jobs when the size/cost is too small to justify anything less. But 400V in a 9V job seems absurd.
(While doing my homework I found a $3 "4700UF 400V" on Mouser. And film! Turns out someone screwed-up the listing: 4700nFd, not uFd.)
Have you checked size and price??
4,700uFd @ 400V seems to be $40-$80 and as big as a can of soup (76x115mm).
4,700uFd @ 25V seems to be $2-$5 and can be size of a thumb, 16x40mm. (1/64th the volume)
While I do believe in using an 8-inch tree-trunk where a 3-inch post would do the job, I would not use a 24-inch trunk. (I have a couple laying around.) If nothing else it takes-up good space for no great advantage.
There is also an old-tech's belief that a way over-volted Electrolytic which never gets anywhere near rated voltage will "decay" and lose uFd value. There is a documented case from ~~1960 where this happened in a production run. That may be a fluke and caps have got much better. We routinely use 50V in 1.5V jobs when the size/cost is too small to justify anything less. But 400V in a 9V job seems absurd.
(While doing my homework I found a $3 "4700UF 400V" on Mouser. And film! Turns out someone screwed-up the listing: 4700nFd, not uFd.)
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Choosing components seems to be just as hard if not harder than putting them together. At least it is for me, there's too many options and specifications. Also figuring out the Mouser search tools is tricky.
Yes a cap that's the size of a soup can would be a problem.
OK so 25vdc it is for the electrolytic caps. How about for the film caps the Metalized polypropylene (MKP) seem to come in high voltages. I'm looking at a 1.0 uF that's
630vdc. ECW-FD2J105KC Panasonic | Mouser Canada
would this be OK for the 12v area?
Yes a cap that's the size of a soup can would be a problem.
OK so 25vdc it is for the electrolytic caps. How about for the film caps the Metalized polypropylene (MKP) seem to come in high voltages. I'm looking at a 1.0 uF that's
630vdc. ECW-FD2J105KC Panasonic | Mouser Canada
would this be OK for the 12v area?
The least expensive 1.0 μF. MKP part Mouser carries that's suitable is this. The WVDC is way higher than needed, but "better to looking at it than looking for it".
As the part in question is in the 12 VDC heater supply, worries about HF linearity are not present.
It's time to go "Cheap Charlie". This part saves a few cents (BFD), but the space it saves is consequential.
As the part in question is in the 12 VDC heater supply, worries about HF linearity are not present.
It's time to go "Cheap Charlie". This part saves a few cents (BFD), but the space it saves is consequential.
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Hey Eli,
Would the first cap be suitable for the 250v section?
ECW-FE2W105K Panasonic | Mouser Canada
For the 330pf in the 250v section I picked
BFC237540331 Vishay / BC Components | Mouser Canada
For the .33 uF in the 12v section i picked
ECW-FD2J334JB Panasonic | Mouser Canada
Do these look like good choices?
Would the first cap be suitable for the 250v section?
ECW-FE2W105K Panasonic | Mouser Canada
For the 330pf in the 250v section I picked
BFC237540331 Vishay / BC Components | Mouser Canada
For the .33 uF in the 12v section i picked
ECW-FD2J334JB Panasonic | Mouser Canada
Do these look like good choices?
Attached is a BOM for the power supply components. I used a homemade printed circuit board for the PS, but point to point may be possible, or a perfboard for the parts with PC mount leads. I also tried to stick with Mouser, but Digikey and Allied have some of the parts in other brands.
I didn't need heat sinks for the small high voltage regs. They hardly warm up at all. The 7812 has a TO-220 Rat Shack heat sink with a mica spacer. It does get a little warm, but not hot at all. Heat sink parts are not on this BOM.
Sorry for some minor typos in the text around the parts. The part numbers should be accurate. Prices and part numbers are valid as of today. Surprising how some prices have dropped since 2009, and others are only slightly higher!
Jeff
I didn't need heat sinks for the small high voltage regs. They hardly warm up at all. The 7812 has a TO-220 Rat Shack heat sink with a mica spacer. It does get a little warm, but not hot at all. Heat sink parts are not on this BOM.
Sorry for some minor typos in the text around the parts. The part numbers should be accurate. Prices and part numbers are valid as of today. Surprising how some prices have dropped since 2009, and others are only slightly higher!
Jeff
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