| Electronics > Projects, Designs, and Technical Stuff |
| My first power supply |
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| n3vti:
Your power supply looks awesome! Maybe I should get back to rebuilding mine at some point... need to get a bench first. |
| queennikki1972:
Treez the linked work great. Thank you |
| MarkF:
--- Quote from: queennikki1972 on April 29, 2019, 02:06:05 am ---Yes MarkF, its a small transformer and fairly low current I was thinking that too about using the 1n4000 series for the small power supply, but I did order some 1.5amp diodes today so I'll have them. I am taking notes on everything you guys have suggested. I have no need for the variable pots on this project as I have other power supplies on hand. And I read up on why you have a third binding post for earth ground and that chassis ground (ac ground )should not be same as - negative binding post by default. i hope I said that right. --- End quote --- Not exactly. You want "earth ground" and "chassis ground" to be connected together for safety reasons. Chassis ground being the metal enclosure you put your project in. You don't want any voltage on the metal enclosure. When you bring the earth ground to the front panel, you have the option to tie it to any of the other outputs as a reference. The "common ground" (labelled as such in my earlier drawing) is your circuit reference in most cases. Typically, people call it ground but it is floating and not tied to "earth" or "chassis" ground for most power supplies. If the common is left floating (i.e. the secondary transformer windings are NOT tied to earth ground), you can put multiple power supplies in series to create other voltages. In my triple supply above, you can tie the +5V COM output to +12V output. You would then have +17V, +12V and -12V outputs referenced to the +/- COM connection. |
| m3vuv:
why not go down the lm327 route with pass transistors? |
| ArthurDent:
MarkF – --- Quote --- You want "earth ground" and "chassis ground" to be connected together for safety reasons. Chassis ground being the metal enclosure you put your project in. You don't want any voltage on the metal enclosure. When you bring the earth ground to the front panel, you have the option to tie it to any of the other outputs as a reference. --- End quote --- Here is one of the first little supplies I put together a few decades ago that illustrates that above principle. It was just a small linear supply board with transformer that I removed from some piece of scrap equipment that put out a couple of hundred milliamps on each output. It was convenient to test small circuits so I added a switch for +/-12 and +/-15 VDC and built it into this small metal case. As you can see, the common for the 3 outputs is not connected to the earth/line/case ground but the ground terminal is available on the front panel. This project is old enough so it actually uses a line powered neon panel light and not an LED |
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