| Electronics > Projects, Designs, and Technical Stuff |
| I have a short ( i think) and don't know where to start |
| << < (5/13) > >> |
| Mechatrommer:
--- Quote from: james_s on December 17, 2018, 02:25:00 am ---and you'll have some time to take measurements.. --- End quote --- did he make any? what his multimeter (continuity tester) told him? |
| Hextejas:
This is strange. I am using a benchtop power supply ( ps ), a GPC3020, that can put out 0-35v DC. I have it set to 20v and this is what happens. It has 3 output connections. (--- GND +++) I connected the +++ to U1 and when i connected the --- to U2, the ps blinked and turned off the C.V. led and turned on the C.C. led. I think that it means it switched from constant voltage to constant current. I don't know if that was good or bad and the implications. Anyhow, what measured 20Vdc before now measures a lot less. I am thinking I need to do something to fix that. Secondly, when I try the same thing with U4 +++ and U3 ----, the ps stays at CV (20v8 dc), but none of the output shows any voltage. Let me see if I can find a 1N4148 or some such. |
| Hextejas:
Whoa, I found a tube of 8, MUR860s :-DD so here we go. |
| sokoloff:
--- Quote from: Hextejas on December 17, 2018, 02:43:53 pm ---This is strange. I am using a benchtop power supply ( ps ), a GPC3020, that can put out 0-35v DC. I have it set to 20v and this is what happens. It has 3 output connections. (--- GND +++) I connected the +++ to U1 and when i connected the --- to U2, the ps blinked and turned off the C.V. led and turned on the C.C. led. I think that it means it switched from constant voltage to constant current. I don't know if that was good or bad and the implications. Anyhow, what measured 20Vdc before now measures a lot less. I am thinking I need to do something to fix that. Secondly, when I try the same thing with U4 +++ and U3 ----, the ps stays at CV (20v8 dc), but none of the output shows any voltage. Let me see if I can find a 1N4148 or some such. --- End quote --- A typical bench power supply will supply a set voltage or a set current, whichever is less. If you set it to 20V and a max of 100mA, it will provide 20V and 0mA when not connected to anything (and will be in "constant voltage mode"). If dead shorted, it will supply 100mA and way less than 1 volt. (It will be limited the voltage to whatever can push 100mA through the short. This is "constant current mode".) In your case, it's telling you that you have a very low resistance path (maybe a dead short) on the U1/U2 side. --- Quote from: Hextejas on December 17, 2018, 02:43:53 pm ---I am thinking I need to do something to fix that. --- End quote --- Yes. Find the short. :-DD |
| Hextejas:
Well, I found a 9v AC wall wart so here goes. Hmmmm, how do I wire this ? I have the 2 wires coming from the wall wart and I need ac1, ac2, and 0v1 and 0v2 ? Where do I get 0v ? And thank you very much sokolof. I wondered how that worked. |
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