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I put a 4.7K resistor in each output and it came out good, now it's +12V and -12V and no heating, I'll do a PCB and post the results later, thanks guys!
D2 was already inverted dselec, I forgot to make that clear. I checked the voltages in the transformer and in the diodes and it seems to be working properly, 13.5Vac each side and 27Vac between extreme wires. In the anode of d1 and tap centre there's 15.7Vdc, and in the cathode of d2 and tap...
Now I put a 1K resistor instead dselec, and following your diagram without ic2. I checked the input voltage between d1 cathode and gnd and is 15.7Vdc, so I guess that's good. Then I measured the voltage in c2 and this is -5.7Vdc. are these values expected?
dselec, I've tried your way, first i took off ic2 and put a 330 ohm, 1/2W resistor between pin 1 and pin 2 of ic2(already taken off of course), but it gives me -10Vdc aprox (black lead in pin 1 and red one in pin 2), and the resistor gets really hot pretty soon, and there is 0Vdc in the output...
dselec, in your diagram you're connecting pin 1 from the 7812 through a resistor to the pin 1 of ic2, and also pin 2 from 7812 (GND) to ic2's pin 2, is that right? ... I don't understand quite well why are you doing that, if you could explain it I would really apreciate it.
Yes alexan_e, I also measured the AC voltage in the output of the 7812 and it is 19 Vac, in the input there's 24.5 Vac... now I'm a little confused because I expected a lower value ...anyway ...I imagine there should be a similar value between pin 3 and pin 1 in the 7912 but it gives me 0Vac. In...
I tried what you said dselec, I took off the 7912 and then I put a 330 ohm resistor between the spots where were pins 2 and 3 of the regulator. It gives me -18Vdc aproximately. It seems that the transformer is working properly, at least I think it does... About the dropout that I mencioned, is...
Thanks dselec, I saw your drawing, I took that in consideration for regulator conections. It doesn't really get hot alexan_e, it gives me low voltage only. I measured the center tap - end transformer wire and it's 13.5 VAC, which I think is OK. Also i measured 0VAC in the output (where is...
oh, I misunderstood ... sorry about that... I took off the 7912 and checked the voltage in the diode's anode that was connected to it and is -18Vdc aproximately. Then I put back the regulator and measured the voltage in the input of the 7912 regulator and it is -6.3 Vdc.
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I've checked the input in the 7912 and is just -6.3 Vdc. Maybe as you said alexan_e I damaged the regulator. Is that the only possibility? I'm gonna get a couple of 7912 right away :)
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I've just checked only the...
I've checked the input entrance of the 7912 and its only -6.3Vdc, also I checked the transformer voltage and is still 14-0-14. ... Maybe I've damaged the 7912 as you said alexan_e . Sadly I don't have another regulator, I'll try to get one as soon as I can!
Thank you guys for your reccomendations. alexan_e, I inverted the diode you told me and dselec I connected the center tap, now from the 7812 I get +12V and from the 7912 I get -4.6V. Is there any way I can get -12V from the 7912?
Thanks for your reply dselec, I didn't use a bridge rectifier because I'm using low currents (max = 100 mA). If I connect the tap centre is not gonna heat the circuit? for an overcurrent maybe? I hope you can clear me that up please, I't the first time I'm doing a power supply.
Now I'm just trying with both 7812 and 7912, I'm using TO-220 plastic package dselec. Also I should have said that is a L7912CV. I forgot to change in the scheme I provide that is 7812 and 7912 instead of 7815 and 7915.
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