Recent content by eggy1

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    0-30 Vdc Stabilized Power Supply

    I tried to build it, but...ha some troubles with programming atmega8 ( dil28 package) and finally voltage regulator 78L05 fried to short circuit...result? Atmega8 had 13V between Vcc and GND...it fried...haven't got new one yet. By the way....is it me, or the ISCP part of DIP package Atmega ( on...
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    0-30 Vdc Stabilized Power Supply

    End pins of RV1 are connected to pins 1 and 5.
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    0-30 Vdc Stabilized Power Supply

    Got mine working. Voltage is 0-30,0V. One problem remained...R2 is heating....quite fast, after few minutes I can also smell the resistor besides seeing it.
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    0-30 Vdc Stabilized Power Supply

    Actually transformer output has 25V AC before diodes and caps. After, 31V. Capacitors are 4x2000uFx50V. Have to test this 3A load part, but what do you mean by "without 100Hz ripple"? PS! Now the R2 is heating....even without op-amps... PS2! Voltage on U2 pin3 is varying from 5.1 to 16.4V not...
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    0-30 Vdc Stabilized Power Supply

    Okei, negative supply is now OK. I had some bugs with the AC wire from the transformer to R2. :)
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    0-30 Vdc Stabilized Power Supply

    Just to be sure....I have to measure it between pin 4 and...pin 7 or negative rail(the one with R7)? I know, but when D7 is reversed then current led will not light up when 1,5Ohm resistor is connected between output terminals of PSU. Its like Op-amps stops working.
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    0-30 Vdc Stabilized Power Supply

    Non of the diodes are connected reverse...when I revers any of[ D5,D6D7] diodes the current limit led stops working.
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    0-30 Vdc Stabilized Power Supply

    So, reversed D7. Voltage across it is 5.6V, but....voltage across pins 4 and 7 of U3 and U2 is ~5 volts lower than U1's voltage at the same pins...it should be higher, not lower, right?
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    0-30 Vdc Stabilized Power Supply

    Okei, Replaced Q4[actually connected wires to another transistor]. D10 was backwards...C2 and C3 seemed to be fine. I have replaced D5,D6,C2,C3,D7(R3 is OK, 230Ohms)...nothing-voltage drop across D7 is still  near 0.7V...all op-amps has same voltage across pin 4 and 7. At least one thing is...
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    0-30 Vdc Stabilized Power Supply

    Okei, I was away from the PSU for a while. Voltage at the pin 6 on U2 varies from 4,1 t o 26.6V when voltage pot is turned. Pin 6 on U3 does hold its voltage at near the power supply voltage. I tested opamps within one test circuit and the worked fine, so the should be alive.[atleast at the...
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    0-30 Vdc Stabilized Power Supply

    Yes it does. Nope
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    0-30 Vdc Stabilized Power Supply

    a little mistake by me: Voltage on pin6 of U1 is 11V... >>>and the slider of the pot should change from 0V to 11.2V.<<< Which pin voltage should it change?
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    0-30 Vdc Stabilized Power Supply

    I know that Q1 is for bringing output voltage lo. Base of Q1 is not short circuited to positive supply, only through r13 which is not connected at the moment. Let's assume that I remove Q1 temporarely, I loose thats protective idea in the circuit, BUT i should be able to chance output voltage...
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    0-30 Vdc Stabilized Power Supply

    Hi. I have just built the PSU but surprise-surprise it does not work. Output voltage of the PSU is constantly 33V. Voltage between pin4 and pin6 of u1 is chancing from 0 to 9.9V when turning voltage pot. I am using UA741 opamps. [+-22V] Voltage over pins 4 and 7 is 38V on U3 and U2. On U1 it's...
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