Recent content by Tintin

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    0-30 Vdc Stabilized Power Supply

    I, I had the same problem of you. To fix it, make a minimum load with resistor. For me a 25mA load was the minimum to decrease this. See there :  
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    0-30 Vdc Stabilized Power Supply

    Hi, as promised I made an English translation of my working. Maybe there is few mistakes and I am sorry for that ! Good reading.
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    0-30 Vdc Stabilized Power Supply

    Hi, I just finish my power supply ;) ! I made a PDF document (with a lot of picture and explanation) who resume all the story about this adventure, and made a lot of measurment ! It is in French but I will translate in English soon. I thank all this community, who made a great job ! I...
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    0-30 Vdc Stabilized Power Supply

    Hi Audioguru, Sorry I do not understand your last phrase " The opamp used for U3 and the negative supply voltage must be allow the output of U3 to go low enough so that the input to the output amplifier is shorted to 0V when the output of the project is shorted. Then R7 is the load. " If my...
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    0-30 Vdc Stabilized Power Supply

    Ok finally I test limited current and the voltage above R7  with 500mA is 165mV and 313.8mV with 1A. I measure with milliohmeter and I have 430mR for R7. I don't understand why the voltage drop is not 0.43*0.5=215mV and 0.43*1=430mV ? So I make some test : a) For max 3A output with Pot2 max I...
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    0-30 Vdc Stabilized Power Supply

    I find the problem of the fallen voltage, it is due to a Fucking wire like this who have a 2.8 ohms resistor :mellow: : So I can test now the current limiter function correctly !
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    0-30 Vdc Stabilized Power Supply

    If my theory is good, the wire between output and banana plug have a resistance of 2.82R. How to calcul it : R1=U*R2/U2 - R2 R1=5V*10R/3.90V-10R=2.82R. That explain : a) why the chinese voltemeter "see" 5V and not 3.90V after bananaplug B) why with 10R load for 5V =>3.90V at output...
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    0-30 Vdc Stabilized Power Supply

    Oh I measure without my my chineese multimeter and so I have 3.90V on the 10R charge load. I decided to measure voltage directly on the output of the PCB and surprise I have 5V ! So I think It was the cable between the negative output and the banana-plug who make this voltage fall ! Sorry...
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    0-30 Vdc Stabilized Power Supply

    So I make my measure and this is result : 1) If a have no load (D is my ground) : -UR7 (U_CD )= -12.6mV -U_AC= 0.745V with RV3 set  to 100K -U_AC=2.47V with RV3 set to 0K -U_BD=11.7mV -U_BC= 24.8mV (11.7-(-12.6)) If I put a 10R load for 5V to output : -UR7=-115mV, so...
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    0-30 Vdc Stabilized Power Supply

    Ok thanks Audioguru for your explanation, I wil take measure but I have one questions : When you write on shematic +1.41V above R21, it is between Circuit OV, not the output ? I wonder if the ground have to be before or after R7 ? Is there any importance ?  
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    0-30 Vdc Stabilized Power Supply

    Hi, I made a lot of test yesterday and it's works fine, i.e it could deliver 3A <20V, 2.5A<24V and 1A to 30V. It's ok for me, I thinks what did you say and maybe I will buy a 28VAC 160VA toroïdal transformer. So I test for ripple  voltage for 5V 1-2-3A, and it was pretty good. I test...
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    0-30 Vdc Stabilized Power Supply

    Hi audioguru, You are right with the fact with 27VAV =>  44VDC after bridge rectifier is not normal, even without a charge. My hypothesis is on my PCB : -we see the wrong side of the things : maybe it is not the V+ who go up to 44VDC but the V- who go down to -8VDC when there is no charge...
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    0-30 Vdc Stabilized Power Supply

    Ok, finally I replace R1et R1-1 (1K+1K2) by two 2k2 1W in // and it's works very well. The first test are pretty good. If you want I made a final review when I will finish my Power supply ;) . The odd things is the fact that the transformer need a small charge (not too small - 30mA) on PCB to...
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    0-30 Vdc Stabilized Power Supply

    Hi : I am not sure if you understand my problem : I measure Voltage on the PCB without AOPs and Transistor, to make sure all is ok before put the AOPs. The voltage I give is on The collector of TIP3055, just after the KBK. 1)My transformer is not cheap : I test him on breadboard with same...
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    0-30 Vdc Stabilized Power Supply

    Hello, I make a PCB with this schematic, with a 24VAC transformer, who give normally 36VDC after main capacitor. I test my PCB without AOPs and Tmain transistor (BD139 and TIP3055) and I measure Voltage after main capacitor C1 : -The voltage start to 36VDC and grow up to 44VDC and stabilize...
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