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rufinus's Achievements


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  1. D10 was shorted. Many thanks goes to audioguru, the man, who cares. Respect. Now i wont connect ammeter between emitter of Q4 and output. I will better use voltmeter to measure across R7. I did build one based on 7107 and it works fine (as a panel meter for this project). Now i have one more, also based on 7107, configured for 200mV full range and with a voltage divider at the input to have full scale of 20.00v. I guess, i can use it as ammeter if i measure voltage drop across R7? Another issue is grounding. Here in Germany we have a grounding pins on the plugs. Should i connect the common of the psu to the ground, or just leave it floating and ground only the enclosure?
  2. pin6 U3 31v pin3 U2 8v pin6 U2 3v base q4 0.5v base q2 0.7v all measurements with the load of 20 ohm without load, pin6 u2 is 25v
  3. Tried with 20 ohm. I did set voltage pot to 25v and current pot to half-way. When i connect the load, voltage drops to 0.6v and current is about 0.03-0.04 amps. Current and voltage regulation pots do nothing then.
  4. With the load of 1 ohm voltage stays at 0, it can not be regulated. Current pot is in the middle. LED is off. Voltage pot does not change anything. Current pot also does not change anything. There is no current regulation. Ammeter in the series with the load (1ohm) shows 0.03amps independent of current or voltage pot adjustment. Load resistor stays cold.
  5. Here are the voltages measured at U3 with the current pot half way, load on (680ohm): pins: 1 - -5.6 2 - 0v 3 - 1.48v (can be regulated with the current pot 0-3v) 4 - -5.6v 5 - -5.6v 6 - 31v 7 - 31,8v
  6. With the load of 1 ohm voltage stays at 0, it can not be regulated. Current pot is in the middle. LED is off. With the load of 680 ohm voltage can be increased to 17.6v and then stops, but LED is still off. Current pot is in the middle. LED goes on only when current pot is completely down. Both loads are cold. It looks as there is no current basically ???
  7. Hi audioguru. Thank you very much for your reply. Fuse is inserted straight after secondary winding before rectifier in order to protect the winding. It had a value of 2.5 amps and before everything was working excellent. I do have a 24v transformer and for building this psu i used your 24v mod parts list. So, do you suggest that D9 or U3 is dead?
  8. And here what i measured: pin4 (both) -5.65v; pin6 u1 +11.32v; pin6 u2 0~27v. LED goes on when there is a load and current pot is to minimum. Both Q4 seem to be ok.
  9. Finally i managed to put it all together. Everything was working fine. I connected 1 ohm resistor to the output and measured up to 2.5 amps through it. Voltage and current regulation was excellent. Then i decided to insert ammeter between emitter of Q4 and output, as audioguru suggested. And i got a blown fuse. After replacement, i can regulate the voltage. But with the same resistor connected voltage drops to 0 and does not regulate anymore. Current is something like 30 maA. :( Any ideas??
  10. OK, found the problem, now everything seems to be working. Q3 was bad somehow and had to be replaced. Thanx, audioguru! ;)
  11. Well, the problem is that the LED is constantly on!
  12. Just finished building mine!! But not without a problem. :'( Voltage regulation works fine, but current LED stays on all the time ???
  13. I just sampled some TC7107 from Microchip ;) I have some spare LED 7-segment displays, so i will try them first. But i still like the idea with PIC 8)
  14. Yes, thank you, audioguru, but i already saw it. It is based on a chip from Atmel plus it is a surface mount version of chip, which will be difficult to mount for beginners. I work with PICs and program in PicBasic. There is no sourse code for development and in general schematics and project are not very clear, at least for me.
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