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paul .a larner

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  1. its this schem,except im using a 5.1v zenner for the -v supply not the regulator+ im using the mc34071 opamps.,in supposed cc mode the led lights but i can still increase the voltage and the output waveform is horrid,full of spikes,they increase in amplitude as i rotate the voltage pot cw ie increase the voltage,its fine in cv mode. also i dont have the opamp etc on the top portion of the schematic
  2. any idea why i can still increase the voltage after the cc led lights and the output of u3 goes high?,ive checked d9 its ok.
  3. Hi all,ive built this but have issues with current regulation,ive added another led as well fed frompin 6 of u3,its a dual colour led,fed fromq3 its red indicating cc and from u3 pin 6 its green indicating cv,when i load the output and turn my current pot ccw untill the led turns red,ie cc,i can still increase the voltage using p1,im using MC34071AP opamps,d9 is fitted good and works,any ideas?,also when in cc mode if i wind p2 ccw(its a 10k 10 turn pot,about 1/4 turn from the end the voltage suddenly jumps up by about 3 volts,thanks in advance.
  4. well i found d7 shorted,that fixed the u2 getting hot+low output issue,only trouble is now is with the current regulation,its like all or nothing,when it goes into cc mode,if i wind the volt pot ccw the led stays lit,funny tho as it still lets me turn the voltage up when in indicated cc mode,r18 is 33k.
  5. ive built this psu,when q1 is connected u2 gets hot+ output drops to 0,if i cut the emitter of q1 it seems to work ok,any ideas,btw in cc mode i get a spike on switch off,in cv mode its fine,cheers in advance.
  6. heres a better schematic i hope,the first is the same as mine,my rv1 is 5k,2nd schem is origina,also i still have q1 in my version,should i remove it?,cheers m3vuvl. heres a better original version
  7. ive built this psu as per the schematic,the issues i have are,the output is 30v with the voltage pot fully ccw,if i turn the current piot almost fully ccw the output drops to 0 with the led on,if i turn the current slightly cw it oscillates from 0v to 30v about every 3 seconds,the led flashes in time with this also,im using mc34071 opamps ,the only thing i havent changed is d7,its stil the 5.1v zenner,q2 is a bd137 and im using 4x 2n3055 pass transistors with 0.1r emitter resistors,any ideas on whats causing this wierd behaviour?,cheers m3vuv.
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