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x_dadu

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  1. one quastion pls, is there a problem if I use 390ohm for R1 ? I use that rezistor because I have just a 10kohm potentiometer and a 2,2k one. I use r1=390ohm and r2=10kohm pot. Is that ok ? If I use the 2,2k pot, I must use aprox. 100ohm for R1, it will be ok a 100ohm/0,5W ?
  2. ok thank you for answer but there sitll something that I dont like. I measure now the ripple on a 25ohm/18W rezistor with 20Vcc on it, riple was 20mV with 770mA trough the resistor. But when I rise the volotaje to 22 or more (25 is maxim with my 19vca traf) the riple was > 350mV. It seems that after 21 Vcc the ripple is rise imidiatly . What is hapaning with LM317 closer that the maximum output V? I also have the 10uF capacitor on ADJ and a 4700 on it input, but I put an 100uF at it output, is that ok?
  3. ok I understand that but if I put a paralel tranzistor, short circuit protection is still active ? What can u tell me about ripple output rejection ? how can I measure that ? I set output for 3Vcc and conect an lihgt bulb who draw 530mA from 317. On the osciloscop I se an ondulation of 15mV. Is it bad ? What level is good for riple ?
  4. I just made the power suply with LM317 - TO220 and the multi-mmeter from the 0-30Vcc power suplply link. I want to know if I can put two LM317 in paralel for more curent, if I need it and how can I connect them, pin to pin or how ...
  5. has someone redesign PCB for duble operational amplifier like MC34072 ? or even quad ? I can't find 34071 or TLE2141 in my place and OPA is to much expensive here ... but I have a few 34072 ...
  6. I just find out about multimmeter with Atmega8 and I'll do soon. After that i find out about this 0-30vcc psu and I see that is perfect for mai multimmeter :) but is something that i dont like : -with 24Vca transformer the Vcc result will be 34Vcc -D5-D6-C3-R3-D7 make a negative -5,6V power unit U3 and U2 are bouth powered between +34 and -5.6. Is'nt that 39.6 ? Is'nt that dangerous for TL081 who has 36 (+/-18in datasheet) up limit ? Or maybe something I dont get'it . Thk's
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