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  1. sureshot

    LM317 question.

    Ok thanks, i think the regulation is going to be less than perfect, but i've never put one of these simple series pass transistors together using the 2N3055, its a taste it and see thing i think to be honest. the diode at the ground pin on the 7812 is a 0.7 volts boost i think to replace what's...
  2. sureshot

    LM317 question.

    Save starting another thread, could I ask opinions on this circuit. It appears to be from a good source, I have a few value 78xx voltage regulators laying about. Its the output tolerance I was wandering about, and how much it might drop voltage under load. Thanks for any input on this question...
  3. sureshot

    LM317 question.

    Many thanks for the schematic, I will try both as a challenge. Thanks again to you all for the help.
  4. sureshot

    LM317 question.

    C Does this circuit look feasable to the more experienced ? I was thinking its capable of about 3 Amps at 12 volts.
  5. sureshot

    LM317 question.

    Thank you for the explanation, yes sorry my mistake typing 2k2 not 2200k yes my mistake.
  6. sureshot

    LM317 question.

    So my lower fixed resistor is 2200k so power dissipated 22uW .
  7. sureshot

    LM317 question.

    Thank you for the help, maths is not my strongest point lol, but I understand what you've laid out in a formulae. I'm looking at this simple circuit, but struggling with the transistors base. Most have a direct base resistor for series pass transistors, this one has me stumped to be honest.
  8. sureshot

    LM317 question.

    Merry Christmas to the Community, hope every one is enjoying the holidays. Just a quick general question on the popular LM317 voltage regulator. For better precision, can you use 0.25 watt +/- 1% metal film resistors for R1 and R2 or do they have to be 0.5 watts, which I can only get in +/- 5%...
  9. sureshot

    Pwm of regulated output.

    Thank you Harald for your help, much appreciated.
  10. sureshot

    Pwm of regulated output.

    Thank you Harald. I was looking to control the final 12 volt out put of a converted server psu. Putting the smps regulated voltage into the unit in the picture. It would be a model railway DC controller I would build with reverse toggle switch, making use of the few converted server power...
  11. sureshot

    Pwm of regulated output.

    I've never tried this, so just some advise if anyone can help. Can I pwm a smps using a pwm unit to control the smps voltage for DC motor control. All is 12 volts. Smps is a converted server psu, the pwm unit has a 2.5 - 35 volt input, load on the modual is 6.5 Amps maximum. Would the pwm unit...
  12. sureshot

    Converted atx psu whistle

    Thanks KrisBlueNZ for the very in depth explanation, I had an incling it might have been load but was just not sure. Its is in a cupboard at the moment so I don't notice the noise to much.This is a very cheaply made old atx, but thought a of some use rather than the bin, so first I will try and...
  13. sureshot

    Converted atx psu whistle

    Wander if anyone can throw some light on a converted atx PSU issue. OK so I followed the normal route and loaded the 5 volts rail with 10 ohms 10 watts resistor to use the 12 volts output, only there is an audible whistle, whilst it does not affect my use of the unit it is annoying, I have found...
  14. sureshot

    Resistance heater.

    Sorry on late reply internet connection problems, thanks for all your help guys, plan is a converted atx or large linear transformer, using a large car amplifier aluminium chassis as the heater with 4 x 50 watt power resistors running from 12 volts , current drain expected about 16 amps, i will...
  15. sureshot

    Resistance heater.

    Oh yes i see what you mean, at the max rating its stressing things a bit, Yes my diy bathroom heater as its a tiny room and 200 watts would heat it up in there, i could wire up to a thermostat, its just an idea and no mains voltage in the bathroom only lead in feeding 12 volts. Learned a bit...
  16. sureshot

    Resistance heater.

    Ah ok thank you Kris and Steve think i have it now, i need four 50 watt resistors at 2.88 to make the 0.72 value in parallel and get the 200 watts i need. Many tanks for your help.
  17. sureshot

    Resistance heater.

    So my working out is 4 x 0.75 ohm 50 watt resistors with 12 volts across the four parallel resistors dissipates 192 watts and draws 16 amps if i have it right looking to achieve 200 watts.
  18. sureshot

    Resistance heater.

    Thanks for your help Kris. So i need to lower the resistance to get the resistors power up really then, so resistors of 0.75 ohms should be ok for four 50 watt resistors i think, maths not my strong point.
  19. sureshot

    Resistance heater.

    Looking for some help if possible to building a resistance heater. Would i be right in thinking that four 12 ohm resistors in parallel will give me 3 ohms and with 12 volts an output power heater of 200 watts if my four resistors are 50 watts each. Any help appreciated, my issue is thinking my...
  20. sureshot

    Locking DC Power Socket

    Try XLR or XLR mini often used for low voltage dc locking as well. Also available in number of poles.
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