Recent content by Spagbol

  1. Spagbol

    Switching charger for SLA battery

    Unitrode produce a switch mode IC specifically for Lead acid charging, the bq2031. If you still want to use one of those PWM ICs you mention you could always have a look at the application note for the bq2031 to see how it works: http://focus.ti.com/lit/an/slua017/slua017.pdf
  2. Spagbol

    0-30 Vdc Stabilized Power Supply

    Presumably output taken from top of C7 in new circuit rather than emitter of Q4, just to clarify.
  3. Spagbol

    0-30 Vdc Stabilized Power Supply

    Not sure I understand about Q1s emitter, looks ok in original cct to me. It is a safeguard against there being no -5v rail isn't it? So when there's no -5v the transistor (Q1) conducts and pulls U2 to ground so there's no drive to the output transistors??
  4. Spagbol

    0-30 Vdc Stabilized Power Supply

    Aha, suppose I must read thru the thread again. Nice photos by the way, I've never made a PCB before but maybe I will try it.
  5. Spagbol

    0-30 Vdc Stabilized Power Supply

    What's the Q2 emitter modification you mention? I've skimmed this thread, maybe I missed something? I've built the Op-amp bits with a pair of TL082s with their supply rail clamped at 22v by a zener. So far so good, but not sure how to change the output stage to give it some voltage gain...
  6. Spagbol

    LM317 Variable power supply

    Could try putting a bulb in series between the rectifier/cap and the regulator. (eg a 12v/21w car brake bulb?). Shouldn't affect the cct at low current but if you get a short it'll light up and take some power away from the regulator!? Haven't tried it mind....
  7. Spagbol

    0-30 Vdc Stabilized Power Supply

    Sallala, before you blow up another transistor...... If you test with a 1 Ohm resistor at 2-3 volts as you say, the 2N3055 will have to disspate a lot of power! (~100W!!) You really need to use more than 1 2n3055 (like in the cct in the thread for the 5A version) and they will need a very...
  8. Spagbol

    LM317 Variable power supply

    Don't forget the diodes in a bridge only conduct up to 50% of the time, halving the average current, so you might get away with 1n4000s, wouldn't use the 4001s though as they'd only be good for about an 18v supply!
  9. Spagbol

    0-30 Vdc Stabilized Power Supply

    Hi all, I like the design for this PSU and would like to build it, but with some changes. It seems only U2 needs a high supply voltage to drive the output to 30v, U1 & U3 would be happy with a lower supply voltage. I'm wondering about changing the transistor o/p stage to have a voltage...
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