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  1. smokyLED

    unkown ic

    thanks for finding that.
  2. smokyLED

    unkown ic

    I'm trying to find a replacement for an IC in my frequency counter. It's a 8 pin DIP, and could possible be a opamp. But i'm not sure. I have googled but haven't had any luck. This is with is printed on the package: TFK 731 666 BS TFK666BS seems to be the product code. Thanks in advance.
  3. smokyLED

    Goodwill gfc-8100g frequency counter

    anyone have a user/service manual for this? my channel b shows random values even when there is no input.
  4. smokyLED

    heating ammonium/sodium persulphate

    what is the best way to heat up used ammonium persulphate? i store it inside a plastic bottle after using it, and i don't want to put it in the microwave.
  5. smokyLED

    Iron-on PCB's w/ photo paper

    i've tried the photo paper method, but fine traces doesn't stick to the pcb very well. transparency film work great though, as 98% of the toner comes off. all u have to do is touch up the missing traces with a pen.
  6. smokyLED

    0-24V 4A bench supply

    nah, the bands are correct, but the resistance was 2k ohm, even though it's a 1% tolerance resistor.... i'll remember to check resistors with a meter in future, instead of relying on the markings
  7. smokyLED

    How to Use a 555 Timer for PWM

    you should post of picture of the 15hp motor installed in ur car :D
  8. smokyLED

    0-24V 4A bench supply

    replaced the 10k resistors and it works now. what is the point of having TY1 and SW2, when TR4 already provides current limiting by shorting IC2's supply to ground. There doesn't seem to be any short circuit protection in this circuit... because when i short the output, current limiting kicks...
  9. smokyLED

    DC/DC Converter

    buck regulator or a flyback regulator with a  tl494 maybe?
  10. smokyLED

    How to Use a 555 Timer for PWM

    here's an example of a pwm to contorl a motor, http://www.dprg.org/tutorials/2005-11a/ otherwise the 555 datasheet might be useful, http://www.fairchildsemi.com/ds/NE%2FNE555.pdf
  11. smokyLED

    0-24V 4A bench supply

    pin 4 and 11 is connected. i get full rail voltage at pin 1, and  there is a voltage on pin 14
  12. smokyLED

    0-24V 4A bench supply

    yep, just what i thought. but it still doesn't work. i've triple checked the wiring and components and tried different LM324. still doesn't go high when there is a difference.
  13. smokyLED

    0-24V 4A bench supply

    I have built this circuit, and i can adjust the voltage and current correctly using the pots. However the current limiting and temperature cutout doesn't seem to work. I am getting no voltage at pins 7 or 8 of the LM324. PARTS TF1 230/24V 100VA transformer F1 1A fuse F2 6A fuse SW1 on-off...
  14. smokyLED

    LM317K regulator current problem

    thanks for all the help u've give audioguru
  15. smokyLED

    LM317K regulator current problem

    yea it's all good now. just needed a cap across the zener. i'm using a bridge rectifier instead of the 4diodes
  16. smokyLED

    LM317K regulator current problem

    got it fixed. stablized the zener voltage by sticking a 47uF cap across it
  17. smokyLED

    LM317K regulator current problem

    ok, it seems to work a little now. the input voltage slowly drops and the voltage across the zener slowly rises. didn't measure the voltage for long enough before to see this happen. but with only a voltmeter connected across the zener and ground, the voltage seems to drop by itself. once it...
  18. smokyLED

    LM317K regulator current problem

    i got 34V across C2, no voltage anywhere else
  19. smokyLED

    LM317K regulator current problem

    wierd thing about that circuit is that i'm not getting any voltage across the zener diode
  20. smokyLED

    LM317K regulator current problem

    oh, the whole circuit was powered by a bench supply @ 35V 2A (current limited) the -6v is fed from another 10v transformer feeding a 7805 regulator. the ground pin of the reg is connected to the -6v, and the output is connect to the circuit's ground. is there a better way to do this, like using...
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