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Recent content by Lazzer408

  1. Lazzer408

    So you want PWM control of your 3-pin fan?

    It's going to be something along these lines. Not sure how it will work with the PWM signal being 5v but a low/hi signal driving this circuit will give you a low/hi out. Choose a Q1 large enough to drive your load, Choose R2 to drive enough current into Q1's base. Q2 should be large enough to...
  2. Lazzer408

    So you want PWM control of your 3-pin fan?

    High side switching via. MOSFET will require gate drive >12v. Use a BJT transistor. Because it's switched mode, losses are minimal. Typically (.6V*A)*PWM=dissipation. If you had 3 amps worth of fans (a lot), and PWM is 100%, you will only have ~1.8w of heat to dissipate from the transistor. I'm...
  3. Lazzer408

    So you want PWM control of your 3-pin fan?

    All of that had been mentioned in the thread.
  4. Lazzer408

    So you want PWM control of your 3-pin fan?

    The capacitor should be placed in parallel with your supply voltage. Duty cycle (pulse width) is controlled by the motherboard. If you can't adjust it in the BIOS then there's nothing you can do about it.
  5. Lazzer408

    So you want PWM control of your 3-pin fan?

    The PWM frequency is a function of the motherboard. All the board does is ground the PWM pin at varying widths. If you don't have complete control over the fan curves in your BIOS, this circuit may not work for you. The "correct" way to control a fan (using Intel's PWM spec) is a more...
  6. Lazzer408

    So you want PWM control of your 3-pin fan?

    Put your meter on AC and measure that charger. Read anything? If so, that's the ripple in the DC caused by the chargers lack of filtering (they don't need it). Next, place a capacitor in parallel with the charger and measure the DC voltage. Is it higher? If so, that's the peak DC voltage coming...
  7. Lazzer408

    So you want PWM control of your 3-pin fan?

    I think it's in quotes because we have no idea of knowing what type of charger it is. If it's a trickle charger for lead acid batteries, then it's likely much higher then 12v and it's not DC either. If the fans run full speed with the PWM unplugged, your gate drive is ok. What happens with you...
  8. Lazzer408

    So you want PWM control of your 3-pin fan?

    He mentioned in #79 that he tried the charger... "with a few Deltas and San Aces, 8 fans total, they all seemed to run full bore with no PWM connected". I think it's in his computer now.
  9. Lazzer408

    So you want PWM control of your 3-pin fan?

    Not a very good component but RDS(on) at 4v is .07 ohms so you 4.1v is plenty of gate voltage. NTE parts are junk (for future reference) but not the cause of your problem. The switching frequency is a function of the motherboard and should be around ~20khz. What do the fans do if you pull the...
  10. Lazzer408

    So you want PWM control of your 3-pin fan?

    Are you using a logic-level mosfet?
  11. Lazzer408

    So you want PWM control of your 3-pin fan?

    Which hurts who in what way? Information doesn't have a "sell-by" date. If people are still benefiting from the thread, it's not dead.
  12. Lazzer408

    So you want PWM control of your 3-pin fan?

    What's that have to do with anything?
  13. Lazzer408

    So you want PWM control of your 3-pin fan?

    Sounds like it's working fine. Good job.
  14. Lazzer408

    So you want PWM control of your 3-pin fan?

    Connect it to your 12v source. PWM lead should have ~5v on it. With PWM lead disconnected, the fan should run full speed. With the PWM lead grounded, the fan will stop. I'll look over your pics tonight. Velict's diagram looks fine other then the diode's anode connection doesn't have a dot...
  15. Lazzer408

    So you want PWM control of your 3-pin fan?

    Did you bench test it?
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