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  1. Alec_t

    Basic voltage divider question

    This would give you a +5V to -5V swing, provided the load on the pot wiper is small (say 100k or so) :-
  2. Alec_t

    Strange battery behaviour in portable radio?

    IIRC, early DAB radios generally gobbled batteries faster than traditional AM/FM radios. Don't know if that's true of modern radios. But yes, sounds like bad batteries. They might not have liked being run down to 0.5V.
  3. Alec_t

    Boosting the Amper and altering the frequency

    The battery discharge time will depend on the current, which in turn will depend on wire gauge, how long each wire is, how many wires altogether, and whether the wires are in series or parallel.
  4. Alec_t

    Boosting the Amper and altering the frequency

    I think that's to stimulate the bees into ejecting venom. I'm guessing resistance wire (nichrome?) is used mainly for its weather-resistance and the heating effect is a secondary property?
  5. Alec_t

    Boosting the Amper and altering the frequency

    That's useful info. Glass isn't conductive. What sort of electrodes will you use? Is the 0.2A-0.6A flowing through the bees? if not (seems unlikely), where is it going?
  6. Alec_t

    Boosting the Amper and altering the frequency

    Is your "XL6009E1" a regulator module, or just the bare IC? If a module (most likely), can you post a link to it? 100% is not really PWM; it's plain DC. If you want pulses, 50% would be better.
  7. Alec_t

    Boosting the Amper and altering the frequency

    Doesn't sound right. Which pin? That IC has a single feedback pin. The pin voltage is compared internally with a 1.25V reference for adjusting the output voltage of your DC-DC voltage converter. I doubt the output voltage could be modulated at 1kHz. Edit: The 100n output cap typically used with...
  8. Alec_t

    Convert 12v a switched ground (-) sensor signal to switched +12v signal. (Automotive)

    Looks workable now.
  9. Alec_t

    Convert 12v a switched ground (-) sensor signal to switched +12v signal. (Automotive)

    Welcome to EP! Do you have a datasheet for the IFR9Z30? Is it a P-channel MOSFET?
  10. Alec_t

    Instantaneous charge state of supercapacitor detection

    How about this (assuming the threshold levels aren't too critical)?
  11. Alec_t

    Seeking help with 12v dc motor controller on golf buggy #2

    I'm not familiar with that controller board, but I would guess Q1 and Q2 are power MOSFETs and D1 is a power diode (or pair of diodes in one package). Perhaps another forum member knows that board and could confirm. It is quite common for MOSFETs to fail short-circuit.
  12. Alec_t

    Happy new year

    I second that.
  13. Alec_t

    Seeking help with 12v dc motor controller on golf buggy #2

    Welcome to EP! It sounds as though either Q1 or Q2, or both, could have failed short-circuit. Note that they, and D1, all need to be in good thermal contact with their heat-sink(s).
  14. Alec_t

    Ebike motor controller

    Enjoy the build.
  15. Alec_t

    Ebike motor controller

    For a DIY build, something based on the circuit in your first post should work for a brushed motor, but it would probably be simpler and cheaper just to buy a suitably rated brushed motor controller from an online source. I'd go for one rated at >30A
  16. Alec_t

    Ebike motor controller

    Any other markings on its name-plate? Amps, Watts, HP, ...? Does it have brushes?
  17. Alec_t

    Ebike motor controller

    Is that the normal running current or the stall current? The latter might be ~ ten times the running current of a brushed motor. Depends on motor type, which you haven't specified. What motor supply voltage will you use? Are you aware of the legal requirements for e-bikes in your country?
  18. Alec_t

    Ebike motor controller

    Brushed or brushless motors? Brushless with internal commutation may not play nicely with external PWM. You probably want a FET with lower Rdson resistance than IRF540, to handle high motor currents.
  19. Alec_t

    Any infos on µA circuits?

    The circuit I provided is a standard constant-current configuration. Nothing novel apart from the choice of components to try to meet the low current and small size conditions. I doubt there is anything easier. Instead of a button cell you could use a couple of AAcells, but even a small button...
  20. Alec_t

    Any infos on µA circuits?

    What is the maximum tissue resistance likely to be? If you must keep the voltage across the sample below 1V then the maximum resistance dictates the maximum allowable current, as per Ohm's law. Edit: In my previous post the reference to MAX4006 should be corrected to MAX40006.
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