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  1. Alec_t

    MOSFET PWM Circuit Not Working

    Bear in mind that the starting/stall current of the motor could be ~ ten times its normal running current.
  2. Alec_t

    Low cycle Pulse generator ?

    It can pull its output almost to the +ve rail. It draws less current. The disadvantage is that it can't source or sink as much current as the bipolar 555, so will probably need a transistor to drive an automotive relay coil.
  3. Alec_t

    Help Needed Electric Motor

    One of these might be suitable as a replacement.
  4. Alec_t

    Low cycle Pulse generator ?

    So you want a single 1S pulse to occur during cranking. How soon after starting cranking should the pulse occur?
  5. Alec_t

    Reaction Game

    That should work. Be sure to use very robust momentary switches as input devices. Kids can be very enthusiastic/destructive :D.
  6. Alec_t

    Help:Locating break in electric cable

    Personally, I'd cut off about 10-20 cm from each end and test the remainder for continuity. If no continuity then I'd scrap the cable, on the basis that the wires have probably been stressed so may not be safe to use (through work-hardening, embrittlement, partial fracture). Even if you could...
  7. Alec_t

    Water detector with NE555

    Yes. Brain phart.:D
  8. Alec_t

    Water detector with NE555

    Your maths looks about right (I haven't checked it fully). From the Vo2 values you can see why Q1 turns off when Q2 turns on. For this purpose you don't need to worry about actual hfe values (which can vary quite widely from 'typical' values quoted in datasheets). Assuming a notional 100 would...
  9. Alec_t

    How do I add a wireless controller to a PWM box?

    How good are your mechanical skills? One option would be to drive the PWM-control pot mechanically with a RC servo.
  10. Alec_t

    Water detector with NE555

    In that case I'll give a hint rather than spell things out in full :). Consider R7,R8,R5 as a potential divider. Calculate/estimate the voltage at the base of Q1 (in my add-on), when Q1 (in your circuit) switches on/off. Sorry about the duplication of transistor designations.
  11. Alec_t

    Astable timer with nmos

    You already have an explanation on the AAC forum.
  12. Alec_t

    Vibration/shake switch

    Sorry. Don't know. I've never used one. You would have to check the datasheets of likely candidates.
  13. Alec_t

    16 mm sound troubleshooting (no sound)

    Welcome to EP. I'd suggest the first steps would be to 1) check that the voltages at the secondaries of the mains transformer are reasonably correct (taking care to keep well clear of the LIVE primary side of the transformer), 2) identify the various power rails on the pcb and see if their...
  14. Alec_t

    Water detector with NE555

    No probs, Chris. It must be a self-contained buzzer, since it's being pulsed at only about 1Hz.
  15. Alec_t

    555 on/off circuit for 5v motor (w/ schematic)

    Simply disconnecting tpin 4 won't reset the circuit. It needs to be pulled down to < ~0.7V for that. Power-up reset is often used with 555 circuits to ensure they start up in a known state. It's not used in your circuit.
  16. Alec_t

    Vibration/shake switch

    A sensor such as this could be used to trigger a latch, which in turn would control a transistor to turn you device on/off. Instead of the vibration sensor you could use a reed switch and magnet, perhaps. So how will you recharge the battery?
  17. Alec_t

    Water detector with NE555

    Glad it's now doing what you want.
  18. Alec_t

    Cheap Motion sensors , chinese I think

    According to the ebay listing the delay time is "60-120mS*. Do you believe that? My guess is that either of the two electrolytic caps nearest to the PIR sensor is the timing cap. You could try substituting a lower value cap.
  19. Alec_t

    USB Microwave Radar Trigger

    Welcome to EP. Did you find these HB100 modules in your search?
  20. Alec_t

    Power Amplifier for thermoelectic cooler with Op-Amp and Power MOSFET PROBLEM

    No. If it did you would have 0A or 6A (too much for the power supply). Instead it provides proportional/linear control of the current.
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