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  1. Alec_t

    Simple alternative to 300 deg twist pot

    Depending on what the pot is connected to, can't you use just part of the rotary range and compensate electronically for the fact that the resistance range will be from something more than zero to something less than 25k?
  2. Alec_t

    dc-cdi 12/220 issue

    You might want a series resistor when charging the cap, but the ignition coil primary should be in series when discharging it.
  3. Alec_t

    Convert square wave to sine wave

    Do you realise you've just necroposted in a 5-year old thread?
  4. Alec_t

    12V Battery on a 230V/50Hz Pump

    Yeah. Guess I was thinking of small ornamental ones :).
  5. Alec_t

    LED garden lights malfunctioning

    I think the only way you'll get one of those black blobs is by cannibalizing another garden lamp. Good luck though.
  6. Alec_t

    Need help reading ABS wheel speed sensor

    Welcome to EP! Messing with the ABS is dangerous (particularly so given your inexperience) and is likely to invalidate your insurance. Why do you want to it anyway?
  7. Alec_t

    dc-cdi 12/220 issue

    Yes, but the discharge should be via the primary of the ignition coil and not a dead short across the transformer/rectifier-bridge output.
  8. Alec_t

    Disable "all" mode on LED fairy lights

    You'd probably have to bypass the processor (that multi-legged component half way across the pcb) and re-configure connections to the 5 wires feeding the LED array. Without knowing the specs of either the processor or array the chances of success are slim :(.
  9. Alec_t

    dc-cdi 12/220 issue

    As Duke37 commented, why are you shorting the transformer output to ground with Q5? That will probably cause Q3 and Q4 to fail.
  10. Alec_t

    circuit help

    What do you want help with?
  11. Alec_t

    Will this switch work with what I'm trying to do?

    The dp4t switch wired as you describe in post #1, using a common (unswitched) ground should be fine.
  12. Alec_t

    How to make Toy Voice Changer (AA battery) Run on 12 Volt

    Depends on the spec of the amplifier you get, but I'd guess no more than 1A.
  13. Alec_t

    Site feature suggestion

    My thanks too, Ian.
  14. Alec_t

    Ultrasound driver

    In the present context it's an oscillator which drives the piezo and has positive feedback (to maintain oscillation) obtained by sampling the current through, or oscillation amplitude of, the piezo. See, for example, Fig 9 of this article.
  15. Alec_t

    How to make Toy Voice Changer (AA battery) Run on 12 Volt

    I don't know. Like you, I see kits advertised. Looks ok.
  16. Alec_t

    indoor localisation for minute positional changes of moving objects

    If you did have sensors placed as shown, how far apart would they be? Metres? Kilometres? Bearing in mind that radio signals travel at around 30cm per nS, any method involving time delays would need extremely accurate timing of very short delays.
  17. Alec_t

    Ultrasound driver

    To get maximum output from a piezo it needs to be driven at its resonant frequency. That frequency may not be constant if the loading on the piezo varies. Therefore, a standard way to drive a piezo is to make it a frequency-controlling part of a self-resonant circuit. Google should find you...
  18. Alec_t

    12V Battery on a 230V/50Hz Pump

    Absolutely not. Pond pumps for domestic use are designed for low voltage in the interests of safety. Mains voltage and water are not good companions. Surely Belgium has somewhere (a Garden Centre?) selling 12V pumps?
  19. Alec_t

    How to make Toy Voice Changer (AA battery) Run on 12 Volt

    A 3 inch (8 Ohm) speaker (cheap transistor radio type) will typically handle about 1W of power, so a 1W amplifier should suffice for that. We don't know the current draw of the toy, but I doubt it would be as much as 500mA. The fuse would go between toy and converter (not battery). The converter...
  20. Alec_t

    LED garden lights malfunctioning

    The black blob hides a miroprocessor. It's possible (I'm only guessing) that it monitors current produced by the solar panel and only turns on the LED when it detects a reduction in current, which would normally occur at twilight. There is no such reduction if you just insert a fully-charged...
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