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  1. Alec_t

    20v 1.7a 3-Pin Din Power Supply

    Here's a cheaper alternative adapter (19.5V), with a higher current rating (an advantage). I'm sure the piano won't miss 0.5V !
  2. Alec_t

    20v 1.7a 3-Pin Din Power Supply

    Not in the least sure. If you can measure the pin sizes and spacing you might be able to get some technical data from DIN/manufacturers datasheets to try for a match. Not dodgy; just inelegant. For most (all?) switch-mode supplies the output has no ground connection linked with the mains...
  3. Alec_t

    20v 1.7a 3-Pin Din Power Supply

    The supply in that link is unsuitable on its own. From the label on your digital piano it's clear you need a dual-polarity 20V supply, but perhaps two of those linked supplies could be pressed into service if you're desperate. Looking closer at the first pic, it seems the pin positions are...
  4. Alec_t

    Micro LED Bar

    Plenty of 10-LED arrays available. Any use?
  5. Alec_t

    20v 1.7a 3-Pin Din Power Supply

    You'll probably have to rewire the output cable of an otherwise suitable supply.
  6. Alec_t

    Over-voltage protection for op amp

    Belt and braces. I wouldn't like to rely on a 'probable' diode :) .
  7. Alec_t

    Replacing alarm keypad

    Can you adapt the keypad off an old phone or other gizmo?
  8. Alec_t

    Mini wind turbine to light an LED

    Indeed you do. Might be simpler to source than the real McCoy.
  9. Alec_t

    20v 1.7a 3-Pin Din Power Supply

    Is this any use? Or one of these?
  10. Alec_t

    How to create a magnetizer

    He discharged the caps into a step-up transformer. As for why is it necessary to discharge the caps, what would be the point of charging them if you didn't intend to put them to work? If you value your life (or the lives of those around you) DON'T replicate this. Judging by the questions you are...
  11. Alec_t

    Mini wind turbine to light an LED

    Here's a circuit which, if the turbine voltage is > ~4V, allows the cap to charge to ~3.2V then automatically turns on the LED to discharge the cap (partially). Be warned; with a 1.5 Farad cap the charge time, assuming the turbine puts out 5V, is nearly two hours! :)
  12. Alec_t

    Over-voltage protection for op amp

    You could connect your input via a resistor R1 to the anode of a diode having its cathode connected to the +ve supply. That will clamp the input to 0.6V above the supply. Diode current max=(35-5-0.6)/R1. A second resistor R2 could go between the anode and the inverting input. R2min=0.6V/100uA=60k.
  13. Alec_t

    Mini wind turbine to light an LED

    Welcome to EP. What LED are you using? A white one needs about 3V to light, whereas a red one needs about 2V. A series resistor can control the LED current, but drops a small voltage. Such low voltages create a challenge for a circuit to switch the LED on, which is probably why you haven't...
  14. Alec_t

    RPI Supply

    The battery obviously can't provide enough current. Perhaps use a 6V lead-acid battery instead and a low drop-out regulator?
  15. Alec_t

    Control Circuit for a ( Linear motion ) Motor

    Operator error. To avoid stress on the motor and its gearing the motor should halt before being reversed.
  16. Alec_t

    Slayer Exciter Woes

    Get a more powerful supply :).
  17. Alec_t

    Slayer Exciter Woes

    The power supply is probably shutting down to protect itself from being overloaded.
  18. Alec_t

    24 Volt Motor Control w/ 12 Volt Timer

    Enhancement type. Polarity would depend on the timer output spec. Can you post a link to its datasheet?
  19. Alec_t

    Questions conservation electronic

    Silica gel should do the job, but only if the bag is hermetically sealed. Simply tying it closed is no use.
  20. Alec_t

    24 Volt Motor Control w/ 12 Volt Timer

    For an extra layer of protection you could use the timer to switch on a power transistor (e.g. MOSFET) which in turn operates the relay. BTW a 60A relay is probably inadequate for this task. The rated running current for that 400W motor is ~ 18A but its startup (stall) current will be several...
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