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  1. kellys_eye

    PWM Control with Shift Register Support for 3w White LED's

    Practically any MOSFET switching device will work - suggest you look for the smaller surface-mount variety with low Rds(on) values simply to reduce device dissipation.
  2. kellys_eye

    Switch button reading function

    First determine how the keypresses will result in a signal being generated. You can use pull-up resistors on each switch and read their logic level, detecting a 'low' when a key is pressed. This would mean a routine to continually scan the input ports and branch out for a detected keypress...
  3. kellys_eye

    TV lift board replacement

    U4 is a voltage regulator to provide 5V to the daughter board (wireless receiver) and is unlikely to be the cause of the problem - they do tend to get 'warm' (sometimes hot) to the touch - but it shouldn't get too hot to touch. You should be able to power the board without a motor connected and...
  4. kellys_eye

    Plug-in supply (switched) with ac output

    Do you have the correct wattage halogen bulb fitted? If you fit one that is too high powered the power units will overheat and cycle on-off as the protection circuitry kicks in.
  5. kellys_eye

    Is this dc adapter safe to plug into my keyboard instrument

    ...luckily! The smaller centre pin potentially saved the day by failing to make contact!
  6. kellys_eye

    Transceiver Circuit

    The schematic shows the speaker connected to the common pin of a change-over switch that is part of the transmit/receive push button.
  7. kellys_eye

    Transceiver Circuit

    Where the schematic tells you to.
  8. kellys_eye

    Which Component is This ? Inductor or Resistor?

    Need a 'wider' view of the board really - if that 'resistor' has the same grey body colour as all other resistors on the board then it's a 6.8Ω resistor. You do get inductors that are similar in appearance but you're unlikely to have a board full of them.....
  9. kellys_eye

    Is this dc adapter safe to plug into my keyboard instrument

    9V at 7.7W is approximately 0.8A so your 1A adapter is rated ok for such use. Check that the power plug (barrel plug) is the correct size - quite often the centre pins are different and if you use a larger barrel on a thinner pin they don't touch and power won't flow.
  10. kellys_eye

    1/4 hp lathe motor only runs slowly and won't reverse switch since I overloaded it.

    Does the motor otherswise spin freely when unpowered?
  11. kellys_eye

    Fidget Spinner Generator :)

    Given the fidget spinners bearings are probably as good as you're ever going to achieve then the only way to reduce the slow down is to reduce the load. High efficiency LEDs would help but you'll never make any significant improvements.
  12. kellys_eye

    Pacific 3404 Intercom

    AC1 and D0 will be shorted to operate the door open solenoid. You could use a wireless doorbell as a simple remote - to activate a relay with contacts connected across AC1 and D0.
  13. kellys_eye

    Project MOSFET H-Bridge to generate single phase signal

    The grounding around the top opto-coupler seems wrong to me.
  14. kellys_eye

    TV lift board replacement

    If a replacement board is easily available (and affordable) then obviously sourcing one is the simplest solution as repairs, whilst fairly simple to do, require soldering skills and, potentially, some test voltage measurements with a meter. Can you post a picture of the board (both sides). We...
  15. kellys_eye

    Expanded Electronic Cigarette circuit design

    Well you could go 'brutal' and adapt such devices as Lidl's inverter welder (good for 80A so purchase three!) indeed there may well be other welders that would adapt or you could search for hacking mods of standard PC power supplies. Given PC power supplies vary from 300W and upwards, they...
  16. kellys_eye

    Expanded Electronic Cigarette circuit design

    Core saturation is the usual limitation on SMPS designs - given I haven't seen any 'massive' ferrite cores (you could stack them though) but there's nothing stopping you paralleling multiple (smaller - but still high current) modules and developing a system that brings extra modules into...
  17. kellys_eye

    TDA 7293 power supply?

    OK, I've seen the eBay pictures and, as suspected, the supply is indeed AC-0-AC and therefore a 'spit-rail' requirement that cannot be found in an automotive system. You only option using this board would be to use an inverter to derive the AC and feed that to a suitable transformer which then...
  18. kellys_eye

    Understanding impedance

    Reasearch 'maximum power transfer'. In any circuit, if you don't match the source and load you get losses and the 'idea' is to maximise efficiency at all times. Of course there are occasions where this is simply not possible or practical but the maximum power transfer concept explains how and...
  19. kellys_eye

    TDA 7293 power supply?

    If the input shows AC- ZERO and AC then you need a centre-tapped transformer. You can connect DC if you know the correct voltage required - it would wire (basically) across the main smoothing capacitors and would (presumably) need to be a 'split-rail' supply.
  20. kellys_eye

    Need Help

    J3 would be connect to a supply voltage (positive). J4 would connect to your load (LED, alarm, whatever) Supply negative would connect to the negative side of your load/
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