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  1. GPG

    Activate transistor with piezo disc

    The cap will be charged to ~9v and when the output of t C555 goes high it will add another ~9v until the cap discharges. Hence the comment about timings. The timer output will have to remain high for the duration of the noise signal which is controlled by C6 R4. And there is the possibility...
  2. GPG

    Activate transistor with piezo disc

    You could try this, Connect D1 anode to 9V. Connect C6 neg terminal to 555 pin3. This will jack up the voltage to the transistor. Add a protection diode across C6 You may have to play with the timing and R4 to get what you want.
  3. GPG

    Activate transistor with piezo disc

    Different mechanisms. http://www.lumerink.com/courses/ECE310/f11/Docs/Junction%20Breakdown.pdf
  4. GPG

    LED FLASH/ON

    OP: resistance value for change? Flash rate? abrupt change or gradual?
  5. GPG

    A few questions about coils from someone with no knowledge

    The core offers a lower "magnetic resistance" so a higher field and greater inductance. Relative to a vacuum this is relative permeability. https://en.wikipedia.org/wiki/Permeability_%28electromagnetism%29 The other side of the galaxy is more than 55y away https://en.wikipedia.org/wiki/Milky_Way
  6. GPG

    Activate transistor with piezo disc

    The noise is generated by avalanche current through the reverse biased b-e junction. Do some selection of transistors, as this is variable, to find one that is well below 9v
  7. GPG

    Help me to chose the proper photodetector

    Pulse-oximeter? A silicon photo diode will cover it.
  8. GPG

    A Control circuit's Vcc

    Is your micro driving the converter Show circuit so far.
  9. GPG

    Digital programmable CDI ignition for 2-stroke engines

    The divider resistor/signal needs a bypass cap to remove the hash.
  10. GPG

    Electron Flow vs Energy Flow? - Help me understand

    You would be surprised at how much similarity there is in the real world Hydraulics have circuit diagrams without which makes troubleshooting that much more difficult.Hoses have resistance valves often have pressure regulators and so on.
  11. GPG

    Getting additional voltage/power to pc water pump

    Got a link to the pump? Also you could use the 12V from the psu connector and use the MB supply to switch it. (no load on the MB connection) Other possibilities include a switch mode psu and use the signal from the MB to ramp the voltage up or down.
  12. GPG

    Getting additional voltage/power to pc water pump

    If the pump will run on 5V with a Schottky power diode in series this would isolate the 5V from a higher voltage.There are other solutions,
  13. GPG

    Variable resistor separate from control circuit?

    Red, junction of 1N4148s Green Collector zero pulse. The bridge is existing supply.
  14. GPG

    Wiring pot as voltage divider across polarities

    There are low power versions. 78L05 and 79L05 .You will need a ground connection,
  15. GPG

    Electron Flow vs Energy Flow? - Help me understand

    Ground is a convention that gives a reference to measure voltages and current relatively. In a circuit ground may or not be actual ground. and ground may not be 0V.The energy travels faster than the electron speed.so https://en.wikipedia.org/wiki/Speed_of_electricity Don't know if this helps or...
  16. GPG

    Need Help Fixing Kenmore microwave-Hood 721.62752100

    Do you hear a relay click when the start is pressed?
  17. GPG

    Roberts radio

    For how long?
  18. GPG

    Relay Behaving Strangely

    That or close by is what I am thinking too.
  19. GPG

    Variable resistor separate from control circuit?

    like
  20. GPG

    Variable resistor separate from control circuit?

    What IC? Can be done with a couple of 1N4148 3 resistors and a NPN transistor
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