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  1. duke37

    Discrete FET driver turns off slowly

    I am not too sure what turn off speed you require, a solenoid is not a rapid device, but the circuit you show does not pull the FET gate to ground. It only pulls down to about 0.6V. What is the voltage output of the microcontroller? If it is 5V then it can drive CMOS which can pull up to 5V and...
  2. duke37

    inductive capacitance???

    If a small capacitance affects the output, it looks as if the amp is oscillating at high frequency. Have you by-passed the power supply properly? You should try a Zobel network (Wkipedia) across the output, perhaps a 100n capacitor in series with 10 ohm to correct the phase of the load and...
  3. duke37

    Help with coil limiting Spark Duration

    The coil is "charged" with 12V and "discharged" with about 300V, Thus the charge time will be 25 times the burn time. At high speeds (10,000rpm) the limit is the charging time. This is where the capacitor discharge system wins since it can input the 300V directly. Presumably, the burn time will...
  4. duke37

    Output transformer ambiguity

    duke37 Most valve radios have transformer primary resistances of about 500 ohm so that for the low anode current (24mA) of the ELL80, 900 ohm primary seems to be possible. Anything much higher than this is faulty. Shorted turns can only reduce resistance so the high reading is due to partial...
  5. duke37

    Gallagher M800 electric fence

    Gallagher M800 cicuit I repaired a Gallagher M800 a few years ago and took some notes on the circuit but did not generate a full diagram. The fault with the unit I had was that it had had an argument with a thuderstorm. The thunderstorm won, the copper strips on the output board were blown off...
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