Search results

Search Forums New Posts
  1. duke37

    Can a low side driver control three N-type MOSFETs connected in series?

    I would appreciate an apology from you for wasting my time by describing a circuit which you do not have. Alec_t has been very patient, I admire his attempts to get some sense out of you.
  2. duke37

    Nixie clock runs too slowly

    Then you will need to measure over a day or more with the capacitor in various documented positions. You can get one second pulses from a GPS satellite to better accuracy than you require. Comparing the phase of the two one second pulses should enable you to set the capacitance in a reasonable time.
  3. duke37

    Nixie clock runs too slowly

    You have not said how slow the clock is running. A capacitor trimmer is unlikelt to be able to shift the frquency more than 1% or so. If the deviation is more than this, then the crystal is not controlling the oscillator frequency. You may be able to hear the oscillator or its harmonics on a radio.
  4. duke37

    What happens if you connect 2 isolated power supplies backwards?

    The power supplies are in series so there is 8V to play with. You can get the voltage across the bulb if you know its resistance and the value of the resistors. The 5V psu will try to pull excessive current out of the 3V psu. Connecting one psu the other way round, will push current back into...
  5. duke37

    Power supply ratings

    Did you read #2? The output voltage is 24V DC and can be adjusted slightly by the screw. The minimum output current will be zero if nothing is connected:). The actual current (5A Max) will be what the load demands. The limit may be by a current limit circuit, a fuze or by a fire.
  6. duke37

    Spark gap transmitter

    Rekin229 I assume you are in Shropshire. There are two radio clubs in the area. SalopARS does a foundation course for an amateur licence and TelfordARS meets at Harper Adams. To get sparks, use a car ignition coil with a driver circuit. Some people have used them to charge electric fences. The...
  7. duke37

    Programable commutator

    A fet is a type of transistor with three connections, source, drain and gate. They are polarity sensitive and normally n-type is used. When the gate is connected to the source, the fet will be turned off. When the gate raised by a few volts, the fet will be turned on and will have a very low...
  8. duke37

    Programable commutator

    A relay needs a positive connection and a negative connection. Put your relays in a square so with 16 relays you will have four rows and four columns. Thus eight connctions will be needed. 25 relays will have 5 rows and 5 columns so 10 connections will be needed. The bigger the array, the more...
  9. duke37

    Tesla coil driver mosfet problems.

    No You have gone back to kinky wires. Ground has three levels - why? Turn off spikes put high voltage on the drain, not negative spikes. The zeners should go to the gate to limit the turn off. The diode you have added across the fet is in parallel with the internal diode and may reduce the fet...
  10. duke37

    Tesla coil driver mosfet problems.

    There will be a diode in the fet so that the source/drain potential cannot be reversed. Thus the lower 10 zeners will do nothing. The souce/drain voltage can be limited by putting a zener between drain and base so limiting the turn off speed when the drain gets too high. If the oscillation...
  11. duke37

    Tesla coil driver mosfet problems.

    Yes, draw with a positive horizontal line at the top and another for ground at the bottom. Use straight lines if possible. The diodes limit the voltage swing on Q1, probably too high for the transistor. A zener across Q2 gate/emitter would limit the drive voltage to a safe level.
  12. duke37

    VFD (Variable Frequency Driver) for 3-phase motors.

    3 phase motors have contactors which drop out if one phase is missing due to the excess cuurent in the remaining winding. A capacitor will add a small amount of power to the missing connection to get the motor started. There will not be rwo phases with any connection, it will either be three...
  13. duke37

    Use an ignition coil to charge an electric fence.

    That depends on the energy aching the fence. 0.1J is sufficient to fence off a silage pit. 20J will charge several km and will start fires if the sparks ignite dry vegetation. The area will depend on the shape of the fenced area. Once the animals are trained, you do not necessarily need a...
  14. duke37

    Proximity sensor for parking

    Just put down a thick plank of wood such as a railway sleeper to act as a kerb
  15. duke37

    resistor value

    There is one of them there things in the sensor. Thermister ?
  16. duke37

    One of my colleagues...

    Does zener D1 limit the base voltage swing and so limit the output voltage?
  17. duke37

    Vintage Radiomobile 501T question

    Yes, MES minature Edison screw. Get a bulb with a voltage rating above the supply voltage. 0.3A is common but you may prefer 0.1A to limit heat to nearby parts.
  18. duke37

    Isolating electric shower

    How about putting in a shower water pump which will suck all the available water. Use the solenoid supply to turn it on.
  19. duke37

    Frequency response ?

    LEDs are used in internet fibre optics. Don't know the details. White LEDs using fluorescence might be quite slow.
  20. duke37

    Blocking Oscillator

    There is no resonating capacitor, that is not how a blocking oscillator works. You need a much smatller transformer which can be saturated with 1.5V supplied by the BC337. 1.5 V is low to turn on two silicon transistors in series. A disposable camera will have flash circuit to do the job. Are...
Top