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  1. duke37

    Replacing standard pot with plunger type on mobility scooter setup

    Try it but don't exceed warp level three
  2. duke37

    Transistor Question

    The 2N3055 transistors seem to have a wide spread of gain. The 2N3055C could have a bit higher gain than the others. The TIP3055 may have a little more gain but is in a plastic package. A pair of cheap 3055s could be used to find if there are other faults and may be good enough. Since two...
  3. duke37

    Please Help with room temperature project.

    The circuit you show has no positive feedback to give hysteresis. This does not matter when driving leds where flickering at the crossover point is likely. Relays need a definite decision to stop relay chatter. A conventional power relay will need a considerable drive current so a transitor...
  4. duke37

    need help with reducing DC voltage

    The 120V AC valves will probably work on DC. You may need to drop the DC voltage to around 50V with a resistor equal to the valve resistance. I have some 240V AC Norslo relays here. They pull in and drop out at 130V AC. They pull in at 60V DC and drop out at 7V DC. Some experimentation...
  5. duke37

    Please Help with room temperature project.

    A standard room thermostat will do what you want and, depending on heater load, may be able to switch the heater directly.
  6. duke37

    Replacing standard pot with plunger type on mobility scooter setup

    You could switch the motor but a small switch to change the ends of the pot should do the same thing. You could measure the resistance of the pot and replace with a new one with the mechanical setup you require.
  7. duke37

    inverter help

    Looks like a common mode choke to me. If so, the current should be equal in each wire. Perhaps there is a another route for the current.
  8. duke37

    SMPS boost regulator using a schmitt trigger oscillator

    A very neat drawing, I will perhaps look at digikey when I have time. What does R2 do or IC1b for that matter? I am wanting to produce about 400V, I will start a thread, asking for help.
  9. duke37

    Oxygen machine back up power

    Are you connecting the mower battery to the internal battery? Are they the same voltage?
  10. duke37

    Need help with Heathkit io-10 o-scope repair

    The valve base is noval or B9A. Use a ceramic or PTFE base.
  11. duke37

    Replacing standard pot with plunger type on mobility scooter setup

    Electronic organs used to use rotary potentiometers for volume control driven by levers or rack and pinion. These wore out or got noisy and then light sensitive resistors were used in a light tight box with a variable flap between thr resistor and a bulb. The system you have probably produces...
  12. duke37

    Transfer function of an opamp

    Yes you could short circuit R2. BUT have you got the circuit wrong, surely C2 should be connected to the other end of R2. R2 would then have a reason and this would be the standard circuit for a low pass filter.
  13. duke37

    Thank You

    Now you have to keep it at 37 celsius.:):)
  14. duke37

    Help with identify component (extra small)

    Just a guess but I would keep under 10mm for a 10pF capacitor. Some experiment is necessary.
  15. duke37

    Schmitt trigger relaxation oscillator

    If the hysteresis were constant with supply voltage variation, then the frequency would be constant since the capacitor will be charged and discharged with a current proportional to supply voltage to a voltage proportional to supply voltage.. The hysteresis goes from 12% at 3V to 24% at 18V...
  16. duke37

    CE EMITTER-BIAS CONFIGURATION

    An emitter follower cannot be common emitter, it will need to be common collector. I have understood the the output impedance in CC is the input impedace, including base resistance divided by beta.
  17. duke37

    Help with identify component (extra small)

    The capacitance input is a couple of spring loaded contacts so that a capacitor can be plugged in directly. You can make leads with a short length of stiff wire at the end. If you are dealing with low capacitance, then the leads should be very short.
  18. duke37

    Schmitt trigger relaxation oscillator

    According to my SGS-Thompson book, the trigger points are 1.8v and 3V for the 4093 with 5V supply. The hysteresis is not a constant percentage of the supply voltage, it goes up with a rise in Vdd. At 18Vdd the trigger points are shown as 7V and 10.5V The frequency will therefore be dependant on...
  19. duke37

    Rectifier Help

    For an op amp to work properly, you need feedback from output to - input. The diode will isolate the feedback on half the cycle allowing the op amp to go mad. It seems you are going to rectify the output. Why not make a standard precision rectifier? Edit I think I am wrong, it does happen...
  20. duke37

    Hybrid Electric Engine

    The magnetic force is very low if the distance between the magnets is large so I think the electric output power would be low. It may be possible to use it as a replacement for an alternator for cheapness. Some small engines use magnets on the flywheel to produce electricity. The sliding...
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