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  1. duke37

    Electric motor needs start capacitor

    It will need a capacitor to start regardless of frequency. You will not be able to get a centrifugal switch to disconnect by turning by hand, you need about half motor run speed. You have a winding between 3 and 4, you need another winding. What does 1 and 2 connect to? You say that 2 is...
  2. duke37

    Electric motor needs start capacitor

    The motor is labelled 60Hz, you have 50Hz in Bosnia. Has it ever run? The capacitor reactance varies with frequency.
  3. duke37

    Designing Circuit by BC546

    RL is not part of the amplifier, it is the load. Looking in to the amplifier, you will see R6 and the transistor are effectively in parallel. The output impedance of Q2 will be very high so you are left with R6 as the output resistance, assuming C1 has a low impedance at the frequency of interest.
  4. duke37

    How to Pass Power to spinning components on a High DC Speed Motor

    Brushless alternators have a static field which generates AC in a rotating winding. A rectifier is then used to provide the excitation to the main part of the alternator. If you are going to use high speeds, then you will need to take into acount centrifugal forces. Look how a car alternator...
  5. duke37

    1W audio power amplifier driven by electret ?

    The speaker output is not likely to exceed 1mW, the efficiency of even big speakers will not be above 5%.
  6. duke37

    HELLO i have a problem with fm receiver

    Q5 and Q6 do not do anything. R9 and R10 are connected in parallel to ground. R9 should be connected tp base of Q5. C6 will give a lot of top cut.
  7. duke37

    Need Help Rebuilding Hamm's Beer Rippler Motor

    There is no rotating magnetic field, just an alternating field so that the rotor will vibrate forwards and backward, eventually jumping on the the next position. This may be forwards or backwards. The synchronous clock in my kitchen has a tendancy to start backwards, I do not know why. This is a...
  8. duke37

    High RPM Slip Ring Recommendation

    Please tell us where the slip rings will be connected on the rotor and what signals they will be passing. I was involved with getting strain gauge signals from a railway wheelset which could go to 1000rpm. The slip ring unit cost the earth and was unreliable due to vibration. When I left the...
  9. duke37

    Need Help Rebuilding Hamm's Beer Rippler Motor

    There seems to be a direction controller to start the motor the right way. There is a steel plate with a tang on the side which locates into gear 2. There will be a small amount of friction to turn the tang into the gear and jam it. With the correct design, the motor will bounce in the required...
  10. duke37

    DC-DC Isolator

    The motors in the track will generate voltage spikes which may be very high. The reduction in voltage due to the input resistors will help but may not be adequate. Put a zener across the ADC input to limit the positive and negative voltages.
  11. duke37

    Need Help Rebuilding Hamm's Beer Rippler Motor

    If the bearings are worn, you could have the rotor touching the stator, thus preventing the motor starting. You did state that it was noisy.
  12. duke37

    Denon DRA-335R receiver - Left speaker channel not working on speakers A/B.

    If you have a mono switch, then switching to mono will provide the same signal to both audio amplifiers. If sound comes out of both sides, then the tuner (switch?) is faulty, the amplifiers,cables and speakers are OK. If one side is still faulty, I would compare the amplifier voltages with the...
  13. duke37

    Where to find scrap electronics?

    In the UK there is an organisation FREECYCLE, did it start in the US? The main problem is that once you are known to take rubbish, you will not be able to get in your house. Your local radio club may hold junk sales where good stuff can be obtained at little cost. If you want to pop over, I...
  14. duke37

    Hall effect ignition

    D1 is not a freewheeling diode, it is the wrong way round. It may be there to reclaim unused energy. A freewheeling diode stops the drain voltage rising much above the supply voltage, this would kill the spark. A better arrangement would be to put a 500V zener across the fet to protect it from...
  15. duke37

    RF sensor to detect cat

    Try a fluffy ball tied to a microswitch.
  16. duke37

    Stepping up the voltage for a Geiger Counter

    I agree with this. I assume the Arduino is providing 5V for the power supply. A capacitor cross this supply would help. Better to use a separate supply for the power supply. The diagram would be much easier to read if you had a straight horizontal ground connection at the bottom of the page and...
  17. duke37

    A total beginner needs help on a simple 'beat the buzzer' project.

    I would use galvanised iron wire such as is used to support the vines in your vineyard or for electric fences. There are two varieties, one soft which is what you want and one hard drawn which will be much more difficult to handle.
  18. duke37

    Tamperproof sink

    Public toilets are often fitted with timed valves, press to operate and they will automatically turn off after a time.
  19. duke37

    help i.f transformer how to make one

    You will need to decide the purpose of the transformer. Is it to change the impedance or to provide a tuned circuit or both. The traditional IF transformer has an input winding and an output winding, both tuned with a capacitor and critically coupled together. The transformers are often wave...
  20. duke37

    Astable Multivibrator Circuit (Flashing LEDs)

    Running a mutivibrator on a voltage in excess of the permitted emitter/base voltage, can lead to degradation of the transistors. Do not supply more than 6V depending on the particular transistors or place diodes in the emitter leads to prevent reverse current.
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