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  1. duke37

    Tool-activated vacuum

    A current relay could be used where a high current instead of a high voltage is used to pull the relay in. Alternatively, a current transformer with the saw current passing through the primary and the secondary connected to a load resistor and the SSR. I think that devices similar to what you...
  2. duke37

    Setting up idiot led's...

    I would add a resistor (1k?) in series with the transistor base to limit the transistor current otherwise an accidental large load current will go through the transistor and damage it.
  3. duke37

    Inverter Output Transformer Saturation

    What has temperature (K) to do with it? The H bridge needs two n channel fets and two p channel fets and a level shifter to drive the p channel fets. The four transistors will need to be matched to get an average zero transformer current. Passing high voltage, high current AC through a low...
  4. duke37

    handyman component tester

    C7 is almost certainly an electrolytic capacitor. Picture please:)
  5. duke37

    Converting 110v Trafo To 220v Version

    Doesn't the heater come from the transformer? If so it should not need replacing. 600W seems a lot. Is this to solder a funnel on a liner? The primary needs to have twice the number of turns so you will have to count the turns as you take them off. The primary is usually the first winding...
  6. duke37

    Treadmill control board repair.

    If a fuse is failing, thrn too much current is being taken. Is this taken by the motor? What type of motor is it? If a motor with brushes and a commutator, look at the commutator condition. Arcing between segments indicate a bad winding in the armature so a dead motor. Disconnect the motor and...
  7. duke37

    Guidance

    This forum is based in the UK, it is as valid in India just as much as Canada.
  8. duke37

    Low Induction Modules?

    The leads to a resistor will be inductive and wire wound resistors will be inductive. What power and frequency is involved.
  9. duke37

    How to test a transmitter circuit?

    You do not have a power supply or a RF bypass capacitor. You need to measure if the oscillator is working, a 1N4148 diode in series with an analog meter may do this but it may stop a working oscillator. I would use a grid dip oscillator to find the resonant frequency of the tank circuit but you...
  10. duke37

    Calculating the value of the resistance for controlling the speed of AC fan

    The motor is equivalent to a resistor of about 3500Ω. Try a 1kΩ and 2k2Ω resistor. You may need to dissipate more than 10W. If you have an arduino then this could control a triac to get what speed you want. See #2. I do not know in detail how this could be done.
  11. duke37

    Calculating the value of the resistance for controlling the speed of AC fan

    The motor is only 33W so three switches and three resistors should do it, What is the blue block for? The motor torque will be much less at low speeds so it will be very difficult to calculate resistors.
  12. duke37

    What phase is this please

    A single phase motor will be much bigger than a three phase motor, it needs to fit. A single phase motor needs a starting circuit and a high current supply. In one case that I was asked about, there was too much voltage drop to get the compressor up to speed even though the cable was probably...
  13. duke37

    Component Storage

    I use cigarette packets for small components, one drawer for resistors, one for capacitors, one for silicon transistors and one for germanium transistors and diodes but my supply has stopped. The big C got him.
  14. duke37

    Pavilion 560w MB w/bulging caps

    I have an HP Pavillion which failed just after the guaranteed ended. HP wanted a large amount of money to mend it so I went to a local man who changed the mother board for a very reasonable price. He said "I know what that is, I have one upstairs which failed just after the guarantee ran out"...
  15. duke37

    Finding a good soldering iron....

    I do not know the action of the flux, perhaps a lot of it is due to surface tension, perhaps it is due to dissolving oil based compounds. One of the best fluxes used to be made by dissolving zinc in hydrochloric acid. This is obviously very corrosive but will allow dirty car radiators to be...
  16. duke37

    Finding a good soldering iron....

    I use Ersin Multicore solder for most electronic purposes. For some cases I use extra flux. These are:- 1. Soldering components which are over 50 years old. 2. Connecting broken insulated, stranded aerial cable which has been wet. 300Ω ribbon cable is particularly subject to fatique. I do not...
  17. duke37

    Finding a good soldering iron....

    To divert a little, what is a good flux? I have a tin of Fluxite about 40 years old which I occasionly use. I have recently bought a pot of LA-CO "regular soldering paste". Non acid, non-toxic. Hot and cold water. Heating and gas services. This seems to be more active than Fluxite. I have...
  18. duke37

    Fm receiver circuit .

    Modern schematics do not need a dot at a T junction for connection but do at a cross It is both common base and common emitter, depending on the frequency being processed. A difference between a regenerative detector and a superregenerator detector is that the oscillator works intermittently in...
  19. duke37

    Vacuum in a Can

    That could be a lot of fun:)
  20. duke37

    Fm receiver circuit .

    I am in (*steve*)'s second category and know enough to realise that I am ignorant. So take what I say with a pinch of salt. L2, R2 are there to isolate the emitter from the rest of the circuit at RF. They should not be resonant? It does not slope detect an AM signal. The AM signal is detected...
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