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  1. C

    Help please Charger problem

    Get the globe out of a 6v torch and connect it to the output of the charger. This is the only way to test this type device.
  2. C

    H-bridge 12v DC motor

    The motor controller you have specified is only 2 amp as H-bridge. You need between 4 - 8 amps and preferably up to 20 amp.
  3. C

    Transistor alternative

    Any transistor can be used BC547 BC338 2N2222A . . . . any junk NPN transistor
  4. C

    CRT TV Board Replacement

    I told you to replace the delay line. It can go faulty.
  5. C

    Calculating Load Impedance

    The input impedance is effectively about 1k because the capacitors are merely transferring energy from one part of the circuit to the output. The diodes are in series and only effectively produce a very small voltage drop. The only thing you have to work out is the size of the capacitors to...
  6. C

    Calculating Load Impedance

    We need to know the frequency of operation, the value of the capacitors and the resistance of the LOAD.
  7. C

    New LEDs from 0.8V !

    They have a miniature tripler inside
  8. C

    basic of radio controlled devices

    In general Radio Control is too complex for you to be able to build the circuits yourself. The transmitters and receivers are available in the shops but it is much cheaper to buy a ready built plane copter or car.
  9. C

    understanding circuit operation

    Once you get over 10cm for 2cm coin, let me know. Pin 7 is the same as pin 3
  10. C

    CRT TV Board Replacement

    All delay lines are the same. Any delay line will work
  11. C

    CRT TV Board Replacement

    It's just a coil of wire but mine went open after it warmed up and even tapping it did not detect the fault. Just try another delay line
  12. C

    CRT TV Board Replacement

    I have had the delay lines go open.
  13. C

    understanding circuit operation

    Basically the circuit is a square wave oscillator using the 47k and lower 2u2. These get the circuit operating. The inductor and 2u2 (in series) have a certain "resistance" at this frequency and now the circuit operates at a completely different frequency because the two components are just a...
  14. C

    understanding circuit operation

    That is my circuit from my website. Most of my circuits are copied by others. The circuit is only designed to pick up a pipe in a wall at a few cm.
  15. C

    It is designed to run off of 12VDC, I would like it to run off 24VDC

    Just change D2 for a 12v zener
  16. C

    Request help interpretting LED max Vf spec in spec sheet

    Why complicate things with a constant current source???? Just use a resistor from the battery and connect the dynamo to the LED via a diode.. This will allow you to illuminate the LED when riding and the LED will glow dimly when at the lights.
  17. C

    ID diode help

    The only thing to do is put them in tester and see if they break down below say 100v. The tester is generally called a zener tester. Then you put them in a power supply and draw about 700mA to 1,00mA and see if they work for a few hours. If they do, you can use them for a 1 amp power supply...
  18. C

    Two phone batteries in parallel?

    "extra battery must be at or close to the same voltage as the cell it is being paired with to prevent excessive current flow between the batteries." The point you are missing is this: We are talking about two batteries for a cell phone. If one battery has a slightly lower voltage than the other...
  19. C

    Two phone batteries in parallel?

    "until the charge levels are similar." This is incorrect. It should be: Until the voltage of both batteries is the SAME. We have put cells in parallel for the past 80 years. The 1.5v battery in a "portable" valve radio consisted of 10 x 1.5v cells in parallel for the filaments. This was...
  20. C

    Common Base RF amp - CE feedback capacitor?

    Firstly you have to realise the circuit is actually an oscillator and it fills the surroundings with a very low field of signal. Because the circuit is already oscillating, it is very easy to "upset" it. This means it is very sensitive to detecting another signal of the same frequency. All the...
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