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  1. duke37

    Optical Pickup

    You can get a device with a slot between an emitter and detector for counting purposes. If this is a digital switch it will be no use for you, you will need an analogue version with the string attenuating the signal.
  2. duke37

    Fan speed control

    I have never seen a capacitor connected across the LM317T. A capacitor should be connected across the LM317T input. Is the circuit going into oscillation?
  3. duke37

    Soldering High Amperage Transistors

    The transistor is cooled by the collector/drain tag connected to the middle pin. The transistor leads are cooled by soldering them to substantial copper tracks. Soldering will be better than just clamping. Plastic/nylon will not help.
  4. duke37

    Actulator/Solenoid Help

    Relays consist of a solenoid which pulls a pole piece a short distance to activate electrial contacts. They are made to be efficient and to stand contiuous use. You will need mechanical skills to adapt them. An ordinary solenoid is probably designed for a large travel distance so the magnetic...
  5. duke37

    Actulator/Solenoid Help

    You seem to want very little movement, could you adapt relay? Post office relays turn up at radio rallies for not much dinero. Film projectors used a device for traversing the film (Geneva drive?), this could be switched off once in the locked position.
  6. duke37

    Dashboard repair

    They could be tantalum capacitors. Have you got the power supply the right way round?
  7. duke37

    Proper Ground

    "A" is the best but you need good connections. I have wasted a lot of time finding rusty connections. A red hot choke cable is not good.:) I clean the area with abrasive, make the connection and then slop WaxOyl on it in the hope that further corrosion will not occur.
  8. duke37

    How to drop 18.5V 6A DC to 15V 6A DC

    If you wish to drop 18.5V to 18V, then you only need to put a (10A) diode in series. A couple of diodes will give a little more latitude.
  9. duke37

    Forward and Reverse on Low Volt DC motor using solid state electronics.

    2.5V is plenty to turn on a junction transistor. If this is not enough, then you can use the transistor to turn on a powerful MOSFET with your 12V supply.
  10. duke37

    Digital Piano Low Volume

    The 6V on the LA4708 outputs is reasonable since there are two amplifiers working in anti-phase. You could use a little amplifier to trace the signal, before and after the LA4708. Note that the LA4708 has a mute connection, check again that this is above 2.5V
  11. duke37

    Transformer output puzzle for tube pre-amp project

    I did not see a schematic. You have stabilisers to control the output so why are you so fussy about the transformer volage? Keep the voltage as low as possible to keep dissipation low. Presumably the 6J5s will need 6.3V for the heaters or 12.6V if connected in series. Surely you will need about...
  12. duke37

    Boosting transformer current output

    A transformer for double the current (power) will be about double the weight. What is the LM317 for? A fan should work even on unsmoothed rectified AC.
  13. duke37

    Lenco 600 Transformer identification

    There is a 6V bulb connected to the transformer so a 6V (1A ?) transformer would be wanted. The smoking may be due to the rectifier or smoothing being faulty. Just fitting a new transformer may just give more smoke.
  14. duke37

    Digital Piano Low Volume

    Check that there is 12V on pin 18 of the LA4708. Have a good look at C38 and the voltage on it.
  15. duke37

    Digital Piano Low Volume

    A crackling output would make me suspect a capacitor. Varying volume could also be due to a capacitor in the power supply. I suggest that you do not use it until the fault is found. You do not want to take out the mains transformer. A photograph of the relevent area and a schematic would be a...
  16. duke37

    Motor controller fix- parts id

    Very gratifying that we have been able to help. It is nice to know when we have succeded, that is what we are here for.
  17. duke37

    Fried circuit repair

    Show us a picture of the disaster. Normally it is possible to solder a wire in place of the damaged track. Make sure it does not touch adjacent tracks and use a liitle hot melt glue to hold it in place if it is long and thin. A tutorial will not tell you how to burn your fingers.:)
  18. duke37

    Motor controller fix- parts id

    Looks as if the black blob could be ooze from the capacitor. If the capacitor is across the mains, then it will be responsible for its own demise and the grinder should work without it.
  19. duke37

    Cash deposit for battery

    In the UK, most supermarkets have a bin to put used batteries in. I have no idea what they do with them.
  20. duke37

    Calculating resistance of winding in coil conductor?

    The resistance is the resistivity * length / area You will need to get the area in meters squared and the length in meters.
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