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  1. duke37

    Function Generator Circuit

    The first op-amp produces a square wave. the second op-amp acts as an integrator to generate the triangle wave and the third op-amp is another integrator to round off the triangle wave. The integrators are low pass filters so are frequency sensitive. The 8038 IC uses resistors and diodes to...
  2. duke37

    Need signal generator help.

    Go to quick reply, then go to advanced. Click on the paper clip and brouse to find the file, open it and upload it. Close that window (down the bottom). Preview the post to check that it is right. If so, upload it.
  3. duke37

    Different type of potentiometer

    If it is a hall effect device, the magnet could be inside the detector and shunted by the wiper. For torque control perhaps it is measuring the magnetic field produced by the current into the drill. Try a lump of iron and a lump of copper to see if there is any difference. A copper wiper...
  4. duke37

    Different type of potentiometer

    Could it be a Hall effect device?
  5. duke37

    Need signal generator help.

    A signal generator will put out an AC signal. I googled Rufus Turner dip adapter and all I got was references to grid dip oscillators. You would not need an oscillator if using a generator. Show us a circuit diagram (schematic).
  6. duke37

    Split Rail Power Supply

    Very posh Kris. It all depends on the specifications to be met but the bases of Q1 and Q2 could be connected together and the output emitters connected together. Some capacitance from 0V to V+ and V- would help. This is a simpler version which may be good enough. The circuit will pass...
  7. duke37

    detector circuit falling off too quickly

    I do not see how the circuit can work. The 3130 will have negligible gain at cellphone frequencies. Also the input is bypassed with a 100µF capacitor. You will need a detector at the input. Get a whisker from your cat.
  8. duke37

    Analog Joystick to Variable Speed/Reverse DC Motor

    Hi Duke One way would be to put the 12V across the potentiometer so that you get 6V in the central position. Add an amplifier to give sufficient motor current. Make a voltage divider to give a 6V reference with sufficient motor currnet. Connect the motor between the two sources. Twiddle...
  9. duke37

    add light to 1930s fuel pump

    You are welcome. It is nice to help someone who is willing and able to learn.
  10. duke37

    add light to 1930s fuel pump

    The battery + will be at +6V relative to chassis. When you connect to a device, coil (pump or trafficator) or bulb there will be a voltage across the device. This voltage can be used to light a led. The first diagram shows A and B connected together so there will be no voltage to drive the...
  11. duke37

    add light to 1930s fuel pump

    You need to understand the difference between a parallel circuit and a series circuit. Parallel The two circuits (components) are connected to a common power input. They have a common voltage but the currents can differ enormously. Series When connected in series the current has to pass...
  12. duke37

    add light to 1930s fuel pump

    That looks right. However, I have had a look at the construction of the solenoid. The armature is solid so there will be in effect a shorted turn which will restrain the flyback voltage to some extent. Also, the pump will work for quite a while without modification so I would not bother fitting...
  13. duke37

    add light to 1930s fuel pump

    Please don't cry, there has been enough water in the south. This looks promising. You have not shown where you intend to connect D1. It should go directly across the coile with the cathode (marked with a bar) towards the positive input. Note that the diode will need to pass the full coil...
  14. duke37

    add light to 1930s fuel pump

    No, it is not connected across the coil (in parallel). Move the wire which is connected to one contact to the other contact. Look at my original diagram. The idea is that the capacitor is charged whenever the coil is energised. The led is lit for a little extra time until the capacitor is...
  15. duke37

    add light to 1930s fuel pump

    1. Get rid of D!, this protects the points but adds complications. You can replace it later. 2. Connect the circuit across the coil. The circuit you show has the circuit always connected between earth and earth so there will be no input. My neighbour cannot find an SU pump, he has even...
  16. duke37

    add light to 1930s fuel pump

    The pump is a resistance and an inductance. When connected the current will rise gradually depending on the inductance and will settle at a level depending on the resistance. The pump will pass about a thousand times the current that the led passes so will appear as just a piece of wire if...
  17. duke37

    add light to 1930s fuel pump

    D1 is there as a flyweel diode. It passes current when the coil is switched off. This limits the voltage seen by the points. The small capacitor that you have passes current for a very short time on switch off so that the points can open before a strong arc is generated. The 1000µF capacitor...
  18. duke37

    PC power supply

    Are the tops on the big electrolytics flat or domed?
  19. duke37

    add light to 1930s fuel pump

    I have had a mull and if you are happy about getting wires out of the pump, here is a simple circuit which should work. Note that it is polarity sensitive. Is negative earth used on 6V systems or have you changed polarity. I had a look at SU pumps and see that the later ones have a diode...
  20. duke37

    add light to 1930s fuel pump

    My first car was a Morris 8. I used to do 200 mile journeys in it. The thought of doing this now would be mind bogling. I could travel at 55mph but had to slow down when the engine got warm as the big ends would rattle. It was ideal for tavelling in London, the Rolls Royces would give me a wide...
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