Search results

Search Forums New Posts
  1. duke37

    Op-amp circuit of an electronic card for a turbine flow meter (m3 Counter)

    There is no DC connection to the op-amp -input so the output could be anything.
  2. duke37

    Mechanical noise DC brush motor

    So what were these motors used for? I have looked at hundreds of motors from very small to 250kW and never seen one. Any sideways force on the output would be likely to displace the rear dimple. Motors on organ blowers are often fitted with plain bearings to keep the noise down.
  3. duke37

    20-30V input 12v high current output regulator, not working

    You do not need any voltage drop across Rb. The resistor is there to limit the current in the case of a fault condition so it should be quite low. The gain of the overall circuit is colossal and you could run into instability problems. The 500Ω will control the current through the BC556, only a...
  4. duke37

    Mechanical noise DC brush motor

    Possibly a series wound AC/DC motor. There must be a bearing at each end of the motor shaft ot the rotor will be attracted to one side or the other. It looks as if the the shaft has moved so that there is very little bearing surface at the top. A big hammer might solve this.:)
  5. duke37

    20-30V input 12v high current output regulator, not working

    Rb at 13.8MΩ seems to be wildly excessive. Use say 10k to protect the BC556 base from too much current. I have not looked up where the capacitors should be fitted for stability. A diode across the circuit is often used to protect against reverse polarity.
  6. duke37

    Constant current LED drivers - faulty, flashing panels

    I have not used current controlled supplies. A voltage controlled supply should not be fed into a low load which demands too much current. A current controlled supply should not be fed into a high load which demands too much voltage. A halogen lamp will go up and down like a yo-yo in...
  7. duke37

    Constant current LED drivers - faulty, flashing panels

    R = V/I so 35V 1A,, R = 35 Power = V*A = 35W so you will need a big fat resistor of say 33Ω or less as your load.
  8. duke37

    Pioneer SA-505 clicking

    I did not ask for the reading across TP2 and TP3.
  9. duke37

    Pioneer SA-505 clicking

    The circuit should turn on the output when it has settled to its working condition which is close to zero relative to the chassis. Measure voltage between TP2 and chassis (left), also TP3 and chassis (right).
  10. duke37

    Need help reading a rectifier diode.

    If possible, get a schematic of the amplifier and a hack saw, then you can chop out the parts you require in one block. My time with building anything is often mostly spent on the box and the mains feed. Make sure the finished PSU is safe.
  11. duke37

    Frequing resonance at audio taper

    5mHz is an incredible low frequency for any audio system. 30Hz to 10kHz is the normal range. Show us a schematic of what you have with component values. You can simulate the circuit with LTspice to see the effect.
  12. duke37

    Pioneer SA-505 clicking

    I think you mean that it is the acceptable range. There is no threshold. It looks as if the positive and negative power supply and the output transistors are working properly. This is confirmed by sound output when the relay is pushed in.
  13. duke37

    Pioneer SA-505 clicking

    Measure the voltage between TP1 and TP2 (Left) also TP3 and TP4 (Right).This is a measure of the current through the output transistors. The correct voltage should be found in the details, excess voltage, hence current, will stop the relay actuating (I think).
  14. duke37

    Pioneer SA-505 clicking

    I am not logging on to look at your pretty picture, I have had enough trouble with funny thing hapening. Put the schematic as an attachment here.
  15. duke37

    Do SLA chargers fight if paralleled?

    Have you tried the alternator on its own, they are speeded up a lot from the engine so I would expect that 5000rpm would be needed.
  16. duke37

    Simple Low Frequency Sound Generator

    To shift more air you will need bigger speakers. A better solution would be to alter the coupling between speaker and skull. A direct physical connection would be much better.
  17. duke37

    PSU advice

    You have the plug labelled wrongly, looking at the BACK of the plug where the wires are connected, the neutral is on the left. We used to say red to the right but they have changed red to brown which doesn't scan so well.
  18. duke37

    Pioneer SA-505 clicking

    I think that you have the 2SA1104 correct but the other two will not be 2SC2679. What is the correct type number? I see that you are in the UK but this is quite large. You could be in Stornoway or Pensance. I was wondering how far from mid Derbyshire.
  19. duke37

    Can this PCB section be salvaged? Beginner struggling...thanks

    I use a broad tip to get plenty of heat from a simple Weller iron. Tip it on its side if too large.
  20. duke37

    Pioneer SA-505 clicking

    It looks as if you can get a servicing manual down load for $17 from servicemanuals.net.
View older results
Top