Search results

Search Forums New Posts
  1. duke37

    Trying to fix home subwoofer amplifier. Any help is appreciated.

    I cannot help with solving the problem but I would use a lamp limiter in the mains input.This would enable you to run without blowing a fuse and give voltages to measure.
  2. duke37

    Soldering Iron not fluxing the tip or working right ?

    Soldering irons are often fitted with iron plated copper bits. It is necessary that the bit is clean to get solder to wet it. Clean the tip with wire wool or fine emery with the minimum amount of rubbing, you do not want to wear the iron plating through. As soon as the iron is hot, then flux...
  3. duke37

    Looking for oscillator and frequency divider schematics

    9V supply may exceed the permitted e/b voltage in the dividers. I do not know what the effect of the e/b junctions acting as zeners will be. Try dropping the supply to 5V. The Livingston Monarch organ used pnp junction transitors wirh permitted e/b voltage of 25V? It was run on 12V.
  4. duke37

    Sizing a mosfet

    The IRFZ40 threshold voltage could be up to 4V. This means that 5V drive would not be adequate. It may be better to use an npn transistor.
  5. duke37

    solar tracker

    Comparators often have outputs that can only pull down so to get a rise inoutput voltage, it is necessary to have a resistor to the supply. The outputs of more than one comparator can be connected together whereas two op-amps cannot.
  6. duke37

    Sizing a mosfet

    The IRF610 is a high voltage low current power mosfet. I have not looked at the on resistance which needs to be low if it is to be used without a heat sink. What voltage will the fet be switching and what will be the driving voltage?
  7. duke37

    Need SS Design for Vibrator ckt

    Two things. 1. In my sketch, I connected the fets to one output of the 4047. This is of course wrong. They should be connected to P10 and P11. 2. If your new transformer is a replacement for a synchronous vibrator, then it will have a centre tapped output so only two HT diodes will be...
  8. duke37

    Trying to repair an amplifier

    The brown gunge has come from overheating the transformer. I do not understand why the thermal fuse did not blow. The transformer is now probably dead. Disconnect all secondaries and see if the fuse still blows or better, use a lamp limiter. The overheating could be caused by faulty...
  9. duke37

    horizontal polarization of a satellite signal

    Horizontal at the satellite will not be horizontal at the ground unless the receiver is due north of the satellite? A nice bit of 3D geometry which is beyond me. Prehaps if it is 30 deg west, the signal will be tilted 30 deg?
  10. duke37

    Need SS Design for Vibrator ckt

    The circuit is running slowly so the fets could be fed directly from the 4047. The timing components for the 4047 should be sized for 120Hz or so. The frequency must not be so low as to put the transformer into saturation. F=1/(4.4*R*C) Normal fets need more than 6V to turn on fully, 10 or...
  11. duke37

    Load resistance, dissipated power (AC)

    Starting with 1. The wire reistance is not 0.3R, it is 0.6R. You can calculate the total resistance, 120V, 100A You can therefore find the load resistance. You can then calculate the dissipation in each component.
  12. duke37

    Transistor instead of relay

    Am I missing something here? In the original circuit, the optocoupler drives the darlington which drops the collector voltage which turns off the optocoupler. The result is that the circuit will sit halfway turned on. The optocoupler needs to be fed with a constant supply.
  13. duke37

    Idiot Question About RF burn

    If you carry on playing with high voltages, then this thread will become much less interesting! A DC or low frequency AC voltage will give a shock with the current passing through the flesh and damaging the nerves (see electric chair). A high frequency voltage will constrain the current to...
  14. duke37

    Electric fence energiser

    A possibility An oscillator is used to charge a capacitor to about 300V. The capacitor is discharged with a SCR which is triggered by a pulse each second. The circuit needs to be designed to allow the SCR to turn off.The current from discharging the capacitor is fed to a high voltage...
  15. duke37

    Need SS Design for Vibrator ckt

    And here is a picture.
  16. duke37

    Need SS Design for Vibrator ckt

    Here is a circuit for 12V input, A couple of diodes from the drains of the fets to supply the chip would be necessary for 6V input.
  17. duke37

    Need SS Design for Vibrator ckt

    Please give more details of what you wish to do. Are you going to use the original transformer? What frequency was the transformer run at? What is the transformer core, ferrite or Si-iron laminations? What is the input current and voltage? What is the output current and voltage? How big...
  18. duke37

    Can anyone find a IC for this please?

    The LM331N is a voltage to frequency convertor. You will need to condition the signals to supply the LM331N.
  19. duke37

    Linear position Sensor for tiny Hydraulic Cylinders

    The pressure will depend on the seal friction and the inertial force as well as the spring force. The fluid flow could be integrated to get the position.
  20. duke37

    DC voltage regulator

    Here is a sketch of the diagram. The zener should be over 1W.
Top