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  1. duke37

    DC Motor drive

    I would appreciate any help here. I have a 1/2-40 tap and and will see a friend on tuesday, he may be able to get a couple of half nuts made with standard thread form. Perhaps there will be enough bite to work, obviously the correct waveform will be much better.
  2. duke37

    child safety in cars

    Why should a hot car have high CO2 in its air? Surely the problem is temperature.
  3. duke37

    Transformers

    Bore da. There are persons out in the wild world who repair old valve radios and want to use them with various signal sources. The diddy transmitters have been called pantry transmitters. Various ones are out there, either built, in kit or circuit only. Some are quite complex and give low...
  4. duke37

    Shaft help

    Do you have the correct measurements? Be very careful of 1/4 inch (old, 6.35mm) and 6mm (new). You may have to drill out the doofer.
  5. duke37

    DC Motor drive

    The 1/2-40 thread is designated ME or model engineering but of course is a normal thread form. I managed to get a tap for about £5; one company will make a buttress tap for £100 which is over the top. The half nuts need to be fitted the right way round but my eyes are not good enough to be...
  6. duke37

    DC Motor drive

    Thank you for the link to North American Tools, I see they have a distributor in Derby, I will give them a ring on Monday.I have purchased (cheap) a 0.5 inch diameter, 40 tpi tap with standard thread and will get a friend to make a nut to cut in half. Perhaps the standard thread form will give...
  7. duke37

    DC Motor drive

    I contacted Barnes but they did not have tools to make this thread. Thank you for the link.
  8. duke37

    Railgun question!

    The voltage will be limited by the construction of the capacitor. A 3F capacitor will be very large if it is high voltage. For a rail gun you need a certain amount of energy to be delivered. The energy in a capacitor is E=C*V*V/2.
  9. duke37

    Newbie needing help with amplifier problem

    The ohmmeter gives inaccurate readings on the board because some current goes wandering off to places unknown. There is the same problem with measuring voltage.
  10. duke37

    Building a 1 kW automotive voltage regulator

    Early auto alternators had the control circuit external to the alternator, more recent ones have the control inside. The rotor has current applied to give the correct output voltage. The alternator has to run at various speeds and a cunning method is used to enable this. There is built in...
  11. duke37

    help on a RF wireless LED project please

    What is wrong with a piece of wire? At one time the RAC used to spend the day towing vehicles away from the Rugby transmitter and the Sinclair car would come to an emergency stop if close to a mobile transmitter. I presume that you are in the UK. You will need approval from your insurance...
  12. duke37

    Rotating tv help

    So, you are using a set-top box to supply the TV and the box does not rotate with the TV. The set-top box changes a channel using a remote control thus if it is facing one room, it faces away from the other room. Is this the problem? The box is almost certainly controlled by an infra-red remote...
  13. duke37

    Automotive coil on plug conversion HELP

    I agree with this sentiment. I do only a few miles a year but have had to replace two 4-coil systems of different makes. It is much cheaper to replace a single coil. There is also the effect on the catalytic convertor of one cylinder not firing. Keep the electrical and electronic components off...
  14. duke37

    Automotive coil on plug conversion HELP

    The rotor arm does not make a contact with the distributor cap. There is a long running thread which deals with a two stroke motor. It is now up to 141 messages and seems to nowhere near getting to a resolution. Do you understand this? What is wrong with the existing system? Capacitor...
  15. duke37

    Electronic System Design

    Where is 'here'? I pop 10miles down the road to Derby University if I wish to look up some technical stuff. Also, the county library will order books from the National Lending Library. Most libraries have dictionaries, you may be interested.
  16. duke37

    Seeking help on circuit design for LED rudder indicator

    Pin 9 controls single led or bar.
  17. duke37

    DC Motor drive

    I did try a feedback circuit. This used a rectified but unsmoothed supply. A SCR was activated when the motor voltage was low, giving a pulse if necessary 100 times per second.This was used on a 12V Ford fan motor with strong cogging. It managed to run the motor well at very low speed but I did...
  18. duke37

    Four way UK traffic lights

    I made a traffic light driver using a 4017 and fets to drive a full sized light to train children. A 4017 can give 10 time periods but with a simple oscillator these will be all the same. In the UK the sequence is red red and amber green amber red For a two way layout there will be a time...
  19. duke37

    DC Motor drive

    I have a very old AVO coil winder which I have fitted with a 24V DC motor. I need a variable speed and have achieved this with a Variac and 12V battery charger. This works OK but is bulky and I need my Variac for other duties. The motor takes 400mA unloaded at any speed. The current will be...
  20. duke37

    Toggle Switch - Momentary Pulse Circuit (problem!)

    I do not know what the drive circuit of the relays is. I would think that you will need a smaller capacitor and maybe a series resistor to lengthen the on time.
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