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  1. duke37

    delay circuit

    1. The input goes from Vcc to ground as described in #1. 2. I can't write properly! It is not 100µF it is 100nF, charged and discharged from the input 10k. 3. Yes, the 4093 is a quad dual input Schmitt NAND. One gate not used. I used a 4093 since I bought what I thought was one at a radio...
  2. duke37

    delay circuit

    I interpreted a stall as increasing the load to stop the engine. I think the attached circuit will do what you want, it will need a FET of sufficient size to drive the solenoid and will need a flyback diode across the solenoid with sufficient current capability to pass the solenoid current...
  3. duke37

    100v supply for UK usage?

    Equipment intended to be used in various countries often has a transformer with two primary windings which can be connected in parallel for 110V or series for 220/240V. The specification should be found since changing from 60Hz to 50Hz will also have an effect. I recently sorted out a ghetto...
  4. duke37

    Need help with 555 circuit

    The trigger pulse can be shortened by passing it through a capacitor/resistor combination with the appropriate time constant. The main problem will be that you do not want the circuit to actuate again the next time the door is opened, thus you need a memory, perhaps a latching relay, and some...
  5. duke37

    delay circuit

    This seems strange logic. You do not say what the solenoid does, it is unlikely that it stalls the engine. Does it push a stick against the flywheel? The normal situation is to have a fuel valve which is turned on when the ignition is activated and sprung into the off position when the...
  6. duke37

    Motor spluttering at low speeds

    I would have thought that it is extremely unlikely that you have an intermittent electronics fault. Most semiconductors either work or dont. It could be a poor connection which is jiggled. If the speed is controlled by a mechanical governor, then any friction in this will give poor control.
  7. duke37

    How does overload protection in an UPS work during a short-circuit?

    Tjhe light bulb method is good for limbering up old valve radios. If you want 1kW for bigger things, then go for a one bar electric fire. You could also provide your workbench with low current high speed trips which are faster than fuses and perhaps faster than the landlords tackle.
  8. duke37

    Motor spluttering at low speeds

    A motor controlled by a diac/SCR pair is given a power thump when it is too slow. There is a minimum speed which gives a smooth control. Some motors have strong cogging, they go round in jerks and need a certain speed to get them from one cog to the next. A series wound AC/DC motor is not...
  9. duke37

    Variac

    Any resistance readings should be very low. As Harald has said, try energising the winding with the arm disconnected. Nothing should happen. You could use a second hand motor brush cut to size. I would make it only wide enough to be able to travel smoothly from one turn to the next. A...
  10. duke37

    ELECTROMAGNETS

    It seems like you are wanting to make an electric motor to drive the fan. The battery supplies electricity. The electricity makes a magnetic field in the motor. The motor rotates to energise a different winding. The process is repeated. You can get fans coupled directly to well...
  11. duke37

    Do I need a stornger UV LED?

    The colour will be determined by the fluorescent dye which is being energised.
  12. duke37

    Variac

    A metal disc will short out some turns of the transformer. Variac brushes are made of carbon so there is some resistance between turns. This is increased by using directionally made carbon or by using two brushes glued together so the output current will use the two sides in parallel and the...
  13. duke37

    some insight please

    I do not understand what you have. Two wires can be used to send 24V power. Most relays work on DC so if you put a diode in series with the relay, it will work when the wires are connected one way round but not the other. Using another relay, with a diode connected the other way round...
  14. duke37

    12V / 24V CHARGER / STARTER

    Cemont Velox 420 I found some details, it is a manually controlled charger. 12/24V 38A 15kg It probably has a simple circuit which can be traced. It will have a tapped transformer, rectifier and ammeter. You could be right about the wire sizes.
  15. duke37

    Need help in identifying this part:

    What is written on it?
  16. duke37

    Cable Size (DC Long run)

    My data book is old with a mixture of imperial and metric units but I think that 20m at 0.26A would drop 0.05V which is neither here or there.
  17. duke37

    Transistor Resistor Help please

    A Darlington transistor needs more voltage across it than a simple npn transistor. With two leds in series and the drop across the Darlington, you may be very close to the limit when using 6V. Depending on the led voltage.
  18. duke37

    24VAC power supply question about VA spec

    Hi Kewpy, I tried to PM you but it didn't seem to work. I have a stream of spring water passing my house at 10C. I would like a water to air heat pump which I cannot find in the UK. What is the make of yours? Duke37
  19. duke37

    Relay configure trouble

    This is a typical case of poor information. In #4 it is suggested that power is transferred from one motor to something else. Depending on where the signal comes from, if manually, perhaps a change over switch would do. There must be a reason for proposing a relay, latching is one so that...
  20. duke37

    12V / 24V CHARGER / STARTER

    This place is as good as any other. When you get more information, someone may be able to help. I would look at relay contacts and motor brushes.
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