Search results

Search Forums New Posts
  1. duke37

    invention/adapter

    I do not think that your adaptor should re-connect when it cools down. It would be safer to have it trip and need a manual reset.
  2. duke37

    Hioki Resistance Check - Fluctuation

    My digital meter does its nut when trying to measure the resistance of an inductance. I presume that this is because it uses a short pulse of current. I use an analog meter for this purpose.
  3. duke37

    Transformer noise - what can be done about it?

    The MC34063A should be fine. I might get one to produce a high voltage supply for the primary of an electric fence controller. You will need a ferrite cored transformer and a pot core would be the one to use. You will not need to run it very fast with your minimal load. If you run at ultrasonic...
  4. duke37

    Transformer noise - what can be done about it?

    A transformer with a laminated core will show as metal when scratched. Ferrite will stay dark. Ferrite cored transformers are used for high frequencies, they are not suitable for audio or mains. A transformer needs to have sufficient inductance for the job in hand. Your audio tranformer...
  5. duke37

    Increasing Voltage With Multiple Ignition Coils?

    To go back to the original question, the answer is no. Ignition coils are auto transformers with input and output connected together. In order to connect the secondaries in series for higher voltage, it is necessary to have the primary and secondary isolated from each other. An alternative...
  6. duke37

    How to make vacuum tubes light up?

    Sorry, I thought that that you were looking at the scope which will have a large voltage to excite the tube. The signal generator will have a couple of hundred volts on the anodes, this is enough to give a severe bite. The filaments are likely to be 6.3V AC. If you have a rectifier valve...
  7. duke37

    How to make vacuum tubes light up?

    The filaments will be barely visible. If you do get it working, then there will be over 1000V around. Do you want a Darwin award?
  8. duke37

    Odd LED question

    I presume that the microamp figure is the leakage current taken in the reverse direction. You should limit the voltage to a few volts in this direction. The led emits light when current is passed in the forward direction.
  9. duke37

    3 digit panel meter to read -volts

    DO NOT PLAY WITH THE MAINS. YOU ARE NOT EXPERIENCED ENOUGH TO BE SAFE.
  10. duke37

    3 digit panel meter to read -volts

    The Jameco transformer is 12.6VAC and is half wave rectified. Reservoir voltage is 12.6*SQRT(2)-0.7 = 17V, this is then reduced by the regulators. Show us a diagram.
  11. duke37

    3 digit panel meter to read -volts

    You have stumped me since I do not understand what you have. 1. I assume that you have a dual power supply that can be adjusted between +/-5V and +/-16V. 2. You have a 3 digit panel meter with no information on power requirement or input range. 3. You have an op-amp to invert the signal...
  12. duke37

    What exactly is Amplitude Modulation?

    Have a look at Wikipedia, Alexanderson alternator. The Swedish one is still operational once each year. I believe they had problems this year and the transmission ws delayed
  13. duke37

    AC Electromagnet

    If you have DC power supply, why do you need the complication of going to a less effective solution? Whether it is AC or DC makes little difference to the danger of leakage in a hand held device. It is the voltage which is important, keep it under 24V.
  14. duke37

    What exactly is Amplitude Modulation?

    AM is amplitude modulation i.e. the strength of the signal goes up and down. Your method of producing it was used in early transmitters. The main problem is that the alternator will have far too low a frequency for radio transmission. There is a very old, very high powered transmitter still in...
  15. duke37

    AC Electromagnet

    I am not able to answer your specific questions however I would like to make the following points. !. A DC electromagnet would be more efficient than an AC electromagnet. 2. If it is hand held, it should be low voltage. 3. The wire gauge will depend on the power and the voltage. 4. Coke...
  16. duke37

    How to increase 555 timer output voltage

    LEDs need a defined current drive, perhaps peja5081 could tell us why he needs more voltage.
  17. duke37

    Need advise on controlling the speed of a drill motor.

    Here is a picture of my drill which looks similar to yours (B&D KD355CRE). It has a twiddle knob as you require.
  18. duke37

    How to increase 555 timer output voltage

    I should have read the link. Pin 8 is the power input to the 555 and this is derived from the output of the first 555. Pin 4 is not power input as I assumed, it is reset.
  19. duke37

    How to increase 555 timer output voltage

    How can you increase to 12V when you already have 12V? 5V should be plenty to drive LEDs, just adjust the series resistors. The green LED has a lower series resistance than the red LED. Will the current be too high?
  20. duke37

    Need advise on controlling the speed of a drill motor.

    The drill looks to have a knob to adjust the speed on the trigger. I have a drill with a speed control like this and will do what you want. Have you bought the drill and investigated the control?
Top