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  1. duke37

    Improvised immersion

    That looks like a UK socket. Part of the loop is the supply transformer winding. This would work without any earth (ground) connection but consider what would happen if there is some leak through the transformer from the 11kV or 33kV supply. That would curl your hair! For safety, one...
  2. duke37

    Using a cheap digital hydrometer as a relay control for humidifier

    I am sure someone can help but you will need to provide the specification of the hydrometer and the misting valve. It should all be low voltage for safety.
  3. duke37

    Base Current req to switch on Transistor

    It depends on the collector current you want. If you want a collector current of 1A, then with a gain of 10, you will need a base current of 100mA. However to be sure that the transistor is fully on you could double this. The maximum permitted base current is 1A. FETs make better switches.
  4. duke37

    video over cat5 without baluns

    Baluns can be made cheaply but need to be made for the frequency to be transmitted, they have limited bandwidth and introduce loss. you need the right core. What is the attenuation of cat5 cable at the frequency you are using? As an alternative you could use a common mode choke and accept...
  5. duke37

    Improvised immersion

    The resistance which generates the heat is the water itself. The actual value of the resistance depends on the purity of the water. There is likely to be a lot of electrolytic corrosion of the razor blades and the water can conduct to elsewhere, giving dangerous voltages downstream.
  6. duke37

    Mythbusters bridge resonate attempt

    Why is the accelerometer too small? You could glue it to a brick.
  7. duke37

    Organizing Resistors

    I use fag packets in a drawer, I got these from my neighbour. Unfortunately cancer got him so my supply has dried up.
  8. duke37

    Electromagnetic radiation production and detection

    If you give a kick to a tuned circuit, it will oscillate and the oscillation will decrease as energy is lost. If more energy is put into the circuit than is lost, the amplitude will rise until there is a balance between energy in and energy out. This is an oscillator. There are many circuits...
  9. duke37

    12 V Power

    If you have a battery with a capacity of 10Ahr and you draw 3A then the time is about 3 hours. If you are drawing 2A and have a 40Ahr battery, then the time is 20 hours.
  10. duke37

    Help wanted

    Where did the schematic come from? It looks to me as if the LED is connected the wrong way round. I have not looked at the LM334 details. Building this with wire ended components on to strip board would be easy. The fitting in a box will be more difficult.
  11. duke37

    Stepper Motors. Any Experts?

    The resistance of the motor could be much less than 113ohm. The output depends on the voltage (118V pk-pk) and the resitance and inductance in series. Car alternators have a leakage inductance built into then so that they will current limit. The voltage will be propotional to speed and the...
  12. duke37

    NE555 damaged by ultrasonic operation?

    Post your 555 circuit. To get a high frequency I presume that the pot would have a low resistance. Have you shorted something?
  13. duke37

    Variable Transformer & Home Made Resistor

    Any resistor passing current will get hot. If you put it into a cabinet, there will be no health hazard and it could be made to look pretty. To keep the temperature to a reasonable level, use a fan.
  14. duke37

    Stepper Motors. Any Experts?

    As I understand it, MadMechanic is intending to use a stepper motor as an alternator. Experiments would be needed to determine the voltage/speed constant. There will be no synchronous speed considerations. The current output and voltage sag with load could be esimated from winding resistance...
  15. duke37

    High Voltage cables

    You could look at RF co-axial cable. Anything with a diameter of over 0.25 inch would seem to be able to withstand your voltage. RG8 is a common variety used by hams, this has a limit of 4kV. There are many others.
  16. duke37

    Hello, I've just arrived here !

    You could put a bulb in each phase to limit the current.
  17. duke37

    Unijunction transistor trigger

    I wouldn't think you could work in a vacuum, there's plenty of wind in the Orkneys. Have you tried to get information from Gallagher? After some effort, I managed to get some information on the use of their DVM3. The address I used was [email protected] and had a reply...
  18. duke37

    Unijunction transistor trigger

    I looked up the data for the 2N6027 and it should be limited to under 40V A-K, you seem to have this. The SCR normally will have a fairly low resistance gate-cathode (earth), perhaps 1k. I would expect the cathode of the UJT to be connected directly to the gate of the SCR. If the anode of...
  19. duke37

    Unijunction transistor trigger

    Having two SCRs in series seems a little strange. If you wish to do a bit of bodging, you could use a small capacitor charged with a resistor and then via a DIAC to the SCR gate (used by Gallagher) or you could use a similar system but use a neon indicator as the trigger, this will need a...
  20. duke37

    Ultra light / small / bright clip-on LEDs

    I would not think that temperature would be a problem, you will have to experiment and place some insulation beween the LED and the kite if necessary. I presume that there will be a good cooling air current. If the battery is on the kite, it cannot be very powerful. LEDs can be obtained that...
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