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  1. duke37

    Thermostat

    By running on a lower voltage you are unlikely to do damage. I would try it on 110V and see if it works.
  2. duke37

    Reading Current of Solenoids

    Your circuit does not have the clamp diode so excessive voltage is generated on switch off. Having a higher voltage chip may not work since the solenoid can doubtless produce several hundred volts if turned off fast enough.
  3. duke37

    Appropriate diode fo my circuit

    Geranium diodes are very pretty:). Germanium diodes have lower voltage drop than silicon but have more leakage. They are usually used for low voltage applications such as crystal sets. They have largely been superceded by Schottky diodes which have low voltage drop but also more leakage than...
  4. duke37

    Appropriate diode fo my circuit

    Any diode in the 1N400x series will do. If you get 1N4007, then they can work up to 1000V. 1N4148 fast diodes can probably manage the current that will be drawn by the LEDs. Both of these are cheap and will be handy for future projects.
  5. duke37

    Convert DC to AC without motors

    What frequency? What voltage? What current? What waveform? What power source?
  6. duke37

    oscillator help

    Careful Chris or I will set Martin on to you.:) The transistor DC conditions are set by the base voltage and the emitter resistance. Driving either the base or the emitter via a capacitor will vary the collector current to give it an AC component. The phase will differ in the two methods of...
  7. duke37

    oscillator help

    Colin Do you agree that C2 is the primary tuning capacitor? 20pF is within the range of the tuning capacitors for VHF/FM radios. Just chose an inductance to suit. It is not my circuit so I have no intention of optimising the capacitors to try to get it to work. The HT line is live and will...
  8. duke37

    Delayed buzzer for Motorbike

    I think the circuit power could be obtained from the blinker supply with a couple of diodes. This would save finding a switched power supply.
  9. duke37

    oscillator help

    Colin, you are fond of CAPITALS.:) I attach a copy of the circuit with the capacitors labeled. The tuned circuit consists of L1 with C1, C2 and C3 in series connected across it. Typically, C1 and C3 will be 1nF and C2 may be 20pF so the total capacitance will be about 19pF. As I said this...
  10. duke37

    Reducing Voltage to Reduce Current - is it a proportional reduction?

    A fan normally has a torque proportional to the square of the speed so reducing the voltage by say 20% will reduce the speed by less than 20% since the fan turns easier, you can work the maths for a motor which has speed proportional to voltage but the speed will also depend on the torque. Some...
  11. duke37

    pulse

    A magneto generates energy and stores it in an inductance, this is then discharged into the spark gap at high voltage. This is not what you want. A better source is a car alternator which generates AC and rectifies it to DC to charge the battery. Or you can use a DC motor as a generator. If you...
  12. duke37

    Adding "on" light to 240V thermostat

    My mains thermostats have a neutral to supply a diddy resistor to reduce the dead band. The mains situation is different in the US.
  13. duke37

    LED light Lamp COB chip

    The LED uses 3000MA, that is quite something:p. It is more likely to be 3000mA or 3A. The LED consumes 93W, that is 8A at 12V which is about as much as you should take from a car battery unless you want the light for a short time. The booster will run without an aditional heat sink but the light...
  14. duke37

    Adding "on" light to 240V thermostat

    Just connect the neon across the heater circuit. Make sure it has a series resistance to limit the neon current. This is often built into a neon indicator. There is no need for any ground reference. Are you really 100?
  15. duke37

    Fan Header Question: Volts, Amps & Watts Multiplication & Multiple fans...

    The speed depends on the voltage. If both are 12V fans and fed on 12V they will run at design speed. They are in parallel so the voltage is the same and the total current is the sum of the two fan currents.
  16. duke37

    Fan Header Question: Volts, Amps & Watts Multiplication & Multiple fans...

    What is a fan header? If the power supply has to provide 12V at 0.21A, then as you calculated the power is 2.5W. It doesn't matter what the physical load is. In your case with two fans taking 0.11A each, then each will use 1.32W, total 2.64W
  17. duke37

    LED Strips Display driven from 555 / 4017 counter

    If you can understand the 555 as an oscillator, then a Schmitt trigger oscillator will come as a pleasant surprise. Put a resistor from output to input and a capacitor from input to ground. You will get an oscillator with equal on and off times, just the job for flashing LEDs. A 4093 gate has...
  18. duke37

    oscillator help

    The effective capacitor across th coil is the one from collector to emitter. It is not how I would do it. The components at VHF are never simple. Capacitors have inductance and inductors have capacitance. Wires have both. Meters are available to measure capacitance and inductance but these only...
  19. duke37

    LED Strips Display driven from 555 / 4017 counter

    A 4093 (4 gates) or 40106 (6 gates) Schmitt nand gate can make a very simple oscillator with one resistor and one capacitor on each gate. You need to know the voltage and current consumption of the LEDs before chosing the MOSFET.
  20. duke37

    Interesting...HFT Faux Pas

    But 5/16 is half 5/8.
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