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  1. duke37

    Reptile Heater Help please

    The picture you show is a solid state relay, this is a switch which will be used to turn the heater on and off. The fan may also be connected to this supply. Take a photo of the original fan and any data which is on it. It could be a low voltage DC fan or a shaded pole motor fan. The latter...
  2. duke37

    diode for super low voltage?

    A schotky diode will have a lower voltage drop than a silicon diode such as a 1N914 or 1N4148. If a small schotky diode does not work, you may have to amplify the pulse.
  3. duke37

    Frequency accuracy

    You have an oscillator in your counter and another in the frequency reference. Beating these together will give an indication of the frequency difference. In the good old days of Radio 4 200kHz I could set up a 100kHz crystal oscillator to give a beat of longer than 10 seconds on a simple radio...
  4. duke37

    circuit

    Please give more details. Why should you wish to use a triac on DC? I had to look up the triac (600V, 8A, 2.5mA trigger), Why me?
  5. duke37

    Frequency accuracy

    I had a look at what the Icom 718 is. It is a transmitter/receiver running on the normal HF bands. It uses digital signal processing with several filters and frequency offsets so I do not understand how it can be old. How the frequency is displayed will need to be determined. The frequency...
  6. duke37

    Help regarding possibility and planning

    Pusur. Thank you for corektin my spelin.:) I can never remember whether such words should end with or or er. Have you got a simple rule? You missed another mistake. The frequency counter is simpler than a clock since it has to divide by ten whereas a clock has more complicated logic. This can...
  7. duke37

    Help regarding possibility and planning

    I do not think that heat would be a problem since a Nixie tube is quite large and dissipates little power, it does however need a high voltage, something over 100V. You will not get this from a USB supply so will need an invertor or voltage multiplyer. There are various Nixie tubes with...
  8. duke37

    Without resistors

    The circuit oscillates with the feedback through the resistors, they are crucial to the operation. Normally capacitors are used for feedback and there are resistors to give the base current. In this case, the circuit switches when the transformer saturates so I suspect that it will be hard on...
  9. duke37

    Without resistors

    PC power supplies normally use high frequencies and a ferrite cored transformer. These can not produce 50 or 60Hz. The resistors are necessary to limit the transistor current and they will not last long without them. The frequency will depend on the transformer parameters and will be square...
  10. duke37

    Need help with long distance circuit

    This thread seems to be going nowhere. Measure the resistance of the loop. Measure the resistance of the loop to ground. The resistance of the loop can be compensated by increased driving voltage or a more sensitive detector. Any connection loop to ground indicates a failure of the loop...
  11. duke37

    Peculiar MOSFET operation ??

    Have you got the fet the right way round? It has a diode in it which will pass current if Source and drain are interchanged. Also, the load should be on the drain Not the source as you say.
  12. duke37

    Creating an LED array in series circuit using PCB

    If each led drops 2.2V, then four in series will drop 8.8V. That leaves 3.2V to drop by the resistance. R = V/I = 3.2/0.02 = 160Ω, find a resistor fairly close to this. You could use five leds but the resistor would be very small and so the current would vary greatly with any change of supply...
  13. duke37

    What is the Mah of AA Primary battery ?

    or 0.000 003 MAh
  14. duke37

    Bench PSU

    There are four wires, two for the power and two for the voltage sense. The supply ups the voltage to take account of the voltage drop. The sense wires take very little current and so the voltage drop in them is negligible. Normally, they are connected to the power supply output with resistors so...
  15. duke37

    Radio, ac or dc?

    I googled "din plug wireing". Note that the pin numbers are not sequential. The plugs started as mono and the stereo plugs have pins in between the original three.
  16. duke37

    Radio, ac or dc?

    That symbol is two reels of tape of a tape recorder. I did have details of the connections, input/output, left/right but seem to have mislaid them. You can find out by trial and error. Edit2 The centre pin is ground. Edit: I suggest that you put the set wireing back to where you found it...
  17. duke37

    what's the part number of the chip?

    The device looks like an oscillator controlled by a 4MHz crystal (very common). To get an output of 9.08Hz, you need a division of something over 440 528, not common and a lot in a little chip.
  18. duke37

    Radio, ac or dc?

    So it is a Selena transistorised radio, but no model mumber is shown. What wavebands, does it receive stereo? Have you looked for a circuit diagram? It has a DIN 5 pin socket, these were normally used for stereo input and output to a tape recorder and would be ideal for your purpose.
  19. duke37

    Radio, ac or dc?

    If it is an old radio, it will use valves and will have lethal voltages.:(
  20. duke37

    Trying to identify this "fuse"?

    According to KrisblueNZ data, it is by MuRata. Trevor
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