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  1. duke37

    Help with voltage controlled switch

    Does the LM311 need a pull-up resistor (1k) output to 12V?
  2. duke37

    DC-DC Converter Design

    Have you got the phasing of the input windings correct? Have you got the inductance correct? The current will go to a high level instantly if the load can take it but this does not look like the reason. Show a circuit diagram, looking at a list of numbers hurts my brain!
  3. duke37

    Help with voltage controlled switch

    Your fet looks to be the wrong way round? The main problem here is that the fet will need a few volts to turn on so that diagram you have given, will need 13V plus a few to get the fet into the start of conduction. You need several volts on the gate to turn it on fully. You will need a...
  4. duke37

    Watch project for the blind

    Have you contacted the RNIB for advice? My thought is that you would need a lot of power. Could the pulses be activated by turning the rim? Most of the blind people that I have had contact with were quite elderly and a big display would help with poor hand coordination. All power to...
  5. duke37

    LED tachometer project

    I think the lines should cross but not connect, you can check this by looking at the data sheet. You should separate the F to V convertor from the display (use a potentiometer as substitute) to get the display working first. Is the 2917 producing output pulses, should there be a capacitor...
  6. duke37

    oscilloscope question

    It may be a Philips !00MHzscope. An analog scope will not show non repetative signals, you will need a storage scope for this. The scope will have its case earthed so that you can get a mains short if you are not careful. I suggest that you use an earth leakage trip and an isolating...
  7. duke37

    Membrane Keypad Repair for Wall Oven

    Dave, If it occurs in humid weather, it could be condensation causing a short in the control panel. Could you put in some silica gel to absorb the moisture or warm it up slightly to evaporate it? Duke
  8. duke37

    Need help building a proportional circuit for my RC Tank

    The regulator has given me an idea. Use an LM317T set up to give 3V but instead of referencing it to ground, reference it to the motor voltage. When the motor voltage is zero, it will give out 3V, and when the motor voltage rises, it will rise also.
  9. duke37

    Polarity tester for 9 core cable

    That is an elegant solution but could perhaps be improved by having another line of leds showing the transmitted signal. Then a matching pair of leads would show that the correct wire was connected to the right place.
  10. duke37

    What is with these kids today?

    I am also an old fogey, what annoys me is that when advice is given it is disregarded. Also, it can be difficult to know whether the poster is working in a foreign language or whether they cannot be bothered to explain clearly. Cool init right?
  11. duke37

    Hybrid 36v bicycle

    Where is the energy comming from?
  12. duke37

    Ultrasonic transmitter

    Looking at the data sheet and the drive circuit, I think that Vp is the peak voltage (in volts) to be applied to the transducer. The specification gives output for a given input.
  13. duke37

    How to repair this

    Please tell us why you will not change the cable and be safe. The first picture you show does not use solder, it is a crimped connection. Do you have the tools for this? The second picture shows a soldered connection which would work until the cable is bent when the wire would either...
  14. duke37

    how to convert analog output voltage (3V to 5V and 4.6V to 5V) to (0V to 5V)

    Give us a diagram of your circuits so we can advise. What is the input voltage range?
  15. duke37

    Which relay do i use

    Hi James, Relays contacts are rated differently for AC and DC since on AC the arc is extiguished when the current reverses, on DC an arc can be drawn for a considerable time so harming the contacts. Accordingly, the DC voltage rating may be a quarter of that of AC. In your case, switching...
  16. duke37

    A few quick questions

    A tip on drawing diagrams. In your diagram, some wires cross without connecting and some cross with a connection. It must be made clear which is which. The convention is that the wires are not connected if they just cross over. To make a connection, you can put a blob on the connection...
  17. duke37

    Which relay do i use

    Most relays are intended to be driven by DC, AC relays are available but use more power and tend to buzz. I would put a bridge rectifier in the AC supply to a DC relay. If you cannot find a 24V relay, then a 12V relay with a series resistor equal to the relay coil resistance would do. As for...
  18. duke37

    How to repair this

    I agree with Resqueline. NEVER splice mains cables. It may work for a short time but when it is moved around, the contact will fail. Remember, your life is in your hands. If one end of the cable is not long enough to move the plug, then put in a new cable.
  19. duke37

    Sweet sweet vacuum tubes...

    Spring is on the way in the northern hemisphere, now is the time to crawl out of our holes. Redraw the power supply as I suggest and when that is right, we will go from there.
  20. duke37

    LVDT Signal Conditioning Circuit

    U3 output is shorted to earth, pin 3 has a staight wire finishing in a connection to earth. I have no idea why this is! Please give a description of the theory behind the circuit.
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