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  1. duke37

    Nuclear Plant help

    The BWR boils water in the core to form steam which is passed to the turbines. The PWR is pressurised to such a level that steam is not produced. Instead, the very hot water is passed to a heat exchanger which produces the steam from a separate supply of water.
  2. duke37

    Voltage Follower

    The transistors will give extra gain. Without the capacitors, this may be enough to set the circuit into oscillation.
  3. duke37

    27" TV is blue in one corner

    If this is a TV using a cathode ray tube, then they are susceptible to external magnetic fields. Have you installed it near a loudspeaker?
  4. duke37

    Question about RF coil

    The thickness of the wire is not critical. The thicker the wire, the lower the resistive loss, the resistance should be very low. You must not use a nail for a former, this is conductive and the currents in it will give massive losses at radio frequencies. Use a non conductive former, a piece...
  5. duke37

    Demodulation

    A poduct (mix) of two sines produces a frequency of the sum of the two input frequencies and the difference of the two frequencies plus other stuff which needs to be filtered out. To get back to sin(bt) you need to multiply the waveform with sin(at) and select either the sum or the difference...
  6. duke37

    Alternatives to Power Inverters

    You are up early! The 7805 will probably do the job but remember that it is limited to 1A without using a bypass transitor. Even so dropping from 14V to 5V (9V) will dissipate 9W and will need a heat sink. I do not think that you will need resistors of more than 1/4W but each should be...
  7. duke37

    Rewiring Ceramic Fuse - Question

    You do not say where you are. The regulations differ in each country. Do not connect up an electrical circuit if you do not know what it does. With your older house, the circuits may have been disconnected because they are faulty. If your fuses blow, you have a fault. You have the choice...
  8. duke37

    LED tail lights.

    I am sure that you do not want the LEDs to break when the pedal is pressed! Vehicles in the UK used to have rear lights that increased in intensity when the brakes were applied. They were a disaster and caused many accidents. The brake lights should be in a different position to the...
  9. duke37

    2:1 ratio step down transformer question from newbie

    If the motor does not run up properly, either the motor is not powerful enough or the voltage is not sufficient. Measure the voltage at switch on. A resistor may make the problem worse since the motor will take more current at switch so the resistor will drop more voltage. The resistor...
  10. duke37

    556 clock problem

    From what I remember, the 555 (so 556) is an invertor. If the output is high, then, the trigger/threshold will be low. Measure this voltage and discharge to see if they are low. Is there a short to ground? What is the method of construction?
  11. duke37

    556 clock problem

    Just a thought, how are you measuring the output voltage? What is the supply voltage? If the voltage is varying at 10kHz, a slow meter will measure the average voltage.
  12. duke37

    AD620 INPUT PROTECTION

    As *steve* says, a diode will conduct if the input exeeds the voltage of the power supply by 0.7V. This limits the input voltage to the amplifier. That circuit looks very complicated, the voltage measured will be 0V when the contact is closed and 13.5V when it is open. Depending on the detail...
  13. duke37

    infrared LED

    The way I would do it would be to take some paper and black it with ink or find a black area in a newspaper and cut it into strips. Take a 5mm (?) drill, wrap the shank with plumbers PTFE tape and then wind the paper round the drill and glue with PVA adhesive. Several turns would give a strong...
  14. duke37

    infrared LED

    Great minds think alike! If you are using a phase locked detector, background light should have little effect. If the background is too strong the detector can go into saturation. A collimator would help in this repect.
  15. duke37

    infrared LED

    What will a cap do other than keep your head dry? An led is small so if it is fitted to a tube the light will be collimated. A tube 3mm diameter and 10mm long will restrict the light to a few degrees. Adding a collimator to the receiver will also help. If the transmitter is driven with a...
  16. duke37

    Oven heater element.

    Power = V*V/R so R=V*V/P 240*240/2000=28.8 Resistance goes up as temperature rises so could be significantly different to this when cold. Would be interesting what the new element measures.
  17. duke37

    1.5 KW power supply

    I could not access Sheet1.zip. It locked up my computer and the only way I got out was to restart. Are you trying to access my computer? Why not post the diagram in a standard format?
  18. duke37

    2:1 ratio step down transformer question from newbie

    The value of a resistor can only be found by experiment. At 125mA you need 200 ohm to drop half the voltage but the motor will not be a simple resistance so there may need to be some deviation from this. The voltage across the motor would need to be measured off and on load and the value...
  19. duke37

    2:1 ratio step down transformer question from newbie

    The old primary will need insulating properly and you should hide the transformer inside the machine so that no-one can get at it. An advantage of a special wound auto transformer is that there will be no high voltages unless the common connection fails when it becomes a current transformer -...
  20. duke37

    equivalent fet for 2n3818

    Is your fet a 2N3819 - a very common old type?
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