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  1. duke37

    Single Transistor Circuit Current Question

    Add up the voltage across D1, D2 and D3 and Q1 then subtract this from V1. This voltage is across the 1K resistor so you can calculate the current.
  2. duke37

    Electrical generation in power stations - how AC Hz and voltage fluctuates

    The frequency and voltage can be controlled independently. Frequency in the UK is very accurate and synchronous clocks are rarely more than a few seconds out. Voltage can drop if the demand is too high and the DC connections to the continent cannot compensate. Dropping the frequency can...
  3. duke37

    Pie Network , Transmitter Tuning and Loading Questions

    You do not want maximum power, that will give maximum smoke. The output tuned circuit has to transform the load resistance (50Ω) to the optimum load on the final valve. It also has to keep the harmonics down to a reasonable level, a Q of about 12 is often used to achieve this. Loads are rarely...
  4. duke37

    help me to design simple buzzer

    The circuit you show looks as if it provides the high frequency signal to a simple piezo transducer. If so, you will need an extra circuit to turn it on and off at the time you require. There must be details on the net to determine the components required with a bistable. I would do do it by...
  5. duke37

    Capacitor replacement

    You have several 100μF 16V. It is worth a try but will they fit in? There is no information on ESR. Some hot melt glue could be used to take the weight if you are going to bump it about.
  6. duke37

    Capacitor replacement

    Comparing the other capacitors, it looks as if the shaded area is negative and the chamfered area is positive.
  7. duke37

    Need some help with this temperature sensor

    Thermocouple? Platinum resistance thermometer? But could not stand high temperatures.
  8. duke37

    Boost Converter with mc34063

    R1 is shown as 0.07Ω and you have replaced this with a link. The Texas sheet says that this resistor should be above 0.2Ω but perhaps this is only necessary without Q1 to limit the IC current. Q1 is switched off when the voltage across R1 reaches 330mV. With your link in place, the current will...
  9. duke37

    single polarity voltage supply

    I looked up the specification for the TDA7052A (you could have done this) and see that it will run with input voltages between 4.5V and 18V. It will therefore run on 9V. No regulator is needed, it will just waste power. You can use a battery (PP3) or a plug-in power supply, 9V stabilised. The...
  10. duke37

    Boost Converter with mc34063

    But you are not working with DC, if it were pure DC you would not need any capacitors and the inductor would have no effect. The circuit takes an amount of energy from C1 and transfers it to L1 when the transistor in turned on. This energy 'lump' is transferred to C3 when the transistor turns...
  11. duke37

    Boost Converter with mc34063

    1. A poor quality L1 as you say. 2. C1 not having a low enough ESR so not able to provide the peak current. Try shunting with another similar capacitor. 3. C3 not able to accept the peak current. Does anything get warm?
  12. duke37

    High Voltage component

    They show no connection. If they were inductors, the wire would need to be mighty thin. At the time I looked at this fencer I did not have a capacitance meter. My thought is that they could be a diode with sufficient series elements to appear open circuit on a normal low voltage meter or maybe...
  13. duke37

    High Voltage component

    I have repaired various electric fence units and there are some components connected in series/parallel across the output. They are light brown with a white end. I have never changed one of these even if the diodes have been blown apart. They seem to have no connection. Any idea what their...
  14. duke37

    DIY Peak Volt circuit alternative

    If you have a mechanical switch (points) then I would expect that the pulse height will vary. If you can see the points, then the spark moves across the points. A transistor switch should be much more consistent.
  15. duke37

    How to debug a halogen ceiling fixture

    What voltage are the bulbs, are they supplied through a low voltage transformer?
  16. duke37

    Equivalent of IR2155

    It is very difficult to find an exact equivalent of a component. There are often deviations in the specification. I think you would be better off to find out the duty that the component has to contend with and then find a device with plenty of spare capability.
  17. duke37

    Transformer/Coil

    Using a transformer in reverse gives a low output because the transformer is designed to give a high output which drops to the design voltage under load, perhaps by 5%. If the output voltage is too high, then use a doubler, not a tripler. Edit. If you up the frequency, then you should be able...
  18. duke37

    Transformer/Coil

    It seems as if you are wanting about 100W or so. You will need a fairly large and heavy transformer if you if you use a mains transformer. Incidentally, why 115V if you live in the UK? I have never seen a ferrite cored mains transformer. You can wind your own transformer using a TV line output...
  19. duke37

    Why is relay latching? :(

    To go one step further with the current dump. Put a forward facing diode in series with the relay coil, this will drop 0.6V or so. There will be negligible current through the relay until the voltage across the dump resistor exceeds 0.6V.
  20. duke37

    Why is relay latching? :(

    It may work if you put a resistor (try 100Ω) across the relay coil to dump some current. You could probably do away with the 5V supply by using a resistor to drop the 12V to a suitable level.
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