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  1. Arouse1973

    Understanding a 5-transistor radio circuit

    Common collector is this configuration will supply approx. 260mA into 8R resistive load and the transistor will dissipate 240mW. In the configuration shown common emitter, the transistor will supply 340mA into a 8R resistive load and the transistor will dissipate 106mW. Can you see now why this...
  2. Arouse1973

    Understanding a 5-transistor radio circuit

    Good point Steve about 10n, missed that point. Adam
  3. Arouse1973

    circuit components

    I am pretty sure the data sheets will tell you. If you have any questions after YOU have looked through them then come back here. Adam
  4. Arouse1973

    Can a metal box become a resonator?

    5-7/8 what's that about 150mm. Just recalculated and dukes right the box is too small for that frequency. Adam
  5. Arouse1973

    why we need Load resistor?

    I have seen people get confused with this and state for maximum power transfer to the load they match the source to the load? Their theory is if you have an 8Ohm impedance speaker then you must make the source 8Ohms for maximum power transfer. In this case they are calling the source the output...
  6. Arouse1973

    Transistors

    Hi Ratch Yes I meant energy, you can't have power without energy either so Voltage is needed for all of them . I think I said that earlier volts is Joules/coulomb or more correctly joules per unit charge. It's interesting to note that an open circuited battery might have a rating of 9Volts...
  7. Arouse1973

    Temperature compensating a transistor?

    So how are you heating up the circuit and to what degree. Are you just heating up the transistor on it's own and with what?
  8. Arouse1973

    Measuring the inductance of a wirewound resistor

    I bet the weight was because it had bricks in it to make the price tag seem worth while.:)
  9. Arouse1973

    Transistors

    This is my probably retarded view on all of this. Without an electric field you can’t have a current which means you can’t get any energy. So this gives you an indication that voltage might have quite a big part to play in all this, considering the unit of volts is actually Joules/Coulomb which...
  10. Arouse1973

    Can a metal box become a resonator?

    He doesn't give a size does he? Adam
  11. Arouse1973

    Understanding a 5-transistor radio circuit

    The 10n is probably a filter for noise and to stabilise the operating point of the transistor. The 100K biases the transistors the first transistor is only just on but the second one is fully on with only 1V on it collector. It is held out of saturation by the feed back resistor and this...
  12. Arouse1973

    Temperature compensating a transistor?

    Your welcome
  13. Arouse1973

    Temperature compensating a transistor?

    It's called reverse active mode. If that's of any help. I mentioned a bit about it in post #21 Adam
  14. Arouse1973

    Can a metal box become a resonator?

    Yep, it's called cavity resonance. This will occur if any dimension of the enclosure is equal to or greater than 1/2 wavelength of a frequency. What are the dimensions of the tank. I bet ones about 120mm ? Adam
  15. Arouse1973

    Temperature compensating a transistor?

    Hi Kris I have modified your circuit, hope you don't mind. It now runs from an op-amp, which it should do really as you have closed the loop with the diode. Thanks Adam
  16. Arouse1973

    Transistors

    Good point. Have a look at the Temperature compensating a transistor thread. I think you will find this interesting. I would be interested on your thoughts. Adam
  17. Arouse1973

    Temperature compensating a transistor?

    I'll be interested to see what the other guys think. I value your input as always. Adam
  18. Arouse1973

    Temperature compensating a transistor?

    Thanks Kris. Don't quote me on this. But as far as the transistor is concerned it doesn't know which way around it is connected. It can only obey the laws of physics. The reason I think they are not used like this is because of the limited gain due to the doping differences when they are made. I...
  19. Arouse1973

    Transistors

    Spot on Ratch. I have always thought a BJT was voltage controlled, but then told I was wrong. I still didn't believe them because I knew that if I changed the voltage on the input to a BJT I would be able to change the current through the device. The fact that an NPN base clamps itself to what...
  20. Arouse1973

    Temperature compensating a transistor?

    Just interested Kris can I see your original circuit that was playing about? Adam
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