How does a radio tuner work?
Discussion
I’ve been reading up on the basic principles, and I’m OK on the idea that (to simplify) an alternating current in the transmitting aerial causes an alternating current to be picked up by the receiving aerial.
When it comes to tuning the receiver to select the desired frequency, again to simplify. You have an induction coil which will allow current to pass providing it’s alternating below a particular frequency. You have a capacitor which will allow current above a particular frequency. Anything too high for the induction coil and too low to get through the capacitor ends up going through the earpiece or audio amplifier because it can’t go anywhere else.
If there was simply one frequency at a time coming down the aerial I could understand it (vaguely). But the whole point of tuning is that you are picking up loads of frequencies and just want one. How can you have signals alternating at different rates in the same component? Can you have electrons going both ways at once?
When it comes to tuning the receiver to select the desired frequency, again to simplify. You have an induction coil which will allow current to pass providing it’s alternating below a particular frequency. You have a capacitor which will allow current above a particular frequency. Anything too high for the induction coil and too low to get through the capacitor ends up going through the earpiece or audio amplifier because it can’t go anywhere else.
If there was simply one frequency at a time coming down the aerial I could understand it (vaguely). But the whole point of tuning is that you are picking up loads of frequencies and just want one. How can you have signals alternating at different rates in the same component? Can you have electrons going both ways at once?
Max_Torque said:
We turn on the record player, the bin revolves, and every so often (depending on how fast the bin is spinning) the hole is facing us. Now, we fire a load of tennis balls at that bin with a serving machine. The only balls that pass through the hole are those that arrive exactly when the hole is facing the firing machine. In effect, even if we fire balls at the bin at random moments in time, the only ones that get in, and those matching the rotating frequency of the bin. We have built a band pass filter.
This is same with a tuned electronic circuit. Using inductors and resistors and capacitors, the circuit oscillates at a specific frequency. Hence it only increases in energy if electrons arrive at the matching frequency on average.
So does the tuning set up the frequency of the circuit, then the circuit will only pick up signals that match the frequency of the circuit? That would make sense, it was explained to me as if the tuning circuit somehow selected the required signal to go one way and the other frequencies to go the other.This is same with a tuned electronic circuit. Using inductors and resistors and capacitors, the circuit oscillates at a specific frequency. Hence it only increases in energy if electrons arrive at the matching frequency on average.
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