Electronic – Is it possible to make a coil-less simple Shortwave Receiver

transmitter

I am really a newbie here in Electronics and I'm into it as a hobby/passtime.
I was going through this simple coil-less Shortwave Transmitter circuit on a blog.

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Q1 – BC548, X1 – 10.7 MHz ceramic resonator, 3 terminal, C1 – 10 nF, C2 – 100 nF, C3 – 100 pF, R1 – 10 kOhm, R2 – 150 kOhm, R3 – 1 kOhm

My questions are:

  1. Does circuits like this work? I want to know how this circuit oscillates at a shortwave frequency without LC Tanks. Is it entirely done by the ceramic resonator?
  2. Can I create a similar circuit to receive Shortwave audio signal, which won't use a old-days coil and ferrite rod? If someone could help me with a simple circuit diagram for a shortwave radio receiver which uses such ceramic resonator I will be grateful. I couldn't find it on the web.

Best Answer

Ceramic and Crystal resonators are very high Q resonators with equivalent circuits the same as an LC parallel tank cct here. ( Q= 5k to 10k ) They work by passing a bandpass where the phase shift is 180 deg together with C3 such that with the inverting transistor the result is some gain with positive feedback to become an oscillator.

Which won't use a old-days coil and ferrite rod?

You would need multiple stages of ceramic and crystal bandpass filters. Coils are good for the intial stage LC resonant band filter with high passive gain.

Coils are very useful and should not be ignored. enter image description here But here are some ways of finding more info by adding keywords

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