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Building projects from the schematic diagram - a one transistor crystal oscillator

One of the most important skill in electronics is putting something together from a circuit diagram. In doing this you need several skills that you don't get when building a kit. For example you need to obtain parts, design a layout and solder them in correctly. And there is no writing on the circuit board, or sometimes even no circuit board at all, to guide you.

To maximise your chance of success start with something simple. Maybe a reliable circuit with one transistor and no more than 10 other components. Preferably one that is useful in its own right or can be extended on to form a receiver or transmitter project.

The crystal oscillator described in the video below is ideal.

 

  The crystal is not critical. You could use something salvaged from an old computer, modem or set top box. Anything in the 3 to 25 MHz range should be suitable.

Then when you have it going (use an HF receiver to test its operation) you can do various experiments with it. For instance add a variable capacitor and (optionally) inductance to shift its frequency a little. A 'super VXO' arrangement with multiple crystals in parallel can let you move frequency even more. The same applies to ceramic resonators. More on variable crystal oscillators here. Ceramic resonators in the amateur bands like 3.58 MHz or 7.2 MHz can be particularly useful for later projects. For example use in a BFO for an AM-only shortwave receiver to enable SSB reception. See my BFO project here for an example.

The next progression is some sort of receiver that uses the ceramic resonator oscillator as a local oscillator. That can be a 7 MHz direct conversion receiver or DSB transceiver like the Beach 40. This puts out 2w but can get contacts up to 2000 km or more distant under good conditions. See my Beach 40 project write-up and watch videos here.

Many other ceramic resonator projects are on the web so maybe also try some of those. Ceramic resonators and crystals can be bought from Minikits in South Australia.

 

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