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In search of the simplest oscillator...

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twistchi

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Hi everyone! I just recently go back into the hobby of electronics recently and have refreshed myself with the basic principles of components and circuits. I have a good understanding of the basic 'law's' and am once again stuck where I was 10 years ago. Oscillator circuits. All I want is a simple, the less components the better, circuit with one transistor, one coil, one capacitor that is capable of operating in the .5 to 1Mghz range. The output does not have to be a sinusoidal, square, or sawtooth. I am not looking for perfection here. I just want a circuit that I can 'see' working so I can understand how and why it work's. I know it is not impossible because I have made, by accident, a circuit that made interference on channel 8(VHF) but cannot remember how I did it. I know I used a 470uF Electrolytic capacitor, one npn transistor, and I am guessing for the coil I had a voltage meter in the circuit. Don't ask how it was hooked up because I can't remember. I wish to use DC voltage as well (3-9) volts and don't care if it's a feedback, hartley or whatever oscillator. Though I wish to stay away from that center-tapped coil kind. Bear with me in my ignorance but if I don't ask I won't learn. Thank you everyone.
 
Lots of amateur radio publications have precisely what you've described. The ARRL publishes a new handbook every year that has plenty of that stuff. You might search for colpitts, hartley or VFO (Variable Frequency Oscillator). Some of the old (and possibly new) Radio Shack publications have simple circuits as well.
 
twistchi said:
.5 to 1Mghz range.

Do you mean 0.5 to 1 Mhz, or 0.5 to 1 Ghz (500 to 1000 Mhz).
It makes a big difference.

JimB
 
re:frequency

500 Khz to 1000 Khz. Yes, part of the AM radio band so I can cause interference in a radio to make sure the circuit is working and any modifications I do to that circuit work. Thanks.
 
stevez mentioned the Colpitts and Hartley oscillators.

The Hartley is the one with a tapped coil.

The Colpitts uses a tapped C instead (two capacitors in series aross the coil.)

A Google search will no doubt give you many leads to follow.
 
where to put battery?

I looked at the colpitt's circuit and ya that's simple enough thank you. To make it work can I do this?

attachment.
 

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No. The inductor is a short across the battery.

The transistor has to be biased correctly and it needs a collector supply.

Do a Google search.
 
Thank you all.

All right, from the circuit that Ron H. has pointed out it is simple enough to understand and learn from this oscillator. This is what I needed to get started. Thank you all for your comments as well.
 
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