Tuesday, April 10, 2012

Low voltage oscillator experiments

No rocket science here, I just wanted to see how low can we go on voltage for a simple crystal oscillator.... following the idea of a possible solar cell powered beacon....

Schematic (from BITX transceiver):

Crystal connected directly to ground and I used 390pf capacitors...just run out of 220pf :) and the 120K replaced by an 100K resistor.
Transistor is the incredible 2N3904... what else!

And the lousy photo on the assembly, I used the AM modulator part from my laser experiments (an LM317 regulator)... without modulation of course...



Here the consumption at 1.78V:
..That's mA...

Didn't tried any lower voltage...

And with another voltages...





Emitter is connected to the high impedance input of the frequency counter

Just tested an 10Mhz crystal.

Have fun....

7 comments:

Sverre Holm said...

Nice test. I wonder for how low in voltage it would have worked? Maybe as low as the 1-1.5 Volt circuits Whatever happened to the 1 Volt QRP Transceivers?

Ricardo - CT2GQV said...

Hello Sverre,

Thank you for the comment, I hadn't read your post before (what a coincidence, hi) but will follow the blog for sure.
I didn't tested lower voltages just because I was lazy and didn't bothered to change the voltage divider on the LM317 output.

pedro said...

http://www.swharden.com/blog/2010-05-24-solar-powered-qrss-beacon/

pedro said...

http://wa0uwh.blogspot.pt/2012/04/qrp-tests-for-night.html

Ricardo - CT2GQV said...

I tested latter on with one of those garden solar cells but could not get a stable oscillation, probably will need 2 in parallel and series with another 2 to get more current and voltage.

pedro said...

tens de usar alguma coisa para armazenar a energia, se insistires em usar a corrente directamente dos paineis nao vais longe....
Imagina que passa uma nuvem !!!! a corrente baixa ;)

Ricardo - CT2GQV said...

Viva Pedro,

Sim, tenho consciência do facto :)