27.12 MHZ Crystal

[sleepless]

Helo All how to generate a 27.12 Mhz sine wave from a xtal oscillitor .I have to design this Using only 3 volts battery as i have to use this to design a small prototype of threaphy device for healing and pain relief. .Does anyone have any idea?

 

[rjenkinsgb]

A simple colpitts oscillator and a single transistor buffer should give a reasonable sine wave, IF the crystal is cut at that fundamental frequency.
It may be an overtone type, that requires a tuned oscillator.

This is a basic colpitts crystal osc.
You would have to reduce the bias resistor value for 3V operation:

https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRcDe7ponedx_J0Thqd3QCMmJM-Aix3-lGFbffjQqIXgCPBEIm0

This is a third overtone circuit for 30MHz, which should be OK for 27MHz as well with minor adjustments, though again resistor values would need adjusting for 3V
I'd use a trimcap for C1, either 47pF or 22pF with 10pF in parallel.
.

[Image from this page: https://electronics.stackexchange.c...ration-of-higher-freq-from-lower-freq-crystal ]

 

[unclejed613]

threaphy device for healing and pain relief.

diathermy? i thought those machines ran a bit of wattage, as well as being restricted to the ISM bands.

 

[Boxnut]

There are different chrystals for given application. The Colpitts shown should fill your bill.
Now just the oscillator is not going to produce enough power for your job. a gain stage would be needed to provide that as many diathermy devices get up to a few watts output.