Where to put a crystal?

Thread Starter

nerdegutta

Joined Dec 15, 2009
2,684
Hi.

I have this schematic, built on a homebrew PCB. I have build some FM minitrasmitters, but they are jumping up and down the frequency.

I also have a lot of crystals, and I would like to use one of them to stabilize the frequency. Is this possible?
 

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rjenkins

Joined Nov 6, 2005
1,013
You need a decoupling capacitor across the power supply. As shown, the battery and it's wiring are part of the RF current path..

Fit a 0.1uF as near to the R7 / L1 power connections as possible. That should help with stability.

Also, if you connect the antenna to a tap on the coil (possibly a quarter of the way down from the positive end), it should be even more stable and give better output.
 

Thread Starter

nerdegutta

Joined Dec 15, 2009
2,684
Hi.

Bertus:
Thanks for the link. Lots of good reading. :) Need to buy some IC's.


RJenkins:
I've edited the schematics, but I'm not sure where to put the 0.01uF near the R7 / L1.
 

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