headbuttking2

Hello, I frequent these forums alot, but this is my first actual post so please bare with me.

I have a garage door opener that operates at 310 MHz and I want to find a way that I will be able to switch between 310 MHz and 390 MHz.

Linear Corp (the makers of it) refuse to give me any help.
There is an IC made by semefab to linear corp's specs, but I can not get data from either of them, so I am pretty much left in the dark with that.

I drew the schematic of the oscillator from looking at the circuit, which looks to be a Collpit oscillator; however, I did not see the center tapped cap anywhere (I must have missed it).
As seen in the schematic I did on pspice, there is a variable cap inside of the netowork.

I could not get pspice to run a simulation on it either.
I am pretty new to it, and we just started using it in school, so I really do not have a very extensive knowledge on that.

If anyone can help me with this I would greatly appreciate it.
I need any help I can, especially how this works and what not.

Q1 is a KSP10 VHF/UHF NPN Transistor
D1 is an LED

The 5 V power should be 9 V, that was a mistake I made.
and I have no idea the capacitance of the variable capacitor

Thanks in advance,
Jim

Attached Images

oscillator_350.jpg (18.1 KB, 246 views)

fsahmed

Well, to shift the frequency, u will have to experiment with the capacitances. As for SPICE, u have shown the supply ground, but u dont seem to have defined ground anywhere in the circuit.

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F. S. Ahmed