Tuesday, September 21, 2021

Adding a Lamda Diode Oscillator and V-Cap

 

The four transistors produce a Vcap to tune the oscillator. The sim is stepping the 10k pot from 1k to 10k in 1k steps. The 100p cap (C2) set the range while the pot produces band spread. If C2 is a variable air cap you could tune with it and use the pot as a band spread. You could use a switch to select C2 as a band selector.

* I need to do some adjusting on the circuit but this is a good start. Putting it here so I don't loose it.



Friday, September 3, 2021

3 volt earbud amp

 Back to the project. I will be going with the 3 volt supply. My earbud is rated at 1ma. This amp look good.



The input is 500uv for 1 ma output. 

The battery drain is a little less than 1 ma. R6 could be adjusted to vary the Q current. If R6 was 1 meg it would probably be good but for I'll go with 100k and expect to need a volume control. 

Time to clean off the bench and gather parts for a build.