my Superregen is better

[mstechca]

The two pictures represent two schematics. One is my updated Superregen detector, and the other is my automatic station changer (ASC for short). When I connect the ASC to the green area of my superregen, the ASC works well, but the stations do not work well. In fact, I'll be lucky if I get 1/4 of the FM band. If I replace the tuning capacitor (in red) with the ASC, then the speaker emits no tone, but when I press the button, it sounds like the stations are changing, but nothing is actually happening.

If I didn't apply the ASC at all to the circuit and left it alone, it works nicely. It even works better when I add anything between 1 and 10pF across the inductor highlighted in green.

If I have to add a transistor to make the ASC to work, I will.

Because right now, for me to change stations will be somewhat of a pain because the most I can turn the tuning capacitor is about 10 degrees. Anything beyond that will cause me to miss a station. I wouldn't have this problem if my ASC can do it's job.

By the way, no parts are damaged, and the transistor I am using is 2N3903 (not 2N3904).

 

[Nigel Goodwin]

If I replace the tuning capacitor (in red) with the ASC, then the speaker emits no tone, but when I press the button, it sounds like the stations are changing, but nothing is actually happening.

Everyone has told you that the circuit can't possibly work, which it can't, there's no circuit to switch the capacitors - even if there was, you can't go round switching 1pf, 2pf and 4pf capacitors, the stray capacitance introduced wil be higher than the values of the capacitors.

 

[audioguru]

Isn't the super-regen's transistor saturated?
For 5.0V to appear across the 45k collector load, its current is 0.11mA.
If the transistor has an hFE of 100, then only 0.4V across the 120k base bias resistor provides more than enough base current (3.3uA) for the transistor to saturate.
Maybe the emitter and collector of the transistor are reversed. Then it needs an hFE of only 1.6 to work in this circuit. Backwards transistors have a gain of more than 1.6.

I have never heard of using a Cmos counter to select low-value capacitors. The capacitance between its pins is much more than the capacitors it is selecting.