mstechca said:
How were you able to determine the bandwidth of my circuit?
Its positive feedback increases the Q of its tuned circuit, especially at high gain required for low signal levels. Isn't it very distorted with distant stations? The super-regen was intended to track a beeper, not to listen to the radio.
I built it differently because I want broadcast bands instead of aircraft bands and I wanted to try to avoid oscillation noise.
For example, you replaced the low resistance coil that feeds power to it with a 27K resistor, seriously reducing its supply voltage.
I replaced the input coupling capacitor with a diode (as shown in the circuit) because I was afraid that the capacitor will cut off a set of frequencies, some which may be broadcast frequencies.
What is the best way to bias the transistor in my case to get the maximum output?
The diode and base-emitter junction of the amp's 1st transistor are seriously loading-down the DC output voltage of the super-regen. The amp's input should have a coupling cap and its 1st transistor should be biased with a voltage-divider and have DC and AC negative feedback from the output. If you bias the amp's input so that its output voltage is at half-supply, and add another resistor and capacitor to the 1st transistor's collector for bootstrapping, the output will be much more.
If you add another diode between the bases of the output transistors and add small-value emitter resistors to them, you will eliminate its crossover distortion.
How do I fix the threshhold problem?
Use an opamp instead of a transistor.
I feel that by using transistors, I will learn more about electronics. Also, I want to use the least amount of space possible for my designs. Some IC's are also more difficult to find than others.
I know, it is best to do things yourself but you should also study the theory. I don't know where you are, but in North America orders are placed on the web or by phone and the parts are delivered the next morning. "Yeah, that's the end of my order, I'm glad you always have everything I need. Here's my credit card number, just a minute someone's at the door" (its the delivery)
Many different manufacturers make the same parts. You get to choose, frequently their prices are slightly different.