Yet another Variant of the Junk Box Regen – this one is really weird but is an excellent performer

In this version, I removed the darlington detector and added a emitter follower(Q3) to bias Q1 and act as a reflex detector. With this arrangement the circuit works best with a supply voltage from one to two volts or so. I used three diode drops in series to achieve this. You could also use a LED.  It has extremely smooth regeneration. The selectivity is excellent.

Again I got it to work with a wide range of values, so it should be easy to reproduce. I hope someone builds this and gives me their opinion on performance.

Schematic (revised 07/01/2015)

2222A regen_rev3


Variation on Junk Box Bipolar Regenerative Receiver

This version removes the direct coupling of Q2 in the previous version and increases the emitter resistor as well, finally the regeneration control is moved to the emitter circuit. The result is little better performance with less loading of the tank and less detuning caused  by  regeneration adjustment. Probably other optimizations possible also. I tried to make this thing not work…and it was difficult requiring extreme deviation from shown component values. It should be very easy to get this thing up and running with all sorts of tank circuits. It works well with a broad range of supply voltages also the values for R7, R8, R9, and R10 have a wide range of functional values. So one probably wants to start with my values and then tweak for best performance, once the circuit is up and running.

Schematic Diagram(modified TDA7052at circuit 07/01/2015)

2222A regen_rev2