Page 114 - Build Your Own Transistor Radios a Hobbyists Guide to High-Performance and Low-Powered Radio Circuits

) from the collector of Q3 therefore does not load the secondary winding with
resistance and thus further allows the antenna coil Ll to retain a high Q.
By turning up the signal from VRl, regeneration occurs, and increased RF voltage
gain is achieved at the output of Ql's emitter. The RF signal from Ql is further
amplified by Q2. The output of Q2 then is connected to a power detector Q4, which
demodulates the AM signal.

At 3 volts for the supply, this radio drained less than 300 JjA. So two D cells should
last about 5 years continuously. It should be noted that this radio will work down to
1.4 volts as well. Of course, three vegetable/fruit cells or about four to six solar
cells can be used to power this regenerative radio.

Depending on how the antenna coil is wound, regeneration mayor may not occur..
Thus, the secondary winding connections should be connected one way or reversed
to achieve regeneration. That is, if regeneration does not occur the first time, try
reversing the secondary winding's leads, which should then lead to regeneration or
positive feedback of the RF signal.