This project uses a strange way to get lts power. lt uses power "extracted"
from the tuned station to give to the amplifier transistor. With a reasonably
strong applied modulation envelope, this type of detector produces astrong
demodulated output.
Naturally, the closer you are to a strong station, the more current your radio
will be able to supply.
For best results, you must do everything possible to deliver a strong signalto
the transistor detector. We recommend a good antenna and ground, the latter preferably being made to a water pipe or solid external ground composed
of a pipe driven at least 5 feet into moist earth. This is important for ensuring
maximum signal pickup. I
lf you have plenty of space available, the longer the antenna (up to about 100
feet), the better the results.
Figure I shows the schematic diagram of the Free-Power AM receiver. Observe that the heart of the circuit is a germanium transistor that works as a
detector and audio amplifier.
Gomponents placement on a terminal strip used as a chassis is shown in
Figurc 2.The terminal strip can be fixed on an experiment board that can be
constructed using some common tools and materials.
Ql is any germanium transistor, such as GE-2 or 2N107.You can find germanium transistors inold nonworking AM transistor radio receivers. Nonworking
AM radios can also supply the variable capacitor and the loopstick (ferrite
rod).
Earphone must be a high-impedance crystaltype. Low-impedance earphones
don't function in this circuit.
Parts List - Free-Power AM Receiver
Q1 - NPN or PNP germanium transistor - see text
XTAL - Crystal earPhone
L1 - LooPstick - see text
CV - 365 pF variable capacitor - see text
Rl - 12,000 ohm, 114W,57" resistor
C1 - 1 uF, 25 WVDC electrolytic capacitor
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