Here is a simple circuit for a one transistor
Audion type radio powered by a 1.5 V battery. It employs a set of standard
low-impedance headphones with the headphone socket wired so that the two sides
are connected in series thus giving an impedance of 64 Ω. The supply to the
circuit also passes through the headphones so that unplugging the headphones
turns off the supply. Using an Audion configuration means that the single
transistor performs both demodulation and amplification of the signal.
The
sensitivity of this receiver is such that a 2 m length of wire is all that is
needed as an antenna. The tap on the antenna coil is at 1/5th of the total
winding on the ferrite rod. For details of the antenna coil see the article
Diode Radio for Low Impedance Headphones. This circuit is suitable for reception
of all AM transmissions from long-wave through to shortwave.
Back to ..
The
sensitivity of this receiver is such that a 2 m length of wire is all that is
needed as an antenna. The tap on the antenna coil is at 1/5th of the total
winding on the ferrite rod. For details of the antenna coil see the article
Diode Radio for Low Impedance Headphones. This circuit is suitable for reception
of all AM transmissions from long-wave through to shortwave.
Back to ..