Simple AM Receiver circuit diagram on IC ZN415
The IC ZN415 represents the full-fledged of the broadcasting receiver for work with amplitude modulation including the amplifier of a radio frequency, the detector, the LF amplifier for work on headphones. Rated supply voltage - 1,5V.
The IC ZN415 is an improved version of IC ZN414 which is executed in the three-output "transistor" case, but differs from it in existence of telephone LF Amplifier, and is executed in the DIP-8 case.
The IC ZN415 can be used as a basis of the receiver, and as a path of intermediate frequency and telephone LF Amplifier of the simple superheterodyne AM-receiver.
The figure shows the circuit diagram of simple AM receiver working in the range cover the mediumwave band and high-frequency part of long-wave broadcasting band.
Reception is carried out on the magnetic antenna consisting of a ferrite rod and the L1 coil. The entrance of RF-amplifier rather high-resistance therefore coils of communication or branch isn't required, and the entrance contour consisting of L1 and the variable C1 capacitor is connected to RF-amplifier entrance (PIN 1) directly (without branches or coils of communication).
The magnetic antenna consists of a ferrite rod with a diameter of 8 mm and length so big, on the receiver case how many allows. The L1 coil is reeled up on a self-made framework. It represents the sleeve which is stuck together from a Whatman paper or dense paper. The L1 coil contains 75 turns of super enameled copper wire 0,43 or another, with a diameter from 0,3 to 0,6 mm.
Winding - a round to a round. Previously record the ends of a winding threads, rubber rings or an insulating tape, - perhaps in the course of adjustment it is necessary to select number of turns that all powerful local radio stations working both at averages, and at long waves got to the range of control.
The variable capacitor C1 - from the superheterodyne receiver. It has two sections for AM of ranges on 7-270 pF. They are included in parallel therefore it turns out 14-540 pF. It is possible to use the capacitor and other capacity, for example, 5-240 pF (at parallel inclusion will be 10-480 pF).
Detector output - the pin 2. Via the C4 capacitor the signal arrives on telephone LF Amplifier. Phones are connected to the Pin 5 via the standard socket. For listening stereophones are used, their general pin isn't connected anywhere therefore earphones are included consistently. It is possible to use standard stereophonic small-sized headphones or single mono - phone. The power supply - one galvanic cell like "AAA" of 1,5V.
Installation is executed on the PCB.
Before construction of this simple AM receiver it is necessary on example of the ready receiver of industrial production with AM ranges to be convinced available local powerful radio stations of MW-Band or LW-Band, and their frequency.
At desire it is possible to add in this simple AM receiver the volume adjuster, as shown on the next picture: