AM transmitter using Integrated Circuit

Many beginners give up playing with RF due to the difficulty of building coils and problems with self oscillations that are common in many electronic circuits of RF. I always point out to beginning the construction of a small FM transmitter, myself have made available a simple circuit and an explanatory tutorial in Article Micro FM Transmitter and Micro Spy FM Transmitter Spy Bug in SMD.

The RF is really a very critical area, but on the other hand, it is the most rewarding, especially when we see one of our creations give the air of grace and drop its waves through the air. I always say that we learn more from mistakes and making mistakes is part of the electronics, I even today burst capacitors and transistors see loose tufts of smoke, the difference is that today I have fun with these errors.

Here I will publish a simple electronic circuit RF, so simple that does not use a single coil. This is a small tone transmitter modulated (AM) for the band of medium waves (AM) using an integrated inverter hex 4049 and a crystal circuit. The circuit is very simple, but effective, as can transmit smoothly.

AM transmitter using Integrated Circuit

The operation of this AM transmitter is simple, the RF oscillator in the transmitter circuit uses an inverter (7-6), whose frequency is determined by the 1 MHz crystal, as we see in the scheme. Two more drives (9-10 / 11-12) amplify the 1MHz oscillator signal.

Have the two inverters (3-2 / 5-4) produce an audio tone, which is modulated with the RF signal by the last inverter (14-15). You can use a piece of wire as an antenna, the signal, a buzz, should be easily capitate until a few meters from the transmitter at 1000 kHz in any AM radio.

With this circuit it is possible to work with the fundamental frequency and its harmonics at all integer multiples of a 1 MHz (or 2 MHz, 3 MHz, ... 10 MHz). This circuit can also be used as a frequency standard to verify the calibration of the display of a short wave radio.