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You'll find that this is a very easy project to build. It will transmit good quality sound in the FM band ( 88 - 108 mhz ). One inportant item is that the IC chip operates on 3 volts DC. The chip will get destroyed if it is operated on any voltage higher than 3.5 volts. The antenna can be a standard telescopic antenna or a 2 foot length of wire. The input is in the millivolt range and you may need to add additional pots for the inputs. I was able to use this circuit for a walkman and a portable CD player in my car. I used the headphone jack on both and varied the signal with the volume control. FM Stereo Transmitter Circuit Diagram To adjust the circuit tune your FM radio to a quite spot then adjust the trimmer capacitor C8 until you hear the signal that you are transmiting. When you have a strong signal adjust the resistor R4 until the stereo signal indicator lights. If the input is to high of a signal you may over drive the IC chip. Use two 15 turn pots on the input signals to b...

The post explains a 10 km long range transmitter circuit using ordinary components .PCB fabrication also explained. With the increased activity on 2 metres, some who may have contemplated working this band, have possibly been deterred by the cost of a " black box " and the uncertainty of modifying commercial equipment. With this situation in mind, the Author has , designed a simple , easily-built 2m f.m. transmitter, that can be assembled by anyone who can use a soldering iron and small tools whilst possessing a reasonable amount of patience. The completed unit will perform well, being as versatile as the constructor ultimately wishes to make it. An r.f. output of around 1 watts can be expected if the unit is constructed as described but power far in excess of this may be, achieved if the design is regarded as a working basis and the p.a. stage is developed. Construction Procedures for the proposed long range transmitter circuit A simple printed circuit technique is employed...

The use of transmitters which have a more powerful output than the ‘flea-power’ are sometimes required when there are many obstacles in the path of the surveillance transmitter and monitoring station receiver, or the distance between them is too far so as to make a low powered device feasible. Whereas a typical micro transmitter will produce an RF power in the order of just a few milliwatts, i.e. a few thousandths of a watt, the VHF-FM transmitter described has a power output of between around a half and 2 watts, depending on the power source, which may be anywhere between 6 volts and 30 volts d.c. . Circuit diagram : Long Range FM Transmitter Circuit diagram The battery or batteries should be of the alkaline high power type, since the current drain will be found to be relatively higher when compared to microtransmitter current drain The power output of this device is somewhat proportional to the current drain and so therefore both may be decreased by altering the value of R6 to a...

Audio input from PL1 frequency modulates the VCO section of a 4046 PLL chip. The VCO output drives Q1, a switching transistor. Q1 drives two IR LEDs. The signal produced is around 100 kHz, FM carrier VCO sensitivity is around 7.5 kHz/V. Wireless IR Headphone Transmitter Circuit Schematic