Circuit-Zone.com - Electronic Projects
Posted on Wednesday, February 3, 2016 • Category: FM Transmitters
FM transmitters can be complicated to build, but not this one ó this iPod FM transmitter about the easiest you can possibly make. And though the science of radio is well understood, thereís a magical, emotional quality about it that we donít often stop to appreciate. You will not forget the first time you pick up a transmission broadcast from a device you soldered together, yourself, from a few bits of copper, carbon, plastic, and wire.
Posted on Monday, January 18, 2016 • Category: FM Transmitters
The circuit is a simple 88-108 MHz VHF FM transmitter circuit. It is basically a VHF Colpitts oscillator capable of transmitting sound or music to any standard FM receiver. The circuit is powered by 9V battery which makes it easily portable. It also has a capacitor microphone which picks up very weak sound signals. The output frequency can be easily adjusted by potentiometer thanks to onboard MV2109 varicap diode and the frequency stability is quite good. The range of this transmitter is 100 meters.
Posted on Friday, December 18, 2015 • Category: FM Transmitters
This simple circuit is based on BA1404 FM Transmitter, works with two AA batteries and can drive a 300W dipole antenna for improved range. There are many applications for an FM transmitter, particularly if it can broadcast in stereo. You can broadcast stereo signals from your CD player or any other source to an FM tuner or radio. The transmitter uses a single IC and a few other components. It broadcasts on the FM band (88-108MHz) so that it can be received by any standard FM tuner or portable radio.
Posted on Thursday, December 3, 2015 • Category: FM Transmitters
This basic RF oscillator circuit is easy to build and the components are not critical. Most of them can be found in your junk parts box. The circuit operated with 9V DC power supply. The L1 antenna coil can be made by close winding 8 to 10 turns of 22 gauge insulted magnetic wire around 1/4 inch form such as a pencil. You can experiment with the size of the coil and the number of turns to see how it affects the frequency and signal output of the oscillator. You should be able to pick up its signal with standard FM radio receiver. Signal In to any audio player through 0.1uF capacitor.
Posted on Thursday, November 26, 2015 • Category: FM Transmitters
This 7 Watt FM Transmitter was originally a 200mW unit, without the universal power stage added. Together with the power amp 2SC1971 / MRF237 / NTE342 it then became a 7W unit. I used this transmitter with a half-wave open-end dipole in a vertical position 50 feet above ground. Together with about 70 feet of coax, this transmitter delivered great audio at a distance of 10 miles ... overall distance was 17 miles, but the audio signal was weak. I had no equipment, other than a watt meter to measure it's power and a digital FM tuner with a 5-LED Signal Strength Bargraph display to use as capturing the main oscillating frequency, which was right at 87.5 MHz. This circuit worked well for me, as I had experimented with it for nearly a year. Of course, one would be better off with more equipment than I have had to capture the main oscillating frequency. That was, by far, one of the hardest things to capture. It was thru trial and error, with the FM tuner, in finally finding out how to grab the right frequency. When I finally did get used to find out where my 'main' frequency was, the unit performed extremely well. Like I had said above, right at 10 miles, the unit was at its best giving clear audible audio into the speakers of my car. With the transmitting antenna at 50 feet above ground, I decided to see how well I could receive the transmitter signal from an overpass than is exactly 15 miles from the transmitter. When I got to the top of the overpass in my car, the audio signal came in as 'clear as a bell'. I now understand what is meant when one says FM signal travels best in a line of sight. Well, being on that overpass, if I had a strong telescope with me, I am sure I could see the 50 foot antenna in my oak tree. So with the overpass being right around 50 feet in height also, the transmitter surpassed my judgement call on its signal. I surrender this circuit to anyone who likes to experiment in things like this. Enjoy!
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