Archive for the ‘Radio Transmitters’ Category

Pocket size FM radio station

The above video claims  you can make a pocket size FM radio station and  the highlight is you dont need an antenna to do this. A small battery is enough to power and it will last for 5 to 7 hrs. This small battery powered FM radiostation even dont need a antenna to broadcast your program into the entire neighborhood for up to a mile or more . It use’s a Onboard Magnetic Loop Antenn, which is the outside copper layer. It is nothing but 2 transistors connected as a pushpull oscillator. Well, I haven’t tested this yet, so its…

Read More

FM adaptor circuit for car stereo

Description. With this compact FM adaptor circuit plugged into the audio out of your cassete player or i Pod out put,you can listen your favorite music on your car stereo.This circuit is very useful if your car stereo doesnot have an auxillary in socket.The circuit is nothing buy  an short range  FM transimitter. The FM transmitter circuit is based on low power NPN transistor 2N2222.The tank circuit consisting of L1 & C1 producess the necessary oscillations at the collector of Q1.The capacitance C4 , resistance R3 & R4  performs the function of mixing the stereo out put from theaudio player…

Read More

IR to RF converter circuit.

Description. The IR to RF transmitter circuit given here can convert the IR signals from your remote to RF signals to long distances. The circuit given here is a good one for extending the range of your IR remote.Also such systems does not need a line of sight since RF signals are used. The transmitter is based on a St-TX 01 ASK transmitter IC (IC2).The IR signals falling on IC 1 (TSOP 1738) will be converted to RF signals by IC2 and transmitted through antenna.The transmitter has a power output of 16dBm at 5V supply. The receiver is based on…

Read More

Versatile FM Transmitter

Description. Here is the circuit diagram of a versatile FM transmitter that doesn’t have a coil. The circuit is simple and easy to assemble. The gate N1 acts as a buffer for strengthening the signals from the condenser microphone. The inverter N2 with its  associated components forms a radio frequency oscillator in the FM region.The varicap diode  BB109 is used for frequency modulating the audio signal to the carrier wave generated by the oscillator.Inverters N4 t0 N6 are used to drive the antenna.As the N4,N5,N6 are connected in parallel their effective output impedance is very less and can easily drive…

Read More

FM telephone bug.

Description. A simple telephone transmitter circuit that is ideal for transmitting the telephone conversation through small distances.The circuit is very simple and uses only few components.The entire circuit can be easily included in the telephone itself or in the junction box.The circuit is powered from the telephone line itself. The transistor Q2 is wired as a a Colpitts oscillator to produce oscillations in the FM transmission band.The audio signal from the telephone line is coupled to the the base of Q2 to obtain the frequency modulation.The LED D1 acts as a power on indicator. Circuit diagram with Parts list. Notes….

Read More

FM Tracking transmitter

Description. The circuit presented her will transmit a audio tone in the FM  band. The circuit can be used as a tracking signal transmitter or a remote control transmitter. The circuit uses only easily available components and any one can build this. The transmitter has a range of 100m @ 9V supply, with a matching antenna. The NE555 timer (IC1) is used for producing the audio tone. The first JFET (Q1) is wired as a Hartley oscillator which is frequency modulated by the audio tone. The second (Q2) JFET is wired as a buffer to isolate the oscillator based on…

Read More

Simplest FM Transmitter.

Description. Here is the circuit diagram of the simplest FM transmitter using a transistor. Great performance or range is not guaranteed here, because this is an elementary design. General purpose radio frequency transistor BF 494 (Q1) is used here for obtaining FM modulation. A condenser mic is used here to pickup the sound. The condenser mic converts the sound to electrical variations and this variations are fed to the base of Q1, which performs the amplification as well as modulation. The capacitor  C2  and L1 determines the frequency of transmission. The circuit can be powered from a 9V transistor radio…

Read More

Single chip FM transmitter circuit

Single chip FM transmitter Description Here’s a single chip FM transmitter circuit using Maxim semiconductors IC MAX2606. The MAX2606 is a compact, high-performance intermediate frequency VCO specially designed for wireless communication circuits. They have monolithic construction with low-noise and a low-power operation in a compact 6-pin SOT23 packing .Th1s low-noise IC feature an on-chip varicap diode and feedback capacitances that avoid the need for external tuning components, making the MAX2606 perfect for portable systems. Only an external inductor is needed to set the oscillation frequency.In addition to this, an integrated differential output buffer is also there for driving a mixer…

Read More

Long Range FM Transmitter

How to make a long range FM transmitter at low cost Description 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…

Read More