8W Broadband FM RF Amplifier
Here's 8W broadband FM RF amplifier using 2SC1971 VHF power transistor. The RF Amplifier PCB layout designed for FM broadband 88-108 MHz transmitters using microstripline technique. This 8W RF amplifier circuit provides an appropriate power boost for transmitters with an input of 500 mW.
8W PLL Stereo Transmitter with LCD
Very stable PLL FM transmitter based on TSA5511 synthesizer. Frequency is performed with three buttons through PIC16F84 microcontroller. Frequency is displayed on 16x1 LCD. Transmitter oscillator is based around BF981, BFR91, BFR96 transistors. 2SC1971 RF power transistor can be replaced with 2N4427 or 2N3553 but they will provide less output power.
A Wide Dynamic Range Field Strength Meter
This unit is an updated version of the Wide Dynamic Range Field Strength Meter. While the basic function is the same, it has several critical differences:
It uses a specialized integrated circuit, the Analog Devices AD8307. This chip is designed specifically as a logarithmic amplifier for use through 500 MHz.
Using the AD8307, it has a wider dynamic range (85 dB versus 55 dB) and it has built-in temperature compensation.
Because of the different nature of this type of detector - and the fact that it has temperature compensation - means that there is no need for a "zeroing" control.
One disadvantage of this approach as compared to the diode approach is that the AD8307 has a lower frequency response than the diode. The frequency limit of the meter is dictated pretty much by the diodes themselves along with their physical layout and related components: There is no reason why the earlier version could not be constructed to work through 10 GHz or so - but the AD8307 is falling flat by the time you get to 1 GHz, making it unsuitable for detecting wireless LANs or PCS-type cell phones.
ALTOIDS Tin Part 15 Version FM Transmitter
The transmitter uses 2 MPSH10 (equiv BF494 or NTE229) transistors in a double-ended free-running voltage controlled oscillator (VCO) operating at half the output frequency on each side and combined at L2, which is tuned to the 2nd harmonic of the VCO and covers the 88-108 MHz range. A standard 9 volt battery is used for power and fits inside the tin. The mono audio input circuit is totally passive with 70us pre-emphasis provided and the audio quality is great.
AM Radio Transmitter Using 555 Chip
This project shows how to build a simple AM radio transmitter based on 555 timer IC. The circuit parts are: the 555 timer IC, a NPN transistor three caps, three resistors and a potentiometer. The circuit is able to generate an amplitude modulation signal at 600Khz and you are able to receive it using a plain AM receiver. The range is about 30-40 feet.
BA1404 3V Stereo FM Transmitter
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.
BA1404 Transmitter with UPC1651RF Amplifier
BA1404 transmitter includes onboard RF amplifier for increased transmitting range. Operating voltage range is 1-3V, the circuit contains FM stereo mixer, 38KHZ oscillator, FM modulator and high-frequency amplifier monolithic integrated circuit. As the "electronic newspaper" BBS there are many users requiring detailed information on the FM stereo transmitter, so I re-collect the relevant information on the simple discrete, merge, integrated FM stereo transmitter experiment, that BA1404 with μpc1651 mix of the most easy to make and debug, and very high frequency stability (relative to the previous circuit BA1404), transmission power is increased by UPC1651RF amplifier.
This bandpass filter is in fact a combined high- and lowpassfilter. The first stages are a highpass (f>70MHz) and the last stages a low pass (f<180MHz). The lost of this filter is several watts when driven with 20[Watts], but the output signal is (when adjusted with a spectrum analyser) very clean.
Basic FM Transmitter
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.
BH1415F FM Stereo PLL Transmitter
Transmitter power amplifier, the output signal from BH1415F by 2 SC9018, 2SC3355, 2SC2053 amplified signal can reach more than 500 mW, adjusting well to achieve greater power. Measured by the pull rod antenna used to be launched in the open 800 meters above. Uses external antenna will be launched even further. attention in 2053 need to be installed and tested at the load connected to leave, or else very easily burn 2053, 50 European amateur production of 2 W can be used instead of resistance. installed and tested at three levels circuit can be installed and tested.