This project is car hands free that retransmits the audio signal from a cell phone to the FM broadcast band. By placing the cell phone’s speaker near the microphone, the user can use the phone as a hands-free device while driving.
MAX2606 – Hands-Free Car Kit for Cell Phones - [Link]
Locally broadcast your cell phone through FM band using MAX2606 from Maxim:
This design idea presents an integrated IF voltage-controlled oscillator (VCO) that can retransmit the audio signal from a cell phone to the FM broadcast band. By placing the cell phone’s speaker near the microphone, the user can use the phone as a hands-free device while driving.
VCO enables a hands-free car kit for cell phones - [Link]
A team of Columbia Engineering researchers, led by Mechanical Engineering Professor James Hone and Electrical Engineering Professor Kenneth Shepard, exploring the properties of graphene have demonstrated a new electro-mechanical resonant component.
The resonator’s structure consists of a 2-4 micrometer long strip of graphene suspended over a metal gate electrode. The strip of graphene has a natural resonance governed by its physical dimension and is used in the demonstration as the frequency determining element in an RF feedback oscillator circuit. Applying a voltage to the gate electrode stresses and deflects the graphene strip changing its resonant frequency. The team applied baseband audio and tones to the gate electrode to produce a 100 MHz FM signal.[via]
Tiny FM Transmitter uses Voltage Controlled Graphene Resonator - [Link]
This is a VCO FM Transmitter with range 500m – 4km depending on antenna used
- Power supply: 12-14 V stab., 100 mA
- RF power: 400 mW
- Impedance: 50-75 ohm
- Frequency range: 87,5-108 MHz
- Modulation: wideband FM
FM VCO Transmitter - [Link]
This is a small circuit with two maxim’s ic, MAX4467 as microphone amplifier and MAX406 as VCO FM transmitter. It’s suitable for short range FM transmittion aka wireless FM microphone.
Here is a very simple, inexpensive and interesting project which provides lot of fun to a home experimenter or hobbyist. This simple transmitter can transmit speech over a short range. It can be used as a simple cordless microphone. The circuit uses two integrated circuits from Maxim. IC1 a MAX4467, is an amplifier raising the microphone signal to a level suitable for frequency modulation (FM). IC2 is a voltage-controlled oscillator (VCO) with integrated varactor (a.k.a. varicap diode).
FM Transmitter MAX4467 & MAX2606 - [Link]
Making an FM using TEA5767 module:
I’ve started to build a little FM radio with one of this cheap modules with a Phillip chip, the TEA5767. I will control it with a MSP430, probably I’ll use some kind of encoder to change stations and a potentiometer for the volume.
The TEA5767 is a single-chip electronically tuned FM stereo radio for low-voltage applications with fully integrated Intermediate Frequency (IF) selectivity and demodulation. Most of the information of this devices is from the datasheet and this app note.
Making an FM radio-Part 1; the TEA5767 - [Link]
This project describes an Arduino-based FM transmission using the KT0803K Digital Stereo FM Transmitter Radio-Station-on-a-Chip. The KT0803K device is designed to process high fidelity stereo audio signal and transmit modulated FM signal over a short range. It features an on-board 20-bit audio ADC and supports standard I2C interface for frequency setting and power control. [via]
DIY FM transmission station using Arduino - [Link]
This article shows you how to build a very simple FM transmitter from thirteen components, a Printed Circuit Board (PCB) and a 9v battery. This project was designed to be mounted on a PCB, however you don’t have to. You could construct the project on Vero board (strip board) or any other 0.1” pitch style of project board. If you just want to experiment with this circuit, you don’t even need a board; you can just solder the component s together and let the completed project just rest on the work top. No matter which style you choose, try to keep all component leads nice and short. You could also make the PCB much smaller than the one shown here which is approx. 3 cm square. This is a good size to keep the unit small but nicer to work on for beginners. If you wanted to make one really small, you could use all SMT parts.
Simple FM Transmitter - [Link]
VHF FM Aircraft receiver:
VHF FM Aircraft Receiver is a superregenative receiver developed for listening to FM transmitters but also tunes the aircraft band and the top portion of the FM broadcast band. Receives both AM and FM (107mHz to 135 MHz). You can use this receiver with the any FM transmitter. The receiver is amazingly simple using only one transistor for the receiver section and one IC for the audio section. This circuit is a self-quenching regenerative RF receiver also known as a superregenerative receiver.
VHF FM Aircraft receiver - [Link]
This small transmitter can reach more than 1 km under good conditions . The input can either be an electret microphone or other audio source. The frequency is given by CV (trimmer common 2-20 or 3-30pF) and L1 4 or 5 turns of 22 AWG enameled wire with a diameter of 1 cm with air core.
FM transmitter with 2N2218 - [Link]