electronics-diy shows you how to easily make a mini FM transmitter:
It transmits FM waves so you could easily receive the signals on your mobile phone, radios, etc. As the name and the picture indicates it is very small and is approximately the size of a 9v battery clip. With this FM transmitter you could start your own mini FM station. The circuit uses BC547 transistor to amplify the signal and then frequency modulate it. It uses “frequency modulation” most commonly known as FM, the same principal to transmit audio signals captured by the microphone.
Mini FM transmitter - [Link]
Stream your music to your entire home !!!
Zola Lab – Portable FM Transmitter
Sparkfun Circular LED
Adafruit Si4713 FM Radio Transmitter
2 x Arduino Pro mini
Sparkfun Rotary Encoder
Catalex 4-Digits 7seg Display
On the top there is a: P2 audio input, a switch on/off, and a female micro-usb for charging Lipo.
DIY portable FM transmitter - [Link]
by ASCAS @ instructables.com:
Have you ever wanted to broadcast your own radio station within the neighborhood? Ever get curious on where people get those “Surveillance Bugs” from spy and action movies? This small and simple FM transmitter is the toy that geeks have always wanted.
FM transmitters can be complicated to build, that’s why I’m teaching you how to make a foolproof FM transmitter. There’s no need to buy kits, this tutorial includes the PCB layout and the schematics. It has a range of up to 1/4 mile or more. It’s great for room monitoring, baby listening and nature research.
The Ultimate FM Transmitter (Long Range Spybug) - [Link]
by brmarcum @ instructables.com:
I got the idea for this circuit from one of my professors at Washington State University. However, the frequencies used in that project would not have allowed for passing higher frequency audio, e.g. 2kHz+. So I built this by modifying the carrier and signal frequencies, using only the Digilent Analog Discovery and the Analog Parts Kit. It should be noted that this circuit is primarily for educational purposes. Also note that there is no radio transmission here either. FM doesn’t necessarily mean radio waves have to involved.
Throughout this Instructable I will be going through some of the functions and features of the Analog Discovery, but it will not be an exhaustive tutorial.
FM Modulation/de-modulation Circuit - [Link]
lamefreaks @ instructables.com writes:
In this instructable I’m going to show you how to build your own portable audio transmitter. This transmits FM waves so you could easily get the signals on your mobile phone, radios, etc. As the name and the picture indicates it is very small and is approximately the size of a 9v battery clip.
Mini Audio Transmitter - [Link]
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]