How to Use a FM Transmitter to Listen to Internet Radio

How to Use a FM Transmitter to Listen to Internet Radio

Gone are the good old days of Internet radio when you had to stay chained to your desktop PC to enjoy the music. The FM transmitter takes any audio coming from a computer and transmits it to a FM radio, allowing you to use your FM radios as speakers.

Now you can wander through the house listening to your favorite songs.

Decide which type of FM radio transmitter is best for you. There are several types on the market that differ in size, transmission distance, power supply method, number of FM transmitter frequencies, portability and price.


Purchase a FM transmitter. You can buy them online or at a local electronics retailer.Such as http://www.papatek.com/Cell%2DPhone%2DAccessories

Connect the FM transmitter to its power source and then to your PC. Read the manufacturer's instructions for your model. Depending on the type of FM transmitter you buy, it may be powered by batteries, computer USB port or AC power. Most models come with the necessary connection cables. A FM transmitter USB simply plugs into a USB port of any computer
 http://www.papatek.com/Cell-Phone-Accessories/Blue-LED-F ...


Locate an available FM frequency on the dial of your FM radio. The manufacturer's instructions will list the frequencies that are available with the FM transmitter. It is not uncommon that you will probably need to try more than one of the listed frequencies before you find one that works.

Listen and enjoy your favorite Internet radio music or program with the freedom to move around. http://www.papatek.com/Cell-Phone-Accessories/FM-Transmitter-Hands-free-Car-Kit-For-Blackberry-Phone.html

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Broadband Colpitts VCO for TV Tuner

Broadband Colpitts VCO for TV Tuner

The high performance of modern set-top DBS TV tuners require broadband voltage control oscillator (VCO) designs at a competitive cost. To realize these goals, design engineers are challenged to create high performance, low-cost VCOs.

The traditional design of Colpitts oscillator is used for many VCO applications. Designing a broadband Colpitts oscillator with coverage from 1–2 GHz requires the selection and interaction of an appropriate varactor diode for its resonator. This design describes a broadband Colpitts VCO that incorporates the SMV1265-011 varactor diode.
 
 

Broadband Colpitts Variable Controll Oscillator 1-2 GHz Schematic

Broadband Colpitts Variable Controll Oscillator 1-2 GHz PCB Layout

This varactor diode was specifically developed at Alpha for this application. The VCO design, based on Libra Series IV simulation, shows good correlation between measured and simulated performance. This application note includes a board layout and materials list.


More info: A Colpitts VCO for Wideband (0.95–2.15 GHz) Set-Top TV Tuner Applications
 
http://www.ziddu.com/download/9053779/1-2ghzvco.pdf.html

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VGA to TV Converter Circuit

VGA to TV Converter Circuit

This converter circuit basically takes VGA signals and converts it to RGB + composite sync signal which can be fed to TV via SCART connector. VGA card picture components RED, GREEN and BLUE are already at the correct voltage level (0.7Vpp) and has correct impedance (75 ohm) for direct connection to correspondign inputs in the TV.

VGA to TV Converter Ciruit

VGA to TV Converter Printed Circuit Board (PCB)

For combining separate horizonal and vertical sync signal from VGA card to one composite sync signal needs a sync signal conversion which is feed to TV video in pin in SCART connector. The tv converter circuit has also sends correct level signal to the TV RGB input enabling control pin in the SCART connector (pin 16).

The circuit is simply based on one TTL chip with four XOR ports, two resistors and two capacitors. TTL chip was logical choise because VGA sync signals are TTL level signals.



The sync signal combiner has a system to adjust to different sync polarities so that it always makes correct composite sync signals. VGA card uses different sync signal polarities to tell the monitor which resolution is used. This circuit adjusts to sync signal polarity changes in less than 200 milliseconds, which is faster than setting time of a normal VGA monitor in the display mode change. The tv converter circuit needs well regulates +5V (+/-5%) power supply and takes about 120 mA current.



VGA to TV converter parts list are as follow:



Main circuit

U1 74LS86 (74HC86 or 74HCT86 can also be used)

C1 22 microfarads 16V electrolytic capacitor

C2 use 47 uF 16V electrolytic for more reliable operation (22 uF listed schematic can cause problems in some cases)

R1,R2 2.2 kohm, 1/4 W

R3,R4,R5 2.2 kohm, 1/4 W

R6,R7,R9 47 ohm, 1/2 W

R8 120 ohm, 1/2 W

T1,T2 BC547B (2N2222 should also work but note the different pinout)

P1 15 pin SUB-D connector (DE-15)



Output connector

21 pin EURO/SCART connector

Wiring:

Red, Green, Blue and Composite Sync lines should be wired using 75 ohm coaxial cable for best picture quality, but can be replaced with normal shielded wire.



Power supply components

7805 regulator chip

100 uF electrolytic 25V

10 uF electrolytic 16V

100 nF polyester or ceramic condensator

Wall adapter which outputs 8-18V DC and 150 mA or more current

Connector for connecting wall adaptor to circuit





Source: http://www.tkk.fi/Misc/Electronics/circuits/vga2tv/circuit.html

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Simple High efficiency Inverter Circuits

Simple High efficiency Inverter Circuits

Description


1. Field of the InventionThis invention relates generally to the field of electrical energy conversion systems and more particularly to push-pull inverter circuits utilizing a solid state active element oscillator of the multivibrator type to convert an input DC voltageto a high frequency AC output voltage.2. Description of the Prior ArtPush-pull inverter circuits are generally recognized as the most efficient type for converting DC voltage into an AC output voltage. Such circuits typically include a source of DC potential, an output transformer, and a pair of switchingtransistors connected to control the flow of current through the output transformer for thereby producing an AC voltage output across the transformer. Efficient conversion of the DC voltage into the AC output voltage requires that the conduction of theswitching transistors be precisely controlled. Such precise control can serve to minimize undesirable energy losses within the circuit itself. Some of the causes of such energy losses have been recognized and are generally regarded as inherent in suchcircuits, or in the components making up such circuits. Some of these losses are:1. Common-mode conduction which occurs when both of the switching transistors conduct simultaneously. This loss is usually related to the inherent and generally unavoidable delay associated with the turn-off action of the conducting transistor,coupled with the fact that there generally is no corresponding delay associated with the turning on of the other transistor.2. Turn-off transition loss which is due to the power dissipation that occurs within each transistor during its turn-off transition. To minimize this loss, it is necessary to operate each transistor near its maximum switching speed capability. This in turn requires that the charge carriers stored at the transistor base-emitter junction be evacuated as rapidly as possible.It is also more important to prevent the collector voltage from rising significantly be

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