Showing posts with label transmitter. Show all posts
Showing posts with label transmitter. Show all posts
Tuesday, December 24, 2013
TV audio video transmitter Schematic Diagram
This is a simple TV audio video transmitter circuit can be constructed using this schematic diagram . This TV audio video transmitter circuit can be used to transmit video signals from VCR ( or some other device ) to a TV without using any cable .
Video signals input at jack J1 are first terminated by resistor R6 and coupled through capacitor C1 to clamping-diode D1. Potentiometer R3 is used to set the gain of the video signal; its effect is similar to that of the contrast control on a TV set.
TV audio video transmitter Schematic Diagram
Bias-control R7 can be used to adjust the black level of the picture so that some level of signal is transmitted, even for a totally dark picture.
RF-transformer T1 and its internal capacitor form the tank circuit of a Hartley oscillator thats tuned to 4.5 megahertz. Audio signals input at J2 are coupled to the base of Q3 via C2 and R4: the audio signal modulates the base signal of Q3 to form an audio subcarrier that‚s 4.5-megahertz higher than the video-carrier frequency.
The FM modulated subcarrier is applied to the modulator section through C5 and R9.
Resistor R9 adjusts the level of the subcarrier with respect to the video signal.
Resistor R9 adjusts the level of the subcarrier with respect to the video signal.
Transistors Q1 and Q2 amplitude modulate the video and audio signals onto an RF-carrier signal. The operating frequency is set by coil L4, which is 3.5 turns of 24- gauge enameled wire on a form containing a standard ferrite slug.
The RF output from the oscillator (L4, C7 and C9 ) section is amplified by Q5 and Q6, whose supply voltage comes from the modulator . Antenna matching and low-pass filtering is performed by C12, C13, and L1.
Resistor R12 is optional; it is added to help match the output signal to any kind of antenna.
To align this audio video transmitter you need to tune a TV receiver to an unused channel between 2 and 6. The TV must have an indoor antenna connected directly to it; an outdoor antenna or cable wont work. Make sure both potentiometers (R3, R7) are in middle position and apply power to the transmitter. Adjust L4 with a nonmetallic tool until the TV screen goes blank ,then fine-adjust L4 for the "most-blank" picture.
Connect the video and audio outputs from a VCR(AV source) to jacks J1 and J2 (respectively) of the transmitter .
After that you should see a picture on the TV screen: if you do, readjust L4 for the best picture; if you dont, check the board for any bad connections. Next, adjust R3 for the best picture brightness and R7 for the best overall picture.
Finally, adjust T1 with a nonmetallic tool for the best sound .
The TV transmitter combines line level audio and video signals, and transmits the resulting signal up to 300 feet. The circuit can be powered from a 9-12V power supply circuit .
Tuesday, April 30, 2013
FM Stereo Transmitter
Youll find that this is a very easy project to build. It will transmit good quality sound in the FM band ( 88 - 108 mhz ). One inportant item is that the IC chip operates on 3 volts DC. The chip will get destroyed if it is operated on any voltage higher than 3.5 volts. The antenna can be a standard telescopic antenna or a 2 foot length of wire. The input is in the millivolt range and you may need to add additional pots for the inputs. I was able to use this circuit for a walkman and a portable CD player in my car. I used the headphone jack on both and varied the signal with the volume control.
Circuit Diagram
Circuit Diagram
To adjust the circuit tune your FM radio to a quite spot then adjust the trimmer capacitor C8 until you hear the signal that you are transmiting. When you have a strong signal adjust the resistor R4 until the stereo signal indicator lights. If the input is to high of a signal you may over drive the IC chip. Use two 15 turn pots on the input signals to bring the level down. You can balance the signal by using headphones. The inductor L1 is 3 turns of .5 mm wire on a 5 mm ferrite core.
Sourced: extremecircuits
Tuesday, April 9, 2013
FM transmitter using UPC1651
Here is the circuit diagram of an FM
transmitter using the IC UPC1651. UPC1651 is a wide band UHF Silicon
MMIC amplifier. The IC has a broad frequency response to 1200MHz and
power gain up to 19dB.The IC can be operated from 5V DC.
The audio
signals picked by the microphone are fed to the input pin (pin2) of the
IC via capacitor C1. C1 acts as a noise filter. The modulated FM
signal will be available at the output pin (pin4) of the IC. Inductor
L1 and capacitor C3 forms the necessary LC circuit for creating the
oscillations. Frequency of the transmitter can be varied by adjusting
the capacitor C3.Circuit diagram with Parts list.
Notes.
Continue reading...
transmitter using the IC UPC1651. UPC1651 is a wide band UHF Silicon
MMIC amplifier. The IC has a broad frequency response to 1200MHz and
power gain up to 19dB.The IC can be operated from 5V DC.
The audio
signals picked by the microphone are fed to the input pin (pin2) of the
IC via capacitor C1. C1 acts as a noise filter. The modulated FM
signal will be available at the output pin (pin4) of the IC. Inductor
L1 and capacitor C3 forms the necessary LC circuit for creating the
oscillations. Frequency of the transmitter can be varied by adjusting
the capacitor C3.Circuit diagram with Parts list.
Notes.
- The circuit can be assembled on a Vero board.
- Inductor L1 can be made by making 5 turns of 26SWG enameled copper wire on a 4mm diameter plastic former.
- A ¾ meter insulated copper wire can be used as the antenna.
- Do not give more than 6V to the IC.
- Mic M1 can be a condenser microphone.
Saturday, April 6, 2013
VHF Video Transmitter 60 200 MHz
Heres a simple video transmitter for VHF TV channel will accept baseband video input, hence it can be driven by most CCD cameras and VCR video outputs. It ouputs roughly 80mW and when used with a 40cm telescopic antenna over 100 metres range is possible.
The transistor of the video transmitter can be a BC108, BC546, BC337 or a 2N2222. L1 is wound on a 10 mm air former. Use 6 turns 24 SWG for frequency 60-80 MHz, 4 turns for 150-180 MHz, and 2 turns for 180-200 MHz
You can use this with a monochrome or color video signal. To transmit sound just build the wide band FM transmitter and tune it to the audio channel.
Thursday, March 28, 2013
Single Chip Stereo FM Transmitter Circuit
ROHM (www.rohm.com) is originally a resistor producer company, but finally expand their business and produce monolithic IC, and this one used in our circuit is the example. The internal structure of this FM transmitter integrated circuit consist of stereo modulator that creates a stereo composite signal, an FM modulator that modulate a carrier frequency with the composite signal, and an RF amplifier that provide enough power to be transmitted through antenna. This is the figure of the circuit;
The core of this stereo FM transmitter is BA1404 integrated circuit chip. from ROHM. This FM transmitter is ideal for wireless microphone, or for audio interface and distribution for home or car appliance. For example, you can now play your portable mp3/mp4 player on your old car radio sound system that doesn’t have line-input plug. This stereo FM transmitter chip is designed for 75-108 FM band, and you can adjust the operation by trimming the LC network connected to pin 10 of this IC chip. To ease the adjustment, you can use a 22-33p variable capacitor for the 15p capacitor connected to pin 10. Finally, this stereo FM transmitter works with only 1.5-3V power supply, ideal for battery operation. More than 3.5V supply voltage could burn this FM transmitter circuit. [Circuit diagram source: ROHM Application Notes]
Friday, March 22, 2013
FM Radio Transmitter schematic with pcb
For those of you like / love to talk in the air can assemble this simple circuit that can be received by the radio receiver to within a few hundred feet. The voice that issues by this circuit at all clear without rustling. Can also be used to link communications over the air using this radio transmitter, provided that other person also had the same circuit.
This PCB design :
Description :
Resistor
R1__________________1K
R2__________________18K
R3__________________82K
R4__________________1K2
R5__________________5K6
R6__________________39K
R7__________________18K
R8__________________68K
R9__________________470R
R10_________________100R
R11_________________50K
XTal
Q1__________________ Crystal according to the desired frequency
Inductor
L1__________________10uH
Capacitor
C1__________________10uF
C2__________________30uF
C3__________________20uF
C4__________________47uF
Transistor
Tr1_________________2SB175
Tr2_________________2SB175
Tr3_________________2SB178
Antenna
X1-1________________10-20 meters
Connector
X2-1________________Ground
X2-2________________VCC 9-12 Volts DC
X3-1________________Input
X3-2________________Ground
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