Showing posts with label fm. Show all posts
Showing posts with label fm. Show all posts
Monday, December 23, 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
Sunday, October 13, 2013
Bully FM radio signals
Interfere with fm radio signal is fun, if youre bored or no work, you can do at home, where neighbors , at school , or even near the transmitter. With the circuit above you can interfere with the speech signal in condenser microphone , and the signal will be issued by the circuit will then be received by FM radio receiver and a voice that we remove it before going out mixed with the signals emitted by radio FM transmitter.
Part List :
R1 = 4K7R2 = 2K2C1 = 1n5C2 = 47pFC3 = 33pFL1 = Nikelin wire coil with a diameter 0,8 mm and 5mm in diameter wound coil 10 xT1 = 2N3906Mic= Condenser Microphone
If the circuit does not work on the errors may occur :
Installation of the opposite transistor , incorrect placement of components , less voltage, the voltage is too high , the microphone is broken, transistor is damaged , broken coil .
Please note this circuit can work and receive FM radio reciver at distance of about 500 meters. And not to much use , because the radio will be able to slam his own neighborhood because they can not listen to good radio . :) good Luck :)
Saturday, October 12, 2013
4 Transistor 500mW FM Transmitter Circuit Diagram
4 Transistor 500mW FM Transmitter Circuit DiagramAs shown, the audio ascribe is a microphone, which uses 2 x 2N3904 as the microphone audio preamplifier. The audio/mic ascribe akin is adjustable by agency of a 5k preset / potentiometer.
The ambit uses a Colpitts oscillator for abundance generation, which is chargeless active and operates at the axiological abundance i.e. no circuitous abundance multiplication or control. The abundance affability basic of the ambit consists of 2 5pF (picoFarad) capacitors and a distinct 10uH (micro-Henry) inductor. These apparatus can be adapted if a change in abundance is appropriate - conceivably alike replaced with capricious capacitors (if youre up to the challenge).
An achievement RF amplifier takes the abundance produced by the Colpitts oscillator and amplifier to about about the 500mW (0.5 Watt) ambit - so this is the almost achievement ability of this FM transmitter. You are brash that back this transmitter operates at the axiological frequency, and because there is no achievement filter, there is acceptable to be some abundance alluvion and harmonics/spurious emissions.
Friday, October 11, 2013
Miniature FM Transmitter
Miniature FM Transmitter Circuit Diagram
The default for the capacitors type is ceramic, preferably the npo 1% (low noise) type or equivalent. But basically nothing critical here. Use any capacitor you have laying around, but NO electrolytic or tantalum caps. Only if you intend to use this circuit outside the home you may want to select more temperature stable capacitors.
To find the signal on your receiver, make sure there is a signal coming into the microphone, otherwise the circuit wont work. I use an old mechanical alarm clock (you know, with those two large bells on it). I put this clock by the microphone which picks up the loud tick-tock. Im sure you get the idea... Or you can just lightly tap the microphone while searching for the location of the signal on your receiver.
MC2833 FM Transmitter
A very simple FM transmitter circuit can be designed using MC2833 integrated circuit, designed for cordless telephone and FM communication equipment. It includes a microphone amplifier, voltage controlled oscillator and two auxiliary transistors.This MC2833 FM transmitter circuit has an low drain current ( ICC =2.9mA typically ) and supports a wide range operating voltage ,from 2.8 to 9 volts .
MC2833 FM Transmitter
Crystal X1 connected at pin 16 and pin 1 ( trough a 5.1uH coil ) is fundamental mode, calibrated for parallel resonance with a 32 pF load.The final output frequency is generated by frequency multiplication within the MC2833 IC. The RF output buffer (Pin 14) and Q2 transistor are used as a frequency tripler and doubler, respectively, in the 76 and 144 MHz transmitters.
The Q1 output transistor is a linear amplifier in the 49.7 MHz and 76 MHz transmitters, and a frequency doubler in the 144 MHz transmitter.All coils used are 7 mm shielded inductors, CoilCraft series M1175A, M1282A–M1289A, M1312A or equivalent.Power output is 9 + 10 dBm for 50 MHz and 76 MHz transmitters, and 9 + 5.0 dBm for the 144 MHz transmitter at VCC = 8.0 V. Power output drops with lower VCC.
MC2833 FM Transmitter
The Q1 output transistor is a linear amplifier in the 49.7 MHz and 76 MHz transmitters, and a frequency doubler in the 144 MHz transmitter.All coils used are 7 mm shielded inductors, CoilCraft series M1175A, M1282A–M1289A, M1312A or equivalent.Power output is 9 + 10 dBm for 50 MHz and 76 MHz transmitters, and 9 + 5.0 dBm for the 144 MHz transmitter at VCC = 8.0 V. Power output drops with lower VCC.
Tuesday, October 8, 2013
300m FM Transmitter
This fm transmitter circuit is very simple and it has a acceptable transmission . The signal transited from this fm transmitter circuit can be received at almost 300 meters in open air .The circuit require a 3volts operating voltage and can be tuned anywhere in the FM band.The coil should be about 3mm in diameter and 5 turns. The wire is tinned copper wire, 0.61 mm in diameter.
300m FM Transmitter Circuit diagram
After the coil in soldered into place spread the coils apart about 0.5 to 1mm so that they are not touching. If you don’t have a trim cap you can use a fixed value capacitor and you can vary the TX frequency by adjusting the spacing of the coils or placing a small piece of ferrite inside the coil , but the better way to change the transmission frequency is to use a variable capacitor .Connect a half or quarter wavelength antenna (length of wire) to the aerial point. At an FM frequency of 100 MHz these lengths are 150 cm and 75 cm respectively.
300m FM Transmitter Circuit diagram
After the coil in soldered into place spread the coils apart about 0.5 to 1mm so that they are not touching. If you don’t have a trim cap you can use a fixed value capacitor and you can vary the TX frequency by adjusting the spacing of the coils or placing a small piece of ferrite inside the coil , but the better way to change the transmission frequency is to use a variable capacitor .Connect a half or quarter wavelength antenna (length of wire) to the aerial point. At an FM frequency of 100 MHz these lengths are 150 cm and 75 cm respectively.
Sunday, September 29, 2013
87 108MHz FM Wireless Microphone
This FM wireless microphone is easy to build and has a useful range of transmission (over 300 meters outdoors). Despite its small number of components and an operating voltage of 3V to easily penetrate over three floors of an apartment building. You can tune anywhere on the FM band (87-108MHz) and its transmissions can be picked up at any point of view of the FM receiver.
The coil (L1) should be approximately 3 mm in diameter, 5 turns 0.61 mm copper wire. You can vary the Tx frequency by simply adjusting the distance between the coils. The antenna should be a half wavelength or quarter-time (100 MHz, 150 cm or 75 cm).
Parts list:
The coil (L1) should be approximately 3 mm in diameter, 5 turns 0.61 mm copper wire. You can vary the Tx frequency by simply adjusting the distance between the coils. The antenna should be a half wavelength or quarter-time (100 MHz, 150 cm or 75 cm).
Parts list:
- T1,T2,T3: 2N2222 transistor
- R1: 10k 5%
- R2: 33k lin.
- R3: 12k 5%
- R4: 5.6k 5%
- R5: 2.2k 5%
- R6,R8: 47k 5%
- R7: 470 ohms 5%
- R9: 180 ohms 5%
- C1,C2: 47nF
- C3: 1nF
- C4: 33pF
- C5: 5.6pF
- C6: 8.2pF
- C7: 10nf
- L1: 3mm in diameter with 5 turns 0.61 mm copper wire
- K1: SPDT toggle switch
- Other parts: 2 AA battery holder, Electret microphone, antenna wire
Wednesday, September 25, 2013
TDA7012T Single chip FM received
Feature contained in FM receiver IC TDA 7012T is quite tempting to an FM receiver. Among features an FM receiver TDA 7012T is a low-voltage applications micro affability arrangement (MTS), Frequency Loked Loop (FLL) to 76 KHz range and selectivity of FM receiver with RC Filter. In an article by FM Radio Receiver IC TDA 7012T can be seen in the FM receiver circuit which can be made.
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| TDA7012T- Mini FM received Schematic |
R1 = 8kΩ2
R2 = 10kΩ
R3 = 390Ω
C1,C3 = 10nF
C2,C6,C9,C16 = 100nF
C4 = 33pF
C5 = 25pF trimmer
C7,C10 = 1nF5
C8 = 820pF C11 = 1nF
C12 = 68pF
C13 = 220pF
C14 = 47μF 10V
C15 = 3nF3
L1 = 36nH
L2 = 1μH,
IC1 = TDA7021T
Wednesday, September 11, 2013
USB FM transmitter circuit
Heres a simple VHF FM transmitter that could be used to play audio files from an MP3 player or computer on a standard VHF FM radio. The circuit use no coils that have to be wound. This FM transmitter can be used to listen to your own music throughout your home. When this FM transmitter used in the car, there is no need for a separate input to the car stereo to play back the music files from your MP3 player.
To keep the circuit simple as well as compact, it was decided to use a chip made by Maxim Integrated Products, the MAX2606 [1]. This IC from the MAX2605-MAX2609 series has been specifically designed for low-noise RF applications with a fixed frequency. The VCO (Voltage Controlled Oscillator) in this IC uses a Colpitts oscillator circuit. The variable-capacitance (varicap) diode and feedback capacitors for the tuning have also been integrated on this chip, so that you only need an external inductor to fix the central oscillator frequency.
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| USB FM transmitter schematics |
It is possible to fine-tune the frequency by varying the voltage to the varicap. Not much is demanded of the inductor, a type with a relatively low Q factor (35 to 40) is sufficient according to Maxim. The supply voltage to the IC should be between 2.7 and 5.5 V, the current consumption is between 2 and 4 mA. With values like these it seemed a good idea to supply the circuit with power from a USB port.
A common-mode choke is connected in series with the USB connections in order to avoid interference between the circuit and the PC supply. There is not much else to the circuit. The stereo signal connected to K1 is combined via R1 and R2 and is then passed via volume control P1 to the Tune input of IC1, where it causes the carrier wave to be frequency modulated. Filter R6/C7 is used to restrict the bandwidth of the audio signal. The setting of the frequency (across the whole VHF FM broadcast band) is done with P2, which is connected to the 5 V supply voltage.
The PCB designed uses resistors and capacitors with 0805 SMD packaging. The size of the board is only 41.2 x 17.9 mm, which is practically dongle-sized. For the aerial an almost straight copper track has been placed at the edge of the board. In practice we achieved a range of about 6 metres (18 feet) with this. There is also room for a 5-way SIL header on the board. Here we find the inputs to the 3.5 mm jack plug, the input to P1 and the supply voltage. The latter permits the circuit to be powered independently from the mains supply, via for example three AA batteries or a Lithium button cell. Inductor L1 in the prototype is a type made by Murata that has a fairly high Q factor: minimum 60 at 100 MHz.
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| Layout PCB USB FM transmitter |
Take care when you solder filter choke L2, since the connections on both sides are very close together. The supply voltage is connected to this, so make sure that you don’t short out the USB supply! Use a resistance meter to check that there is no short between the two supply connectors before connecting the circuit to a USB port on a computer or to the batteries.
P1 has the opposite effect to what you would expect (clockwise reduces the volume), because this made the board layout much easier. The deviation and audio bandwidth varies with the setting of P1. The maximum sensitivity of the audio input is fairly large. With P1 set to its maximum level, a stereo input of 10 mVrms is sufficient for the sound on the radio to remain clear. This also depends on the setting of the VCO. With a higher tuning voltage the input signal may be almost twice as large (see VCO tuning curve in the data sheet). Above that level some audible distortion becomes apparent. If the attenuation can’t be easily set by P1, you can increase the values of R1 and R2 without any problems.
Measurements with an RF analyzer showed that the third harmonic had a strong presence in the transmitted spectrum (about 10 dB below the fundamental frequency). This should really have been much lower. With a low-impedance source connected to both inputs the bandwidth varies from 13.1 kHz (P1 at maximum) to 57 kHz (with the wiper of P1 set to 1/10).
In this circuit the pre-emphasis of the input is missing. Radios in Europe have a built-in de-emphasis network of 50 μs (75 μs in the US). The sound from the radio will therefore sound noticeably muffled. To correct this, and also to stop a stereo receiver from mistakenly reacting to a 19 kHz component in the audio signal, an enhancement circuit Is published elsewhere in this issue (Pre-emphasis for FM Transmitter, also with a PCB). Author: Mathieu Coustans, Elektor Magazine, 2009
MP3 FM Transmitter Parts List
Resistors (all SMD 0805)
R1,R2 = 22kΩ
R3 = 4kΩ7
R4,R5 = 1kΩ
R6 = 270Ω
P1 = 10kΩ preset, SMD (TS53YJ103MR10 Vishay Sfernice, Farnell # 1557933)
P2 = 100kΩ preset, SMD(TS53YJ104MR10 Vishay Sfernice, Farnell # 1557934)
Capacitors (all SMD 0805)
C1,C2,C5 = 4μF7 10V
C3,C8 = 100nF
C4,C7 = 2nF2
C6 = 470nF
Inductors
L1 = 390nF, SMD 1206 (LQH31HNR39K03L Murata, Farnell # 1515418)
L2 = 2200Ω @ 100MHz, SMD, common-mode choke, 1206 type(DLW31SN222SQ2L Murata, Farnell #1515599)
Semiconductors
IC1 = MAX2606EUT+, SMD SOT23-6 (Maxim Integrated Products)
Miscellaneous
K1 = 3.5mm stereo audio jack SMD (SJ1-3513-SMT
CUI Inc, DIGI-Key # CP1-3513SJCT-ND)
K2 = 5-pin header (only required in combination with 090305-I pre-emphasis circuit)
K3 = USB connector type A, SMD (2410 07 Lumberg, Farnell # 1308875)
Notice. The use of a VHF FM transmitter, even a low power device like the one described here, is subject to radio regulations and may not be legal in all countries.
source [ Link ]
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