PIC16F876 RF Power Meter 0-500MHz

RF Measurement has been an expensive work so far the cost of measuring instruments are concerned. This RF power meter is based on PIC16F876 microcontroller, AD8307 and 2x20 LCD display. Frequency range measurement is 0-500 MHz and Full documentation is included.

This rf power meter kit has two push buttons to control the functions. Very cost effective and simple to use. 4 Push buttons used in this kit are right angle type and are sufficiently long enough to come out of the box, if you decide to house this meter in a case.






For more documentation of rf power meter, please follow this download links Project Domumentation, Schematic, Hex Code, and Visit page

See more: FM Transmitter - FM Stereo Transmitter - FM Amplifier

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TV RF Amplifier 5W With BLW98

This application circuit is a TV RF amplifier for driving small UHF TV transmitters, with gain is 7dB and can amplify a signal between 470-860 MHz. Drive input the circuit with 1 to 1,5 Watts signal. Better use double layer PCB with the second layer connected to earth.

Use a stabilized power supply 24 volts and at least 5 Amps. The transistor case is the SOT-122A and be careful because the transistor is very toxic for your health. Tuning of this tv rf amplifier can be achieved turning the two variable capacitors. Do not forget to use heat sink for both transistors, specially for the BLW98 and it would be better if you place a small fan as well.
For more details for constructing this tv rf amplifier, please download datasheet

See more: Transistor FM Transmitter - FM Stereo Transmitter - FM Amplifier

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TV RF Modulator With FM-AM Audio Input

Circuit Description
This TV RF Modulator has option for AM and FM audio input mode, but frequency still controlled by PLL Oscillator.

Oscillator
The RF-oscillator is available at pins 3-7. The oscillator operates as a symmetrical Colpitts circuit. The oscillator chip ground, pin 5, should be connected to ground at the resonance circuit shielding point. An external oscillator can be injected inductively or capacitively via pins 3 and 7.

The layout of the TV RF Modulator PCB should be such as to provide a minimum shielding attenuation between the oscillator pins 3-7 and modulator output pins 15-17 of approximately 80 dB.

For optimal residual carrier suppression, the symmetrical mixer outputs at pins 15, 17 should be connected to a matched balanced-to-unbalanced broadband transformer, e.g. a Guanella transformer with good phase precision at 0o and 180o. The transmission loss should be less than 3 dB. In addition, an LC-low pass filter combination is required at the output. The cut-off frequency of the low pass filter combination must exceed the maximum operating frequency.


Video
The video signal of the tv rf modulator with the negative synchronous level is capacitively connected to pin 12. The internal clamping circuit is referenced to the synchronizing level. Should the video signal change by 6 dB, this change will be compensated by the resonance circuit which is set by the peak white value. At pin 13, the current pulses of the peak white detector are filtered through the capacitor which also determines the control time constant. The RF carrier switches from negative to positive video modulation, when pin 14 is connected to ground. By varying the value of resistance R at pin 14 between ¥ ... 0 W the modulation depth can be increased from 70% to 100% when the modulation is negative and decreased from 100% to 70% when the modulation is positive.

Audio
Via pin 1, the audio signal is capacitively coupled to the AF-input for the FM-modulation of the oscillator. A parallel resonance circuit is connected to the audio carrier oscillator at pins 19, 20. The unloaded Q of the resonant circuit must be Q = 25 and the parallel resistor RT = 8.2 kW to ensure a video to audio carrier ratio of 12.5 dB. At the same time, the capacitative and/or inductive reactance for the resonance frequency should have a value of XC » XL » 800 W.

Via pin 18, the audio signal is capacitively coupled to the AF-input for the AM-modulation of the oscillator. This signal is forwarded to a mixer which is influenced by the AM modulation input of pin 18. The video to audio carrier ratio can be changed by connecting an external voltage to pin 18, which deviates from the internal reference voltage. Through an additional external dc voltage at pin 18, the set AM-modulation index can be changed by overriding the internally adjusted control voltage for a fixed AM-modulation index.

At the output of the above described mixer the FM and/or AM modulated audio signal is
added to the video signal and mixed with the oscillator signal in the RF-mixer.

Source
The internal reference voltage is available at pin 2 and has to be capacitively blocked there. (For the details, please download datasheet)

See more: TV Transmitter - VHF UHF TV Modulator - Transistor FM Transmitter

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Audio Video RF Modulator With LM2889

The LM2889 is designed to interface audio video RF modulator signals to the antenna terminals of a TV receiver. It consists of a sound subcarrier oscillator and FM modulator, video clamp, and RF oscillators and modulators for two low-VHF channels.

Audio Video RF Modulator with LM2889 allows video information from VTRs, video disk systems, games, test equipment, or similar sources to be displayed on black and white or color TV receivers.


Features :

• Pin for pin compatible with LM1889 RF section
• Low distortion FM sound modulator (less than 1% THD)
• Video clamp for AC-coupled video
• Low sound oscillator harmonic levels
• 10V to 16V supply operation
• DC channel switching
• Excellent oscillator stability
• Low intermodulation products
  

For the detail about this audio video RF modulator, please follow this link for datasheet - Application Note.

See more: TV Transmitter - VHF UHF TV Modulator - FM Transmitter

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MC1374 TV RF Modulator

The MC1374 includes an FM audio modulator, sound carrier oscillator, RF oscillator, and RF dual input modulator. It is designed to generate a TV signal from audio and video inputs. This TV RF modulator based MC1374 IC from Motorola with wide dynamic range and low distortion audio make it particularly well suited for applications such as video tape recorders, video disc players, TV games and subscription decoders.

The IC features:
* Single Supply, 5.0 V to 12 V
* Channel 3 or 4 Operation
* Variable Gain TV RF Modulator
* Wide Dynamic Range
* Low Intermodulation Distortion
* Positive or Negative Sync
* Low Audio Distortion
* Few External Components

For more info about TV RF Modulator, please download datasheet - application note

See more: TV Transmitter - VHF UHF TV Modulator - Transistor FM Transmitter

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2.4 GHz Power Amplifier

The following single-stage transistor linear amplifier posseses a gain of approximately 7 dB and an output power of 1 W in the 13 cm band (approx. 2.4 GHz). It is thus suitable for use, for instance, together with the 13 cm transmit converter. This hybrid power mixer equipped with a varactor diode type BXY. This mean that the described 2.4 GHz power amplifier can provide linear output power in the order of 1 W.

CIRCUIT DESCRIPTION
A transistor type F1E6 manufactured by CTC is used. In this case of this transistor, the emitter is internally connected to the cooling bolt. This ensures that there are no problems with respect to the high-frequency grounding of the emitter. The circuit diagram of this 2.4 GHz power amplifier is given in figure 1. The matching of the transistor input and ouput impedance to 50 Ohm is made using standard method in (2) The circuit for adjusting and stabilizing the DC-operating point is similar to the method described in (3)


CONSTRUCTION
Double coated, epoxy glassfibre material is also for applications in 13 cm band. PC Board DC 3 QS 003 has dimensions of 70 mm x 45 mm, and it shown in figure 2. Of course, it would have been possible to use the more expensive material, non-readily available PTFE PC Board material, but it is not necessary for applicating this 2.4 GHz power amplifier. Download documentation: 2.4 GHZ Power Amplifier R. Heideman Article. Source : 6mt.com

See more: FM Preamplifier - TV Transmitter - Transistor FM Transmitter

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Audio Video RF Modulator With MC44BS374

This Audio Video RF modulator application working on VHF UHF Band uses a MC44BS374TI from Freescale. MC44BS374 is audio and video modulator for use in Transmit Video audio and similar device.

These IC are the next generation of the MC44BC374TI with the following new features :
- TV output level 83dBuV
- 5V and 3.3V compatible I2C bus
- Logic Output Port pin (pin 3) available


SCHEMATIC DESCRIPTION

Download Schematic in PDF format, Trial HEX CODE

A MC44BS374 audio video RF modulator IC is used to provide the RF output and amplified by RF IC UPC2709 and UPC1678GV. It will have output about 17mW. The TV modulator is controled via microcontroler I2C interface and can tune the R.F Output to broacast channel. Microcontroler will set the frequency to 471.25Mhz - 895.750Mhz and have frequency step 250Khz. The modulator can set to VHF, it only depending on which software is used.

The audio video RF modulator IC has two input. One called Audio Input, and one called Video input. You can directly attack your VCD/DVD output to this modulator and transmit to UHF frequency.

To change frequency use either up or down buttons, it will change frequency with 250Khz. Status button will have some function: Read Memory, Write Memory, Reset Memory and Lock status of the modulator.

The microcontroler is used to control I2C and drive LCD 2x16 Display. it will set the frequency, PWC (Peak white clip) default is on (System B/G), Sound Carier default is set to 5.5Mhz (PAL System), Picture to sound ratio 12dB, etc. Source: Audio Video RF Modulator

See more: FM Preamplifier - TV Transmitter - Transistor FM Transmitter

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150 WATT FM AMPLIFIER BASED SD1407

This FM amplifier is originally designed by Broadcast Warehouse, based transistor SD1407 with redrawn schematic and redesigned pcb.



You can drive the FM amplifier with maximum 1 watt input for 150 watts output.

Working frequency of this fm amplifier is 88-108 MHz VHF band II and Power supply voltage 18-28 VDC.



Download : schematic, PCB all layer, top layer, bottom layer. More info ...

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MC145151 PLL FM Stereo Transmitter

This transmitter use pll chip MC145151 from Motorola and stereo encoder chips BA1404 with vco built in. BA1404 from MC145151 is to overcome the single-frequency instability in the BA1404. Modulation of the emission control BB910 frequency. B571C kept in control procedures, the procedures required to prepare another.

Amplifier section of this FM Stereo transmitter use 2sc2053 with power 250 mWatt out.

read more "MC145151 PLL FM Stereo Transmitter"

300mW FM Transmitter 2SC2538

The FM transmitter using a varactor diode way radio, plus a Class C amplifier, RF output power of up to 300 mW more open to more than one kilometer distance communications. Select components: Q1 with ≥ 100 mA, Ft ≥ 300 MHz, β ≥ 100 tubes available 3 DG82, 3DG122, 3DG130, 2G711; Q2 with 2SC2538, 2SC1970, etc.. It must be noted that RF Baffles circle L8, L9, L10; C13, C14, C17, C18, C19, and so can not be omitted, otherwise it would cause unnecessary self-excited oscillation.

L1, L5 need to tap extraction, data such as icons, not otherwise due to impedance matching, the output power of less than maximum. Such as a battery-powered, Q3 (Darlington tube), C15, R6 can be omitted. ebugging steps: first in the output termination of testing circuit to regulate the C7, C9, C12 to the largest multimeter readings, remove test circuit connected to one meter in length pole antenna to pull to fine-tune C12 simple reading of the largest field will be completed debugging.

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PLL FM Transmitter With BH1415F 500mW

This article is wang1jin (Old: Primary Color love) for the design of RF EDNCHINA.COM FM transmitter board for further analysis, making friends for reference. This EDNCHINA PCB board can be free. Need friends can make reference to relevant websites Learn more.

Designed with PLL technology, BH1415 FM transmitter system block diagram, LCD1602 from STC2052 - M62429 MIC - BH1415 infrared keyboard amplification and high frequency components.
(Website procedural reasons, the picture may not clear to the local Save Show) More info ...

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High Quality wireless microphone Macsot MR-700

This is collected by the Macsot MR-700 wireless microphone system launch of the circuit for maintenance reference. High Quality Audio on receiver output.

Active components:

• Microphone or Audio Preamplifier with IC MC4458
• Dynamic Audio processed with one NE571 From Philips
• Frequency Oscillator generated by one crystal 20.05 MHz and Varactor diode 2CB11A. No drift frequency is guaranted.
• 9V DC power supply or battery. More info ...

read more "High Quality wireless microphone Macsot MR-700"

CD4066 FM Stereo Encoder

Circuit schematics IC1-4069 in the Y1, Y2 formation of a 76 KHZ frequency of the oscillator, the Y3-Y6 isolation plastic, into IC2 dual JK flip-flop CD4027 composed of two components- frequency circuit, a symmetrical + / 38KHZ-19 KHZ and the square wave, + / -38 KHZ IC3 the square used to control analog switches CD4066, a stereo audio input signal after switching modulation used for the 19 KHZ frequency mixed signal to the transistor into FM 9014 after isolation Modulator.

Click to access the debug FM modulator and 5 V power supply, with a multimeter measured IC1 CD4069 the legs and IC2 CP, Q, Q, the legs should be half the supply voltage, the oscillator has been start-up. If a digital frequency meter measured IC1 output frequency, frequency regulation RW1 to 75 KHZ + /-10HZ can. If not, can be transferred to the prospective radios, RW2 half-good, and then transferred RW1, the bright lights stereo radio, and no speakers in the temple frequency whistle sounds. From the input into the stereo audio signal (1.5 Vpp, output amplifier available), this will be able to receive stereo radio broadcasting.

Input signal can be obtained from the line, but at R7 should be changed. Finally, can be transferred R7 to the smallest high-frequency noise, in fact R6, R7 equivalent BA1404 in 13, 14 feet of external components, the Pilot mixed signal and composite signal circuits, and input to the amplifier, the circuit of is 9014, and BA1404 from 12 feet on the entry. More info ...

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uPC1651 FM transmitter

The circuit has been produced by Japan's NEC as a major upc1651 IC devices, the high gain circuit, work stability, thereby ensuring the microphone performance. Use of FM transmitter.

Used it 40 - 50 cm soft drag line for antenna, the effective range of more than 30 launch M. L carefully spacing adjustment and fine-tuning capacitor, will launch frequency coverage for 88 - 108 Mhz. Map L enameled wire with diameter of 0.51 mm in diameter, 4 mm cylindrical Tuitai from around 5 laps. More info ...

read more "uPC1651 FM transmitter"

FM Transmitter With Transistor 2SC1815

I Will have to introduce a system of simple and small FM transmitter. Not only does it meet the requirements of the launch distance, but also at the same time using microphone and voice input signal line, background voice. Modulation circuit surveillance has also joined the table first,

so that they can better control and the proper use of transmitters, the following circuit diagram, read briefly, whether it's just like a radio station equipment as many functions. Yes, this small transmitter can help you easily set up an amateur FM radio stations! 500 M in the coverage around. Echocardiography the bar, act immediately!



Principle smallFM transmitter circuit components and options:

Signal to the microphone after intake, the C1 coupling into the BG1 and external circuit voltage of the single negative feedback amplifier, the voltage signal amplification weak enough to enlarge the extent of U1A and the line to enter the input signal with a mixed U1B. Mixed signal modulation way to the R17 from BG2 FET and the surrounding circuit composed of common than LC finishes the test, the test than the LC oscillator are characterized by a general three-capacitance oscillator simple, but also with high efficiency and high stability. Waveform, and modulation bandwidth, as this amateur production of FM transmitters appears to be particularly important. Finally BG3 cast by the post-amplifier to enlarge the field by launching antenna fired by general can listen to FM radio broadcast. Another component of the signal through the amplifier to enlarge U1C after the wave rectifier D2 SR DC drive microamps table, Near and surveillance signal modulation rate. Use the system for general should not exceed 85 per cent suitable. GM and other integrated circuits using LM324 four operational amplifier and form a single power reverse input, both of the input voltage is set at half the supply voltage. Table surveillance for the first u-200, BG1.BG3 choose 2SC1815. BG2 three DO2 FET, D2 varactor diode using a S2267. Antenna require the use of 1 / 4 wavelength, such as the use of the best pull rod antenna not less than one metre. Otherwise effect will be less than overstaying launch. Final say about, please do not interfere with normal radio! More info ...

read more "FM Transmitter With Transistor 2SC1815"

Making Simple TV transmitter

(1) Soundless version

You are familiar with the most simplest FM transmitter that I designed. Let's try to transform it into a TV transmitter. Just change the input from the audio to the video (video camera or VCR) and check the signal at your television set: in Europe, for instance, choose the channel 2 - 4 and turn the trimmercap at the transmitter.

You will find some images or might watch a clear image. This suggests that it will be not so difficult to build a TV transmitter.

(2) Advanced Version (AV)

When you succeed in this version to work, you may try the advanced version (pdf). In this version, stability and quality are improved. This can have even the audio too. However, in order to complete this, you have to use a proper frequency counter. More info ...

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Preamplifier 88-108 MHz

This VHF amplifier working on Band 2 Radio Spectrum tuning approximately 88 - 108 Mhz
The Preamplifier circuit uses two 2N3819 FET's in cascode configuration. The lower FET operates in common source mode, while the upper FET, operates in common gate, realising full high frequency gain. The bottom FET is tunable allowing a peak for a particular station.

Coil details follow:
L1 4 turns of 18swg air spaced with a 1cm diameter, the tap is one turn up from earth end...
L2 4 turns of 18swg air spaced with 1 cm diameter. The coupling coil is 1 turn interwound from the supply end. Enamel coated wire must be used. More info ...

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Microphone FM Transmitter

This simple transmitter operates from a 9V battery as shown above. The old FM mic system was not a perfect solution, so I built this kit and a mixer for the receivers. using three separate transmitter circuits and a mixer on the receiever, the choir voices were perfect and cleanly reproduced."

From the notes I made experimentally, C3 is vital to the circuit and without it the circuit may become unstable. C4 is in parallel with C5 and presents a moderate load impedance. Finally all transistors are NPN. The circuit works well and has proved reliable. More Info ...

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FM Transmitter with 4 Transistors

This circuit provides an FM modulated signal with an output power of around 500mW. The input Mic preamp is built around a couple of 2N3904 transistors, audio gain limited by the 5K preset. The FM Transmitter oscillator is a colpitts stage, frequency of oscillation governed by the tank circuit made from two 5pF capacitors and the inductor. Frequency is around 100Mhz with values shown.

Audio modulation is fed into the tank circuit via the 5pf capacitor, the 10k resistor and 1N4002 controlling the amount of modulation. The oscillator output is fed into the 3.9 uH inductor which will have a high impedance at RF frequencies.

The output stage operates as a class D amplifier , no direct bias is applied but the RF signal developed across the 3.9 uH inductor is sufficient to drive this stage. The emitter resistor and 1k base resistor prevent instability and thermal runaway in this stage. More info ...

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Voice FM Transmitter Circuit

It is illegal in most countries to operate radio transmitters without a license so take care with transmitter circuits. This FM Low Power circuit may be tuned to operate over the range 87-108MHz band II, with a range of 20 or 30 metres.

Active components in this circuit are BC548 transistors. Although not strictly RF transistors, they still give good results. I have used an ECM Mic (Voice FM) insert from Maplin Electronics, order code FS43W. It is a two terminal ECM, but ordinary dynamic mic inserts can also be used, simply omit the front 10k resistor. The coil L1 was again from Maplin, part no. UF68Y and consists of 7 turns on a quarter inch plastic former with a tuning slug. The tuning slug is adjusted to tune the transmitter. Actual range on my prototype tuned from 70MHz to around 120MHz.

The aerial is a few inches of wire. Lengths of wire greater than 2 feet may damp oscillations and not allow the circuit to work. Although RF circuits are best constructed on a PCB, you can get away with veroboard, keep all leads short, and break tracks at appropriate points. More info ...

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VHF UHF TV modulator

Simple TV Modulator that working on VHF UHF Band, the oscillator generates frequency is modulated with the video signal and the modulated carrier wave thus generated is fed into the TV set's aerial input via a cable. Then all that remains to do is tune the VHF UHF TV set to the correct frequency.

The harmonics generator converts the oscillator signal into a sort of frequency spectrum containing all the multiples of 27 MHz up to about 1800 MHz. The TV modulator's output signal is made up of a large number of little peaks, each of which is a complete transmitter signal. At least one of these will always be in band I (VHF channels 2. . . 4), one in band III (VHF channels S. . .12) and many of them will be in bands IV and V (UHF channels 21.. .69). More info ...

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TV Transmitter Band I and III

This TV transmitter working on VHF Band I and III, using negative sound modulation and PAL video modulation. This is suitable for countries using TV systems B and G, like Australia and Indonesia. Band I (VHF Low) and Band III (VHF High).

This circuit has not been tested at UHF frequencies. The modulated sound signal contains 5.5 - 6MHz by tuning C5. Sound modulation is FM and is compatible with UK TV Transmitter System I sound. The transmitter however is working at VHF frequencies between 54 and 216MHz (band I and Band III) and therefore compatible only with countries using Pal System B and Pal System G. More info...

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300mW FM Transmitter 2SC2538

The FM transmitter using a varactor diode way radio, plus a Class C amplifier, RF output power of up to 300 mW more open to more than one kilometer distance communications.

Select the components of this fm transmitter: Q1 with ≥ 100 mA, Ft ≥ 300 MHz, β ≥ 100 tubes available 3 DG82, 3DG122, 3DG130, 2G711; Q2 with 2SC2538, 2SC1970, etc..


It must be noted in the fm transmitter assembly that RF Baffles circle L8, L9, L10; C13, C14, C17, C18, C19, and so can not be omitted, otherwise it would cause unnecessary self-excited oscillation. L1, L5 need to tap extraction, data such as icons, not otherwise due to impedance matching, the output power of less than maximum. Such as a battery-powered, Q3 (Darlington tube), C15, R6 can be omitted.

Debugging steps :
1. In the output termination of testing circuit to regulate the C7, C9, C12 to the largest multimeter readings,
2. Remove test circuit connected to one meter in length pole antenna to pull to fine-tune C12 simple reading of the largest field will be completed debugging.

See more: FM Amplifier - FM Transmitter - Transistor FM Transmitter

read more "300mW FM Transmitter 2SC2538"

FM Stereo Transmitter With MC145151

This fm stereo transmitter use pll chip MC145151 from Motorola and stereo encoder chips BA1404 with vco built in. MC145151 IC used is to overcome the single-frequency instability in the BA1404. Modulation of the emission control BB910 frequency. B571C kept in control procedures, the procedures required to prepare another.

Parts List and Schematic
Component Values of the fm stereo transmitter you can find out the schematic. Please download schematic for enlarged image



Amplifier section of this FM Stereo transmitter uses a single 2sc2053 transistor with power out about 250 mWatt.

See More : Voice Fm Transmitter - Transistor FM Transmitter - Microphone FM Transmitter

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PLL FM Transmitter With BH1415F

This Stereo FM Transmitter based on BH1415F wireless audio link IC. Phase Locked Loop controller uses Microchip PIC16F628 and the the PLL frequency programming can be displayed with 8×2 and 16×2 LCD display.The frequency range can adjustable from 88-108 MHz.

See PLL FM Transmitter With BH1415F schematic below

PLL FM Transmitter With BH1415F Component Layout and Printed Circuit Board

The PLL Controller Circuit and controller parts is designed by FREDDOSPAGE.
Download HEX Codes LCD 16x2 LCD 8x2, and here's Swith Board Panel Component Layout - PCB

Parts list of  PLL FM Transmitter With BH1415F
C14,C4,C25 = 3 x 2n2
C15,C5 = 2 x 150p
C8,C11,C6,C3
C10 = 5 x 1µF
C16,C20,C22 = 3 x 10µ
C1 = 1 x 2n7
C9,C12 = 2 x 10n
C2,C7 = 2 x 27pF
C18,C24 = 2 x 100µ
C17 = 1 x 10p
C19 = 1 x 100p
C21 = 1 x 330p
C23 = 1 x 47n
C13 = 1 x 1n
CD1 = 1 x SMV1251
GFWB3 = 1 x (Soshin)
IC1 = 1 x BH1415F
L1 = 1 x 20mH
L3 = 1 x 10µH
L2 = 1 x
P1,P2,P3 = 3 x 10k
Qz1 = 1 x 7,6 MHz
R1,R2 = 2 x 100k
R3,R5 = 2 x 10k
R4 = 1 x 22k
R6 = 1 x 1k5
R8,R7 = 2 x 3k3
R9 = 1 x 100
T1 = 1 x MPSA14

Source: PLL FM Transmitter With BH1415F

See More : Voice Fm Transmitter - Transistor FM Transmitter - Microphone FM Transmitter

read more "PLL FM Transmitter With BH1415F"

Macsot MR-700 High Quality wireless microphone

This is collected by the Macsot MR-700 wireless microphone system launch of the circuit for maintenance reference. High Quality Audio on receiver output.

Active components:

• Microphone or Audio Preamplifier with IC MC4458
• Dynamic Audio processed with one NE571 From Philips
• Frequency Oscillator generated by one crystal 20.05 MHz and Varactor diode 2CB11A. No drift frequency is guaranted.
• 9V DC power supply or battery. Source: High Quality wireless microphone

See More : Voice Fm Transmitter - Transistor FM Transmitter - Microphone FM Transmitter

read more "Macsot MR-700 High Quality wireless microphone"

FM Stereo Encoder CD4066

Circuit schematics IC1-4069 in the Y1, Y2 formation of a 76 KHZ frequency of the oscillator, the Y3-Y6 isolation plastic, into IC2 dual JK flip-flop CD4027 composed of two components- frequency circuit, a symmetrical + / 38KHZ-19 KHZ and the square wave, + / -38 KHZ IC3 the square used to control analog switches CD4066, a stereo audio input signal after switching modulation used for the 19 KHZ frequency mixed signal to the transistor into FM 9014 after isolation Modulator.

Click to access the debug FM modulator and 5 V power supply, with a multimeter measured IC1CD4069 the legs and IC2 CP, Q, Q, the legs should be half the supply voltage, the oscillator has been start-up. If a digital frequency meter measured IC1 output frequency, frequency regulation RW1 to 75 KHZ + /-10HZ can. If not, can be transferred to the prospective radios, RW2 half-good, and then transferred RW1, the bright lights stereo radio, and no speakers in the temple frequency whistle sounds. From the input into the stereo audio signal (1.5 Vpp, output amplifier available), this will be able to receive stereo radio broadcasting.

Input signal can be obtained from the line, but at R7 should be changed. Finally, can be transferred R7 to the smallest high-frequency noise, in fact R6, R7 equivalent BA1404 in 13, 14 feet of external components, the Pilot mixed signal and composite signal circuits, and input to the amplifier, the circuit of is 9014, and BA1404 from 12 feet on the entry. Source: FM Stereo Encoder CD4066

See More : Voice Fm Transmitter - Transistor FM Transmitter - Microphone FM Transmitter

read more "FM Stereo Encoder CD4066"

FM transmitter With uPC1651

The fm transmitter circuit has been produced by Japan's NEC as a major upc1651 IC devices, the high gain circuit, work stability, thereby ensuring the microphone performance.

Use of FM transmitter
Used it 40 - 50 cm soft drag line for antenna, the effective range of more than 30 launch M. L carefully spacing adjustment and fine-tuning capacitor, will launch frequency coverage for 88-108 MHz. Map L enameled wire with diameter of 0.51 mm in diameter, 4 mm cylindrical Tuitai from around 5 laps.

Source: uPC1651 FM Transmitter

See More :  Voice Fm Transmitter - Transistor FM Transmitter - Microphone FM Transmitter

read more "FM transmitter With uPC1651"

FM Transmitter With Transistor 2SC1815

Will have to introduce a system of simple and small FM transmitter. Not only does it meet the requirements of the launch distance, but also at the same time using microphone and voice input signal line, background voice. Modulation circuit surveillance has also joined the table first, so that they can better control and the proper use of transmitters, the following circuit diagram, read briefly, whether it's just like a radio station equipment as many functions. Yes, this small transmitter can help you easily set up an amateur FM radio stations! 500 M in the coverage around. Echocardiography the bar, act immediately!

Principle small FM transmitter circuit components and options:

Signal to the microphone after intake, the C1 coupling into the BG1 and external circuit voltage of the single negative feedback amplifier, the voltage signal amplification weak enough to enlarge the extent of U1A and the line to enter the input signal with a mixed U1B. Mixed signal modulation way to the R17 from BG2 FET and the surrounding circuit composed of common than LC finishes the test, the test than the LC oscillator are characterized by a general three-capacitance oscillator simple, but also with high efficiency and high stability. Waveform, and modulation bandwidth, as this amateur production of FM transmitters appears to be particularly important.

Finally BG3 cast by the post-amplifier to enlarge the field by launching antenna fired by general can listen to FM radio broadcast. Another component of the signal through the amplifier to enlarge U1C after the wave rectifier D2 SR DC drive microamps table, Near and surveillance signal modulation rate. Use the system for general should not exceed 85 per cent suitable. GM and other integrated circuits using LM324 four operational amplifier and form a single power reverse input, both of the input voltage is set at half the supply voltage. Table surveillance for the first u-200, BG1.BG3 choose 2SC1815 transistor. BG2 three DO2 FET, D2 varactor diode using a S2267. Antenna require the use of 1 / 4 wavelength, such as the use of the best pull rod antenna not less than one metre. Otherwise effect will be less than overstaying launch. Final say about, please do not interfere with normal radio! Small FM Transmitter

See More :  Voice Fm Transmitter - Transistor FM Transmitter - Microphone FM Transmitter

read more "FM Transmitter With Transistor 2SC1815"

Making Simple TV transmitter

(1) Soundless version, You are familiar with the most simplest FM transmitter that I designed (left). Let's try to transform it into a TV transmitter. Just change the input from the audio to the video (video camera or VCR) and check the signal at your television set: in Europe, for instance, choose the channel 2-4 and turn the trimmer cap ot the transmitter. You will find some images or might watch a clear image. This suggests that it will be not so difficult to build a TV transmitter.

(2) Advanced Version (AV) , When you succeed in this version to work, you may try the advanced version (pdf). In this version, stability and quality are improved. This can have even the audio too. However, in order to complete this, you have to use a proper frequency counter. Source: How to make TV transmitter

Continue reading: TV transmitter - Transistor FM Transmitter - Voice FM Transmitter

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FM Preamplifier 88-108 MHz

This VHF preamplifier working on Band 2 FM Radio Spectrum tuning approximately 88 - 108 MHz. The Preamplifier circuit uses two 2N3819 FET's transistors in cascode configuration. The lower FET operates in common source mode, while the upper FET, operates in common gate, realising full high frequency gain. The bottom FET is tunable allowing a peak for a particular station.

Coil details follow:
L1 4 turns of 18swg air spaced with a 1cm diameter, the tap is one turn up from earth end...
L2 4 turns of 18swg air spaced with 1 cm diameter. The coupling coil is 1 turn interwound from the supply end. Enamel coated wire must be used. Source: Preamplifier 88-108 MHz

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Microphone FM Transmitter

A portable FM transmitter that can be used to replace a FM microphone. This simple transmitter operates from a 9V battery as shown above. The old FM mic system was not a perfect solution, so I built this kit and a mixer for the receivers. using three separate transmitter circuits and a mixer on the receiver, the choir voices were perfect and cleanly reproduced."

From the notes I made experimentally, C3 is vital to the circuit and without it the circuit may become unstable. C4 is in parallel with C5 and presents a moderate load impedance. Finally all transistors are NPN. The circuit works well and has proved reliable. Microphone FM Transmitter Circuit

Continue reading: TV transmitter - Transistor FM Transmitter - Voice FM Transmitter

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FM Transmitter with 4 Transistors

This circuit provides an FM modulated signal with an output power of around 500mW. The input mic preamp is built around a couple of 2N3904 transistors, audio gain limited by the 5k preset.

The FM Transmitter oscillator is a colpitts stage, frequency of oscillation governed by the tank circuit made from two 5pF capacitors and the inductor. Frequency is around 100Mhz with values shown.

Audio modulation is fed into the tank circuit via the 5pf capacitor, the 10k resistor and 1N4002 controlling the amount of modulation. The oscillator output is fed into the 3.9 uH inductor which will have a high impedance at RF frequencies.

The output stage operates as a class D amplifier , no direct bias is applied but the RF signal developed across the 3.9 uH inductor is sufficient to drive this stage. The emitter resistor and 1k base resistor prevent instability and thermal runaway in this stage. Source: Transistor FM Transmitter. See more : VHF TV Modulator

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Voice FM Transmitter Circuit

It is illegal in most countries to operate radio transmitters without a license so take care with transmitter circuits. This FM Low Power circuit may be tuned to operate over the range 87-108MHz band II, with a range of 20 or 30 metres.

Active components in this circuit are BC548 transistors. Although not strictly RF transistors, they still give good results. I have used an ECM Mic (Voice FM ) insert from Maplin Electronics, order code FS43W. It is a two terminal ECM, but ordinary dynamic mic inserts can also be used, simply omit the front 10k resistor. The coil L1 was again from Maplin, part no. UF68Y and consists of 7 turns on a quarter inch plastic former with a tuning slug. The tuning slug is adjusted to tune the transmitter. Actual range on my prototype tuned from 70MHz to around 120MHz.

The aerial is a few inches of wire. Lengths of wire greater than 2 feet may damp oscillations and not allow the circuit to work. Although RF circuits are best constructed on a PCB, you can get away with veroboard, keep all leads short, and break tracks at appropriate points. FM Transmitter Circuit See more: UHF TV Modulator

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TV Transmitter Band I and III

This TV transmitter working on VHF Band I and III, using negative sound modulation and PAL video modulation. This is suitable for countries using TV systems B and G, like Australia and Indonesia.

This circuit has not been tested at UHF frequencies. The modulated sound signal contains 5.5 -6 MHz by tuning C5. Sound modulation is FM and is compatible with UK TV Transmitter System I sound. The transmitter however is working at VHF frequencies between 54 and 216MHz (band I and Band III) and therefore compatible only with countries using Pal System B and Pal System G. See detail of TV Transmitter and see more for VHF HF TV Modulator

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VHF UHF TV Modulator

Simple TV Modulator that working on VHF UHF Band, the oscillator generates frequency is modulated with the video signal and the modulated carrier wave thus generated is fed into the TV set's aerial input via a cable. Then all that remains to do is tune the VHF UHF TV set to the correct frequency.

The harmonics generator converts the oscillator signal into a sort of frequency spectrum containing all the multiples of 27 MHz up to about 1800 MHz. The TV modulator's output signal is made up of a large number of little peaks, each of which is a complete transmitter signal. At least one of these will always be in band I (VHF channels 2. . . 4), one in band III (VHF channels S. . .12) and many of them will be in bands IV and V (UHF channels 21.. .69). See more: VHF UHF TV modulator

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