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In this Electronic Circuit Project , a 74HC14 hex Schmitt trigger inverter is used as a square wave oscillator to drive a small signal transistor in a class C amplifier configuration. The oscillator frequency can be either fixed by a crystal or made adjustable (VFO) with a capacitor/resistor combination. A 100pF capacitor is used in place of the crystal for VFO operation. Amplitude modulation is accomplished with a second transistor that controls the DC voltage to the output stage. The modulator stage is biased so that half the supply voltage or 6 volts is applied to the output stage with no modulation. The output stage is tuned and matched to the antenna with a standard variable 30-365 pF capacitor. Approximately 20 milliamps of current will flow in the antenna lead (at frequencies near the top of the band) when the output stage is optimally tuned to the oscillator frequency. Micro Power AM Broadcast Transmitter Circuit Diagram: A small 'grain of wheat' lamp is used to indicat...

CIRCUIT DESCRIPTION The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (L1 coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor T2. The tank circuit is connected in a Hartley oscillator circuit. Components List R1=220K R2=4.7K R3,R4=10K R5=100ohm C1,C2=4.7uF Electrolytic C3,C4=1nF C5=2-15pF C6=3.3pF Q1=BC547C Q2=BD135 P1=25K MIC=Electret Condenser Type P1 act as condenser microphone volume level. For FM, coil will be small. Use thin gauge enamel magnet wire. the diameter of coil will be a couple mm: use ink tube from pen to form, and try 8-12 turns. Small inductance ...

FM transmitter or often called fm transmitter uses 2 transistors in this article uses 2 transistors 2n2222. If the fm transmitter is in use voltage supply of 9 volt battery and use an antenna whose length is less than 12 inches, then this fm transmitter will be within FCC limits. Signals from the microphone in the fm transmitter is reinforced by Q1, Q2 with carrier frequency generator is determined by the C5 and L1. The frequency of the FM transmitter is in the range 80 MHz - 108 MHz. L1 can be made ​​with as many as 24 e-mail wire wrap and 6 wrap. The following is a picture series for the fm transmitter fm transmitter referred to in article 2 of this transistor. This fm transmitter antenna is connected to the mid point of the antenna length L1 and preferably between 8-12 inches. FM Transmitter is only used for experiment and learning materials are not to be used for day-to-day, because the use of FM transmitter frequency regulated and protected by law may be understandable.

Transmitter and receiver circuit using infra red audio signal is applied to emit an audio signal and will received on a headphones. Making his series is not too difficult, the transmitter and receiver circuit scheme can be seen below. Transmiter schematics Receiver schematics After the series finished, you can try to give the audio inputs on the transmitter and point the LED transmitter to the receiver. Maximum distance is a few meters may not be more than 10 meters, but you can listen to music without wires while using infra red. image[link]

Description. 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. 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.

Circuit diagram Notes: This small transmitter uses a hartley type oscillator. Normally the capacitor in the tank circuit would connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The coil is four turns of 18swg wire wound around a quarter inch former. The aerial tap is about one and a half turns from the supply end. Audio sensitivity is very good when used with an ECM type microphone insert

      In this article we learn about a 1 Watt FM Transmitter amplifier with a reasonably balanced design specified to boost a RF frequency in the 88 – 108 MHz spectrum.             It may be considered a fairly sensitive configuration when used with quality RF power amplifier transistors, trimmers and inductors. It involves a power amplification factor of 9 to 12 dB (9 to 15 times). At an input power of 0.1W the output may be well over 1W. It's advisable to choose T1 transistor on the basis of the fed voltage. Considering you possess a 12V power supply in that case using transistors like: 2N4427, KT920A, KT934A, KT904, BLX65, 2SC1970, BLY87. At 18 to 24V inputs you may want to use transistors such as: 2N3866, 2N3553, KT922A, BLY91, BLX92A. You could also consider using 2N2219 at 12V However that would yield just an output power of 0.4W at the fullest. How to Calibrate this 1 watt fm power amp Initially don't appl...

A compact 2 transistor transmitter for use at VHF frequencies. 2 Transistor Transmitter Schematic Circuit Diagram Notes: Transistor T1 works as an audio preamplifier, gain is fixed at approximately R2/R1 or 100 times. The audio input is applied at the points LF in (on the diagram). P1 works as gain control. After amplification this audio signal now modulates the transmitter built around T2. Frequency is tunable using the trimmer CT and L1 is made using 3 turns of 1mm copper wire wound on a 5mm slug. The modulated signal passes via C6 to the antenna. A dipole can be made using 2 lengths of 65cm copper pipe. A DC power supply in the range 3 to 16 volts is required.

Long Range AM transmitter circuit Diagram The ambit for a able AM transmitter application bowl resonator/filter of 3.587 MHz is presented here. Resonators/filters of added frequencies such as 5.5 MHz, 7 MHz and 10.7 MHz may additionally be used. Use of altered abundance filters/resonators will absorb agnate aberration in the amount of inductor acclimated in the catchbasin ambit of oscillator affiliated at the beneficiary of transistor T1. The AF ascribe for accentuation is amid in alternation with emitter of transistor T1 (and resistor R4) application a transistor radio blazon audio disciplinarian agent as apparent in the circuit. Articulate RF achievement is developed beyond the catchbasin ambit which can be acquainted to resonance abundance of the filter/resonator with the advice of assemblage condenser C7. The abutting two stages formed application low-noise RF transistors BF495 are, in fact, affiliated in alongside for addition of articulate arresting accompanying from beneficiar...

This article should satisfy those who might want to build a low power FM transmitter. It is designed to use an input from another sound source (such as a guitar or microphone), and transmits on the commercial FM band - it is actually quite powerful, so make sure that you don't use it to transmit anything sensitive - it could easily be picked up from several hundred metres away. The FM band is 88 to 108MHz, and although it is getting fairly crowded nearly everywhere, you should still be able to find a blank spot on the dial. NOTE: A few people have had trouble with this circuit. The biggest problem is not knowing if it is even oscillating, since the frequency is outside the range of most simple oscilloscopes. See Project 74 for a simple RF probe that will (or should) tell you that you have a useful signal at the antenna. If so, then you know it oscillates, and just have to find out at what frequency. This may require the use of an RF frequency counter if you just cannot locate th...

Figure 1  The circuit was designed to produce a 500mW output power transmitter whose signal modulated by FM using four transistors. Transmitter – an electronic device that can produce or amplify a carrier wave signal, modulates it with a significant signal, and radiates the resulting signal from an antenna which are being utilized in television, telecommunications, and radio Frequency Modulation (FM) – transmits its signal or information over a carrier wave by changing its frequency but it can also be taken into account as a special case of phase modulation where the carrier phase modulation is the time integral of the FM modulating signal 2N3904 – NPN device designed for general purpose low power amplifier and switch applications; extends to 100 mA as a switch and to 100 MHz as an amplifier 7001 (NTE123AP) – a small signal bipolar transistor having an N channel polarity; collector emitter voltage of 40 V; collector base voltage of 60 V; DC current gain minimum of 20; collec...

2 km FM transmitter With a matching antenna, the FM transmitter circuit shown here can transmit signals up to a range of 2 kilo meters. The transistor Q1 and Q2 forms a classic high sensitive preamplifier stage. The audio signal to be transmitted is coupled to the base of Q1 through capacitor C2. R1, R3, R4, R6, R5 and R9 are the biasing resistors for the preamplifier stage comprising of Q1 and Q2. Transistor Q3 performs the collective job of oscillator, mixer and final power amplifier.C9 and L1 forms the tank circuit which is essential for creating oscillations. Inductor L2 couples the FM signal to the antenna. Circuit diagram. Notes. ■Assemble the circuit on a good quality PCB. ■The circuit can be powered from anything between 9 to 24V DC. ■Inductor L3 can be a VK220J type RFC. ■For L1 make 3 turns of 1mm enamelled copper wire on a 10mm diameter plastic former. On the same core make 2 turns of 1 mm enamelled copper wire close to L3 and that will be L2. ■Frequency can be adjusted by v...

Remote sensor sends data via mains supply, Temperature range: 00.0 to 99.9 °C This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor's output voltage, which is proportional to the measured temperature. The output frequency bursts are conveyed into the mains supply cables. The receiver section counts the bursts coming from mains supply and shows the counting on three 7-segment LED displays. The least significant digit displays tenths of degree and then a 00.0 to 99.9 °C range is obtained. Transmitter-receiver distance can reach hundred meters, provided both units are connected to the mains supply within the control of the same light-meter. Transmitter circuit operation: IC1 is a precision centigrade temperature sensor with a linear output of 10mV/°C driving IC2, a voltage-frequency converter. At its output pin (3), an input of 10mV is converted to 100Hz frequency pulses. Thus, for example, a temperatur...

I use my computer every single minute, I do my work at home and I need to finish lots of paperwork. My computer helps me in almost everything I do. I make sure that my pc is able to do multitasking and functioning well. Just like our body, it should be fit to do all the workload that must be finished within the day. To come up with another task that a pc can add to its functions, an IR remote was created through an FTDI that receives and transmits data other than the Universal Serial Bus. This is definitely a big help that my pc can easily cope up with simultaneously.