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3V FM Transmitter
The objective of this 3V FM Transmitter design is to provide a simple low-power transmitter solution for broadcasting audio from various audio sources. This transmitter transmits audio using small sensitive microphone. Transmitter's frequency, as built is tunable via 15pF trimmer to the desired frequency, and the coil is embedded on the circuit board. This implementation is adapted to rebroadcast the output of a CD player, television receiver, or radio receiver. I use this transmitter so that I can move about the house and listen to my favorite programs without disturbing others. Within and the house, I find that I can get 50 to 100 meters away from the transmitter with the small pocket FM receiver I carry in my shirt pocket.
3V FM Transmitter for 88MHz to 108MHz
The important part of the circuit is formed of the Colpitts type oscillator. C3,C4,C5,C6,CD1-CD2 and L1 determines the frequency. BF982 and dual gate MOSFET are active parts in oscillator. When the input impedance of the MOSFET gate inputs are high, LC tank is not affected. However transistors force the LC tank and cause phase shift.
Two driver stages are added to isolate the antenna from oscillator. First stage (BF199) amplifies the low signal of the oscillator and works as a constant load. The second stage (BFR90) amplifies the signal going through the antenna some more. A short copper wire can be used as an antenna here. Attaching a large antenna to this circuit is unnecessary because the output power is low.
3V FM Transmitter for 88MHz to 108MHz
The important part of the circuit is formed of the Colpitts type oscillator. C3,C4,C5,C6,CD1-CD2 and L1 determines the frequency. BF982 and dual gate MOSFET are active parts in oscillator. When the input impedance of the MOSFET gate inputs are high, LC tank is not affected. However transistors force the LC tank and cause phase shift. Two driver stages are added to isolate the antenna from oscillator. First stage (BF199) amplifies the low signal of the oscillator and works as a constant load. The second stage (BFR90) amplifies the signal going through the antenna some more. A short copper wire can be used as an antenna here. Attaching a large antenna to this circuit is unnecessary because the output power is low.
3V One Transistor FM Transmitter
The above wireless FM transmitter circuit is basically a small RF transmitter built around a single transistor. The circuit functions quite like a Colpitts oscillator incorporating a tank circuit for the generation of the required oscillations. The frequency mainly depends on the positioning and the values of the inductor, C1, C2 and C3. The coil turn distance and diameter may be manipulated a little for optimizing best response over the FM receiver. A small antenna in the form of a 3 inches wire may be attached at the shown point for making the “bug†highly responsive and generates distortion free signals.
3W FM Transmitter Amplifier
Presented is a three stage 3W FM Transmitter Amplifier using 2SC9018, 2SC2053 and 2SC1970 transistors. The circuit is supplied by 12-14V DC voltage and requires at least 500mA of current.
4 Transistor FM Transmitter
This circuit provides an FM modulated signal with an output power of around 500mW. The input microphone pre-amp is built around a couple of 2N3904 transistors (Q1/Q2), and audio gain is limited by the 5k preset trim potentiometer. The oscillator is a colpitt stage, frequency of oscillation governed by the tank circuit made from two 5pF ceramic capacitors and the L2 inductor. The output stage operates as a 'Class D' amplifier, no direct bias is applied but the RF signal developed across the 3.9uH inductor is sufficient to drive this stage. The emitter resistor and 1k base resistor prevent instability and thermal runaway in this stage.
4 Watt FM Transmitter
The following is a simple yet powerful 4W FM transmitter which is tunable to 88-108MHz frequency. Connect to your ipod/computer, etc. When this was first made, I only had a 2N2219A on hand, which resulted in a lower RF output. I have since swapped out the transistor for a 2N3866 for full 4W output at around 15VDC supply. In order to achieve a high output level, you will need a well tuned antenna, and a large heatsink to dissipate the heat from T2 transistor.
Transmitter was mounted in metal enclosure and works extremely well.
40 Watt FM Transmitter Amplifier
Building two stage 40 Watt FM Transmitter Amplifier. RF input power should be between 0.5 and 1 watt. Amplifier is powered by 28V power supply. The diagram shows a 2N3375 driving a 2N5643 but there are many other transistors that will work. I used these two transistors just because they were cheap at the time. If any of the variable capacitors are at full capacitance you can pad them out with a fixed ceramic capacitor of suitable value. Extra capacitance also might be needed on the base of the transistors (i had to add 3 100pF capacitors on the base of the 2N5643). The transistors are bolted to a piece of right angle aluminum which is fixed to the metal chassis to dissipate heat effectively.
400mW VCO FM transmitter
With good antenna (dipole placed outdoor and high) the transmitter has very good coverage range about 500 meters, the maximal coverage range is up to 4 km.
400mW VCO FM Transmitter
This simple 400mW transmitter broadcasts audio on 87.5 - 108 MHz FM radio band. With good dipole antenna transmission range up to 4km is possible. Frequency is selected by adjusting R1 potentiometer. Transmitter should be powered by regulated 12-14V power supply with at least 100mA current rating.
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Accurate LC Meter
Build your own Accurate LC Meter (Capacitance Inductance Meter) and start making your own coils and inductors. This LC Meter allows to measure incredibly small inductances making it perfect tool for making all types of RF coils and inductors. LC Meter can measure inductances starting from 10nH - 1000nH, 1uH - 1000uH, 1mH - 100mH and capacitances from 0.1pF up to 900nF. The circuit includes an auto ranging as well as reset switch and produces very accurate and stable readings. |
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PIC Volt Ampere Meter
Volt Ampere Meter measures voltage of 0-70V or 0-500V with 100mV resolution and current consumption 0-10A or more with 10mA resolution. The meter is a perfect addition to any power supply, battery chargers and other electronic projects where voltage and current must be monitored. The meter uses PIC16F876A microcontroller with 16x2 backlighted LCD. |
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60MHz Frequency Meter / Counter
Frequency Meter / Counter measures frequency from 10Hz to 60MHz with 10Hz resolution. It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc. |
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1Hz - 2MHz XR2206 Function Generator
1Hz - 2MHz XR2206 Function Generator produces high quality sine, square and triangle waveforms of high-stability and accuracy. The output waveforms can be both amplitude and frequency modulated. Output of 1Hz - 2MHz XR2206 Function Generator can be connected directly to 60MHz Counter for setting precise frequency output. |
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BA1404 HI-FI Stereo FM Transmitter
Be "On Air" with your own radio station! BA1404 HI-FI Stereo FM Transmitter broadcasts high quality stereo signal in 88MHz - 108MHz FM band. It can be connected to any type of stereo audio source such as iPod, Computer, Laptop, CD Player, Walkman, Television, Satellite Receiver, Tape Deck or other stereo system to transmit stereo sound with excellent clarity throughout your home, office, yard or camp ground. |
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USB IO Board
USB IO Board is a tiny spectacular little development board / parallel port replacement featuring PIC18F2455/PIC18F2550 microcontroller. USB IO Board is compatible with Windows / Mac OSX / Linux computers. When attached to Windows IO board will show up as RS232 COM port. You can control 16 individual microcontroller I/O pins by sending simple serial commands. USB IO Board is self-powered by USB port and can provide up to 500mA for electronic projects. USB IO Board is breadboard compatible. |
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ESR Meter / Capacitance / Inductance / Transistor Tester Kit
ESR Meter kit is an amazing multimeter that measures ESR values, capacitance (100pF - 20,000uF), inductance, resistance (0.1 Ohm - 20 MOhm), tests many different types of transistors such as NPN, PNP, FETs, MOSFETs, Thyristors, SCRs, Triacs and many types of diodes. It also analyzes transistor's characteristics such as voltage and gain. It is an irreplaceable tool for troubleshooting and repairing electronic equipment by determining performance and health of electrolytic capacitors. Unlike other ESR Meters that only measure ESR value this one measures capacitor's ESR value as well as its capacitance all at the same time. |
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Audiophile Headphone Amplifier Kit
Audiophile headphone amplifier kit includes high quality audio grade components such as Burr Brown OPA2134 opamp, ALPS volume control potentiometer, Ti TLE2426 rail splitter, Ultra-Low ESR 220uF/25V Panasonic FM filtering capacitors, High quality WIMA input and decoupling capacitors and Vishay Dale resistors. 8-DIP machined IC socket allows to swap OPA2134 with many other dual opamp chips such as OPA2132, OPA2227, OPA2228, dual OPA132, OPA627, etc. Headphone amplifier is small enough to fit in Altoids tin box, and thanks to low power consumption may be supplied from a single 9V battery. |
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Arduino Prototype Kit
Arduino Prototype is a spectacular development board fully compatible with Arduino Pro. It's breadboard compatible so it can be plugged into a breadboard for quick prototyping, and it has VCC & GND power pins available on both sides of PCB. It's small, power efficient, yet customizable through onboard 2 x 7 perfboard that can be used for connecting various sensors and connectors. Arduino Prototype uses all standard through-hole components for easy construction, two of which are hidden underneath IC socket. Board features 28-PIN DIP IC socket, user replaceable ATmega328 microcontroller flashed with Arduino bootloader, 16MHz crystal resonator and a reset switch. It has 14 digital input/output pins (0-13) of which 6 can be used as PWM outputs and 6 analog inputs (A0-A5). Arduino sketches are uploaded through any USB-Serial adapter connected to 6-PIN ICSP female header. Board is supplied by 2-5V voltage and may be powered by a battery such as Lithium Ion cell, two AA cells, external power supply or USB power adapter. |
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200m 4-Channel 433MHz Wireless RF Remote Control
Having the ability to control various appliances inside or outside of your house wirelessly is a huge convenience, and can make your life much easier and fun. RF remote control provides long range of up to 200m / 650ft and can find many uses for controlling different devices, and it works even through the walls. You can control lights, fans, AC system, computer, printer, amplifier, robots, garage door, security systems, motor-driven curtains, motorized window blinds, door locks, sprinklers, motorized projection screens and anything else you can think of. |
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