Circuit-Zone.com - Electronic Projects
Posted on Sunday, December 23, 2012 • Category: FM Transmitters
Build your own simple mini FM transmitter. This fun project will show you how to build a mini broadcasting transmitter that can transmit an audio signal up to a quarter mile to any FM receiver. It's easy to build and a good learning experience. It serves as a hands-on learning tool for students or anybody interested in electronics. Having a range of up to a quarter mile, it's great for a house security system, baby monitoring device or simply a listening gadget that you can place anywhere!
Posted on Tuesday, December 4, 2012 • Category: FM Transmitters
The power output of many transmitter circuits are very low because no power amplifier stages are incorporated. The transmitter circuit described here has an extra RF power amplifier stage using 2N3866 RF power transistor after the oscillator stage to increase output power to 250 milliwatts. With a good matching 50-ohm ground plane antenna or multi-element Yagi antenna, this transmitter can provide reasonably good signal strength up to a distance of about 2 kilometers. Transmitter's oscillator is built around BF494 transistor T1. It is a basic low-power variable-frequency VHF oscillator. A varicap diode circuit is included to tune the frequency of the transmitter and to provide frequency modulation by audio signals. The output of the oscillator is about 50 milliwatts. 2N3866 transistor T2 forms a VHF-class A power amplifier. It boosts the oscillator signal power four to five times. Thus 250mW of power is generated at the collector of transistor T2.
Posted on Friday, November 30, 2012 • Category: Test and Measurement
This is a simple 30V volt meter using PIC16F676 micro controller with 10-bit ADC (analog to digital converter) and three 7 segment LED displays. You can use this circuit to measure up to 30V DC. The possible applications are on bench power supply or as a digital panel meter in various systems. PIC16F676 is the heart and brain of this circuit. The internal adc of the mcu with a resistor network voltage divider is used to measure the input voltage. Then 3 digits of comm anode 7 segment display is used to display final converted voltage. As you can see in the schematic the displays are multiplexed with each other. It means we switch on one display and put the corresponding digit on this while other two displays are off this cycle goes for each of the displays.
Posted on Sunday, November 18, 2012 • Category: FM Transmitters
Presented FM transmitter bug is built using BF414 / BF324 / BF606 transistor. The 30cm antenna has a range of about 30m in the building, more in the open field. Power supply 2x AAA batteries have been used with voltage of 2.75 V. I added resistor 10K in parallel with 1.5pF capacitor so that the system works well when connected to an external source (mp3 player / computer). On the computer I had to reduce sound to about 35% of capacity, so that I do not have clipping. I managed to improve transmitter stability with simple shielding. The coil is 5 turns of enameled copper wire wound on 1 mm ø = 5 mm.
Posted on Wednesday, November 7, 2012 • Category: Battery Chargers
Lead Acid batteries have changed little since the 1880's although improvements in materials and manufacturing methods continue to bring improvements in energy density, life and reliability. All lead acid batteries consist of flat lead plates immersed in a pool of electrolyte. Regular water addition is required for most types of lead acid batteries although low-maintenance types come with excess electrolyte calculated to compensate for water loss during a normal lifetime.
Lead acid batteries used in the RV and Marine Industries usually consist of two 6-volt batteries in series, or a single 12-volt battery. These batteries are constructed of several single cells connected in series each cell produces approximately 2.1 volts. A six-volt battery has three single cells, which when fully charged produce an output voltage of 6.3 volts. A twelve-volt battery has six single cells in series producing a fully charged output voltage of 12.6 volts.
Posted on Friday, October 26, 2012 • Category: FM Transmitters
BA1404 transmitter includes onboard RF amplifier for increased transmitting range. Operating voltage range is 1-3V, the circuit contains FM stereo mixer, 38KHZ oscillator, FM modulator and high-frequency amplifier monolithic integrated circuit. As the "electronic newspaper" BBS there are many users requiring detailed information on the FM stereo transmitter, so I re-collect the relevant information on the simple discrete, merge, integrated FM stereo transmitter experiment, that BA1404 with μpc1651 mix of the most easy to make and debug, and very high frequency stability (relative to the previous circuit BA1404), transmission power is increased by UPC1651RF amplifier.
Posted on Tuesday, October 16, 2012 • Category: Test and Measurement
There's something fascinating about electromagnetic fields. Thanks to the modern world and the prevalence of electronics and electricity, they're all around us these days. But because of the extremely limited array of senses that we humans have, we spend most of the time completely oblivious of them. Wouldn't it be cool to make something simple that could not just detect them, but would allow you look at the waveforms on an oscilloscope. An EMF probe in other words.
Posted on Sunday, October 7, 2012 • Category: FM Transmitters
A high quality stereo FM transmitter circuit is shown here. The circuit is based on the IC BA1404 from ROHM Semiconductors. BA1404 is a monolithic FM stereo modulator that has built in stereo modulator, FM modulator, RF amplifier circuitry. BA1404 FM transmitter can be operated from 76 to 108MHz and power supply for the circuit can be anything between 1.25 to 3 volts.
Posted on Tuesday, October 2, 2012 • Category: Antennas
Together with a good directional antenna this high performance two-stage antenna amplifier for the VHF FM broadcast band will enable you to receive distant radio stations. VHF FM Antenna booster will also drastically improve reception of FM signals you’ve come to accept as marginal and noisy in your area. Antenna booster is also great for extending transmission range of low power VHF / FM transmitters.
Posted on Sunday, September 16, 2012 • Category: FM Transmitters
Here is a simple USB FM transmitter that could be used to play audio files from an MP3 player or computer on a standard VHF FM radio by connecting it to an USB port. The circuit use no coils that have to be wound. This USB transmitter can be used to listen to your own music throughout your home. To keep the fm transmitter circuit simple as well as compact, it was decided to use a chip made by Maxim Integrated Products, the MAX2606. 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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