Circuit-Zone.com - Electronic Projects

J-Pole Antenna
Posted on Saturday, June 5, 2010   •   Category: Antennas

J-Pole Antenna

Tuned for 89MHz in the FM broadcast band.

Fast PIC NiMH / NiCd Battery Charger
Posted on Thursday, May 27, 2010   •   Category: Battery Chargers

Fast PIC NiMH / NiCd Battery Charger

This battery charger charges a NIMH 5-pack battery used in the BiPed robot in less than 1 hour, and charges the 10-pack NiCd used in the Snuf robot in about 30 minutes. To prevent overheating of the battery, the charging current is turned off when the slope of the battery-voltage turns from positive into negative. A second termination-criterion of the charging process is provided for safety: the charge time is limited to about 1 hour.

Cell Phone Detector
Posted on Wednesday, May 26, 2010   •   Category: FM Radio / Receivers

Cell Phone Detector

This handy cell phone detector, pocket-size mobile transmission detector or sniffer can sense the presence of an activated mobile cellphone from a distance of one and-a-half meters. So it can be used to prevent use of mobile phones in examination halls, confidential rooms, etc. It is also useful for detecting the use of mobile phone for spying and unauthorized video transmission.

Small FM Radio
Posted on Wednesday, May 26, 2010   •   Category: FM Radio / Receivers

Small FM Radio

Perhaps this is one of the simplest and smallest FM Receiver that can receive the FM stations available locally. Its simple design makes it ideal for a pocket sized FM receiver. The output of the receiver drives a head phone.The circuit works off a small 4.5 volt battery or two 3.6 volt Lithium button cells.

1 Watt Four Stage FM Transmitter
Posted on Saturday, May 22, 2010   •   Category: FM Transmitters

1 Watt Four Stage FM Transmitter

This FM transmitter circuit uses four radio frequency stages: a VHF oscillator built around transistor BF494 (T1), a preamplifier built around transistor BF200 (T2), a driver built around transistor 2N2219 (T3) and a power amplifier built around transistor 2N3866 (T4). A condenser microphone is connected at the input of the oscillator.

Plane Motor Controller with High-Rate ESC, BEC and Brake
Posted on Thursday, May 20, 2010   •   Category: Miscellaneous

Plane Motor Controller with High-Rate ESC, BEC and Brake

This electronic speed control (ESC) for brushed motors combines the features of two of my earlier designs. One was a high-rate 30A ESC with a brake, and the other a high-rate 12A ESC with a BEC (receiver battery eliminator circuit).

Folded Dipole Antenna
Posted on Thursday, May 20, 2010   •   Category: Antennas

Folded Dipole Antenna

A modified version of the simple dipole is the folded dipole. It has two half-wave conductors joined at the ends and one conductor is split at the half-way point where the feeder is attached. If the conductor diameters are the same, the feedpoint impedance of the folded dipole will be four times that of a standard dipole, i.e. 300 ohm. The height above the ground The height of an antenna above the ground, and the nature of the ground itself, has a considerable effect on the performance of an antenna.and its angle of radiation. See PROPAGATION A dipole antenna can be arranged to operate on several bands using other methods. One way is to install "traps" in each leg.

1.2 - 12V / 1A Low Voltage LED Indicator Power Supply with LM317
Posted on Thursday, May 20, 2010   •   Category: Power Supplies

1.2 - 12V / 1A Low Voltage LED Indicator Power Supply with LM317

This is a 1.2 - 12 V, max 1A power supply with a low voltage indicator LED. The indicator part incluedes three diodes and one LED. For example you are charging a battery, you can observe the charge status at that moment. Another advantage of this circuit, when the drawn current exceeds 1A (practically 0.85A), the current protector in LM317 intervens and LED indicator warns you about the very low output voltage. Be careful while choosing the transformer. Most of the products are specified as 10VA but their outputs are not as said. Another good property of this circuit is the mains noise does not pass to the DC part.

Digital VGA Switch
Posted on Thursday, May 20, 2010   •   Category: Video

Digital VGA Switch

Digital VGA switch for switching between two PC monitors with MAX465 IC.

Ground Pole Antenna
Posted on Thursday, May 20, 2010   •   Category: Antennas

Ground Pole Antenna

This Antenna is most widely used all over the world. For example, when you see a police car it has a transmitter with Ground Pole Antenna The body of car serves as ground). It accepts load from 50 ohm source and has larger power output than Half-Wave Dipole Antenna.

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