Circuit-Zone.com - Electronic Projects
Posted on Wednesday, June 15, 2011 • Category: Battery Chargers
This is LiPo battery charger circuit based around the MAX1551 / MAX1555 chip from Maxim ICs. And it happens to be a very easy chip to use. I used the typical circuit from the datasheet and referred to the pin out to see which pin is what. I also used adapter board so that I could prototype the LiPo battery charger on a breadboard. The barrel plug towards the top goes into an LM7805 that can take 7-16V and regulates it down to 5V. Besides that, pretty simply stuff with only a handful of common components.
Posted on Tuesday, June 14, 2011 • Category: FM Transmitters
A very small home made FM transmitter Bug using a single transistor and with a transmission range of 200 meters. This FM transmitter Bug is very easy to build. The size of the circuit board is ONLY 22mm x 10mm.
Posted on Saturday, June 11, 2011 • Category: FM Transmitters
Here's how to build a simple FM Transmitter. This tiny transmitter has smaller radius of the service area, lower quality of the sounds and the relatively unstable frequency. These can be considered as a compromise to easily have your own transmitter for the time being or as a more positive choice. These "defects" are only from the perspective of conventional transmission such as "clear stereo sound to receive anywhere". Artist could change these to another directions. Whether or not, you can experience a convivial wireless imagination by this transmitter.
Posted on Thursday, June 9, 2011 • Category: FM Transmitters
This micro spy PLL FM Transmitter transmits on the 160MHz frequency (if we use a 40MHz quartz) and therefore can be listened through a receiver tuned on this frequency. This circuit can be used to on various frequencies, for example on the FM band 88-108 just modifying some components, among which the quartz (25MHz).
Voice is detected by an electret microphone, then it is amplified and filtered by U1 pass-band in order then to be modulated from the carrier section, where through the varicap diode it "mixes" with the frequency generated by the quartz, that guarantees an adapted stability. Practically the modulating voltage is obtained applying the audio signal to the resonating circuit varicap diode that determines the carrier oscillation. The carrier frequency (160 MHz) must be greater than the modulating frequency (300-3300 Hz) audio band.
The transmission is on the fourth harmonic, therefore 160MHz, the oscillation frequency of the driver RF transistor Q1.
A small calibration is allowed acting on the L1 inductance and the C1 Trimmer Capacitor.
Posted on Thursday, June 9, 2011 • Category: PIC
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PIC Controlled Relay Driver
This circuit is a relay driver that is based on a PIC16F84A microcontroller. The board includes four relays so this lets us to control four distinct electrical devices. The controlled device may be a heater, a lamp, a computer or a motor. To use this board in the industrial area, the supply part is designed more attentively. To minimize the effects of the ac line noises, a 1:1 line filter transformer is used.
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