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Digital AVR frequency meter
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Create multicolored LEDs
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Ultrasonic Parking Sonar Schematic
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Battery Solutions for Energy Harvesting
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Simple Gas Leak Detector Circuit
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FTDI Infrared
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3 Axis Accelerometer Using PIC16F887
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Simple 3V adjustable Car adapter
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Handy Talky 27 Mhz
Handy Talky circuit has the advantage of this kind can double loudspeaker. On receipt, serves as a loudspeaker, and at the radiating function as a microphone.
Transmitter section
Handy Talky transmitter section uses a single transistor level. The circuit was built by Tr. Output frequency is determined crystal X, (in this case the frequency 27,125MHz). Transmitter circuit is part of Handy Talky transmitter oscillator. Transmission power about 100 mW. Of power is not strengthened, but is fed directly to a series of “tank pi” to the next through the rod antenna is emitted into the atmosphere. Although the transmitter is small (only 100 mW k) but with the receiver circuit can be used to communicate both ways as far as approximately 3 kilometers.
Receiver
Transmitter antennas will be received by the receiving antenna and tuned by L1. The signal is fed to the RF amplifier circuits TR1. Then the signals are mixed by a mixer with the results of the local oscillator frequency. The frequency of this mixture the amount of 455 kHz. Furthermore, the signal with a frequency of 455 kHz IF amplifierboosted again by that in the scheme represented by TR3, Tr4, with transformer IF1,IF2 and IF3. The results strengthen the IF amplifier is a mixture of audio frequencies.dam the carrier frequency. By the detector, an audio frequency will be separated from the carrier frequency, and then feeds amplified by AF amplifier section. To be the voice on the loudspeaker remains constant, does not swing, it is necessary to set the AGC. Consider the scheme on the following pages.
