Circuit book free

Wednesday, September 4, 2013

Solar Powered Animal Scarer

Here is a solar powered Flasher to scare away the nocturnal animals like bats and cats from the farm yard or premises of the house. The brilliant multicolored flashes confuse these animals and they avoid the hostile situation. It is fully automatic, turns on in the evening and turns off in the morning.

The circuit has an LDR controlled oscillator built around the Binary counter IC CD 4060.The functioning of the IC is controlled through its reset pin 12. During day time, LDR conducts and keeps the reset pin of IC high so that it remains dormant. During night, LDR cease to conduct and the reset pin will be grounded through VR1. This triggers the IC and it stats oscillating using the components C1 and VR2. Output pins 7, 5 and 4 are used to power the LEDs strings.

VR1 adjusts the sensitivity of LDR and VR2, the flashing rate of LEDs. High bright Red, Blue and White LEDs are used in the circuit to give brilliant flashes. Red LEDs flash very fast, followed by blue and then White. White LEDs remains on for few seconds and provide light to a confined area. More LEDs can be added in the strings if desired. The circuit can also function with 12 volt DC.

Animal Repellent Circuit diagram:

The circuit uses a solar powered battery power supply. During daytime, battery charges through R1 and D1.Green LED indicates the charging mode. During night time current from the solar cell decreases and D1 reverse biases. At the same time D2 forward biases to provide power to the circuit. Resistor R1 restricts the charging current and the high value capacitor C1 is a buffer for current.

Animal Scarer Solar Power Supply Circuit diagram:

ReadMore..

Tuesday, September 3, 2013

Low Power Transceiver Using by ADF7242

This low power transceiver circuit project is designed using the ADF7242 fully integrated low-cost, short-range, low power transceiver designed for operation in the global 2.4 GHz ISM band.The receive path of the ADF7242 low power transceiver circuit is based on a zero-IF architecture enabling high blocking and selectivity performance. The transmit path is based on a direct closed loop VCO modulation scheme. The ADF7242 has a low consumption power that make it suitable for battery powered systems.

Low Power Transceiver Circuit diagram

The ADF7242 supports IEEE 802.15.4 compliant DSSS-OQPSK modulation with a bitrate of 250 kbps and also supports FSK and GFSK modulation with bitrates from 62.5 kbps to 2 Mbps.ADF7242 fully supports arbitrary data rates only for FSK mode of operation. The ADF7242 also has a built in battery monitor features that has a very low power consumption and may be used in parallel with any mode of operation, except SLEEP state. The battery monitor generates a battery alert interrupt for the MCU when the battery voltage drops below the programmed threshold voltage.

ReadMore..

Monday, September 2, 2013

Audio Amplifier with High Clarity Circuit

Circuit Diagram

Description

The heart of the circuit is TDA7294 which acts as an amplifier the right and left input feded from the pre amplifier circuit is amplified after passing through the noise filter which contains an RC circuit, the volume is controlled by the variable resistor 47k. and the automatic gain control is provided by the operational amplifier circuit opp amp IC249 For both right channel and left channel., the speaker used is an 8 ohms 40 watts speaker.

Source - http://www.electronguide.com/circuits_pages/AudioAmplifier.html

ReadMore..

Sunday, September 1, 2013

A Basic IR Link

Description:
A basic Imfra Red Link for audio communication for distances upto 3 metres.

Notes:
Ovo je shema jednostavne bez?i?ne komunikacije sa malo komponenata .Diode d1 i d2 su infracrvene le-diode ,a foto transistor je tako?er infracrveni radi ?to manjeg vanjskog utjecaja .Domet ure?aja je oko 3m no on se mo?e promijeniti brojem le-dioda i naponom koji se dovede na diode.Na izlaz se ?ak mogu i direktno spojiti slu?alice.Link mo?e poslu?iti i za prijenos drugih vrsta signala..Na popisu komponenata nema kriti?nih dijelova i izrada sklopa je jako jeftina. Uz malo pa?nje ne moe da ne radi.
P.S Transistors can be replaced with 2N3904 and 2N2222

Notes:
In his circuit Milan has created a basic Infra Red transmitter and receiver. The transmitter comprises a single amplifying stage driving two series connected IR LEDS. The input source is connected to J1. Please note that the device will pass a small DC current through it and also directly bias the transistor. A suitable device is therefore a high output crystal microphone. These can produce high output voltages up to 1 Volt but this will be reduced by the transistors low input impedance.

The receiver is three stages, the first stage being a phototransistor. Stages two and three form a high gain darlington emitter follower, the bias for the whole stage derived through R2 and the phototransistor itself. C1 and R3 form a filter to reduce interference from flourescent lighting and other hum sources. The output is via Jack J2. Note also that the output device will pass a small DC current so a medium impedance loudspeaker or hwadphones are a good choice here.

ReadMore..

Saturday, August 31, 2013

2 Channel Audio Mixer Using by Transistors

This 2 channels audio mixer is based on the 2n3904 transistors which forms 2 preamplifiers. The first preamplifier of the audio mixer has a high gain and can be used for microphone input, and the second one can be used to control the input of the audio level.

2 Channel Audio Mixer Circuit diagram

This two channel audio mixer require a power supply with the output voltage between 9 to 12 volts . For the audio signal you can use a CD player, mp3 player or other audio device and for the microphone you can use a normal dynamic microphone .

ReadMore..

Friday, August 16, 2013

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.

Working of the circuit is simple. When you speak near the microphone, frequency-modulated signals are obtained at the collector of oscillator transistor T1. The FM signals are amplified by the VHF preamplifier and the pre-driver stage. You can also use transistor 2N5109 in place of 2N2219. The preamplifier is a tuned class-A RF amplifier and the driver is a class-C amplifier. Signals are finally fed to the class-C RF power amplifier, which delivers RF power to a 50-ohm horizontal dipole or ground plane antenna. Use a heat-sink with transistor 2N3866 for heat dissipation. Carefully adjust trimmer VC1 connected across L1 to generate frequency within 88-108 MHz. Also adjust trimmers VC2 through VC7 to get maximum output at maximum range.

image Four Stage FM Transmitter circuit diagram

Regulator IC 78C09 provides stable 9V supply to the oscillator, so variation in the supply voltage will not affect the frequency generated. You can also use a 12V battery to power the circuit. Assemble the circuit on a general-purpose PCB. Install the antenna properly for maximum range. Coils L1 through L5 are made with 20 SWG copper-enamelled wire wound over air-cores having 8mm diameter. They have 4, 6, 6, 5 and 7 turns of wire, respectively.

EFY note. This transmitter is meant only for educational purposes. use of this transmitter with outdoor antenna is illegal in most parts of the world. The author and EFY will not be responsible for any misuse of this transmitter.

ReadMore..

Thursday, August 15, 2013

DTMF Proximity Detector

A DTMF-based IR transmitter and receiver pair can be used to realize a proximity detector. The circuit presented here enables you to detect any object capable of reflecting the IR beam and moving in front of the IR LED photo-detector pair up to a distance of about 12 cm from it. The circuit uses the commonly available telephony ICs such as dial-tone generator 91214B/91215B (IC1) and DTMF decoder CM8870 (IC2) in conjunction with infrared LED (IR LED1), photodiode D1, and other components as shown in the figure. A properly regulated 5V DC power supply is required for operation of the circuit.

The transmitter part is configured around dialer IC1. Its row 1 (pin 15) and column 1 (pin 12) get connected together via transistor T2 after a power-on delay (determined by capacitor C1 and resistors R1 and R16 in the base circuit of the transistor) to generate DTMF tone (combination of 697 Hz and 1209 Hz) corresponding to keypad digit “1” continuously. LED 2 is used to indicate the tone output from IC3. This tone output is amplified by Darlington transistor pair of T3 and T4 to drive IR LED1 via variable resistor VR1 in series with fixed 10-ohm resistor R14. Thus IR LED1 produces tone-modulated IR light.

DTMF Proximity Detector circuit diagram

Variable resistor VR1 controls the emission level to vary the transmission range. LED 3 indicates that transmission is taking place. A part of modulated IR light signal transmitted by IR LED1, after reflection from an object, falls on photodetector diode D1. (The photodetector is to be shielded from direct IR light transmission path of IR LED1 by using any opaque partition so that it receives only the reflected IR light.) On detection of the signal by photodetector, it is coupled to DTMF decoder IC2 through emitter-follower transistor T1.

When the valid tone pair is detected by the decoder, its StD pin 15 (shorted to TOE pin 10) goes ‘high’. The detection of the object in proximity of IR transmitter-receiver combination is indicated by LED1. The active-high logic output pulse (terminated at connector CON1, in the figure) can be used to switch on/off any device (such as a siren via a latch and relay driver) or it can be used to clock a counter, etc. This DTMF proximity detector finds applications in burglar alarms, object counter and tachometers, etc.

Sourced by : Streampowers

ReadMore..