Wiring Schematic Diagram

FM transmitter circuit very stable and simple given here. With an adaptive antenna, the transmitter can reach a range of about 200 meters. Transmitter met this year and got a few good results. Let's see how the circuit.

A condenser microphone (K1) is used to collect the sound transmitted. The capacitor C1 is a DC decoupler and the audio signal is coupled to the base of Q1 which connects a preamplifier.R2 and R3 are the resistances of polarization of Q1. Amplified sound signal will be available at the collector of Q1 and, together with the emitter of transistor Q2 through capacitor C4 and inductor L1 1mH.

C4 capacitor decouples the DC component of the preamplifier output. Q2 does the work of the oscillator and modulator. Inductor L2 and capacitor C5 variable tank circuit is necessary to create oscillations. Capacitor C6 is the feedback capacitor. The FM modulated wave will be available at the collector of Q1 and is transmitted through the antenna A1.

The combination of controller IC LM4651 and LM4652 Class D MOSFET power amplifier IC power amplifier solution provides a high efficiency, suitable for powered speakers, subwoofers and amplifiers car quality.

The LM 4651 is a fully integrated conventional pulse width modulator (PWM) driver, which contain low-voltage circuit, short, overshoot, and thermal shutdown circuit protection. The IC has a standby function which shuts the pulse width modulation, minimizing the current bid.

The LM 4652 is a fully integrated H-bridge power MOSFET IC in a TO220 power pack. The IC has a temperature sensor to alert the LM4651 when the die temperature exceeds the threshold limit.

Used together, LM4651 and LM4652 as a simple, compact, efficient, high quality audio power amplifier complete solution for protection, usually seen only in class AB amplifiers.

The maximum efficiency of this circuit is 85% to 125 W with an expected attenuation of greater than 100 dB. The THD at 10W, 4 ohm, 10 - 500 Hz max. 0.3%. The supply voltage can not exceed ± 22V.

The following schematic shows a simple DEW sensor circuit diagram using LM258N IC. As the humidity around the circuit goes up, the resistance in the DEW sensor increases. When the resistance reaches a pre-specified level, the circuitry displays a warning message, and shuts down the external device

Under normal conditions, resistance of the dew sensor is low (1 kilo-ohm or so) and thus the voltage at its non-inverting terminal (pin 3) is low compared to that at its inverting input (pin 2) terminal. The corresponding output of the comparator (at pin 1) is accordingly low and thus nothing happens in the circuit.

When humidity exceeds 80 per cent, the sensor resistance increases rapidly. As a result, the non-inverting pin becomes more positive than the inverting pin. This pushes up the output of IC1 to a high level. As a consequence, the LED inside the opto-coupler is energised.

At the same time LED1 provides a visual indication. The opto-coupler can be suitably interfaced to any electronic device for switching purpose. Circuit comprising diode D2, resistors R5 and R6 and capacitor C1 forms a low-voltage, low-current power supply unit. This simple arrangement obviates the requirement for a bulky and expensive step-down transformer.

This toxic gas alarm circuit is sensitive to less than 100 ppm of carbon monoxide. This alarm is useful for simple gas boats, sheds and cabins. You could save a life. Some of the companies listed in the Appendix to offer plans and kits for various toxic gas sensors.

Alarm of toxic gases it utilizes a tin-oxide-semiconductor. A coil of thin wire heated by a battery 12 V via IC1 and IC2, the which pulses the voltage to the coil of the sensor, saving a significant amount of energy. Zener diode Dl provides a constant voltage to the filament coil sensors. resistance of the sensor reduces the sensor is exposed to toxic gases Such as hydrogen, carbon monoxide and propane. Reduced to the resistance of the sensor, the SCR gate voltage increases. When the gate threshold voltage is reached, the SCR fires and a buzzer alarm is activated. Once activated, the bell and the switches S1 Should Be used to reset the alarm. Since the sensor has a good deal of thermal inertia, S1 must be off or open for about three or four minutes after the initial activation, allowing the sensor to stabilize, thus avoiding false alarms. Sensitivity control R7 set to the Desired value, before the activation of the SCR.

for more details about TGS813  Gas  Alarm  Circuit please visit http://www.free-circuit.com/toxic-gas-detector-and-alarm-circuit-with-tgs813/

Stereo Amplifier Circuit with BA5406

In the this circuit diagram, BA5406 is configured to deliver 5 x 2 watts at 4 ohm speakers to a supply voltage of 9 volts. The capacitor C3 is a power supply filter capacitor. C11 and C12 are decoupling capacitors DC input for the left and right. C3 and R2 form a Zobel network to output the left, while C6 and R3 is the same for the right channel.

Zobel network purpose is to reduce vibrations and improve the high frequency stability of the amplifier. Potentiometers R5 and R6 serves as a volume control for left and right channels. C8 pair CapacitorsC4 and the amplifier outputs to the speakers. C9 and C10 are the noise filtering capacitors. C1 and C5 are starting capacitors for left and right channels.