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Wednesday, 18 May 2011

Easy LED Photo Sensor Circuit Using LM1458 IC

Using a common benefit of photo voltaics LED, the circuit can recognize a different output darkness and light. This circuit is used J-FET for receive signal to buffer from LED ,About Output voltage, we used IC 1458 or LM1458 , while in the dark is about 7 volts and the drop about 2 volts in full sun. This is the figure of the circuit;

The LED voltage buffered by a junction FET transistor and then applied to the input of an operational inverting amplifier with a gain of about 20 minutes. This is a variation of about 5 volts of darkness and light. You can adjust the 100K potentiometer to set the range of output voltage.

Tuesday, 22 March 2011

Electronic Pest Repeller Mice Repellant

Here’s a circuit for electronic pest rat repellents emit high frequency sound waves to create an acoustically hostile environment that effectively repels rodents from protected areas. This is the figure of the circuit;

Sound is inaudible to people and non-rodent pets. It is ideal for environments were the use of poisons is inadvisable or prohibited. Beware mice, rat and mouse. It is known that a mice can hear ultrasonic sounds between 30 KHz and 50 KHz and this is pretty loud for his ears and this electronic rodent repellant does just that.

Dog Repellent Circuit

Here’s circuit for dog repellent circuit that is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller. Here’s the figure of the circuit;

This circuit can be used individuals to act as a deterrent against some animals. It should NOT be relied upon as a defense against aggressive dogs but it may help distract them or encourage them to go away and do not consider this as an electronic pest repeller. The ultrasonic dog repellant uses a standard 555 timer IC1 set up as an oscillator using a single RC network to give a 40 kHz square wave with equal mark/space ratio. This frequency is above the hearing threshold for humans but is known to be irritating frequency for dog and cats.

Since the maximum current that a 555 timer can supply is 200mA an amplifier stage was required so a high-power H-bridge network was devised, formed by 4 transistors TR1 to TR4. A second timer IC2 forms a buffer amplifier that feeds one input of the H-bridge driver, with an inverted waveform to that of IC1 output being fed to the opposite input of the H-bridge.

Sunday, 20 February 2011

Proximity Detectors Block Diagram Using TDA161

This is a circuit that illustrated the Proximity Detectors Block Diagram using TDA161 from ST Semiconductor. The TDA161 is a monolithic integrated circuits produced and designed by ST semiconductor to be used for metallic body detection by sensing variations in high frequency Eddy current losses. This is the figure of the circuit;

Proximity Alarm Circuit

This is a design circuit for proximity circuit that can be used in alarm circuit. This is the figure of the circuit;

Inverters U1a and U1b are connected in a simple RC oscillator circuit. The frequency is determined by the values of R1, C1 C2 and the internal characteristics of the integrated circuit. As long as the circuit is oscillating, a positive dc voltage is developed at the output of the voltage-couple circuit: C3, D2 and C4. The dc voltage is applied to the input of U1c-the third inverter amplifier-keeping its output in a low state, which keeps Q1 turned off so that no sound is produced by BZ1. With C1 and C2 adjusted to the most sensitive point, the pickup plate will detect a hand 3 to 5-inches away and sound an alert. Set C1 and C2 to approximately one-half of their maximum value and apply power to the circuit. The circuit should oscillate and no sound should be heard. Using a non-metallic screwdriver, carefully adjust C1 and C2, one at a time, to a lower value until the circuit just ceases oscillation: Buzzer BZ1 should sound off. Back off either C1 or C2 just a smidgen until the oscillator starts up again-that is the most sensitive setting of the circuit.

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