Build Your Amplifier Timer Circuit – 15 Minute Delay

Description

This circuit disables an amplifier or any other device when a low-level audio signal applied to its input is absent for at least 15 minutes. Activating P1 engages the device, supplying power to any appliance connected to SK1. The input audio signal is amplified and squared using IC2A and IC2B, and monitored by LED D4. When D4 illuminates, albeit briefly, IC3 is reset and restarts its counting process.

Pin 2 of IC3 remains in the low state, permitting the two transistors to conduct, and the relay operates. After a 15-minute interval, if no signal appears at the input, IC3 concludes its counting, and pin 2 transitions to a high state. Q1 and Q2 cease conducting, and the relay disengages. Consequently, the device is completely off, along with any appliances connected to SK1. C5 and R9 reset IC3 upon power-on. P2 permits switch-off at any moment.

IC3 – 4060 14 Stage Ripple Counter and Oscillator IC

The 4060 is a versatile integrated circuit commonly used as a ripple counter and oscillator. In this circuit, it’s employed to accurately measure time intervals, specifically for the 15-minute delay function. The IC's internal circuitry generates a stable clock signal that is counted by its stages, providing a precise timing mechanism. It typically operates on external clock pulses, which are generated by its own internal circuitry, and is a foundational component for many timing applications.

IC2 – LM358 Low Power Dual Op-amp

The LM358 is a low-power dual operational amplifier IC. In this design, it serves as a high-gain amplifier to boost the input audio signal before it's squared. Its dual nature allows it to perform amplification on both input channels, ensuring consistent performance regardless of the signal source. The LM358 is known for its low power consumption and is commonly used in portable and battery-powered applications.

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