LM555 Timer | Electronic Project Circuits

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Voltage Controlled Switch using 555 Timer

In this circuit the 555 timer is used in a novel way, as a voltage controlled switch.

Notes:
The old and omnipresent NE555 can be very good at something it was not meant for: driving relays or other loads up to 200 mA. The picture shows an example circuit: if the input level rises over 2/3 of the supply voltage – it will turn on the relay, and the relay will stay on until the level at the input drops below one third of the supply voltage.
If the relay and D1 were connected between pin 3 and ground, the relay would be activated when the input voltage drops below one third, and deactivated when the input voltage goes over two thirds of the supply voltage.

It is also a nice advantage that the input requires only about 1 uA, which is something bipolar transistors can’t compete with. (This high impedance input must not be left open.) A large hysteresis makes the circuit immune to noise. The output (pin 3) can only be either high or low (voltage-wise), and it changes its state almost instantenously, regardless of the input signal shape.

The voltage drop across the NE555‘s output stage (at 35-100 mA) is 0.3-2.0 V, depending on the way the relay is connected and the exact current it draws. D1 is absolutely vital to the safety of the integrated circuit.
Circuit : Miroslav Adzic – Serbia & Montenegro

Source :: http://www.zen22142.zen.co.uk/Circuits/Switching/vcs555.htm

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Categories: Digital, Electronic Control, Timer Tags: digital circuit, LM555 Timer, voltage controlled switch

555 IC Timer control relay Switch

This is easy Timer circuit projects. Control by relay. It use IC 555.
This the circuit sets the time to are simple one that interesting , because use IC LM555 Timer be 8 pin integrated circuits. But can set the time accurate can use by fine while VR1 , and use the the Secretariat of the Senate reset the system is new. When want to set the time new every time for electric appliances supervision as a result can control with Relay Switch normal.