The 556 is a dual timer IC contains two 555 timer ICs in single 14 pin package.
The time period depends on the 470uF capacitors and can be adjusted with 1M variable resistors. The 470uF capacitor will provide maximum time delay of 8 to 10 minutes. But by increasing this value to 1000uF will provide time delay of around 20 minutes. Other higher value capacitors than 1000uF will increase the delay more. The operating voltage of the circuit is 5V to 12V DC. Relay switches values should be used according to the supply voltage.
This dual time delay relays circuit is using a 556 timer IC. The circuit is operating two relay switches, both can be adjusted for different time periods. A single push switch S1 will activate both the timers and activate the relay switches for a preset time period. The heart of the circuit is a 556 timer IC.
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