The following schematic diagram is the circuit of solidstate automatic power-off on mains failing.
A really good number of circuits which shut down the power to the load on mains failure have definitely currently shown up in EFY. This circuit is different compared to other similar circuits since it consumes no electrical power when the load is off. Further, the circuit is totally solidstate as it does not utilize any sort of relay or many other electromechanical equipments.
In this circuit, the resistor R1, diode D1, capacitor C1 and also zener D2 are utilized to develop a mains-derived 9V DC source which can be fed to the triac gate. Switches S1 as well as S2 are utilized to execute “off” and also “on” operations respectively.
When S2 switch is immediately depressed, the neutral line obtains extended to MT1 of triac TR1. This in turn makes the DC voltage accessible to the transistor circuit. Capacitor C2 and also resistor R5 give the initial base drive to transistor T2 at power-on. By the time capacitor C2 is totally charged, transistor T1 is driven into saturation by means of transistor T2 and resistor R3.
The collector pin of transistor T1 is joined to the base of transistor T2 with resistor R4, and collector of transistor T2 is joined to base of transistor T1 through resistor R3, that is, there exists a shared symbiosis in between transistors T1 as well as T2. As long as transistor T1 is on, it offers the essential fence existing to the triac via resistor R7. Capacitor C3 prevents phony affair of the circuit.
The lots can be turned off either by pushing switch S1 or by shutting down the power to the circuit. When switch S1 is pressed, transistor T1 is no more in saturation and also therefore it shuts down the triac and also the tons. Because the rectifier circuit may not get line when the triac is off, it consumes positively no power when the bunch is off.
The idea can be accordingly adopted for cooking timer applications where the power to the cooking timer circuit should be shut off after the series time delay. An opto-coupler is able to change switch S1 for making use of the outcome of a low-voltage command circuit for turning off.