single push button ON OFF relay latching switch circuit diagram 
one push button start stop relay

Single push button relay ON-OFF latching circuit 

single push button ON OFF relay latching switch 

 one push button start stop relay

This is ON OFF switch circuit by using the single pushbutton switch. In this circuit used 2 relays. Make the connection as the given diagram. When you give the supply to the connection, the output load is in OFF. Once press the switch for 1 second then the load is turned on, But again press the same pushbutton switch for 1 second then the load is OFF.

Press the switch- ON

Again press the switch- OFF

Working

First, when the switch is not pressed and the power supply on in this circuit the current flows across to the common pin of relay 1st RL1 and the current goes to the 2nd relay coil through it, in this case, the 2nd relay RL2 is activated only and RL is not activated.

When Once press the switch for a second then the positive supply passes through the common pin and NO pin of RL2 to RL1 cross the D1, the RL1 is now activated and the RL2 is Deactivated because the current of RL is disconnected. In this way current also goes to the load and then the load will turn on.

Now, the RL2 becomes OFF, so the COM and NO pin of RL2 is connected. When again pressed the pushbutton, then the short circuit occurs through these pins and due to suddenly short circuit the voltage at the coil of RL1 is 0 and the RL1 is De-activated. Nd again after deactivating RL1 the pin COM and NC is connected of it and the current goes to the coil of RL2  and gin RL2 is activated. In this situation, again Output load is OFF.

If you want to use it for AC load then connect one more relay at the place of output load and then connect the AC load with this 3rd relay.

2 diodes 1N4007

If you want to use it for AC load then connect one more relay at the place of output load and then connect the AC load with this 3rd relay.

circuit diagram

The disadvantage of this circuitWhen you press the push button, A short circuit will occur for a moment (about half sec) between the RL2 NC pin and COM pin. This short circuit will harmful for input power supply and it will reduce the life of battery. 

Simulation video

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