Controlling AC relay with a single push button?

Question

Is it possible to set an AC relay (220vac coil) ON / OFF by using a single push button (non latching) and some extra components but without the need of an additional DC supply? It doesn't have to remember the state when power is off.

This schematic is the only I found for an AC circuit but uses two separate ON/OFF buttons, and also I don't need the second relay or the shared off button.

2 ac relay switching schematic

• Unimportant: Does this answer your question? Single push button relay with reset
• Pete W: I think it's possible with additional relays and a DPDT switch. If you just want it to work, see the e-switch product referenced in an answer below. If it industrial you probably would be better served with the standard two button scheme. If it is household, why not a toggle switch?
• nahero: I have a number of e-switch pushbuttons and ac relays at hand and this would be an ideal case for me considering cost and aesthetics. It is for household devices, not industrial, so two buttons or something bulky is not an option. Looks I will have to go with additional DC circuitry.
• user80875: I think this can be done with three relays that each have 4 sets of form C contacts, The pushbutton needs 2 NO and 1 NC break before make contacts. If you are interested in a schematic for that, I will see if I can verify and present that tomorrow.
• nahero: @CharlesCowie thanks but that's already out of the scope of what I'm trying to achieve.

Answer 1

Yes, it's possible however the required circuit will be rather complex to control a normal AC-coil relay. Basically, you would create a DC supply, make a push-push circuit and then use that DC signal to drive the AC-coil relay through a pilot relay or a thyristor.

The shown circuit has the (possible) advantage it will not turn on if power is interrupted and then restored, which is considered preferable for applications such as band saws, lathes etc. since having them start by themselves when power is restored could present safety issues.

You can buy the power relay packaged with self-hold and on + off switches as a single unit for only about 10ドル in singles. See, for example E-switch KJD17 products.

Answer 2

Here's a circuit, employing a DPDT push button switch and four relays.

The lamp load has been taken as an example.

enter image description here

However, nothing could be simpler than using a single relay and two push

button switches.

enter image description here