On switch seperate from off switch?

There are mechanical versions of this as in this link. Search for start stop switch. These are a variation of a rocker switch (in the second link) so the buttons are side by side.

http://www.sourcingmap.com/electric-tool-on-off-st...

http://www.filshu.com/cn/product/

A style using separate push buttons for on and off (start and stop), uses a feature of the equipment being controlled. In explanation, the on switch operates a relay, and the off switch releases it. The relay is held operated by one of its own contacts. This hold path is opened by the off switch. There are many variations on this using electronic logic or inputs and outputs of a computer system. Basically the on switch operates a latch circuit and the off switch unlatches the circuit. An ordinary set-reset flip-flop can be used this way. The output of the flip flop is high or low according to on or off. The output could operate a relay or contactor through an appropriate driver circuit.

The reason for the stop-start button approach is so there can be automatic shutdowns and an emergency off button located in a suitable place/s (safety).

The link below shows a basic set reset flip flop drawn in a logic gate form, and its relay (contactor) equivalent drawn in electrical form.. Describing the relay circuit, the devices labelled CR are coils of relays, and the contacts associated. S and R are the normally open momentary action start and stop switches (set and reset). Q and not Q are the indicator lamps. A logic gate with more than 2 inputs gives additional controls. This is not quite what is wanted because it starts in an unknown state at power up (needs a power on reset). There is also a race if both switches are pressed together (metastable state). More sophisticated latches provide other features.

However a single relay can be used instead with its own normally open (NO) contact across the start button, which is also a NO contact, with momentary action. This relay operates and latches through its own contact when the start button is pressed. Another relay contact is used for the switching the load (output). The stop button is a normally closed (NC) momentary action switch in series with the relay latching contact. When it is pressed the relay latching is opened so the relay is released.

http://www.allaboutcircuits.com/vol_4/chpt_10/2.ht...

You could get an Arduino and write a simple program to check the status of an "on" input pin and an "off" input pin (the pins of the Arduino attached to momentary pushbutton switches ). If the on pin stays low after a debounce delay, then turn on an output pin (connected to a transistor and relay for turning equipment on). Then while equipment is on, the program can check the "off" momentary pushbutton. If that button stays low after a debounce delay, the output pin is turned off.

If you want the real way industry does it, see the source below.

Only turn ON called Start switch.

Only turn OFF called Stop switch.

Both are depressing spring type switches require to work with a relay to do ON and OFF task.

Hmmm .. that's an odd one. Button #1 turns the circuit on, and does nothing if the circuit is already on. Button #2 turns the circuit off, and does nothing if the circuit is already off.

Here's a link to one possible solution. Of course, you didn't tell us what voltage & power you need to control.

Following are the answers

* No one name for your said arrangement is known to me.

* I would call it ON-OFF system which is a circuitry built around 2-Point Relay

* You must have noticed a green and a red button on most of the machines

* Green push button is normally used for start and RED for stopping electrical outpu

* Attaching herewith a circuit diagram which may be understood easily

* In case you have aquestion, may contact me.

Midhat Luqman

Life-Fellow IE(I)

midhat65@yahoo.com