Special Switch?

[walterwoj]

So .... I have 30 gallon compressor that I use in the shop. The thing is I only need it a couple times each time I'm in the garage so I don't need it on all the time (and my setup is a little leaky) but I always forget to turn it off hen I'm done. Sooooo... I'm looking for a special switch but I don't know what it's called. Here's what I'm looking for: I press the button to turn the compressor on, the compressor runs until it shuts off at pressure, the switch cuts power to the compressor so it won't come on again until I press the button again.

A bonus would be if there was a 'lock' mode that would keep it on until the lock is disabled (for marathon sessions) My compressor is 110v. Ideally this would be 1 piece drop in. I know I could do it with a push button and a relay but I like simple solutions...

 

[Advil]

120v small compressor or 240v large compressor? If this is a small home compressor with typical lever switch, just set it to on and use something like this to control power and let it be on for however long you will be out there (various times up to 6 hours).

BN-LINK Indoor Countdown Timer

We use these to control media tumblers and other stuff. You can't build a mechanical relay to do what you want as cheap as this digital one. Push one button when you want air for however long and you're done.

(EDIT - Way too small for your 30gal compressor, but you could combine it with a relay to do what you want without much complexity.)

 

[RJSakowski]

I think it could be done with a NO momentary switch, a contactor as is commonly used on machines, and repurposing the compressor cutout switch. The momentary switch would apply power to the contactor coil which would apply power to the compressor and to the cutout switch. The cutout switch would be connected to the high side of the contactor coil which would keep the contactor energized when the momentary switch was released. When the compressor reached the set pressure, the cutout switch would open, denergizing the contactor until the momentary switch was pressed again.

 

[3Dogs]

I think it could be done with a NO momentary switch, a contactor as is commonly used on machines, and repurposing the compressor cutout switch. The momentary switch would apply power to the contactor coil which would apply power to the compressor and to the cutout switch. The cutout switch would be connected to the high side of the contactor coil which would keep the contactor energized when the momentary switch was released. When the compressor reached the set pressure, the cutout switch would open, denergizing the contactor until the momentary switch was pressed again.

Yes.
Basically, you want the momentary switch in parallel with the pressure shutoff switch. Pressing the momentary contact switch pulls in the contactor, providing power to the compressor. Assuming that the compressor is under the shutoff pressure, the contactor will stay on until it reaches the shutoff pressure, and then the contactor will open. Note that this has one side-effect - if you keep the momentary contact switch pressed down, the compressor will never shut off, regardless of how high the pressure gets.
So, don’t do that.
.

 

[tq60]

Way too many ways, but this is stupid simple.

WIND UP SWITCH.

These are very common, times vary from minutes to hours.

You turn the knob to the time you want and it goes that long.

It mounts just like normal light switch.

Now we "improve it"

You wire it in a standard wall plate controlling an outlet in same quad box, it uses standard switch cover as knob covers the hole.

You get a contactor for your air compressor, contactor needs 120 vac coil, contacts rated for 20 amps minimum.

This is mounted in a box that can be mounted to wall or compressor.

The contactor supply , (L1, l2) use a normal plug and plugs into normal outlet.

Output of contactor either to an outlet (controls anything plugged in) or to compressor.

The coil of contactor goes to the timer controlled outlet.

Turn timer, runs for that time.

Get a 1 hour unit, gives one hour of work time.

If the tank does not leak you can add a 120 vac controlled ball valve that has auto-close and plug into timer control.

The valve will open and close with the timer control.

Here is Ours, light switch provides supply for control.

The blue box is the ball valve, the large block above once was a solenoid control but it did not close well, now is just the mounting block for the rest.

Alexa can control the air supply then compressor.

If we forget to turn off, the light switch kills it.

The compressor has magnetic starter so the control is a small relay that can break the wire from pressure switch.

Sent from my SM-G781V using Tapatalk

 

[Ulma Doctor]

A simple latching circuit is all that is necessary.
A normally closed momentary stop switch , a normally open momentary start switch , and a relay of sufficient capacity is all that is needed.

 

[lordbeezer]

The above posts are why I tell everybody I run across that are interested in doing their own work on various interests to join up at hobby machinist. Don’t care what the question is somebody somewhere knows the answer. As on this post. People helping when they don’t have to. The class of folks on this site make it what is. Including the administrative type folks running the store. Thanks Phil

 

[walterwoj]

so i have order parts and attempted to build this circuit to no avail. Below is what I designed but didn't realize it would make a dead short when the button is pressed... GOOD NEWS my breaker-tester works (so does the breaker!) and the relay didn't burn out either! Bad news is this circuit clearly does not work! For reference the 2 relays shown are in fact the same relay (it's a DPDT with one coil) and the -(X)- is the load (compressor) and -(~)- is AC power in. The goal is to have a male plug go to the outlet and a female plug to the compressor.

The relay is rated for 110v through the coils (but no coil amperage listed) and the contacts are rated for 10A at 110v. See here: https://www.amazon.com/dp/B07QXWZP3R?ref=ppx_yo2ov_dt_b_product_details&th=1 I do have 2 relays if that will make it work.


Here are my requirements:
1.) Press button and compressor comes on.
2.) Circuit latches on, until compressor shuts off on it's own.
3.) Latching is broken when compressor shuts off.
4.) Cannot run compressor through relay coils (I don't believe they will take the amperage.)

 

[woodchucker]

so i have order parts and attempted to build this circuit to no avail. Below is what I designed but didn't realize it would make a dead short when the button is pressed... GOOD NEWS my breaker-tester works (so does the breaker!) and the relay didn't burn out either! Bad news is this circuit clearly does not work! For reference the 2 relays shown are in fact the same relay (it's a DPDT with one coil) and the -(X)- is the load (compressor) and -(~)- is AC power in. The goal is to have a male plug go to the outlet and a female plug to the compressor.

The relay is rated for 110v through the coils (but no coil amperage listed) and the contacts are rated for 10A at 110v. See here: https://www.amazon.com/dp/B07QXWZP3R?ref=ppx_yo2ov_dt_b_product_details&th=1 I do have 2 relays if that will make it work.

View attachment 457429
Here are my requirements:
1.) Press button and compressor comes on.
2.) Circuit latches on, until compressor shuts off on it's own.
3.) Latching is broken when compressor shuts off.
4.) Cannot run compressor through relay coils (I don't believe they will take the amperage.)

large enough relays will.
also SSR
also Triac

 

[RJSakowski]

Connect the compressor to the N.O. contact of the relay and the common contact to the line. The other side of the compressor goes to the neutral. One side of the relay coil also goes to neutral. The other side goes to the momentary contact switch. It is also connected to the load side of the compressor pressure switch. Pressing the momentary switch will activate the relay, starting the compressor (assuming it is calling for more pressure). Since the pressure switch is closed, it will keep the relay energized when the momentary switch is released. Once pressure has built, the pressure switch opens, deenergizing the relay and shutting the circuit down.

The issue with this is that the circuit won't activate on startup if the pressure is above the cut-in pressure.

Relay coils aren't meant to carry any current other than their energizing current.
.