A momentary pneumatic switch? - Page 1
Forum section: electronics / projects

author: neonhomer
author_rank: Contributor
timestamp: February 03, 2016, 03:00:03 pm
content: I'm trying to find a momentary switch that is powered by compressed air.I want to be able to apply an air signal (under 100 psi), which is to activate a momentary switch, like pressing a key on a keyboard. The air pressure will remain on the switch until turned off.Here is where it gets fun. I need one of them to be like a single action. Apply air, the switch closes, and then the switch opens. The air stays on the switch until released.The other one needs to be like a dual acting... Apply air, the switch closes, the switch opens. When the air is removed, the switch will again close, and then open.I'm open to other options as well, such as using an Arduino to do this, or some other programmable controller. Having the microcontroller mimic a keyboard/controller that a computer can read is a plus. Like I said, to simulate a key press.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: February 03, 2016, 03:27:44 pm
content: All the momentary, pressure on/off would be dead easy to implement with some logic, flipflops and a oneshot multivibrator, like the 74123, if you just had the pressure activate a NO switch.Is it for fun or for serious things? I guess I'd reduce the pressure to very low, and then have it inflate a balloon hitting a switch or something, if it was just for my own amusement, but anything more than that, I'd probably find a pressure->NO switch for sale.update:I just remembered:Simple, small pressure switches are used in the brake lines of cars, so maybe you could get them cheap at an auto parts dealer? it's better than the balloon-solution at least.--Christoffer

author: neonhomer
author_rank: Contributor
timestamp: February 03, 2016, 03:34:31 pm
content: I'm working on a project a controller for a simulator game. European Truck Simulator/American Truck Simulator is a truck driving simulator. What I am building is an "as close to real as I can get" shifter for the game, using a Eaton Fuller range valve and slave valve.The original design uses pneumatic cylinders to activate microswitches. I thought there might be something a bit easier to do, and be a bit more reliable.The air pressure is going to be around 50-60 PSI, as that is what the slave valve requires to function. The range valve (shift knob w/ air switches) tells the range valve what to do, and it sends the appropriate air to the right actuator/switch.At this time, I don't have the means to build any major circuits. I was trying to make this as streamlined as possible. Since the shifter I am using to base all of this on (Fanatec Clubsport v1.5) is USB powered (and I think has a power supply), that I could tap power from it to feed an Arduino or other circuit.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: February 03, 2016, 03:39:54 pm
content: Well you can certainly get regular pneumatic switches and then do everything in a microcontroller, don't know how expensive they are, never worked with them.--Christoffer

author: zapta
author_rank: Super Contributor
timestamp: February 03, 2016, 03:45:02 pm
content: If you look for an off the shelf industrial solution, search for 'time delay relay' or 'impulse timer'. They will provide the timing function.

author: Isad
author_rank: Frequent Contributor
timestamp: February 03, 2016, 04:45:52 pm
content: Well usally old washing machines have them they are called "washing machine air pressure switch"but idk how much this works for you they are momentary but other then that i dont know nothing.

author: grifftech
author_rank: Frequent Contributor
timestamp: February 04, 2016, 11:41:55 pm
content: Air compressor switch..

author: ludzinc
author_rank: Unknown
timestamp: February 04, 2016, 11:55:03 pm
content: 50 PSI isn't a non trivial amount of pressure!Cheap sensors like in washing machines (iirc) are only in the single digit PSI range. 50 will blow them up!Lots of adjustable ones on eBay for the $10 - $20 mark.http://www.ebay.com/bhp/adjustable-pressure-switchFeed that into a micro, dedicate ports to special functions as required.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 05, 2016, 08:07:38 am
content: Maybe use some cheap tire pressure gauges (the kind with the stick that pops out, known for their inaccuracy) to activate microswitches?

author: LaserSteve
author_rank: Super Contributor
timestamp: February 05, 2016, 02:18:57 pm
content: Go to McMaster-Carr,www.mcmaster.com, which is a MRO style supplier (maintain, repair, operations), and get a stock air actuated switch, air switch, air limit switch, air actuated relay, or pressure switch. That way it can safely handle the 50 psi, and you'll have a repeatable supplier that does more then dabble in industrial hydraulics. You'd want to use a variety of search terms, its amazing what they stock.Steve

author: mikerj
author_rank: Super Contributor
timestamp: February 05, 2016, 02:33:31 pm
content: Quote from: ludzinc on February 04, 2016, 11:55:03 pmToo many negativesYou mean it is a non-trival amount of pressure, or alternatively it isn't a trivial amount of pressure.And yes I agree the washing machine pressure sensors are for water level detection in the drum and operate at 1 PSI or less (you can easily operate them with your mouth) and will likely explode with 60psi in them.A cheap and easily available pressure switch that can cope with 100psi or so would be an automotive engine oil pressure switch. They typical operate in the range 5-10psi.

author: Isad
author_rank: Frequent Contributor
timestamp: February 06, 2016, 08:25:06 am
content: Quote from: mikerj on February 05, 2016, 02:33:31 pmWell i never tryed anything then trying them with my mouth.But as for oil pressure switches i have had quite a lot oftime to play with them(my father is a mechanic).The easy one to finde is the rear gear light pressure switch its connected to thegear box and as the name says whenever you put rear gear in it will turn on i bealive you can finde different psi rateted.

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 06, 2016, 08:29:40 am
content: Washing machine switch means you can power it from an aquarium pump and don't need a compressor @50psi.

author: dwpatter53
author_rank: Contributor
timestamp: March 02, 2016, 12:46:21 am
content: Some hot tubs use pneumatic switches and plastic tubing to isolate the wet person from the motor and heater controls.