Air Switch

Many years ago, we learned that startle effects work better when attacking several senses at once. So we don't just pop up a skeleton, we also make it scream and flash a strobe on it when it pops up.

One way to synchronize these effects is through a trigger relay. This page shows a different method - a switch that is itself activated by the same compressed air that activates the prop.

When the solenoid valve activates the air flow, the prop attacks and the air triggers the switch, causing synchronized sound.

Overview
Parts
Construction
Usage

Overview

The gadget is very simple. The heart of the thing is a commercial air pressure switch made by Micro Pneumatic Logic (MPL) http://www.pressureswitch.com/.

[photo] This is an MPL-808-20 PSI unit that I picked up at an electronics swap meet.

Incoming air pressure actuates a SPDT snap-action switch. The switch can withstand pressures up to 250 PSI (burst pressure is 500 PSI). The factory can make these to trigger anywhere between 10 PSI to 250 PSI. This one is set to 20 PSI.

Parts

Please see purchasing electronic parts.

The parts list:

pressure switch with 1/8" NPT input
1/4" -> 1/8" bushing
tee
male quick-connect
female quick-connect

Warnings:

Make sure that the air side of the pressure switch is rated for the pressure that you are using!
Make sure that the electrical side of the pressure switch is rated for the voltage and current that you are controlling!

Construction

This assembly builds the pressure switch into a snap-in component that can be added to any prop.

Usage

To use this:

locate the air line going to the pneumatic prop that will synchronize with your effect

go down the air line, past the solenoid valve
go to the quick-connect after the valve.
unplug that connection
plug the air switch assemply in the line here
take the wire leads from the air-activated switch and wire then in parallel across the switch that turns on the effect that you want to trigger

Thank you for visiting. Your comments are welcome.
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