Hello everyone reading this. I am an exhibit fabricator for a hands on science center. With everything that is happening in the world lately we are looking at getting rid of all push buttons on our exhibits.
I have done some robotics in the past and have used IR for navigation and thought this would be a great use for this application also. I have wired and coded the arduino to detect an object about 6” away with the IR setup.
Then next step is routing this to a time delay relay that we use on our exhibits. This is where I need some help. I need some ideas of what relay to use to go from the low voltage Arduino, make a physical button style connection, then to my time delay relay. Any help and ideas would be greatly appreciated.
Attached are images of the time delay relay I use.
All that is important is the coil specifications of the relay. An Arduino pin is generally limited to 40mA for short duty-cycle, and 20 mA is the recommended limit for "always on". All I/O pins together are limited to 200 mA.
Best method is with a 2N2222 transistor driver and separate power to the relays. It might be possible to replace the switch with an FET and skip the relay altogether.
Indeed, those timer relays are $62 each need 17mA control current. Advantage being AC/DC and adjusting time on the fly with a simple pot and easy to scale up. Can it all be done in micro... of course.
You realize IR sensor can be utilized completely analog with a switching circuit and a comparator. It’s done all the time.
OK, so you have a Macromatic time delay relay, it should be one of these or similar. Depending on the voltage for your module these are triggered using dry contact switching between pins 5&6. Triggering on the low voltage DC powered units can also be done using a transistor like a simple 2N2222 with collector to high side and emitter to low side (common). Pin 5 is normally the high side. Your sensor should have an output and that alone should be able to drive your delay trigger. Yours should be 120 VAC or VDC based on part number so you need a dry contact switching arrangement. Depending on your sensor I really see no need for a uC or use the uC and leave out the Delay on Break timer module and let the uC do the timing. This is the catalog.
Thanks, everyone. Electronics are not my background so all your replies have been helpful. The only reason I thought about Arduino for this project is because it is pretty much all I know when it comes to electronics and even that knowledge is very limited.
