Switching Relay? - Page 1
Forum section: electronics / beginners

author: oceanslider
author_rank: Contributor
timestamp: November 09, 2023, 04:00:33 pm
content: Is there a relay that will switch 12vdc polarity by use of an On-Off switch?I want to reverse polarity to operate a 12vdc Linear Actuator via a foot-switch. And all foot switches that I can find are On-Off switches.

author: themadhippy
author_rank: Super Contributor
timestamp: November 09, 2023, 04:23:13 pm
content: anything with double pole double throw contacts will do the job

author: Zero999
author_rank: Super Contributor
timestamp: November 09, 2023, 04:42:00 pm
content: https://www.google.com/search?client=firefox-b-d&sca_esv=580877352&q=dpdt+reversing+switch&tbm=isch&source=lnms&sa=X&ved=2ahUKEwjirK_nrbeCAxU2WkEAHY9nAbEQ0pQJegQIDhAB&biw=1920&bih=928&dpr=1

author: oceanslider
author_rank: Contributor
timestamp: November 09, 2023, 07:25:02 pm
content: Are you saying that there is such a relay that an On-Off foot switch will reverse polarity?

author: TimFox
author_rank: Super Contributor
timestamp: November 09, 2023, 07:59:18 pm
content: A regular DPDT relay connected as a reversal switch will be one polarity with the coil OFF, and the other polarity with the coil ON, so a normal switch can be used (so long as you maintain it in the ON position).The above reply has many drawings of the reversal-switch wiring for a switch or relay.

author: Psi
author_rank: Super Contributor
timestamp: November 09, 2023, 08:53:15 pm
content: Need more info,Do you want the foot switch to both flip the polarity and also control on/off of the Linear Actuator?Or does something else control on/off and the foot switch just changes the polarity going to the Actuator?In one scenario you need 3 positions, which is hard to do with a single foot switch.- on forward- off- on backwardsOrIf you just want to flip the polarity you can do that easily with a DPDT foot toggle switch. Every time you press it it toggles states and the polarity will flip, but the switch has no control over the on/off state of the motor, just its direction.

author: oceanslider
author_rank: Contributor
timestamp: November 09, 2023, 09:09:42 pm
content: Quote from: Psi on November 09, 2023, 08:53:15 pmFor my shop dust collection, I want to control 12vdc linear actuators, that will open and close my blast gates in the ducting. I am building the blast-gate/linear-actuator setup myself.I can easily find inexpensive footswitches, but they only On-Off. So I would like to use an inexpensive On-Off foot switch to control closing and opening the blast gate. Step on the foot switch once and it will open it, step on it again and it will close it, would be best.Could I use this 12vdc relay with an On-Off switch to reverse polarity supplied to the linear actuator? ...https://www.amazon.com/gp/product/B0BZNPKM9CIt's been years since I worked with relays so I'm going to have to get one in front of me and figure this out.This is the linear actuator I'm going to use to control this blast gate. The linear actuator stops itself when it reaches its limit in either direction.https://www.amazon.com/4-in-Metal-Blast-Gates/dp/B001DSZ3G4/andhttps://www.amazon.com/Electric-High-Speed-sec-Weight-Intelligent-Automation/dp/B07ZJ46947

author: themadhippy
author_rank: Super Contributor
timestamp: November 09, 2023, 09:41:24 pm
content: Quotetry searching for dpdt foot switch and you'll be spoiled for choice,no need for a relay then.

author: oceanslider
author_rank: Contributor
timestamp: November 09, 2023, 10:16:24 pm
content: Quote from: themadhippy on November 09, 2023, 09:41:24 pmI am not finding any DPDT footswitches that are inexpensive. However during this breif search I did find these that looks like they are used for footswitches. I could fabricate my own I guess.https://www.mouser.com/c/electromechanical/switches/pushbutton-switches/?contact%20form=DPDT&product=Foot%20Switches

author: oceanslider
author_rank: Contributor
timestamp: November 10, 2023, 03:56:55 pm
content: Quote from: themadhippy on November 09, 2023, 09:41:24 pmThanks for the idea. I'm not finding an inexpensive DPDT footswitch. But I am finding the actual DPDT pushbutton switch, and that is pretty inexpensive. I think I could fabricate the footswitch part. So I'm going to look into that. Thanks again!

author: TimFox
author_rank: Super Contributor
timestamp: November 10, 2023, 04:54:19 pm
content: Can you mount two on/off momentary switches in one foot-activated box, to give an off condition as well as forward/reverse?

author: donlisms
author_rank: Frequent Contributor
timestamp: November 10, 2023, 05:33:16 pm
content: Yes - you will need to think about turning the motor off at the end.

author: Zero999
author_rank: Super Contributor
timestamp: November 10, 2023, 06:37:24 pm
content: You haven't given a budget.I found this, which isn't cheap, but it appears to be very robust.https://linemaster.com/product/129/Clipper-Single-Momentary/635-S/

author: soldar
author_rank: Super Contributor
timestamp: November 10, 2023, 08:28:51 pm
content: You can use the system used by machines and tools where if the power fails the machine will not turn on again. This has a name but I cannot remember it now.My drill press has a relay, a red button to stop and a green button to start. The red button is normally closed but when pressed it interrupts the power and the relay disconnects.

author: soldar
author_rank: Super Contributor
timestamp: November 10, 2023, 08:38:33 pm
content: Also: