What’s does the diode do?

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=84645
Printed Date: May 02, 2024 at 1:52 AM

Topic: What’s does the diode do?

Posted By: audioduck
Subject: What’s does the diode do?
Date Posted: October 25, 2006 at 9:20 PM

I designed this circuit based on the one from here in the lower right corner. I'm curious as to why there is a diode between 85 and 86 on the left hand relay? Is it really necessary?

Replies:

Posted By: haemphyst
Date Posted: October 25, 2006 at 10:09 PM

No. Your circuit is all hardware. The diode is for reverse spike voltage protection in electronic circuits (ie, alarm outputs). In THIS case only, the diode is optional, but if ever using a solid state control circuit, I would make sure it is there.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Posted By: audioduck
Date Posted: October 25, 2006 at 11:12 PM

I understand, thanks for your reply.

Posted By: hotwaterwizard
Date Posted: October 26, 2006 at 11:38 PM

What are you trying to do here? The circuit needs simplified.

A diode can also be used as a check valve preventing flow of current from going a direction. The Diode may be there to prevent false triggering of the latching relay.

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: hotwaterwizard
Date Posted: October 26, 2006 at 11:42 PM

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: hotwaterwizard
Date Posted: October 26, 2006 at 11:44 PM

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: hotwaterwizard
Date Posted: October 26, 2006 at 11:45 PM

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: audioduck
Date Posted: October 27, 2006 at 7:30 AM

hotwaterwizard wrote:

What are you trying to do here? The circuit needs simplified.
A diode can also be used as a check valve preventing flow of current from going a direction. The Diode may be there to prevent false triggering of the latching relay.

What I"m trying to do is turn driving lights on and off with a 3-way momentary switch on a motorcycle. Of course I know that the best/easiest way would be to simply use a simple on/off switch to control a single the relay but in my case I'd like to use a particular 3-position momentary switch that is already built into the handlebars for turning the driving lights on and off.

Posted By: hotwaterwizard
Date Posted: October 27, 2006 at 8:38 AM

on off on momentary correct ?

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: hotwaterwizard
Date Posted: October 27, 2006 at 8:51 AM

Here is a circuit suited to your application. Needs some work though.

I will work it out if you like.

posted_image

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: audioduck
Date Posted: October 27, 2006 at 10:03 AM

hotwaterwizard wrote:

on off on momentary correct ?

Yep, that's it. The OEM function for the switch is to raise/lower a windscreen. The bike I"m installing it on doesn't have an electric windscreen so I want to convert it for use with driving lights. If there's a simpler way to accomplish this then I'd be all for it.

If there's a simpler way to accomplish my goal then I'd be all fot it.

Posted By: ff-mike
Date Posted: October 27, 2006 at 1:05 PM

What I did:

Took the standard momentary to constant setup, and slapped the relay up top. That will kill the power to the standard setup, effectively turning it off.

posted_image

Posted By: hotwaterwizard
Date Posted: October 27, 2006 at 10:24 PM

Here is one I just drew with 2 Relays.

Load and Output mean the same thing. A light was added for convineance.

posted_image

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Posted By: audioduck
Date Posted: October 28, 2006 at 8:21 AM

hotwaterwizard wrote:

Here is one I just drew with 2 Relays.

Very nice - thanks. Since that has one less relay, I'll probably use that circuit.

Posted By: hotwaterwizard
Date Posted: November 04, 2006 at 1:20 AM

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !