ignition on/off, starter with 1 p/b sw?
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=98514
Printed Date: April 29, 2024 at 5:21 AM
Topic: ignition on/off, starter with 1 p/b sw?
Posted By: apqo1
Subject: ignition on/off, starter with 1 p/b sw?
Date Posted: November 01, 2007 at 4:41 AM
Hi guys, First post from a new member. Looks like there's a lot of great expertise on this site. I'm tearing my hair out on this one, so I hope someone can help! I'm wiring a custom street-rod and trying to work out a keyless switching setup for the ignition, but I can't figure out how to make it work. Here's the easy part: A small (~1/8" dia.) hole is hidden somewhere convenient to the driver, into which a cylindrical magnet is inserted. This closes a magnetic reed switch, which powers an accessory bus through a relay. Basically, the magnet replaces the key. The ignition switching circuit will be powered from the accessory bus, so without the magnet, the car won't start. Here's what I need help with: For the ignition, I want a circuit controlled by a single momentary pushbutton switch, working one of two ways: Preferred: First push/release of the switch latches the ignition ON. Second push engages the starter until the switch is released (ignition stays latched ON). Third push/release unlatches the ignition, killing the engine. Acceptable: First push of the switch latches the ignition ON, then engages the starter until the pushbutton is released. Second push/release unlatches the ignition, killing the engine. I know this sounds a little nutty, but I don't like any of the keyed ignition switches I've been able to find, and I want a smooth "minimalist" appearance on the dash. Thanks! -Eric
Replies:
Posted By: KPierson
Date Posted: November 01, 2007 at 3:02 PM
Check out this thread - it isn't exactly what you are looking for but it takes a look at what it takes to build a smart system that could be adapted to do what you want to do. The simple answer is that there is no easy way. You could most likely do it all with relays, but you'll need some specialized relays and it would most likely be pretty expensive. You could do it with basic digital circuitry and get it to work. Or you could go with a 'smart' processor controlled system. If you want to keep it simple, you may want to consider the magnet for your security (keep it hidden) and then to a toggle switch for the ignition, and the push button for the start. I would then do a hidden keyswitch that would help prevent someone starting it while not defacing the look of the interior. ------------- Kevin Pierson
Posted By: barkster
Date Posted: November 04, 2007 at 8:25 PM
I've seen this before, I guy used to make these here in my town. They were pretty cool. You wave a magnet over a certain place in the car and you had like 10 secs to start it. The link you mention I cannot see, I'd love to see the thread on how to make on these or Eric, how you did it. Thanks
Posted By: KPierson
Date Posted: November 04, 2007 at 8:44 PM
Posted By: barkster
Date Posted: November 05, 2007 at 8:07 AM
Yeah the one I saw was quite simpler. It was a magnetic hall affect switch of some sort that when the magnet was near it tripped a relay that was tied to the ignition switch allowing it to start. It was about a 1/4" cylinder you placed somewhere in the car that was activated by a magnet. This was 10 years ago but he was selling them for $30-40. I should have bought one then.
Posted By: apqo1
Date Posted: November 05, 2007 at 9:27 AM
$30-40 seems excessive. You should be able to find a magnetic reed switch for less than $5. What I'm trying to do is a little more complicated. I want the reed switch to turn on the accessories through a relay, and give permission for the ignition circuit to operate. The pushbutton turns on the ignition, then starts the engine, then shuts it down (with each successive push). I ordered some parts last night to see if I can make it work with relays based on a schematic I found elsewhere on this forum, but I've got my doubts. I have a feeling it's going to take a logic circuit, which is above my head. If I can make the relays work I'll post details here, but don't hold your breath... -Eric
Posted By: barkster
Date Posted: November 05, 2007 at 9:37 AM
Do you have a link to the magnetic reed switch you talk about, I searched last night and all I found were things that looked like large resisters. I just want something to kill the ignition with a secret spot to wave the magnet to start it.
Posted By: KPierson
Date Posted: November 05, 2007 at 9:57 AM
$30-40 isn't that bad, if it included the timing relay. Timing relays, especially 10 years ago, arn't exactly cheap. The DEI timing switch is aroudn $20 from what I've seen all by itself. Throw a few more components on top and mark up a bit to make a profit and $30-40 seems fair to me. Keep in mind, that seems like a very basic system that doesn't allow for many options. ------------- Kevin Pierson
Posted By: barkster
Date Posted: November 05, 2007 at 10:04 AM
yes this was a complete system ready to install. It had a bunch of wires and some relays, there may have been more to it I just knew the basics of how it worked. It was cool, anyone have links to the parts you mention, magnetic reed switch and DEI timing switch??
Posted By: apqo1
Date Posted: November 07, 2007 at 1:22 AM
Here are a few links for magnetic reed switches at several electronics suppliers: All Electronics Jameco Electronics Allied Electronics Digi-Key Mouser Electronics -Eric
Posted By: barkster
Date Posted: November 07, 2007 at 7:31 AM
Cool, I didn't know they were the alarm magnetic latches. I have a ton of the cylindrical ones. Thanks for the links. Now I just need to figure out how to wire it all up.
Posted By: apqo1
Date Posted: November 07, 2007 at 10:08 AM
Wiring a magnetic switch is just like any other SPST switch. Just two wires. Either you switch +12V or you switch ground, depending on what you're trying to do. Be careful using switches intended for home alarms -- many of them are normally closed. You'll probably need normally open. Just test them with a multimeter to be sure. -Eric
Posted By: barkster
Date Posted: November 07, 2007 at 10:16 AM
I'll check thanks, just ordered my dei switch
Posted By: apqo1
Date Posted: November 14, 2007 at 1:04 PM
Kevin, You were right -- the relay circuit diagram you looked at didn't work. It came close, but not quite. With 12V applied, before any button pushes, there was 3.2V at the ignition output (!?!?). One button push did give 12V at the ignition, latched on. Second button push grounded the starter output while the button was held, and the ignition stayed latched. Third button push turned off the ignition, but the relays didn't completely unlatch/reset. Further button pushes did nothing until 12V was removed, resetting everything. I think your solution using a PLC is about the only way this is gonna work. I guess I need to go to school! Anyway, thanks for the assist. -Eric
Posted By: barkster
Date Posted: November 14, 2007 at 1:31 PM
ok, got my dei timer but I'm not quite sure how to wire it. I've started a new thread on building this device
DEI Timer Ignition Circuit
Posted By: INSTALLER_MSS
Date Posted: January 14, 2008 at 1:08 AM
i have an idea that will probably take care of what you need and actually have no external switches. i will draw it up and upload it tomorrow for you or if you want to post your email address i can send it to you directly.
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"If a man made it, another can modify it...it just takes some thinking."
"If you ask questions, you're a fool for 5 minutes; if you don't, you're a fool for a lifetime."
Posted By: INSTALLER_MSS
Date Posted: January 14, 2008 at 1:54 AM
i drew it up already but the file is too large to upload here. gimme your email and i'll mail it to you
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"If a man made it, another can modify it...it just takes some thinking."
"If you ask questions, you're a fool for 5 minutes; if you don't, you're a fool for a lifetime."
Posted By: barkster
Date Posted: January 14, 2008 at 7:32 AM
I think you already sent it to me. I got a diagram from someone which worked perfectly, thanks
Posted By: tweak master
Date Posted: January 22, 2008 at 11:24 PM
I would use the reeed switch to trigger a relay that energizes the ignition . That way, the ignition turns on/off when the magnet is inserted/removed and use the push button switch to trigger another relay to engage the starter. DEI has a pretty cool latching relay/pulse timer that turns a relay on and off with multiple inputs on the same wire. I'll check tomorrow and see if I can come up with a way to make it work and i'll get back to you.
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