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ok i just had an awesome idea and i want you, yes you, to help me come up with something. basically i want to use a biometric reader(fingerprint reader for those of you who dont know that)to unlock my doors and eventually have the same system to start my truck.

now here's the tricky part, there is only one biometric car alarm that i know of and it is $600 but i already have a good alarm so i just need the sensors and a control box that will give me a few negative outputs when it detects a good fingerprint. truthfully i also could use anything that is meant for building security systems because believe it or not it is still a 12v system.(by the way, if you didn't know anything you can buy for a building alarm system can be installed in a car, even cameras, motion sensors, even a cellular backup device. but all im talking about are biometric readers

the problem with those is they usually need to be connected to a control panel as part of a bigger access control system. i just cant find anything that would be small and basic enough to be used in a car. this is definitely going to be my next custom project for my truck so if anybody has any insight or experience in the matter or even just suggestions on what else i could do with something like this would be awesome

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I believe some one else mention about biometrics and was able to do it ,but i think the cold made it unsuccessfull. not sure, but anything is possible

yeah there was a post a while back where a guy said he had it working but it didn't work well in the cold. I would imagine there are sensors available that could withstand the cold.

Why biometric and not an RFID type of system that could detect proximaty to the car?

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Kevin Pierson

here is the post where I remember seeing biometrics mentioned.

https://www.the12volt.com/installbay/forum_posts.asp~TID~108022~PN~3

the poster that says he did it is "misterjimbo"

Jonathan

ok, well i've been thinking a little bit more about it and this is what i have come up with and what i would need to do it. let me know what you guys (n' gals) think

first i would need the above stated fingerprint reader that can provide at least 2 separate pulses when it sees a good fingerprint. i'm thinking that i might just get a biometric door knob for a house and strip it down to just raw parts because they are normally used activate an electronic door strike for security which is pretty much what i need.

then i would need an extra cheapo remote to program to my existing alarm and then take it apart to physically interface with the remotes' disarm button so that it will like pressing the unlock button on a remote except i will be using a relay hooked to the biometric reader as a input to close the circuit on the remote instead of physically pressing it. this is the only way i can think of to interface with my alarm, a viper 791xv

also i will need some sort of charging system to keep a constant charge on the remote. 1.5v probably. same thing if you were trying to bypass a car with a proximity key.

as for the biometric starting function all i would really need to do is mount the reader onto a push button that is only activated with 12v when the reader confirms a good print. i would wire it so when the reader sends its pulse it would engage a latched relay that controls the ignition and accessory circuits and once that happens i would just push harder to engage the push button behind the reader and that would complete the starter circuit. the only problem i see with this is that i would need a separate off switch to kill the ignition because it is on a latched relay that will only de-activate when it loses ground.

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A 1.5vdc voltage regulator can replace the battery to keep the remote powered constantly. That's simple enough.

I wouldn't recomend on relying soley on a latched relay to keep the car running. If you latch a relay with a pulse and then strike the relay it can unlatch itself (because the contacts will bounce). You would be better off to use a toggle switch for the ignition and then just use the fingerprint scanner to control a starter relay. You would need the output to stay on as long as the button is pushed.

The down side to this entire thing is that you are basically eliminating the security of the finger print scanner because all you need to do is access the wiring and apply ground to the right wire and the car will start.

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Kevin Pierson

KPierson wrote:

yeah there was a post a while back where a guy said he had it working but it didn't work well in the cold. I would imagine there are sensors available that could withstand the cold.

Why biometric and not an RFID type of system that could detect proximaty to the car?

because you cant steal my finger without me knowing about it. :) nor can i lose it and i dont have to replace any batteries. i'm not trying to sound paranoid but i do live in New Orleans, the murder capital of the USA. i dont live in a bad neighborhood but sometimes i do have to park my truck in some pretty questionable areas. if i had to replace everything audio related in my truck it would be about $2500, so i'd rather spend $200 on something cool and learn something in the process too. plus, i've been out of the professional car electronics scene for over a year and haven't really done anything new to my truck in just as long so i really just want to do something that i haven't done before

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KPierson wrote:

A 1.5vdc voltage regulator can replace the battery to keep the remote powered constantly. That's simple enough.

I wouldn't recomend on relying soley on a latched relay to keep the car running. If you latch a relay with a pulse and then strike the relay it can unlatch itself (because the contacts will bounce). You would be better off to use a toggle switch for the ignition and then just use the fingerprint scanner to control a starter relay. You would need the output to stay on as long as the button is pushed.

The down side to this entire thing is that you are basically eliminating the security of the finger print scanner because all you need to do is access the wiring and apply ground to the right wire and the car will start.

that's a good point about the relay becoming unlatched with a shock, but i REALLY REALLY REALLY dont want toggle switches mounted everywhere for the ignition. what if i made a shock-proof/resistant box? i was planning on making some sort of box anyway to house the stripped keypad and some relays to make it more theft proof. i could mount the board on springs or soft foam. i'm very good at hiding wires, so im not worried about that. and i should also add that i'm not getting rid of my key switch or factory antitheft. im just interfacing and adding on to it to make it more secure

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Haven't you ever read the news artical about the thieves you cut of a guys finger to steal his car? I don't know if it actually happened, but I do know I read about it.

To fix the "shock" issue I see two options -

1. Use a constant (-) output from the fingerprint scanner to actively keep the relay energized - even if the contacts bounce the coil will keep it pulled in which will keep the car running

2. Use a solid state relay. No coil, no contacts, no problem.

3. Incorporate a cap in to the latch circuit that would keep the relay energized for 0.25 seconds. This will prevent shocks from unlatching the relay.

Yes, I realize that was three, but sometimes ideas just pop in to my head as I type!

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Kevin Pierson

KPierson wrote:

Haven't you ever read the news artical about the thieves you cut of a guys finger to steal his car? I don't know if it actually happened, but I do know I read about it.

To fix the "shock" issue I see two options -

1. Use a constant (-) output from the fingerprint scanner to actively keep the relay energized - even if the contacts bounce the coil will keep it pulled in which will keep the car running

2. Use a solid state relay. No coil, no contacts, no problem.

3. Incorporate a cap in to the latch circuit that would keep the relay energized for 0.25 seconds. This will prevent shocks from unlatching the relay.

Yes, I realize that was three, but sometimes ideas just pop in to my head as I type!

haha,well this is how i would wire the latched relay:
30. 12v constant
85. switched momentary 12v from scanner output
86. constant ground
87. loop back to 85
87a. this is my switch, it will be open when active and 12v when latent and i can diode if i need to

since it is a loop once activated it will stay on until it loses ground, but i can use this to drive the ignition and acc circuits( with other relays ofcourse) it's all very complicated and i probably wont get if perfect until i actually start messing with it hands on but i think it can work. now remember that the above is just for the starter, the locks and alarm disarm is a lot easier.

or i could just make it easy on myself and just use a latched push button switch like a normal push-button starter with the biometric reader to enable or disable the power feed for the switch, how does that sound?

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I'm not understanding what 87A is being used for - you say your "switch" - what switch?

And this is exactly the setup that I'm talking about if you bump it hard enough it will unlatch - I know I've seen them do it. Since you are relying on voltage to flow through the contacts to feed the coil if the contact breaks the coil deenergizes and the magnetic field collapses causing the relay to fall out.

Since I'm extremely bored and can't sleep I made a video - https://www.youtube.com/watch?v=GLpVtDAb5o0&feature=channel_page

Admittingly I was hitting the relay with a little bit of force, but I don't believe it was more force then a relay could see in a vehicle moving 70 mph on a bumpy freeway.

And, it's not complicated at all - just a few signals to create! :) What gets complicated is when you start throwing in fun things like tach monitoring to control crank time and to verify that the motor is running!

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Kevin Pierson

your link doesn't work but thats ok because i get your point about the relay. still i think some soft padding could fix that. also if you want to get right down to physics, i would think that the harsher vibrations in a moving car are typically up and down because of bumps, so if i position the relay so that the internal contacts are vertical to the ground like in this picture so that way the metal contacts support themselves and not the magnetic force.

posted_image

also when i say that 87a will be my switch i mean to say that it is the only pin that will be left after creating the latching circuit. it will read 12v constant when the relay isn't energized at all, and then "switch" to an open circuit. so i'll use that "switch" to operate other relays
and as far as all the extras you mentioned, i dont need any of it because this would be more of a manual push-button starter, if it were designed by rube goldberg. just a complicated way of doing something really simple. truthfully i wish i could just disable the run time of my remote starter and make it unlimited, then i could just use remote start activation input on the brain, but now im just running my mouth, curse my overactive imagination!

edit: i will be using something like this, just stripped down to bare parts.
https://www.locksonline.co.uk/acatalog/TOCA_Stand_Alone_Fingerprint_Scanner.html

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This site must filter links to that site - I noticed after I posted that two of the letters were reversed.

I don't think orientation will have an effect on the relay as the relay contacts are spring return to the "home" position. Therefore, they are always trying to return to that home positon regardless of which way the relay is sitting. Also, bumps in cars turn to vibration and it's ultimately the vibration that causes the contacts to break momentarily. I would think the best way to prevent shock from unlatching the relay is to loosely mount the relay in the car - the more it floats the less severe shocks are going to be to the body of the relay.

I would, at least, throw a cap on the coil to require a ~.25mS delay before the relay shuts off - I do believe there is a relay diagram on this site to do that.

That fingerprint scanner looks cool - expensive but cool none the less! I hope you get this in and working, I would love to see it!

As far as using your remote start I would think there would be ways to eliminate the "run time" feature. The hard part is already done - the car has started. You could possibly use the status output of the remote start and the brake input to trigger a system that keeps the ign and acc latched until you unlatch it. You, of course, would have to disconnect the brake from the remote start and then the remote start would either a. time out or b. shut off due to over tach. Or, you could build in an additional relay that would pulse the brake input of the remote start when you perform the take over. There are LOTS of options, you just have to be creative!

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Kevin Pierson

yeah the cap does sound like a good idea. ive already figured out the whole scheme to rig it to disarm my alarm with just a relay, resistor, and an extra non-2-way remote. i just need to find a way to convert 12v into 1.5v to keep the remote powered up. the only thing that is a little iffy for me would be the inevitable fiberglass work for the reader itself and i dont want to get rid of factory keyhole. so this means i might need to do some cutting. controlling the starter will have to be a project for another day

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Use an LM337 - it's an adjustable voltage regulator. You need to calculate some values to get the right voltage output but there are calculators on the 'net to do it for you!

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Kevin Pierson

so i need this thing, 2 caps, and certain resistors depending on what voltage i want correct? and why does resistor 2 have an arrow through it? is it a special kind of resistor i need right there?

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has anybody tried any of this companys products. there not based in the us, but they make some interesting products. i havent seen any info anywhere else.

https://www.spetrotec.co.il/en/product_cat.asp

they make a car based fingerprint reader used as i guess a starter kill.

if anybody knows more about these units, or knows how much and where to get them please post.