Comments on: Keyless entry using touch sensing

By: Louis II

Louis II — Thu, 23 Oct 2008 09:54:16 +0000

hmm… interesting idea, cool implementation, but not very secure… for a variety of obvious reasons… however… nothing really is secure, is it?

By: threepointone

threepointone — Wed, 22 Oct 2008 08:41:47 +0000

You could do it on the doorknob too–I’ve found that doing touch sensing circuits manually (i.e. provide the analog yourself or just use digital I/Os in less extreme cases. Better yet, if you really know what you’re doing, it’s not unreasonable to sense through the wooden door, provided that you compensate for moisture changes and if there’s no nearby metal.

By: kyle007

kyle007 — Tue, 21 Oct 2008 16:02:11 +0000

@ Metroid48
I totally missed that about the sequence… I was wondering why [Alex] in the video was making contact with the wire several times. I though he was trying to make an initial contact which was eventually connected. Many many moons ago I had a simple touch lamp which eventually found it self taken apart. The touch sensor was a wire just like the one that [Alex] made. And I wired the whole thing up with speaker wire to each of the lights from the lamp. And hung them in my ceiling rafters the touch sensor I connected to a decorative piece of brass, and depending on the moisture of your skin it either made contact or not so you might have to hit the sensor a few times.. this is why I over looked the sequence which you brought to light. Thank you.

@ Smith wth! we should hack your ip and break your computer. jerk!

By: nick

nick — Tue, 21 Oct 2008 06:18:18 +0000

WTF is up with the crap ad post get that crap off of my hackaday! this goes to smith, not Taylor, his grievance is real. (Love the hack) Spam just pushes my buttons.

By: Richard Cook

Richard Cook — Tue, 21 Oct 2008 00:56:10 +0000

Excellent hack!
An alternate touch sensor that I used years ago is an FET amplifier. It picks up the ambient 60Hz when you touch the single wire. This could be used for the doorknob.

Using the circuit at this URL you could reduce it t to give a logic level input:
http://www.uoguelph.ca/~antoon/circ/touch1.html

By: Metroid48

Metroid48 — Tue, 21 Oct 2008 00:41:15 +0000

kyle, it is a specific tap order and length – thieves couldn’t just ‘waltz right in’ unless you were really obvious in entering the series!

I’m hoping that someone does make a real portable version of this – like a box with a retractable wire and the shoelace(s) so that, once you remove the two wires/strings, you really can just pick it up and move it.

By: peter

peter — Tue, 21 Oct 2008 00:09:31 +0000

or you could hook the touch wire onto the doorknob so there wasnt a wire sticking out. just tap your fingers on the doorknob and it opens for you.

By: Haku

Haku — Mon, 20 Oct 2008 22:58:46 +0000

How about a camera in the peep hole connected to a computer that can recognise sign language?

By: twistedsymphony

twistedsymphony — Mon, 20 Oct 2008 22:32:37 +0000

I don’t know if this door had one but the peep hole on most dorm doors would be ideal since it’s usually brass and goes all the way through the door… that way you wouldn’t have a suspicious wire sticking out.

though this reminds me of a few EE friends I had in college that wired a camera flash capacitor with one end on a wire hanging in front of the peep hole with a sign that said: “DONT TOUCH” and the the other end ont he peep hole itself, you’d see people stop as they’d walk by hit the sign and get scared half to death by the resultant electrical _pop_

By: Insipid Melon

Insipid Melon — Mon, 20 Oct 2008 21:27:05 +0000

Maybe you could build a retina scanner into the peep hole.

By: amk

amk — Mon, 20 Oct 2008 20:04:58 +0000

Very cool. Stick the servo, arduino, etc in a nice enclosure, add a flat hook so it can be hung on the door, and run the touch wire alongside the hook.

That would make installation as simple as hanging the thing on the door and tightening a strap around the doorknob. You might even be able to market something that simple to people in temporary housing situations.

Six tap lengths might be pushing it, three seems reasonable. With a key length of 12 taps that would provide about half a million combinations, which is reasonable.

By: D

Mon, 20 Oct 2008 19:07:04 +0000

“An Arduino detects weather…”

Hehe, cool. So it works in the rain too?

By: kurf

kurf — Mon, 20 Oct 2008 18:52:41 +0000

Great project, I’m sure the touch sensor was just a test. It would be really easy to integrate a keypad. I saw something on Sparkfun.com that did something similar. They used a color changing keypad. 8 keys that lite up random colors, you press the right colors in order to unlock the door. Adds a little more security then a numbered keypad even.

By: Buzzkill

Buzzkill — Mon, 20 Oct 2008 17:44:12 +0000

taylor I think you missed the point about not wanting to damage or change the door in any way since he is in a dorm and would be liable for any damages. I like the idea of enclosing the components into something that could be hung from the top of the door with the servo. It is a great hack.

By: Mick

Mick — Mon, 20 Oct 2008 17:40:50 +0000

“damaging the door.” no damage to the door. everything is duct taped or in the case of the servo held in by the spring like metal