I wonder if the same thing will work for my LawnBott

The best way is to just keep a pair of sharpened meter leads, they pierce it nicely, and no sanding is necessary. I’m not trying to bash what you did here, I just can’t believe how much work you put in to this. You should construct a circuit with some flip flops and op amps, and some sort of BJT on the output. That would be pretty badass.

It’s clear from the level of detail put into the signal analysis that Oliver is very sharp, but his final implementation of the signal is rather odd. It seems that the simple signal could just have easily been generated with a microcontroller coupled with the LM386 amp (and the purists would certainly say even that would be overkill).

It is also a bit strange that he put so much effort into this solution, considering his father ordered (and received) the new module during the course of his work. I suppose there is something to be said for the challenge of getting it to work though.

It’s still a clever hack.

HA i used to do that to lock up the carts at the grocery store

Not a hack.

Oh wait, no, yes, I think this actually follows the *definition* of a hack. A bit there-I-fixed-it, too. Awesome :)

HACK!!

Those anti-theft shopping carts use a very similar system, which can be abused in much the same way. just loop a wire around your waist a few times and hook that to the audio out of an ipod and play back a recording of the cart locking signal. it is sooo much fun watching the looks of confusion when the carts stop in the store! (i only do this because i know the employees, and they’re all stoners)

Love how all the “haters” who are complaining
about this project probably couldn’t even begin
to approach the level of reverse engineering
analysis this guy demonstrated.

Yeah, maybe it’s a lot of effort for a small
return, but it’s his time. I for one, would
love to hire this guy if i was an engineering
manager looking for talented/motivated design
engineers.

thanks for sharing! it was a very substantive
article. reminded me of Popular Electronics “back
in the day”.

Brennan, have you ever seen the hard epoxy-type coating? That stuff is extremely cut-resistant, and you’d spend more time sanding it off than you would working on the actual project. I suspect that’s what Mr. Nash was dealing with here, since he said it wasn’t silicone based.

All in all, this is an awesome adaptation of what was already a really neat idea. The relationship between sound and electricity is fascinating to me, so I’m really glad to see something like this.

I don’t get why he tries to mimic the signal with a python based script instead of simply recording the raw output then looping it, that would seem to me a sure-fire way to get a copy of the signal.
Also he should connect a headphone and listen for a while for odd breaks with his ears, to see if there maybe is a periodic identifier signal he missed.

days later…

Many hard conformal coatings can be boiled off, with a slight risk of water impregnation in cheaper fiberglass pcbs. In addition, almost all conformal coatings can be removed by one of three or four solvents – including more conformal coating.

You can play amateur chemist as follows: obtain a half dozen test tubes, or just make some squares of filter paper or fine mesh screen.

Next, scrape off a bit of coating and divide it into batches. Big flakes if you can do it. Then put a batch in each test tube or on each square.

Add a few drops of Alcohol to one, Acetone to another, and perhaps kerosene to a third, and so forth. Nail polish remover, vodka, fermented ferret urine… the possibilities are endless.

Ask a chemistry teacher or google for the names of common solvents. All of them will be available at almost any hardware store. One of them will likely disolve or soften the coating sample.

If one of your materials softens the coating, you can paint it on, wait a bit, then hit it with a toothbrush.

When all done, run the board through a dishwasher and the dry cycle. Use calgon or some other spot removing agent to ensure a clean board.

Some coatings respond to high heat, like from a hair dryer. Some don’t and will bake on. Therefore, test a little. It doesn’t take much to build up some expertise in reverse engineering.

Lastly, to the “It’s a rip-off, just $5 of parts in the circuit.” guy…

I’ll bet you know a lot of people who are totally and astoundingly ignorant about electronics in general. They’re everywhere!

You know the kind: They wouldn’t know a resistor from a capacitor, and to them all of electronics is divided into needs batteries and needs AC from the wall.

The thing is, you may not realize that you know about as much about business as they know about electronics. 5 euro worth of parts, indeed.

That’s like saying you can create a hot super model with an IQ of 135 by combining a sperm and an egg. Trust me, the raw ingredients have very little to do with the end result.

Addendum: Oops I see you used the actual same wiring as the real device to test do that can’t be it.
I know from your blog you decided to end wasting time on it, but damn it’s so close and so curious as to why it won’t work.

One last thing, I think I read that the original transmitter has 2 signals to select from to help people if there’s interference, is that true? And if so did you perhaps compare them? Maye that would give some additional hints to muse upon.

I get you aren’t stupid and thought about it a lot, but I’m just throwing out some things in the hope that maybe it gives you a lead to get an eureka moment of your own, we all know the experience where a random stranger or dumb person says something that makes you suddenly realize something you forgot :)

Imagine being creative enough to put something together with just the parts lying around – instead of buying something.

This board sure has it’s share of snarky fiskers who just *have* to put down what other people have accomplished. Doesn’t really add to the vibe, does it?