Brain Assailant

brain assailant

Ugh, I didn’t expect this “sonic nuisance” meme to last past yesterday, but here we are with a different project from [jay]. ThinkGeek sells a device called the Mind Molester that emits a chirp every three minutes making it hard to find but frequent enough to drive you insane. Jay figures ThinkGeek’s markup was somewhere around 1250% and decided to build his own. The device uses a Picaxe microcontroller and emits four different sounds a random intervals.

35 thoughts on “Brain Assailant

  1. I built a similar device years ago, except it plugged into the ISA slot of an old AT/XT computer (for power). It was also wired into the switch of the old “turbo” button, in case the victum (my manager) started to figure out where it was hidden.

  2. i thank you for this post. especially for the newer generation of people to annoy the crap out people. :D i’m going to start on this ASAP…

    i like the rf idea :)

  3. I thought someone was playing a cruel joke on me a few years ago. There was a chirp from somewhere about ever 10 minutes. Took weeks to find the noise. Turns out a water filter that I has installed under the kitchen sink a few years previous had a “filter dirty” timer built into it… Drove me nuts!!!

  4. Friends and I used to build these and tape them behind bookshelves in the library when I was in university in the late 80’s :) We’d set them to about 10 minutes and they’d last 6 months… Just plain cruel!

  5. All you need is a monostable 555 timer set up to output for the desired chirp length (must be driving a piezo _buzzer_, not speaker)

    Then you want an astable 555 oscillator set up to run at a very low frequency with a very high duty cycle and attach the output to the trigger of the monostable timer. Some example numbers for your astable timer would be something like R1 = 250Kohm, R2 = 470ohm, C = 470uF. That would give you something like a 150ms chirp every 80 seconds (assuming that I did my math correctly running on such little sleep.)

    Of course, running at such a low frequency, the timing won’t be perfect, but it will be close enough for this project.

  6. I would suggest if using a picaxe in this project, leave out the regulator and just use two AAs…. the picaxe runs fine from 3v and it’s more efficient doing this than wasting all that energy in the linear regulator.

    perhaps more than two AAs but wired in parallel? or three in series for 4.5v…. I don’t know which would last longer off hand

  7. I’m not exactly sure what kind of circuit that I had in my mind, but it seems pretty redundant now that I picture it working. You just need a 555 timer running at the frequency that you want to drive a piezo speaker. Then attatch the inverted output of a really low frequency, high duty cycle timer to the reset pin.

    My mind is mush… half of the sleep that I’ve gotten in the last 36 hours has been in the back seat of my car in the parking lot at work… on my lunch hour…

  8. People are missing the potential fun of things like this. Make 10 that have a 30 min delay after you push a button. Go to a local store (walmart comes to mind). Place all 10 devices and get out of the store within 30 min.

    If you realy want to mess with them a long time this random chirping one dose the trick. If you want it to be realy anoying for a short time use some thing that gose of continuously that you can not turn off or remove the batteries from.

    Keep in mind if you do this in ohio you may end up like the girls who hung up super mario power up blocks.

  9. i did a similar project once, using 555s. instead of a chirp, i made a water drip noise, and added a photosensor.

    stick it under a toilet or somewhere similar, and when they turn the lights off at night, it will start dripping every minute or two. turn on the lights to find it, and it stops.

    and it isnt difficult to make a chirp or drip sound using a 555, so replacing the speaker with a buzzer like someone said is kinda iffy.. buzzers suck.

  10. I made a similar project using a pabx system at school. It used a pic micro to generate dtmf tones with a dtmf dialler chip. The device would randomly phone a classroom, give it 4 rings (just long enough for the teacher to reach the phone) and then hang up. The device itself disconnected from the phone lines by relay when not in use to avoid detection. It was hidden in the extension box of one classroom and controlled by using a reed switch. Holding a magnet near the device for different lengths of time would select different modes for caller group, aggressiveness and start time that were preprogrammed into the pic.

    Unfortunately, I dont have the code for this anymore but I’m sure it would be fairly simple to hack together

  11. Fantastic suggestions guys -there seem to be a LOT of people who’ve built similar projects.

    I think we should have a contest to figure out who can build the SIMPLEST such device. Microprocessor programming is fine for a lot of things, possibly not so cool for something to leave behind. I’d be as happy with a simpler device that only ran for a couple of weeks.

    If anyone has linkage to similar projects, or fancies writing short howto’s, I’d be eternally grateful

  12. With a little help from Jason’s post (thanks!) I put this together in my EE lab today.

    It uses a 556 timer, half as a monostable multivibrator (left on the picture). The other is an astable multivibrator. I wired it up with these values earlier today and it worked great. Chirped once about every 45 seconds. I don’t know what frequency buzzer I was using though, so I just randomly assigned 2kHz.

  13. Here are two different ways to do this. The first uses one 555 timer and a piezo buzzer. The second uses two 555 timers and a piezo speaker. Sorry for the size, but I have a 21″ monitor running at 1600×1200, and I always forget…

    With a buzzer:
    This one outputs a 150ms chirp every 5 minutes. It works because the output is attached to the negative lead of the buzzer and will be high for five minutes. Then it goes low and sinks the current for 150ms.

    With a speaker:
    The chip on the right outputs a 3KHz square wave whenever the reset pin is high. When the reset is low, there is no output. You have to invert the output of the timer on the left, because it is not possible to have a duty cycle of less than 50% (meaning the low period is longer than the high) because that would require r1 to be negative.

    Of course, at such low frequencies, the timing is not very reliable. Luckily, in a noncritical application such as this, it really doesn’t matter.

  14. wow that classroom dialer is an awesome project, great imagination! i’ve always wanted to make the opposite device, for disconnecting people on cellphones while driving and what not.

  15. Ok, I’m totally new to all this stuff, and the diagrams for making this thing with a 555 made no sense to me. What would hapen if I just used the schematic in the main article and replaced the picaxe chip with a 555?

  16. “What would hapen if I just used the schematic in the main article and replaced the picaxe chip with a 555?”

    Aside from it not working, it would probably destroy the chip if left on for too long. The Vcc and ground pins are reversed. Even if you were to power the chip properly, there’s still the fact that the microcontroller circuit has all of the timing done in software whereas the 555 circuit needs to be done in hardware.

    A 555 timer that is in a circuit alone is just as useless as a computer that isn’t plugged in. The “brain assailant” behavior comes from the predictable charge/discharge rates of the capacitors and the effect on the timer’s internal comparators, flip flop, and npn transitor.

  17. I am glad to post my views and points in this blog, but I must say that webmaster of this blog has done a very great job to make his blog more informative and more discussable but unfortunately everthing is same here that more than 80% in this and other blogs

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