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Annoy-A-Thing 2.0 Development Answered

Annoy-A-Thing made by let_it_out_org.
After seeing some interest in developing a second iteration of the device, I thought it could be a good idea to start a forum thread for the development.

I think the device should ; Beep at random (or kind of) interval, Use a 555 or a 556 timer, and it should not be powered by a microcontroller.


the random timings can be reached by using 2 or more 555s at very low frequencies (1 pulse = about minute) and AND gate

more 555s = more random. 2 give something like

by using third 555 you may make it give 2 different frequency beeps as well

obviously there is also the 555 that makes the actual KHZs for the beep sound

you may want to replace atleast some of the 555s with multivibrators (multivibrator = 2 transistors + 2 capacitors + few resistors. i think it eats more energy but atleast its more compact)

You wouldn't need a microcontroller to do something like this, however im not too sure about the random interval beeping. Using a 556 you could hook them up so that the signal seems less symetrical and more annoying. Also, if you could fit an op-amp circuit somewhere on there you could amplify the output signal and, by using a higher rated piezo or a buzzer, create a louder sound :)

yeah the 556 or two 555s won't make a random interval, but a seemingly random pattern of time between beeps. the trick will be how to time each timer correctly. also i think a version with a photocell implemented would be cool. i'm gonna try putting one together on the ol' bread board and i'll let you know how it turns out.

As in the photcells used in calculators? It would be a good idea, except it wouldn't be very practical. You see, the places that are normally quite hard to reach (a good place for something like this) are seldom well lit. If it was powered only by a photocell i doubt you'd get enough voltage to power a 556 and a piezo buzzer at the same time.

no, not a solar panel. a photocell detects light and varies resistance depending on how much light it detects.

yes, but if you hide it, say, in the drop ceiling tiles, it is dark up there, or if you put it in a drawer it won't sound until the drawer is open....etc.

well then don't hide the ones with the photocells there ;-)

I think the idea is that hidden will mean in the dark

If it is out where it can be seen, it will be easy to find ;-)

surely not ALL hiding spots get 0 light ALL the time. the point is to make it where it has to be completely dark for it to sound, for hiding where somoene would sleep. look under your desk or a table sometime when the lights are on...there is some light, isn't there?

not to mention light fixtures make great hiding spots.

Sure, I just was noting that there are more options if one puts a switch and timer on it, then just a CDS cell.

Well, I meant that one could place the Timer one anywhere out of sight, while the CDS cell device needs to be in some ambient light

ah yeah, but the point is a combination of both. the fun is that when they turn on the lights to look for it, it doesn't beep so its harder to find. this obviously doesn't work for all annoyance applications, however.

I see, now I understand how you are applying it. Sorry for misunderstanding...

I do believe then, that an LDR would be what you are talking about. If you wanted to get complicated you could use some logic AND OR gates to make the buzzer fire up under certain circumstances but i remember reading the original post saying you wanted to keep it simple. I guess a timer would be more useful, giving you enough time to distance yourself from the thing before it goes off, i guess you'd use a transistor for that or something.

use the cmos version of the 555 for really low power drain usage. For what it does, the normal 555 is a bit of a power hog.

my design does use a cmos 555. i wonder if they make cmos 556s...


9 years ago

Those are some good ideas. I am rather experienced with building digital electronics. If you would like help designing one of these with different workings, I would be glad to assist.