"Timed Soundie" or "12 second sound grenade"!

inspired by a combination of throwies, thinkgeek.com's "annoy-a-tron" and my recently discovered love for 555 timers, I've come up with this little guy. i call it the "timed soundie"

once the switch is flipped on the timed soundie, you have 12 seconds before it emits a nice loud and constant beeeeeeeeeeep, enough for me to hear throughout my whole house. on the underside of the soundie is a magnet, becuase throwing them to places people can't reach is fun!

note:
this instructable inspired in part by:
buzzer throwie
the original LED throwie

Step 1: The nitty-gritty...

parts list:
10uF capacitor
2 3v button cells (cr2032)
1 M ohm resistor
piezo buzzer (about the width around of a 3v button battery)
555 timer
electrical tape
magnet

(this is my first time drawing a schematic, so tell me if its wrong!)

the legs of the 555 are bent out and the whole circuit wraps around the buzzer.

all of the parts are soldered or taped directly onto the 555 or the piezo buzzer. the wires soldered onto the circuit going to the batterys are just taped to the top and bottom of a stack of two button cell batterys. like a soundie sandwich, a battery is added and taped to the bottom. (this is optional, incase its just being used as a sound grenade to bother people or for use in an airsoft or paintball scrim)

NOTE: the buzzer's + should be connected to pin 3. the - is connected to pin 1.

Comments

[techno guy]

is there an equation that can give the values of the capacitor and resistor for a given amount of delay, or visa versa

[biboNL]

ok, so my nearby DIY store sells either 4.7 Mohm or 240 Kohm resistors, and no 1Mohm resistors.
should i just slap a few 240 Kohm resitors behind eachother or should i go for a 4.7Mohm resistor?

[techxpert]

go for the 4.7 MOhms 5min get a way time LOL :)

[Johnny C.]

I build one too!
But mine starts after 8 secs!

[techxpert]

use a bigger resistor like 1.3MOhms :)

[Johnny C.]

And i made a new schematic. Here are the positive and negative parts marked!

[techno guy]

Mine doesnt work. It only works when you disconnect the wire from the piezo and reconnect it.

[techxpert]

when you reconnect it does it go the whole way of just when your reconnecting it try putting a resistor in front and behind the pizzo

[PhilipK73]

This is a great guide and my first look into 555 timers (and electronics in general). I have a question though, how would you make it go off in 3~ seconds and then turn off after buzzing for 5~ seconds? I plan on using this for a "sound grenade" and use the IntrudAlert Alarm ($1 at local store).

To make it go off quicker, I would assume you would use a smaller capacitor (maybe 5uF?) but how would you make it stop?

[jhakker]

Anybody know of a good website to buy these parts cheap

[tesla coil]

Could you use a 1K Resistor ??

[let_it_out_org]

no, not enough resistance. maybe with a bigger capacitor, but a 1K resistor would make the 555's output go to high immediately

[amando96]

what if you use 720M farads? lol an hour timer? :P

[doom8666]

No such thing as a MFarad, plus a farad alone is huge, VERY huge

[a_d777]

Its so huge, you can run this circuit for about 20 minutes on it!!

[doom8666]

also i mean Mega, unless u meant micro with that m

[amando96]

 indeed meant micro :)

[brando112186]

(removed by author or community request)

[amando96]

Actually it's µ.

[tesla coil]

I will have to try that.

[sci4me]

would an electrolitic capacitor work???

[cdousley]

how long do you think this battery will last?

[broken_to_fix]

 wats that thing that says lioorg?

[nadav]

 an add for his site...

[icewolf]

 Mod this thing to fit a 9v battery, then throw it behind a big heavy closet.
Now wait for it to discharge completely !!!


Nice instructable!

[icewolf]

 or add a CDS cell so everytime someone looks for it with a flashlight , it stops working  LOL

[Articas]

could you attach the flash circut fron a camera to make a timed flash grenade

[matstermind]

my timer just heats up

[slinger14]

check your wiring you might have created a short some where. also check to make sure u didn't hook it up backwards since the diagram on here doesn't have polarity symbols on the battery

[bigstiffy]

How do you have the button cells hooked up?

[geeklord]

WOO!, first to comment! Awesome, might have to try this on an Algebra teacher >:-)

[Colonel88]

Noone likes someone who is happy to be the first one to comment.

[revhead]

i made this exactly as outlined by the schematic and it didnt work, why? are the pins 4,5,7 not used, or do they go to ground? any help would be great, cheers!!

[Colonel88]

4 is for RESET, which means that it will reset the circuit when voltage is applied. Here, you time it only ONCE, the "12 seconds"

[let_it_out_org]

4, 5, and 7 should not be connected to anything. be sure you're using a buzer and not a piezo element. if you apply voltage to your piezo (touch both contacts to a button cell) it will beep. it should have a + and -...something i guess i forgot to mention is that the + should be connected to the 3rd pin.

[dcmania21]

I think i bought a piezo element, how do i use that in circuits?

[Colonel88]

Piezo element u need to hook it up to a timer, which is the job of the 555. So really, forget about making something from a piezo u could make a REALLY REALLY annoying thing though from it.

[revhead]

thanks. the problem that I am having is that as soon as I connect my power supply to the circuit, there is no delay in the buzzer sounding. it just starts to beep as soon as the power is put to the circuit. could this be a problem with the capacitor. the capacitor that I am using is a 10uF 35V tantalum capacitor. i am also using a 1M Ohm resistor like you suggested. Thanks for helping me out. Cheers.

[dlcoates1]

Here is a better schematic for this instructable that I made for you.

[Colonel88]

Great idea now i know how to set up a 555 to time it.