Homemade Annoy-a-thing (Annoy-a-tron)

Step 2 Nitty-gritty

the circuit diagram is shown below. hopefully it is readable.

if you've got a breadboard, lay one out first and make sure it all works!

AGH sorry! Revised schematic 4/4/09 (thanks dad)

Comments

[Unit042]

I don't think the MOSFET is needed. Most versions of the 555 (made by different manufacturers) are able to handle bare minimum 50mA (100mA typical for mine).

Last I remember, t=r*c has time in seconds, resistance in ohms, and capacitance in farads....

Hey, wait, why is the diode on the threshold pin and not the discharge pin? Does your 555 have a different pinout from the LM555 or the (radioshack whatever)555?

This gives me an idea...

[let_it_out_org]

sorry, i wasn't specific enough. it's needed for the piezo. even with the low power 555, it doesn't spit out enough juice for the piezo.

[let_it_out_org]

i don't know of any 555s with different pinouts. i tried several variations without the mosfet; it is needed. all the mosfet talk in these comments is mind boggling!

[Unit042]

It doesn't have to be mind-boggling. A cup of capuchino(sic) will help with some things in life.... Now, what is the diode doing, is it supposed to be delivering a voltage drop to the threshold/trigger pin? Or was it supposed to be on the output/discharge pin?

[TXTCLA55]

What does the Mosfet do? Are there any other components that could possibly replace it?

[raykholo]

as you can see below, the mosfet is used to amplify the output signal from the 555 IC. transistors will do the same thing, im pretty sure u should look for an NPN one --> pretty cheap... the mosfet used here is not as common, but it is the same thing as the 2n7000 which u can find on digikey.... again, the answer the your question is that any NPN transistor should work as a replacement...

[sp33dstix]

Hi there, In the circuit diagram what is the halfcircle thing with the + and - on it?

[FreeBaseBuzz]

Are you talking about the electrolytic capacitor? to the right of the 10uF marking?

[jerrystearns]

heheheheheh a battery

[Sagar Gondaliya]

dude. get ur symbols right.

[let_it_out_org]

you're joking, right?

[sp33dstix]

I know which one was the battery, I was asking about the half circle. Never worked with piezo buzzers. Thanks

[let_it_out_org]

oh thats fine, i was asking if jerrystearns was joking good luck with yours

[let_it_out_org]

that is the piezo buzer

[theangrytomato]

So...I'm don't know much about electronics, as you will probably be able to tell in a second.

If t = r*c, then that would mean that this device beeps for a split second every (about) 16.5 minutes. Am I correct? Trying to make sure I actually understand this before I go out and build one.

What exactly is the diode going into pin 6 doing?

Last question - do you know if there is a way to randomize the length of time between beeps without using a microcontroller? Sorry for all the questions.

[theangrytomato]

Yeah...its not 16.5 minutes. Whoops. What am I doing wrong?

[The Lightning Stalker]

I believe the 2N7000 would work as well. It won't handle quite as much current though.

[Sagar Gondaliya]

(removed by author or community request)

[kscience]

If you google mosfets you can learn what the 3 elements are. Pin 3 goes to the gate, not the drain or source. The schematic is clear if you know what components are.