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simple buzzer project

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Ahahaha...thats the way it is at my school. For my freshman, sophomore, and half my junior year I worked as a paid computer technician for the school...that was the best job ever. The lady I worked for got fired, however, and the budget was cut. Once I heard about that I quit and joined the distance track team...now I get call slips all the time from teachers who need help...
 
oh just had a thought since it is going to go from 1.5v to 9v should i add a resistor? but then again it will not light/buzz if there isn't enough power???( do i add a fat resistor then a nice fat capacitor after? )
 
Ductapemaster said:
Ahahaha...thats the way it is at my school. For my freshman, sophomore, and half my junior year I worked as a paid computer technician for the school...that was the best job ever. The lady I worked for got fired, however, and the budget was cut. Once I heard about that I quit and joined the distance track team...now I get call slips all the time from teachers who need help...

That is my dream!! omg i so wish that happened to me:D but my tech guy is an over paid mean jerk who thinks he knows everything and he works at all the schools in the area but hangs around ours
 
The lady I worked for paid me double too...my paid rate was $12 an hour, but she paid me $24...I made $120 a week for working one period! The only reason I have spending money now is because of that job...

But if you really like that stuff, just tell all your friends and see if they know people who need help with computers and what not. Thats what I did and I get people asking for help all the time.
 
Ohhh...didn't think about that. Try to see what the minimum voltage the buzzer and LED will work at. If they both work on 1.5v you're good, but if they don't, we have a problem.
 
no dice... but i did have an idea what if i used a transistor? here is the schematic a quickly drew up. but i was thinking that the transistor might get burned out.

P.S. on the oscillator circuit i tested it with a ohm meter and it shows that hooking the circuit up in reverse will cause fluctuations so i am going to hook it up in revers of what it should be running at just so you know.

EDIT: woops are the battery's the wrong way around :p well i messed that up and i forgot the resistor in between the transistor and the oscillator. last go ahead and think of things to add to it this is the most complicated thing i have thought up in a long time so i may have forgot components.
 

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Hey ok I've attached what I think would work. You will still need to find out where to put resistors and what transistor to use and whatnot. Basically what happens is the battery charges up the capacitor, then once the capacitor is charged the current of the battery and capacitor will want to go through the transistor like a zener diode allowing the transistor to conduct in reverse. You will need a resistor though behind it to control the current through the led.

To do that find out the zener voltage subtract the voltage drop of the led and divide by the led's recommended current (20-30mA). That will give you a resistor value DON'T go below it go above it.

You'll probably have some sort of voltage drop from the buzzer too that you should find first.
 

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if it makes it easyer then just take out the LED it was just for extra if it will be simpler with out it then go right ahead and take it out.
 
Well no you can leave it in...you just have to take into account that a resistor needs to be put in front or behind of it to reduce the current going through it. Otherwise you'll burn it out.

Like lets say you have 9V going through the led but you drop 2 on the buzzer (I have no idea what you drop). Well assuming that the led is 1.2V (also no idea) and you want 25mA (a guess)...then the resistor value would be: (9 - 2 - 1.2)/(.025) = 232 ohm so 240 ohm resistor needed for that situation.
 
i don't understand what you mean by "drop" and the led is 1.5v

EDIT: may need more because i am testing it on a 3.7 850mAh Nintendo ds battery :D and it gets really hot after about 10 min
 
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OK i get your diagram all i have to do is on the third pin of the npn transistor i add the oscillator circuit right?

EDIT: and figure out the capacitor and the resistor values
 
andynerd said:
i don't understand what you mean by "drop" and the led is 1.5v

EDIT: may need more because i am testing it on a 3.7 850mAh Nintendo ds battery :D and it gets really hot after about 10 min

It gets hot because it doesn't have a resistor to control the current it's getting.
 
kk i will draw up another diagram for this *and thank the lord! i can finally apply myself to math because i have something i like that i need math for^_^
 
You see this is where I'm not sure...You have to know the zener voltage of the transistor and that could mean that you would need a really powerful capacitor to get any sort of time that you could hear.

I have a better idea that is guaranteed to get what you want...search up about using 555 timers. They will create a good solid pulse and can definitely work for like 1 second or half second intervals.

I'm really not the one to talk to about timers but there should be a tonne of timer circuits on the internet. The circuit I originally gave you is actually a primitive design.
 
see this is my problem i really have a week but i didn't say anything because i can't order parts off the internet AT ALL my parents will not let me because they are worried about identity problems and creepers out there learning our address. The only reason i said 3 days was so no one would suggest those kinds of parts.
 
i also have really small capacitors and some in the thousands of :mu:F so out of everything i have a lot of them:D
 
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