Project: Night Buzzer

[audioguru]

Since this project uses rather large caps, I was wondering if anyone had input on using these safely.

Your battery is only 9V isn't it? 9V isn't going to shock you. The capacitor won't charge to a voltage higher than the battery.
Your skin is a high resistance that needs a high voltage to cause a shock. The high voltage on your high skin resistance causes enough current to shock you. A capacitor can make a high current but with only 9V the resistance of the load needs to be very low to cause a high current.

 

[Hero999]

If the capacitor is large enough it could burn you though.

 

[loveangel4943291]

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loveangel4943291@yahoo.complz i want to find a design for counter which count the number of papers go out from the copy machine and stored the number of copies in small memory plz tell me ur suggestions about this project

 

[hartc2697]

Not able to get circuit to turn on/off

I'm not able to get the circuit to pulse on/off as I would expect. Rather it constantly stays on. Do I have the wrong expectations of this circuit?

I had thought this circuit created a pulsing of beeps.
If I'm wrong, could someone point me in a direction of how do accomplish the pulsing chirps? Thanks in advance.

 

[tyeo000]

whats the voltage on those caps?

 

[uzzors2k]

Above your supply voltage, so 2 volts and up.

I'm not able to get the circuit to pulse on/off as I would expect. Rather it constantly stays on. Do I have the wrong expectations of this circuit?

I had thought this circuit created a pulsing of beeps.
If I'm wrong, could someone point me in a direction of how do accomplish the pulsing chirps? Thanks in advance.

Does it work otherwise? Turn on after some time in the dark and turn off in light? If so you'll need a different kind of buzzer. You're not using a speaker are you?

 

[tyeo000]

oke-poke

uhh...
noob question but i cant get it to werk at all... :sad:
im using a 3904 and a 4011 as the transa. is this wrong??

 

[Jhoneil Dan]

what would be the values of the capacitors being used to this project?
please send me a reply as soon as possible coz i want to do it as my project in my electronic subject....

 

[scotchbrite]

i used 2 bf194 transistors n a 9 volts battery......the circuit din work.....can some1 plz help me out

 

[audioguru]

i used 2 bf194 transistors n a 9 volts battery......the circuit din work.....can some1 plz help me out

As we discussed here, the circuit is poor because it is missing a very important current-limiting resistor. With a 9V battery instead of the original 1.5V the excessive current probably destroyed the 2nd transistor's base-emitter the moment the battery was connected.

 

[Oznog]

I made one substantially more evil. It was a really high frequency whine and at the higher frequencies it's almost impossible to locate the source in a closed room.

It was designed so it went off after being in the dark several minutes, ran for under a sec, and repeated every few min. 10 sec is way too short a period and they will immediately realize it's associated with light which blows the whole gag. Several minutes and they will not realize it. You just need to make sure the period is not so long that they might fall asleep without hearing it or maybe only hearing it once, which may not arouse their interest in finding the source of the noise. So a period under 10 min is desirable.

Ideally the period should be substantially longer at first when the lights go off, giving them a feeling that the problem has gone away.

 

[ishank thandi]

hi,
ok provide me the PCB of NIGHT BUZZER.

 

[HiTech]

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loveangel4943291@yahoo.complz i want to find a design for counter which count the number of papers go out from the copy machine and stored the number of copies in small memory plz tell me ur suggestions about this project

OMG! How these off-topic, bizzare requests get injected here is beyond me!!! LMAO!
[kneels down with head bowed] "God in heaven, please don't allow these people to reproduce. In all your perfectness, I fail to understand how these amoeba-like people manage to durate on this planet." Amen!

 

[HiTech]

hi,
ok provide me the PCB of NIGHT BUZZER.

By the time you muster up a PC board, you could have this simple circuit breadboarded a dnworking in half the time.

 

[casdon56]

Pls I Will Like To Try This Hence Its Fun But Am Just A Beginner Can I Have A Simpler Diagram And A Better Guide To Construct It. Also The List Of The Components

 

[snareklutz]

I've attached a PCB board for the buzzer. Somebody please check if it works.

 

[pasanlaksiri]

Ha ha haaaaaa. This is funny CCT. OMG Its very very funny. Hmm one of my friend is very mad at me now. Coz of this. Hi hi heeeeee.

 

[tanmaysathe]

Eh Zac,
Thats a wicked little circuit mate, time for me to make one up as the family's gone out for the day and when my son goes to bed tonite :twisted: we can say he's just hearing things in his head. Although when my missus finds out I reckon I'll break the 3 minute mile just running away.

Cheers Bryan1

It will be very difficult to find out the circuit in dark if you choose a buzzer with frequency more than 5KHz.

 

[nightcatz]

can I use S9014 transisistor

hello there,
can I use s 9014 which is an npn silicon transistor as I am not able to find 2n 3904 at my place ....I have got a few s 9014 can I use them

 

[kaibui]

which LDR do you use?