Keys finder circuit

[er3na]

Hello there. Regarding the keys finder circuit, I find the circuit image to be a bit blurry. Some parts of it are quite hard to see. I would really appreciate it if U could help me with a clearer image of the schematic. Really need it for my project.Thank you. :) ;) :D ;D

Project Link: http://www.electronics-lab.com/projects/misc/002/index.html

[EDY]

I hope this will do the trick ;D

Mike you can use this image too but check it for any errors :D



Click the image for full resolution.

[mixos]

Great work EDY !!

You won an ION MOTOR CONTRUCTION GUIDE ;D :

Ion_motor.pdf

[EDY]

Tanx Mike :) :) :)
Its been a long time since I won anything :-X;D
Since I haven't read the text (only few words to be precise) I have to ask what exactly is a usage of it since I don't have a space ship? ;D ;) :) 8)

Cheers

[mixos]

It's just for educational purposes :D ! But... it is used also to ionize your room.. so you don't have to buy a commercial ionizer to keep your room's air fresh ;D!

[EDY]

Nice ;)

I've just read the whole text and it is rather interesting ;D

Only one question remains:
What can I use for 10KV power-up supply? :o

[mixos]

Are you ready to build it :o ??

Here you will find some great Hight Voltage Power Supplies using a TV's transformer:

http://www.geocities.com/CapeCanaveral/Lab/5322/hv2.html

[EDY]

No. Not yet.
My brain is to tired right now of all learnig I have to do for universitiy, and learning about electronics circuits is on hold till further notice becouse of that >:( :( :'(

But I'm most probably ask my few friends who have more expirience in these things to build me a hihg voltage transformer. 8)

I will most probably build it becouse I have chronic bronhitis (don't know if this is the right expresion) and the way I figure it if I make this ionizer it will help me breathe easier during the winter days (becouse heat from the radiators makes air more dry and thus its hevier to breathe and ionizer fresens it) :P

Here I am talking about my medical problems. I wonder what's next ??? ;)
Cheers

[er3na]

Thanx so much EDY. U've been a great help! ;) btw, how do we get the fizzle that we need to produce for the buzzer? Does screeching two keys together help? Or is it possible to just make some hand claps to trigger the buzzer? ::) ???

[bogdan]

a good thing would be to create a SMD version of the circuit. maybe find a beeping cheychain, take it's guts out and put this in.

[jazcannon]

;D I am building this circuit as a project and I would really appreciate it if you could tell me which piezoelectric buzzer would be used. I have all of the other parts but this one is really annoying me. Thank you very much. Jazcannon. ;D

[audioguru]

Hi Jazcannon,
Welcome to our forum.
You don't want an actual piezo buzzer, which would have a built-in oscillator, you need a piezo transducer. The circuit already has an oscillator and a buzzer won't work as a microphone. Bad translation, I guess.

I don't know where you are but my Canadian Newarkinone catalog has many of them. Select one with a resonant frequency of 3KHz to 4KHz.

What on earth is a fizzle? Another bad translation.
I think that you must make a whistle type of sound that is near the transducer's resonant frequency.

[lapsap]

after i connected it to a battery, the buzzer started trigger, wheter i whistle or other sound, nothing is change. is it i use the wrong buzzer? how to make sure i get the correct buzzer?

[audioguru]

Hi Lapsap,
Welcome to our forum. ;D
You don't want a buzzer, the circuit needs a piezo transducer. D4, C7 and D3 are supposed to stop the transducer from whistling after about 1 second.
The circuit is supposed to trigger from nearly any fairly high-pitch sound, not just a "fizzle", whatever that is. ;D

[lapsap]

thx,what the different between piezo buzzer and piezo transducer? and also whats the different between selfdrive (3 terminal) and external drive (2 terminal) which one am i suppose to use?

[Guest Alun]

A piezo buzzer has a built in oscilator to drive it.

A buzzer element has three terminals, ground, dirive and feedback, if you connect the output to the output of an amplifier and the feedback to the input it will form and oscillator and make a sound at its resonant frequency.

http://www.avxcorp.com/docs/masterpubs/piezo.pdf
http://www.murata.com/catalog/p15e6.pdf

Here's the circuit, I got it from the first link, it's a basic common emitter amplifier with the drive terminal connected to it's output and the feedback connected to the input.

EDIT:
I've just noticed this circuit doesn't need a buzzer, it needs a transducer, in this case just connect the feedback and drive togeather and connect them to the output.

[lapsap]

icic, thx for the information, i hope it work perpectly after getting the transducer

[Guest Alun]

I forgot to say, the only difference between a piezo transducer and piezo buzzer element it a buzzer element has an extra feedback lead, a transducer just has drive and ground leads. Just connect the feedback and driver together and use the buzzer element as a transducer.

[lapsap]

i m still very blur with the piezo thing. from the site
http://www.murata.com/catalog/p15e6.pdf
it say that
external drive: 2 terminal
selfdrive : 3 terminal

and what i found out from website that sell these component say that
piezo buzzer or transducer each of them is also having selfdrive and external drive.

so which one should i use.

one more thing, do u mind to explain the circuit how it actually work? i m still quite blur with it, especially the part N1...N3, from what i know is that the inverter work in the digital part, change from 1 to 0, or 0 to 1. how it can be configure to be amplify?

thx for your help, i have just started learning about electronic.

[audioguru]

Hi Lapsap,
Just get a two-wire piezo transducer designed for external drive. Our project uses it as a microphone then drives it to make a sound.

A CD4069 inverter is just a pair of push-pull complimentary Mos transistors. It makes a pretty good linear amplifier with the negative feedback provided by the resistors from output to input. The feedback makes it self-bias, if the output DC voltage tried to be too low then it feedsback into the input which forces the output up to a voltage about half the supply voltage where its Mos transistors have the most gain. ;D

[Guest Alun]

I hope this picture settles the matter. ;D

As long as you don't use a piezo buzzer with an internal driver this circuit will work. You can use either a 2 or 3 lead piezo transducer in this circuit, if you use the 3 lead variety then just connect the feedback to the drive.

[audioguru]

I think a 2-wire transducer will make a more sensitive microphone since its useful area is larger and in a single lighter-weight piece. ;D

[Guest Alun]

I think there will be very little difference between the two, but I agree the two wire unit will be very slightly better and is a more appropriate choice. I was just pointing out that you can also use a three terminal device if it's more convenient to get hold of. ;D

[lapsap]

Posted by: Alun  Posted on: May 28, 2005, 02:20:24 PM
Insert Quote
I forgot to say, the only difference between a piezo transducer and piezo buzzer element it a buzzer element has an extra feedback lead, a transducer just has drive and ground leads. Just connect the feedback and driver together and use the buzzer element as a transducer.


back to my old question, whats the different between transducer ans buzzer?

so it means that this transducer will act as a mic and then become a speaker to produce sound?

[audioguru]

A piezo buzzer usually has a transistor oscillator in it and therefore cannot be used as a microphone. Its oscillator will conflict with the oscillator in this project when it is supposed to be a speaker.

Quote: Our project uses it as a microphone then drives it to make a sound.