Jump to content
Electronics-Lab.com Community

Keys finder circuit


er3na
 Share

Recommended Posts

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

Link to comment
Share on other sites

  • Replies 54
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

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

Link to comment
Share on other sites

  • 1 month later...
  • 8 months later...

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.

Link to comment
Share on other sites

  • 7 months later...

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

Link to comment
Share on other sites

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.

post-0-14279142261491_thumb.png

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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.

post-0-14279142262988_thumb.png

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share


×
  • Create New...