i need help extending the keys finder project. can someone help me out????

[logan_dslasher]

thanks.. that clearly shows that the positive terminal of C2 is not directly connected to

 

[audioguru2]

It still looks bad on the page.
Does this look better?

View attachment 38313

 

[audioguru2]

Tomorrow I'll be busy working in Canada's national election. All day and half the night.
I'm getting paid pretty well to keep politicians away from the polling station because they bribe folks to vote for them by handing out a bottle of booze!
Also, I'm in charge of 10 people who check-in voters and count the ballots. Lots of fun (boring!)

 

[logan_dslasher]

ow.. that would be alright.. you could have a look at it as your time permits.. i'Ve also been a poll watcher once.. yah!  its lots of fun alright.. sitting there for hours doing nothing but tally the votes.. you take care of yourself.. here in the Philippines, things like that could get ugly.. some areas are attacked by rebels.. also, watch out for politicians trying to bribe you.. never give in.. hey! have you watched the pacquiao-morales bout! it was awesome, right?! the Philippines is very proud of pacman!!

 

[audioguru2]

The most exciting thing for me at the election tomorrow will be when sombody tries to vote twice or more. Some people's name is twenty words long and they were given twenty voting cards.
They keep coming back dressed differently but I spot them every time!

 

[logan_dslasher]

the operation of the circuit discussed in the site is very brief. i hope I could get e more thorough explanation about its design. i need to know what's happening in the circuit from the moment someone whistles up to its emission of a beeping tone. i want to know why the parts are wired the way they are. i hope someone (you know who you are.. eheheh) could help me out here..

i have just mounted its parts on a bread board. it didn't work. maybe i didn't whistle at the correct frequency. i tried using my cellphone's ringtone composer, i tried every note i could produce but to no avail. i've checked the connection a dozen times. what could have i done wrong? my bread board is quite small so i have to use lots of wires, could that be the reason?                                      i also used a ceramic capacitor for c2 and c3 instead of polyester. could that be the reason? the mic doesn't have any polarity, right?

i don't know what i did wrong.

 

[logan_dslasher]

the operation of the circuit discussed in the site is very brief. i hope I could get e more thorough explanation about its design. i need to know what's happening in the circuit from the moment someone whistles up to its emission of a beeping tone. i want to know why the parts are wired the way they are. i hope someone (you know who you are.. eheheh) could help me out here..

i have just mounted its parts on a bread board. it didn't work. maybe i didn't whistle at the correct frequency. i tried using my cellphone's ringtone composer, i tried every note i could produce but to no avail. i've checked the connection a dozen times. what could have i done wrong? my bread board is quite small so i have to use lots of wires, could that be the reason?                                      i also used a ceramic capacitor for c2 and c3 instead of polyester. could that be the reason? the mic doesn't have any polarity, right?

i don't know what i did wrong.

 

[audioguru2]

the operation of the circuit discussed in the site is very brief. i hope I could get a more thorough explanation about its design. i need to know what's happening in the circuit from the moment someone whistles up to its emission of a beeping tone. i want to know why the parts are wired the way they are. i hope someone (you know who you are.. eheheh) could help me out here.

Hi Logan, who me?
I'll make a detailed circuit description of the circuit after we get your breadbord circuit working.

i have just mounted its parts on a bread board. it didn't work. maybe i didn't whistle at the correct frequency. i tried using my cellphone's ringtone composer, i tried every note i could produce but to no avail. i've checked the connection a dozen times. what could have i done wrong? my bread board is quite small so i have to use lots of wires, could that be the reason?

It doesn't use radio frequencies so if the contacts on your breadboard work then the circuit should work.

I also used a ceramic capacitor for c2 and c3 instead of polyester. could that be the reason?

C2 and C3 are parts in a bandpass filter. Their tolerance should be as tight as possible. Polyester caps are commonly 5% which is good but ceramic caps could be +80%, -20%.

the mic doesn't have any polarity, right?

Buzz, WRONG! They certainly are polarized. R1 feeds it its positive supply current for the field-effect transistor inside. The electret mic for this project should have only 2 pins or wires. 3-wire electret mics are available that would need to be modified to work in this project.
One pin on a 2-wire electret mic is connected to its metal case and should connect the the shield of a shielded audio cable which connects to the circuit's ground (battery's negative terminal). The other pin should connect to the inner shielded conductor of the cable and connect to R1 and C1. The mic won't be damaged if connected backwards.

i don't know what i did wrong.

1) You said in an e-mail that someone (not you? ;D) accidently used a 12V supply. You said that an LED replaced the buzzer. The IC can withstand 12V but might get a little warm. Without a current-limiting resistor for the transistor and LED then they might be destroyed. The IC is destroyed instantly if the supply is connected backwards.
2) You said you have a piezo beeper from an alarm clock. They are usually a transducer (speaker). This project is designed for a piezo buzzer that has a built-in oscillator.
I said in a reply how the circuit can be modified a little for your transducer, but it will continuously tone instead of make multiple beeps. Did you make the modifications?
3) You showed an excellent pcb layout with its transistor with a CBE european pins layout. American transistors are reversed and are EBC. I don't know which transistor you used so it might be backwards and not be destroyed, just not work.

I think I explained how having a resonant cavity behind the piezo makes it much louder. A tall bottle cap is good.

My daughter got a similar product that beeps whenever she talks and when the TV is playing. I can't make it beep even if I scream at it, but if I whistle at exactly half its beep frequency then it works from far away. It is too small for me to modify to make it work better.

 

[logan_dslasher]

Buzz, WRONG! They certainly are polarized. R1 feeds it its positive supply current for the field-effect transistor inside. The electret mic for this project should have only 2 pins or wires. 3-wire electret mics are available that would need to be modified to work in this project.
One pin on a 2-wire electret mic is connected to its metal case and should connect the the shield of a shielded audio cable which connects to the circuit's ground (battery's negative terminal). The other pin should connect to the inner shielded conductor of the cable and connect to R1 and C1. The mic won't be damaged if connected backwards.

i've changed the polarity of the mic. I was surprised to see that the LED lit. bravo! but it was turned on all the time. a closer inspection revealed that a wire is placed from the +V source to pin1 and also the ground was connected to pin8. that was wrong, right? i think so because the LED turned off when i removed them. is there a way to check if the mic is properly working?



i'm just wondering if there is a way to check if what is wrong with it. what tests could i perform on the circuit to pinpoint the error? is there a particular instrument or way i could use that would certainly trigger the circuit? i am concerned that my whistle or the cellphone's tones is not being picked up by hte mic.

i'm having a hard time connecting to the lab.. is the site having troubles. or the prob is in my internet connection.. anyway, i hope you could give me all the possible things i could do to make the circuit work.. thankz

 

[audioguru2]

i've changed the polarity of the mic. I was surprised to see that the LED lit. bravo! but it was turned on all the time.

Do you have a voltmeter? Is the supply 3.0V? Do you have a 47 ohm current-limiting resistor in series with the LED?
Test if the transistor can turn off by shorting its base to its emitter.

a closer inspection revealed that a wire is placed from the +V source to pin1 and also the ground was connected to pin8. that was wrong, right?

+V source is supposed to connect to pin 1. Ground is supposed to connect to ground.

the LED turned off when i removed them.

Look at the schematic. You disconnected the power to the IC. Ground is everything that is connected to the negative wire of the power supply.

is there a way to check if the mic is properly working?

Of course, measure DC voltages in the circuit. Beg, borrow or steal a multimeter and measure DC voltages in the circuit without sound. They should be close to these numbers:



i'm just wondering if there is a way to check if what is wrong with it. what tests could i perform on the circuit to pinpoint the error? is there a particular instrument or way i could use that would certainly trigger the circuit? i am concerned that my whistle or the cellphone's tones is not being picked up by hte mic.

i'm having a hard time connecting to the lab.. is the site having troubles. or the prob is in my internet connection.. anyway, i hope you could give me all the possible things i could do to make the circuit work.. thankz


View attachment 38335

 

[logan_dslasher]

Of course, measure DC voltages in the circuit. Beg, borrow or steal a multimeter and measure DC voltages in the circuit without sound. They should be close to these numbers:

hahaha.. lol.. do you really have to steal a multimeter? ehehe.. i have one. it's analog though.. anyway, i'll do that. i don't have an internet connection at home. so what i do is check the forum from an internet cafe. save your suggestions in a flash drive or diskette, and dload it into my pc at home. moreover, i can't bring the project here at the cafe..

Quote
a closer inspection revealed that a wire is placed from the +V source to pin1 and also the ground was connected to pin8. that was wrong, right?
+V source is supposed to connect to pin 1. Ground is supposed to connect to ground.

Quote
the LED turned off when i removed them.
Look at the schematic. You disconnected the power to the IC. Ground is everything that is connected to the negative wire of the power supply.

if i would have those wires connected, the LED would alwayz be turned on. if i have the buzzer in parallel with the LED, it would continuously beep. i'll recheck my connections. 

yes! there's another problem. it's a good thing i remembered it. the alarm clock buzzer is not beeping even if the LED is lit. it's connected in parallel with the LED. it only p roduces crackling sounds.

Test if the transistor can turn off by shorting its base to its emitter.

how do i know if the transistor is turned off? what should the reading be?

the mic i'm using is cylindrical in shape.. less than 1cm in diameter and about 0.7 cm tall.. one of its  face is black (its called a diaphragm, it think) and the other face has two "islands" of lead.. i don't have any way of telling which is positive or negative, so i assumed that it doesn't have any polarity. even the schematic symbol is not polarized.. i simply soldered a red and black wire into them and inserted the other ends into the board.

i'm sorry i'm causing lot of trouble to you.. thnks for helping...  ;D

 

[audioguru2]

the alarm clock buzzer is not beeping even if the LED is lit. it's connected in parallel with the LED. it only produces crackling sounds.

It is probably a piezo speaker, not a piezo beeper that has a buit-in oscillator like the project needs.
Do you want me to explain how to test it?
Do you want me to show you again how to modify the circuit so it can beep?

how do i know if the transistor is turned off? what should the reading be?

The LED will turn off.

the mic i'm using is cylindrical in shape.. less than 1cm in diameter and about 0.7 cm tall.. one of its

 

[logan_dslasher]

It is probably a piezo speaker, not a piezo beeper that has a buit-in oscillator like the project needs.

so what could i substitute for it? the commecrcially available buzzer is too big for its purpose. the smallest is about an inch and a half. (bigger than my PCB)

If its case is metal then it is probably an electret type. Use the ohm-meter fuction on your meter to measure which terminal connects to its case. That terminal is ground.
If the wires to it are longer than a few cm then they will pickup interference and need to be shielded audio cable.

the case is metal. 

I wait for the results of your voltages measurements.
What transistor part number did you use?

i'll have the voltage measurements as soon as i could log in again. what transistor part number?

it's already 2 in the morning. i guess i better hurry up home now... g'nite!

 

[audioguru2]

so what could i substitute for it? the commecrcially available buzzer is too big for its purpose.

Connect the piezo to 3V then reverse the wires and try it again. If it beeps then it is a piezo beeper and can be used in the circuit. I it just clicks when connected and disconnected then it is a piezo speaker and the circuit will need modification to use it. The modification will make it tone continuously intead of: beep, beep, beep for a few seconds.

the case of the mic is metal.

Then connect its case terminal to ground and the other terminal to R1 and C1.

 

[logan_dslasher]

Connect the piezo to 3V then reverse the wires and try it again. If it beeps then it is a piezo beeper and can be used in the circuit. I it just clicks when connected and disconnected then it is a piezo speaker and the circuit will need modification to use it. The modification will make it tone continuously intead of: beep, beep, beep for a few seconds.

i'll do that..

what transistor part number? 

ok. i'll find it out...

by the way, auidoguru.. since i can't whistle, what could i do to simulate dound like that of a whistle? i dont have sound measuring devices so i dont know if the sound i'm producing is enough or too high compared to the desired frequency.

 

[logan_dslasher]

i really have to go now.. it's getting pretty early.  (early in the morning!!) i'll have everything you need tomorrow... nite!

 

[logan_dslasher]

i have tested the circuit. all the test points that are expected to have 3.0V  yielded only 2.8V.. those that should be 1.5 have only 1V. Those that should be 0V are actually 0V except for the transistor's base, which gave a 0.9V rating. the mic terminal with c1 and r1 that you said should have a rating of 1.5 - 2.5V, doesn't have any output at all.. zero volts!

i'll double double check the connection again and test it again.. i'll try to see if my test results would change...

the transistor's part number is BC337. and, NO, the LED, the transistor for that matter did not turn off when i shorted its base to its emitter.

the piezo buzzer/speaker only produces crackling sound and no beep at all.. does that mean that it is a piezo speaker? how do you define "beep"? remember that i got it from an alarm clock, and before i removed it from its clock circuit. it was beeping with a 1.5V dry cell..

 

[audioguru2]

i have tested the circuit. all the test points that are expected to have 3.0V  yielded only 2.8V.

Either your meter reads low or the power supply voltage is low. The IC's minimum voltage is 3.0V but might still work if the voltage is a little lower.

those that should be 1.5 have only 1V.

That is OK.

Those that should be 0V are actually 0V

Good, then the IC works fine.

except for the transistor's base, which gave a 0.9V rating.

Oh, oh. And you can't turn it off. The transistor is blown-up! Don't replace it, the modification for the piezo speaker doesn't need it.

the mic terminal with c1 and r1 that you said should have a rating of 1.5 - 2.5V, doesn't have any output at all.. zero volts!

Oh, oh again. The microphone is shorted, maybe where you soldered on it. Don't let the wire on the microphone that connects to R1 and C1 touch the metal case of the mic.

the transistor's part number is BC337. and, NO, the LED, the transistor for that matter did not turn off when i shorted its base to its emitter.

Yes, the transistor doesn't work. It isn't needed.

the piezo buzzer/speaker only produces crackling sound and no beep at all.. does that mean that it is a piezo speaker? how do you define "beep"? remember that i got it from an alarm clock, and before i removed it from its clock circuit. it was beeping with a 1.5V dry cell.

It is a piezo speaker. The alarm clock has an oscillator which makes it beep. Here is the project that will drive it:View attachment 38341

 

[logan_dslasher]

i dont understand the mic terminals? there are two right? one of them is the body? is that the ground? which is the other one? as i have mentioned in one of my posts, there are two "island of leads" in the other face of the mic. i assumed that they dont have any polarity and so i soldered the wires into them. did that shorted the mic? bottom line is, i dont know how to wire the mic?

<-- the mic i have looks like the one in the center.. and its bottom face looks like the one in the middle of the bottom row.

i'll rewire the circuit. and see how it performs..

 

[audioguru2]

Logan,
Here's how to wire your electret mic:

View attachment 38344