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

[logan_dslasher]

case? what case? case of the what? and my mic doesn't exactly look like that.. there are no holes like what is in the picture.. what's the difference between the ground and ground terminal?

 

[audioguru2]

case? what case? case of the what?

Electret mics have a metal case. You said yours also has a metal case. Use the ohm-meter function of your meter to measure which terminal connects to the case, it is ground. Also measure that your soldering to the mic doesn't short your 2 wires to it.

my mic doesn't exactly look like that.. there are no holes like what is in the picture.

There are thousands of manufacturers of them, and they look different. I have one with 3 terminals but only 2 are used for connections to it.

what's the difference between the ground and ground terminal?

The circuit's "ground" is everything that connects to the battery's negative terminal. The mic's "ground terminal" is connected to its metal case inside it, and connects to the circuit's ground with your short separate wire or with the shield of long shielded audio cable.

Your project will be beeping (single long tone) in no time! ;D

 

[logan_dslasher]

i'll do that. anyway, thanks for the encouragement.. i really hope so...

i'll keep yah posted. i'll post again tomorrow noon, after my class... god bless...

 

[logan_dslasher]

i would like to test the modified circuit (the one with the piezo speaker)...  what are the xpected DC voltage ratings in the modified circuit? should they be still the same as the one in your post #28?

if i connect the piezo speaker with an LED in parallel, would it still beep? what if the LED lit and the speaker doesn't function? what does that tell? later in the project, should i use a separate source for the LED. is 3V suffiecient for both the LED and speaker to work?

 

[audioguru2]

The voltages should be the same as before except the microphone's voltage should be 1.5V to 2.5V. Did you change the values of R10 and C5?

Don't use an LED with this modified circuit. It will stop the oscillator. If you want an LED later then I'll show you how to connect it. What color LED? A blue or white LED won't work with only 3V. A red one will be OK later.

 

[logan_dslasher]

i still haven't implemented the changes in the circuit. i still have lots of things to do... too many projects to make.. anyway, this project is still number one priority. i still need to buy the new 1.5 nF.. that's 0.0015uF right?

wait. 3V is not enough for a blue LED? we have this lighters with a mini flashlight (which is actually an LED, or somewhat like an LED)
i think it has a supply of three 1.5V button clock type cells.. which is brighter than a green LED with a 6V supply..  anyway, let's deal with that later..

got to go.. my class started 5 mins ago... later...

 

[audioguru2]

Yes, 1.5nF is 0.0015uF. Over there, a "green-cap" is marked 152.

My blue LEDs require a minimum voltage of 3.2V plus more for a current-limiting resistor. The 3 button cells in a flashlight have the current-limiting resistance built-into them and supply 4.5V.
This Whistle Responder project will work at 4.5V and later I wll show how a blue LED can be added to it.

 

[logan_dslasher]

so,is it a mylar capacitor? i'll buy one later...

 

[audioguru2]

so,is it a mylar capacitor?

Yes.

 

[logan_dslasher]

I have already modified the circuit. i have removed the transistor and made the necessary value changes to the capacitor and resistor. here are tge results of the DC Voltages in the circuit:

(before measuring i measured the output of my AC/DC converter. its output at the 3V setting is 3.0V)

pin2 - 3V
pin4 - 1V
pin6 - 1V
pin10 - 0V
pin12 - 3V

they are good values right? they are the expected values as audioguru have indicated in post#28.

the only problem is with the microphone's voltage that should be 1.5 - 2.5. it has only 0.2V rating. i have rechecked the polarity of the mic, and i'm sure that i have found the round terminal. what does that tell us? what's wrong with my mic? i have noticed that i used ordinary wires (stranded) almost 4 inches long. i have asked a friend to purchase a shielded audio cable. i'll change the wires to my mic as soon as i acquire the shielded wire.

that's the only mistake i made that i can think of right now..

thanks...

 

[audioguru2]

Hi Logan,
The project's value of 22k for R1 with a 3V supply is incorrect!
I just tried it with my electret mic and got only 0.3V across the mic and it barely worked. When I replaced it with 4.7K then it had 1.9V and worked fine. Replace your circuit's R1 with 4.7K and try it. ;D

 

[logan_dslasher]

i just hope that the wrong value of R1 is the reason why this project is not working... i'll try it with a 4.7k then.. i'll let you know about the result as soon as i have them..

by the way. when you modified the circuit for a speaker instead of a buzzer, i think you forgot to indicate the polarity of the speaker connected with pins 14&15.. anyway, i'll try all the possible connection...

thanks.. and also, we have replaced the wires with shorter and smaller ones..

later... 

 

[audioguru2]

A piezo speaker doesn't have a polarity. If more than one is used then they all should be wired the same.
Only a piezo beeper with a built-in transistor oscillator has a polarity.

 

[logan_dslasher]

pressure is on! i really need to get this thing beeping soon. i am running out of time..

i have made all the necessary changes. i've changed the wires. i've modified the circuit for a piezo speaker. i've replaced the R1 from 22k to 4.7K. i also measured the mic's voltage. this time, the rating was above the expected value of 1.5-2.5. it has 2.8V.. almost the same as the source..

i am concerned with the parts i have. one or two of them might be defective, just like the old transistor i had. i want to check if the speaker and mic are functioning. could i do that?  how?

our thesis adviser approached us this afternoon inquiring about our progress. audioguru, remember the first time i mailed you. i asked you to explain to me a certain circuit. it's also a key finder circuit. according to you, that circuit needed a much higher whistle  frequency than this circuit i am working on. i decided to go with this circuit because it's much simpler, with less components and therefore smaller. our adviser gave us two days to have this circuit working. after that, we would start working on his circuit. even if i protested against the idea, i can't make any more contentions, because i dont want him to blame me if ever i can't finish this on time.. my concern is that, if we work on that circuit, we would be back at square one.. i tried to explain that i have gone through a lot with this circuit, and maybe, just maybe, i'm very close in making this circuit work.. i just hope i could get this thing beeping as soon as possible..

please tell me what to do.. thanks a lot!

 

[audioguru2]

1) To test the beep oscillator and the piezo speaker, temporarily connect the IC's pin 5 to ground (the negative wire of the supply).
2) Measure R1's 4.7k resistance with one end disconnected from the circuit, maybe it is bad.
3) Replace the electret microphone. Before (with 22k) its voltage was much too low, now (4.7K) it is much too high.

 

[logan_dslasher]

1) To test the beep oscillator and the piezo speaker, temporarily connect the IC's pin 5 to ground (the negative wire of the supply).

if i do that, what should happen? i already brought my stuff to the internet cafe with me. i connected pin5 to the ground. nothing happened. it is as quiet as ever.

2) Measure R1's 4.7k resistance with one end disconnected from the circuit, maybe it is bad.

the color code definitely tells that it is a 4.7K resistor. (yellow, violet, red) but the meter reading is 5K. i'll see if i can find a replacement with a much closer value.

3) Replace the electret microphone. Before (with 22k) its voltage was much too low, now (4.7K) it is much too high.

can't do that right now, maybe tomorrow..

 

[audioguru2]

Hi Logan,
When pin 5 of the IC is grounded, its pin 4 should go to 3V, its pin 2 should go to ground and its pin 10 should go to 3V. Then D2 becomes reverse-biased which allows the oscillator to drive the piezo speaker. I copied the values of the oscillator's R10 and C5 from the Keys Finder project but maybe they are wrong.
I don't have a CD4049 powerful hex inverter IC but have a CD4069 ordinary hex inverter IC that I will try with my piezo speaker and the same parts for R10 and C5.

I tried my electret mic again with 4.7K (and a 3.0V supply) and its voltage is 1.9V. With 10k its voltage is too low at 0.8V. I guess only a 3V supply is too low for our mics so the resistor's value must be selected for them to work properly. Yours might work with 5.6k, 6.8k, 7.5k, 8.2k, 10k or 12k etc.

 

[audioguru2]

Hi Logan,
I tried the oscillator section driving my piezo speaker. My opamp is a CD4069 ordinary one, not a high power CD4049 so it didn't have enough power to drive the piezo speaker unless the supply voltage was at least 4V. It wasn't very loud so I connected the piezo from pin 15 (your IC's pin numbers) to ground and it was much louder. The frequency kept changing if the piezo was bumped or moved, so my IC isn't powerful enough for the job.
I added a transistor to drive the piezo like in the Keys Finder project and the volume was very low, so I reconnected the piezo from pin 15 to ground. I added a resistor in series with pin 11 to make it a Classic Cmos Oscillator and it worked best. Your IC has a different input protection arrangement so it might not need the added resistor.

 

[logan_dslasher]

???  ???  ???

sorry but i really didn't quite understand what those  info means...

anyway, do you think there's still a chance i could pull this out! should i go to plan B? you have already seen the alternative circuit i was telling u about, would that be easier to build? assuming i can get all the parts it needed, would it be better..

after i grounded pin5, yes, it gave the expected DC voltages.. but still no  beep! 

i'll replace the mic later...

 

[logan_dslasher]

can we still figure out this circuit?

if ever we really cant make this thing work, would the keys finder circuit (http://www.electronics-lab.com/projects/misc/002/index.html) be as much of a problem as this whistle responder? what do you think? should we try building the keys finder circuit? but i still say that we ought to continue with the whistle responder... it's just that i cant come up with any more guesses with what ius wrong, and especially how to fix it!!!

i need your expert advice, audioguru, thankz...