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

[audioguru2]

Hi Logan,
You could use a low power LM324 quad opamp instead of the Cmos inverters IC and design the bandpass filter to operate better. The supply current will be about 1mA and an expensive and fairly large CR2430 3V lithium coin cell battery will last only about 12 days if the circuit doesn't beep.

I just finished testing a CD4069 hex inverters IC with two inverters biased with negative feedback as linear amplifiers. With a 3.0V supply, each inverter had a DC output voltage of 1.8V. The supply current was only 14uA, so a CR2430 lithium coin cell battery would last for 12 weeks. A cheaper smaller battery could be used. Beeping would exhaust the battery quicker.

With the 10k to 4.7M feedback resistors as used in the Whistle Responder project, the voltage gain was 110, and a 2Vp-p sinewave output was slightly distorted. The high frequencies were down -3dB at 2kHz. The 10mVp-p output of an electret microphone would be amplified well to 1.1Vp-p.

With 10K to 1M feedback resistors, the voltage gain was 40 and a 2Vp-p sinewave output looked perfect. ;D

 

[logan_dslasher]

hi there!

i have downloaded the pdf file about LM324.. even with all those info, i still don't know how? can somebody please show me how? i really don't have the luxury of time to experiment..

i have scheduled my defence this coming friday.. i don't have any choice. if i can't really find a way to make the circuit work, the panelist might fail me. and that is not a good thing.. anyway, i'm trying my best to make this thing work.. and i appreciate very much your help...

i have tried the 4069. it didn't work.. even the oscillator is not working.. in the 4049, the oscillator is working, that is because it beeped when i removed D2 or reverse it..

thanks for the help..

 

[audioguru2]

We can't teach you about opamps, your professor should teach you.
Post the voltage readings of the CD4069 circuit and we will fix it.

 

[logan_dslasher]

i was up all night! i haven't gotten any sleep yet.. i haven't tested the circuit last night, cause i left the breadboard the my friend's apartment.. anyway.i spent all night, writing chapters 4&5 and revising chapters1-3.. it took my whole seven sleeping hours to have it "almost" finished.. while writing chapters 4&5, i realized that i have still lots of questions to ask you guyz... for now.. i'll present to you the voltage readings i have with the 4069: (note: the supply is 3.0V)

pin2 - 3V
pin4 - 1.8V
pin6 - 1.8V
pin8 - 0V
pin10 - 1.8V / 2.0V
pin12 - 1.0V /1.2V
mic - 1V    (note:  mic resistor used was 10K instead of the 22K)

why is it that the needle was swaying/waving when i am measuring pins10&12? is it normal?

the moment i swithched on the power supply, it makes faint beeping sounds..

i also removed R5 and replaced R4 with a wire.. still there was the beeping sound..

removing C3 would disable the filter right? and that means that the circuit can recognize all the sounds.. even if i had c3 on, the circuit is beeping.. nothing changes when i remove it..

in the 4049, removing or reversing D2 drives the oscillator, which makes the buzzer beep.. in my 4069 wiring, removing/reversing D2 doesn't have any effect..

i think that's all i can give your right now.. never mind the opamps.. i am not interested.. it's too complicated.. i hope i have given all the necesary data tha will help you help me make the circuit work...

COUNTDOWN TO FINAL DEFENSE: 48hours15mins (DO or DIE!!)
thanks for the help..

 

[audioguru2]

Logan,
You are using a different IC. Which pin number does what?????
Please post a schematic with the pin numbers you used so I can see what they do and which ones if any have a wrong voltage, or a cross-reference list.

Your meter wavers because the oscillator is running at about 8Hz.

 

[logan_dslasher]

i am having a hard time working on the image of the schematic..

CD4049 CD4069

pin1 pin14
pin2 pin2
pin3 pin1
pin4 pin4
pin5 pin3
pin6 pin6
pin7 pin5
pin8 pin7
pin9 pin9
pin10 pin8
pin11 pin11
pin12 pin10
pin13
pin14 pin13
pin15 pin12
pin16

 

[audioguru2]

Like this:

View attachment 38470

 

[audioguru2]

The lousy old intermittent breadboard stopped the circuit from working.

 

[logan_dslasher]

i have only at least 19 hours before my defense starts. my buzzer got damaged. i can't get a new one in at least 11 hours from now.. i'll just concentrate on my manuscript.. the subject is research methods anyway, and 70% of the grade is given by tour research prof. 30% is from the three-man panel of electronic professors.. even if they will give only 30% of my grade they will do the "interrogation"  all the time during the defense.. and most importantly, they will be the one who decides if you pass or not!

if this thing doesn't work out well tomorrow, i hope you guys have a NEW CIRCUIT for me to work on.. i should've been with the eLab community before i chose a topic. that way, you have recommended the best topic to work on.. anyway, have one ready.. just in case..

Thanks for all the help..  ;D

 

[audioguru2]

Hi Logan, Besides having a broken beeper, your project doesn't work because of your intermittent breadboard.

As we discussed on MSN, the Whistle Responder project's design has some mistakes that can be easily fixed:
1) It uses an unsymmetrical output, high operating current CD4049. That's crazy! It should use a CD4069 instead for its Cmos linear amplifiers.
2) It has a 100k to 220 ohm attenuator following its mic peamp which is also crazy. It should have a trimpot there.
3) The lowpass filter parts in its bandpass filter cutoff frequencies above 49Hz, which is also crazy.
4) It used an emitter-follower to drive the beeper with a voltage loss of about 0.8V, which is 27% of its supply voltage. Crazy! It should use a common-emmiter circuit for the transistor with a voltage loss of only 0.1V or less, like I showed.

 

[logan_dslasher]

LUCKY BREAK!!
one of our panelist won't be available at our scheduled defense.. meaning we have to re-schedule the defense! everybody is busy the coming days.. the ealiest possible date and time we can defend is next wednesday, meaning i still have 5 days more to make this thing work..

for now i have to concentrate forst on my other subjects.. i missed again another final exam!!

 

[audioguru2]

Hi Logan,
Now you have time to build this project and to modify it so it works.

You enquired about a tutorial about opamps. This long document from Texas Instruments is the best one that I've seen:

[attachment deleted by admin]

 

[logan_dslasher]

i have downloaded the pdf files of op amps from Ante's thread.. i missed part3 that is why i cant open the first two..

anyway, i'll study also this file.. my mom referred me to an old friend of hers. He worked in Japan for qiute some time.. he is also concerened if an inverter can be used as an amplifier.. he recommended using op amps.. i will still concentrate on the 4069..

i bought a new buzzer. i had it tested in the store where i bought it.. they used a 6V battery to test it. it beeped. when i got home, and tried it on my AC-DC converter, it is not beeping anymore.. it was beeping though at Rx1 setting of my multitester..

 

[audioguru2]

My piezo buzzer reliably works with a supply voltage of less than 1.24V. it isn't loud with such a low voltage but it works.
Return your bad one and take your own 1.5V battery cell with you to find a good replacement.

 

[logan_dslasher]

i've tried your suggestion to make it beep louder... remeber the bottle cap? is that the one from 1.5 liter of coca cola bottles? what is the ideal size of the hole... i've been looking for chassis for the circuit and so far a matchbox is the best  so far.. the piezo buzzer beside the circuit fits perfectly..

i was trying to make a PCB design for the 4069, and i am wondering if i could interchange the inverters..  say for the input, those that are connected to the pin1 will be connected to pin3 instead and for th output, those in pin2 will be in pin4? can you visualize what i want to happen? i hope i explained it properly.. the same with other inverters so that it would be easier to design the PCB layout...

View attachment 38484

 

[audioguru2]

Hi Logan,
My piezo speaker from an alarm clock is without a housing and its back is exposed. It is much louder when its back is very close but with a small space around it to a big bottle cap like from Coke. A sewing thimble also works well as an acousical resonant chamber.

My piezo buzzer is already mounted in an acousical resonant plastic chamber, it is about 3cm in diameter and is about 3cm deep. The housing's size and shape is designed to resonate at the same frequency that the piezo is loudest. Then its oscillator transistor automatically oscillates at that frequency. Its bottom is sealed with a hard glue but its pcb is there with pins from its transistor.

In an IC, all the inverters are exactly the same. You could use the inverter with pins 1+2 as the 1st inverter, pins 3+4 as the 2nd inverter and pins 5+6 as the 3rd inverter in the circuit if they fit together on a pcb better. Or use the inverter with pins 3+4 as the 1st inverter in the circuit instead as you say.

 

[logan_dslasher]

alright, i'll see if i it would be easier if i interchange the inverters.. i've been buzy the whole day working on my business policy term paper.. i'll be ready with the questions (ehehehe) about 4069 tomorrow..

i cracked my damaged buzzer open.. i saw what is inside and didn't understand a thing ehehe.. all i recognized was the components, but i never understood why they are there and what they do ;D

 

[audioguru2]

Here is a schematic of the transistor oscillator inside a Panasonic piezo beeper:

View attachment 38485

 

[logan_dslasher]

i am logged in for about 6 hours and a half now.. i've been downloading lots of things.. and they takre very very long!! imagine downloading the EAGLE layout editor at 2kbps!! and at some point, say 45% it would suddenly stop!!

i found a lot of useful programs! especially the frequency analyzer which i can (can i?) use in my whistle responder proj. but my pc doesn't have a mic.. and i dont know if it has a sound card..

i've also been to the proejcts section and i came across this: http://www.electronics-lab.com/projects/sensors/005/index.html ..

This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms.

The two BC109C transitors form an audio preamp, the gain of which is controlled by the 10k preset.  The output is further amplified by a BC182B transistor. To prevent instability the preamp is decoupled with a 100u capacitor and 1k resistor. The audio voltage at the collector of the BC182B is rectified by the two 1N4148 diodes and 4.7u capacitor. This dc voltage will
directly drive the BC212B transistor and operate the relay and LED.

It should be noted that this circuit does not "latch". The relay and LED operate momentarily in response to audio peaks.

can i use it to amplify the signal picked up by my Electret mic instead of inverters wired as amplifiers?

 

[logan_dslasher]

i've been going through my notes in Yahoo Notepad.. i found this: http://www.electronic-circuits-diagrams.com/audioimages/audiockt9.shtml  it uses  LM324, the same opamp audioguru once mentioned.. i know i said that i am not interested in using op amps in my whistle responder proj, but my thesis adviser is persistent.. if ever, can i use it as amplifiers? can i omit the 4027 it also uses.. it's a flipflop.. here's the schematic: