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


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hi! this day was not like what i imagined it to be.. when my adviser and i met this afternoon, he asked if i had everything with me. i said yes. he asked for the circuit. i handed it to him. he also asked for the spare components i have, including the bread board.. i also gave him the printouts i have - those that were from this forum and also the msn conversations.. after that, he walked away..  he's going to work on the circuit by himself. he said he will just give it to me at school on MOnday... i never got the chance to try the things that you have advised me...

anyway, i guess it's better this way.. at least  he won't totallt blame me if this thing doesn't really work.. maybe, i'll just tell you how his work on the circuit went when i see him on MOnday..

How will i learn if i can't see how my project is done?  :(
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good day! has anybody built the whistle responder circuit and made it work? my adviser thinks it'll never work.. he said that the IC used (CD4069 CMOS Hex Inverter) can never be used as an amplifier..

i want to know if anybody had already made the circuit with a 4069 IC..even if you haven't built it, i need your opinion if a 4069 can be used as an amplifier like that in the whistle responder circuit..

thanks again..
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good day! has anybody built the whistle responder circuit and made it work? my adviser thinks it'll never work.. he said that the IC used (CD4069 CMOS Hex Inverter) can never be used as an amplifier..

i want to know if anybody had already made the circuit with a 4069 IC..even if you haven't built it, i need your opinion if a 4069 can be used as an amplifier like that in the whistle responder circuit..

thanks again..


correction.. i mean a CD4049.. i got confused.. sorry...
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Hi logan,
I have used the CD4069 as a linear amplifier many times and it works well. RCA had an appl. note which is also in National's AN-88 applications note about their 74C04, which is the same as the CD4069.

The CD4069 is completely symmetrical, so operates very well as a linear amplifier and has a fairly low current so has symmetry with high gain.

The CD4049 is fairly high current and is terribly assymmetrical. I haven't seen one. Since it is high current then I think its gain will be low.

post-1706-14279142674783_thumb.png

post-1706-14279142674896_thumb.png

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My 1st graph shows that a CD4069 or 74C04 inverter with a 3V supply and a high resistance as a negative feedback resistor and a low resistance as its inverting input resistor has a voltage gain of about 500 at low frequencies. The Whistle Responder mic preamp can't have a low value for its input resistor so its gain will be a little less than 500.
Our Keys Finder Project uses CD4069 inverters as linear amps.

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hi!

i skipped class to ask you guys about something.. my adviser wired the circuit in the breadboard.. he said that although he wired it correctly and have the same output voltage, the circuit is still not functioning.. he concluded that the circuit will not function.. he said that i should replace the linear amplifiers.. IC1a, IC1b, and IC1c.. he wants me to replace it with transistors or OPamps.. i don't know how? is that possible? how am i suppose to wire them?

i still  think it would be better to use a 4069 instead.. but i am not sure if i will make the correct design with a 4069.. it has only 14 pins compared with 16 on the 4049.. besides, it has a different pin configuration..
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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

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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..
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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..
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