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logan_dslasher
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Posts posted by logan_dslasher
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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! -
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... :) -
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... -
so,is it a mylar capacitor? i'll buy one later... -
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... -
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? -
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... -
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? -
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.. -
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..
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i really have to go now.. it's getting pretty early. (early in the morning!!) i'll have everything you need tomorrow... nite! -
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. -
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! -
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.
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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 -
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
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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. -
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. -
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!! -
thanks.. that clearly shows that the positive terminal of C2 is not directly connected to -
i did a pcb design on the circuit and i needed a second opinion so i asked a friend to make his own version.. the design is similar except for the c2 and c3.. he placed one terminal of r7, r6, and +c2 with pin4.. whereas in my design, i have r7 between pins 3&4 and r6 between pins 4&5.. +c2 is placed in pin5.. i hope i discribed it properly.. i hope you wont have a hard time picturing it out..
i still go with my design.. -
1) Build the simple circuit and show that it works!
that's my main objective this coming week!
3) Make it tiny!
during the defence, the panel asked me how small it would be, i said, i would probably use a 3X4 PCB.. i know ist too big but i dont want them to expect too much..
4) Power it with a tiny but powerful 3V lithium coin cell!
assuming none is available, any other alternative?!
any more suggestions how i could make it smaller?! am gonna design the PCB layout later..
how about the light.. i promised them i would put a LED together with the buzzer.. what llight should i use.. they said an LED is too big.. i also need to put a separte switch for the light so that it could be used as a small flashlight.. -
have you build the circuit sir?! what is its max range?! dimensions?! what battery should i use?! am going to construct the circuit after our proposal defence this afternoon..
thnkz!! -
i still haven't constructed it because i dont have enough money right now.. the construction of the project is on the second sem.. this finlas of the first first sem, we are only required to submit chapters 1-3.. im really broke right now, and i owe everybody.. :(
i hope you could help me in defending my thesis.. thnaks -
i was busy preparing for my defense this coming wednesday.. we are about to defend chapters 1(the problem) chapter 2 (Review of related literature and studies and chapter 3 (research design and methodology.. one of my most feared, anticipated question is...
"are you aware that there is already an existing gadget such as this?! how is your proposed prototype different?!"
how am i supposed to answer?! or what if they said like "where did you get the circuit?! what modifications did you add?!
and one more thing.. i titled our project ELECTRONIC ITEM FINDER.. can anybody please suggest a better one?! thnak again for your help..
tc
i need help extending the keys finder project. can someone help me out????
in Electronic Projects Design/Ideas
Posted
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.
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.
can't do that right now, maybe tomorrow..