Key Finder (pinoy version)

[logan_dslasher]

I've been working on the whistle responder (http://www.electronics-lab.com/projects/misc/008/index.html) project for my thesis. i can't get it to work. i'm trying a new circuit with basically the same principle - the Key Finder circuit (http://www.electronics-lab.com/projects/misc/002/index.html). However, I will use different values for most parts (esp capacitors) compared to the Key finder circuit in the lab/site.

the schematic is just the same except that i'm going to use this parts/specifications..

R1         10K
R2, R5, R8     10M
R3, R4, R6, R7, R9 100K
R10         4.7K
C1         0.027/50V
C2         56p/50V
C3         15p/50V
C4, C8       0.047/50V
C5         0.56/50V
C6         10uF/25V
C7         0.1/50V
C9         0.0015/50V
D1, D2, D3, D4           1N4148
T1, T2         2SC3622 (2SC3245) (2SC3248)
IC1         4069

i know i'm going to need a lot of help from you guyz.. i'll just post my questions the first time i encountered a problem. for now, please just standby..  ;D if you like, if you have already made this circuit, and have encountered probelms, please tell them now, so that, i can be prepared. 

any suggestion or advice is very much welcome!! thanks a lot!! 

 

[audioguru2]

Hi Logan,
Why are you changing the values of 8 capacitors, some of them a lot?

It won't work with your values of C2, C3 and C4 so low.
It won't work with your values of C5 and C9 so high. 

View attachment 38377

 

[logan_dslasher]

i wasn't the one who changed those values. those were the specifications indicated in the copy given to me by my adviser.. I am planning to make the two of them.. if one doesn't work.. i'll try the other.. i have already purchased those parts.. and also the one indicated in the lab. problem is.. i can't complete them..  these are the parts i can't acquire:

My circuit:
- r2, r5, r8, --> 10M resistor (is there really a 10M resistor? i can do combinations right?)
- c6 --> 10uF
- t1, t2 --> 2SC3622  (2SC3245)  (2SC3248)

lab's circuit:
- c4 --> tantalum
- c5 --> 1n5F

can you please suggest replacements for them?
most of the capacitors i've bought were mylar capacitors... was that OK? are they really supposed to be green-caps? is 6V enough for the circuit?

 

[audioguru2]

is there really a 10M resistor?

1/4W 5% carbon-film resistors with values from 10M to 22M have been available "everywhere" for years.

i can do combinations right?

Yes. Lower values in series that add up to 10M. Their extra wiring might pickup interference.

- c6 --> 10uF

Use an electrolytic.

- t1, t2 --> 2SC3622

 

[logan_dslasher]

i already completed the parts except for the tantalum capacitor.. an electrolytic would be fine? OK, i'll use an electrolytic instead.. the same  with the transistors.. i found a  2SC3622.

10V? would 9V be fine? i'm planning to use a 9V battery (the rectangular-shaped one)

 

[audioguru2]

i already completed the parts except for the tantalum capacitor.. an electrolytic would be fine? OK, i'll use an electrolytic instead.. the sameView attachment 38385

 

[logan_dslasher]

i am starting to put hte parts on the breadboard..

about the buzzer.. it's supposed to be a piezo speaker right? so the one i had from the alarm clock would be fine? why can't i use the piezo buzzer?

 

[audioguru2]

about the buzzer.. it's supposed to be a piezo speaker right? so the one i had from the alarm clock would be fine?

 

[logan_dslasher]

Your piezo speaker didn't work in the other project that was modified for it so maybe it will have the same problem in this project. Get another piezo speaker that works.

where could i get a piezo speaker? let's say i can't  buy one on an electronic shop because it is not available... how about the buzzer/speaker from the melody circuit of a Christmas light? or ma ybe the one from those greeting cards that plays a song as son as you open it?  are those speakers or buzzers? how could i test if it is working? will a piezo speaker beep (like a buzzer)  when i test it with an ohmeter?

 

[logan_dslasher]

ow, one more thing.. mylar capacitor codes are read just like in a ceramic, right? the first two digits as their values and the third one as the multiplier.. then its unit is in pF.. is that right? are there other wayz they are read?

 

[audioguru2]

where could i get a piezo speaker?

I have two from alarm clocks that work fine. I looked at RadioShack (now called The Source) yesterday and they had only piezo buzzers, no speakers. I can order online, any piezo speaker that is made.

how about the buzzer/speaker from the melody circuit of a Christmas light? or ma ybe the one from those greeting cards that plays a song as soon as you open it? are those speakers or buzzers?

They are piezo speakers. I think they are too small to make a beep that is loud enough.

how could i test if it is working? will a piezo speaker beep (like a buzzer)

 

[audioguru2]

mylar capacitor codes are read just like in a ceramic, right? the first two digits as their values and the third one as the multiplier.. then its unit is in pF.. is that right? are there other wayz they are read?

I always look at the datasheet for the caps I use then always use the same brand. I don't know who made your caps but the "green caps" I have from the Orient are marked 152 for 1.5nF which is 0.0015uF, and 223 for 22nF which is 0.022uF. My European polyester caps replace the decimal point with the multiplier. 1.5nF is marked 1u5, 22nF is marked 22n and 0.1uF (100nF) is marked u1.

 

[logan_dslasher]

because this circuit requires a piezo speaker, i decided to go back making the whistle responder circuit. i believe that the whistle responder is better because it has its own microphone unlike with the key finder circuit where the ear and  mouth of the circuit is its piezo speaker..

 

[audioguru2]

because this circuit requires a piezo speaker, i decided to go back making the whistle responder circuit. i believe that the whistle responder is better because it has its own microphone unlike with the key finder circuit where the ear and

 

[logan_dslasher]

i can say that it was certainly a good choice! i have already spent so much time on the whistle responder that i am more familiar with it than with the key finder...

besides, i don't know what piezo speaker to use for its circuit. how will i know if the speaker can be used as a microphone?

 

[audioguru2]

If I want a piezo speaker or any electronic part, I look at the millions of things at www.digikey.com or at www.newarkinone.com, select a size or price for a part then look at their datasheets. I order it online and it is delivered to me the next morning.

 

[logan_dslasher]

things like that don't work here in our country. even pizza delivery is not free!! and pizza delivery is restricted only to a few kilometers.. besides, i dont have any credit card or any means of paying it Online..

 

[audioguru2]

A pizza and its delivery is free here if it takes longer than a half hour or if it isn't hot enough. Then the delivery guy brings another one later.

The companies here provide a good selection, low prices and quick delivery to keep their customers.