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logan_dslasher

LOGIC GATES project

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here's what i did..

i have a 4081 (quad 2-input AND).. pins 1,2,3 is AND1 456 is AND2 and so on.. pin7 is ground and pin14 is +9V..  I have a LED placed in pins 3&4 ('im really not sure if it should be placed there..) then I use two wires to connect pins 1 and 2 to pin14.. theoretically (my theory) is should have the LED lit. high input to pins 1&2 should produce a high, turning the LED ON, right? bu what happens is the opposite. the LED is OFF if both pins1&2 are connected to pin14' it is ON if only one is connected. what's wrong? please advise...

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:)i havent used the 4081 before so i have no idea on it but the decade counter itself , well the 4017 yes look in the forums somewhere for the ten led light chasser circuit i posted it may help you with some of the qestions  as i used the 4017 decade counter ic in that with a  4011 i think it was  you can make the leds stop to by shorting out the capacitor in that light chasser

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:)4081 ic i dont know about the use of that ic ive not used it yet  have you seen my 10 led light chasser yet in the forums somewhere it has a 4011 i think it was and 4017 ic and there was one i once biult that uses a timer and decade counter , the way you have it i cant give you any ideas on that as im not much of a technicle exsplanations type but audio guru and ante are  they are good  at the technicle exsplanations , but if you have a bread board you can try on that  and the data on the chip you use if you find any will be helpfull . remember the decade counter can do ten leds hence the name decade counter, thats the 4017. pin 5 and 15 i think are the resett pins  most of the other pins are outputs

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thanks for the additional resources steven!

if i supply the circuit () with 12V, what should be the resistor values? i can't come up with a good schematic on how to wire the three IC's (4081, 4071, 4069)together.. ill try it on my breadboard later.. am still busy with lots of things right now..

thanks for the help!~!

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hi guys.. i think i found an answer to my problem.. i was looking for the pin assignemnt of a 4081 and this turned up: http://www.doctronics.co.uk/4081.htm#pins


i just ha a question: what are the capacitor and transistor for? is it alright if remove them? and how about the unused gates? i thought they are supposed to be connected to something..


4081_01.gif

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what are the capacitor and transistor for? is it alright if remove them?

The capacitor is the supply bypass cap. It keeps the supply at an unfluctuationg low impedance when the internal resistance of the battery rises as it runs down. The circuit might oscillate without it when the battery is a little used.

The transistor drives the LED with 10.6mA (Ohm's Law). The CD4081 can drive the LED directly with about 7mA without the transistor and without the 47k and 680 ohm resistors.

how about the unused gates? i thought they are supposed to be connected to something.

If the inputs of the unused gates aren't grounded or not connected to the positive supply instead, then the gates might draw current when they try to become linear amps or might oscillate.

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ah, alright, audioguru.. i'll just leave them there.. i'll just copy the wiring as is.. assuming that i can make the circuit work, how should i connect it to another IC? i syill have to use an OR (4071) and an inverter (4069) how should they be connected.

in a 4071, does it have the same wiring as that of a 4081? How about for the inverter?

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:)audiou guru is a major doctor in electronics , his skills and the way he can diagnose a circuit by looking at it and exsplain all the functions and technicle details like that makes me envey him,  i wish i can do that he is brilliant like others can be .  he is an asset to electronics lab , and id love to shake his hand and lern from him he would make a good teacher, in electronics .

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in a 4071, does it have the same wiring as that of a 4081? How about for the inverter?

You can't do much without the datasheets or a good textbook like "The Cmos Cookbook". They show the spec's, pins and the logic functions of the ICs.

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I got it finally! its working now!  8)

at first i wired it like that shown in the "tutorial" using a 4081.. it have varying results...i noticed that the 4081 was hot..  knowing that the pins' layout of a 4081 and a 4071 is the same, i repaced the 4081 with a 4071.. it worked! then i also wired a 4049 just like that again with the "tutorial's" diagram.. again, it worked. all i have to do now is look for another 4081.. i concluded that it is damaged..

i also had a problem with the BC547B while i was shopping for it.. it's not available (what's new?!) most of the shops don't have and ECG (electronic components guide? ??? -- wild guess) there's this shop in the locality that sells their goods at almost 5 times the prices in most of the shops.. it has an ECG.. i inquired about a 547 but was not available, so i asked what could i replace it with.. she said a 548 is but costs 65 pesos.. i said i'm short and i have to return to get additional money.. (i just needed the info  :P) i found a 548 at another shop for only 10 pesos..

all i have to do now is mount it on a PCB and placed it on the back of an illustration board and pop the LEDs onto it.. i'll have the schematic drawn to the board with the LEDs placed on its inputs and outputs.. i also placed LEDs on its input.. my friend even requested to have a truth table .. instead on 1's and 0's, we'll place LEDs.. i said that's very impractical and redundant!! it would also cost too much..

question, what's the difference between a TTL and CMOS? can they go together? what if instead of a 4049 i have a 7404 (i think)..

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:)audiou guru is a major doctor in electronics , his skills and the way he can diagnose a circuit by looking at it and exsplain all the functions and technicle details like that makes me envey him, i wish i can do that he is brilliant like others can be . he is an asset to electronics lab , and id love to shake his hand and lern from him he would make a good teacher, in electronics .


hi Steven!
who doesn't envy audioguru? you want him to be your teacher? why, i'd like him to adopt me!!  ;D  ;D  ehehehe.. i'll have the papers ready, audioguru ..  :D

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Hi

ewlectronics lab is the best site on the net


A link to ewlectronics lab would be nice, hehe ;D

I was only joking, but it is something with E-Lab thats appeal to me ;D, that the other forums dont have!

BTW, the pics that Logan uploaded, like this one http://www.electronics-lab.com/forum/index.php?topic=6022.msg37411#msg37411, is it a program, and if so, whats the name, and how to get it?

//Staigen

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