logan_dslasher
- Jul 23, 2004
- 392
- Joined
- Jul 23, 2004
- Messages
- 392
so, i should still connect them?steven said:all unused gates go to ground normally
audioguru2
- Apr 6, 2004
- 12,026
- Joined
- Apr 6, 2004
- Messages
- 12,026
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.logan_dslasher said:
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.
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.
logan_dslasher
- Jul 23, 2004
- 392
- Joined
- Jul 23, 2004
- Messages
- 392
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?
in a 4071, does it have the same wiring as that of a 4081? How about for the inverter?
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 .
audioguru2
- Apr 6, 2004
- 12,026
- Joined
- Apr 6, 2004
- Messages
- 12,026
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.logan_dslasher said:
logan_dslasher
- Jul 23, 2004
- 392
- Joined
- Jul 23, 2004
- Messages
- 392
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) 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)..
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
) 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)..
logan_dslasher
- Jul 23, 2004
- 392
- Joined
- Jul 23, 2004
- Messages
- 392
hi Steven!steven said:
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 ..
Hi
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
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
audioguru2
- Apr 6, 2004
- 12,026
- Joined
- Apr 6, 2004
- Messages
- 12,026
It is an experiment in Chapter 7, Volume VI at www.allaboutcircuits.com .Staigen said:
logan_dslasher
- Jul 23, 2004
- 392
- Joined
- Jul 23, 2004
- Messages
- 392
i have spent all day working on the project. at the very last stage of assembling it, i encountered a problem. the inverter input LED doesn't turn ON even if i apply a high to it.. i've traced evferywhere for the fault but found none.. maybe, i'm just too exhausted, so i tried to unwind by playing online games.. i think i'm ok now.. i'll figure out somehow what is wrong..
just a question, one of the LED is not very bright.. it is connected by a foot-long wire. should i shorten it? how about my question about TTL vs CMOS? can they go together in a single circuit?
thanks all for all the help..
just a question, one of the LED is not very bright.. it is connected by a foot-long wire. should i shorten it? how about my question about TTL vs CMOS? can they go together in a single circuit?
thanks all for all the help..
audioguru2
- Apr 6, 2004
- 12,026
- Joined
- Apr 6, 2004
- Messages
- 12,026
Swap the LEDs. If one side is always dim then the circuit on that side has a problem. Maybe the circuit for the bright side has a problem instead.
TTL and Cmos logic devices are completely different:
1) TTL operates from a 5V supply only. Ordinary Cmos operates with a supply from 3V to 15V or 18V.
2) A TTL input needs a high current to drive it low. An ordinary Cmos output can't supply enough current.
3) A Cmos input needs a fairly high voltage for it to be high. The output voltage of a TTL device doesn't go high enough.
TTL and Cmos logic devices are completely different:
1) TTL operates from a 5V supply only. Ordinary Cmos operates with a supply from 3V to 15V or 18V.
2) A TTL input needs a high current to drive it low. An ordinary Cmos output can't supply enough current.
3) A Cmos input needs a fairly high voltage for it to be high. The output voltage of a TTL device doesn't go high enough.
logan_dslasher
- Jul 23, 2004
- 392
- Joined
- Jul 23, 2004
- Messages
- 392
the problem i encoutered with my inverter was due to the damaged IC.. remember, when i was working on the whistle responder circuit, i used some of the left over parts in making this project.. after i solved the inverter problem, the OR stage malfunctioned.. it's output was always low..
i have solved the problem.. i used the same technique that revealed that my 4081 was defective, since both the 4071 and 4081 have the same pin config, i replaced my 4071 with a 4081. the 4081 worked properly, therefore, the connection was fine. i replaced my 4071 with a new one. it worked fine..
why do ICs gets so easily damaged?
i finished the whole project just in time... i hope my friend will have a good grade.. and i'm pretty confident he would. 8) thanks you guys..
on the other hand, i learned a lot too.. he said the next project they have to pass is an AM radio receiver..
tahnks again for the help..
i have solved the problem.. i used the same technique that revealed that my 4081 was defective, since both the 4071 and 4081 have the same pin config, i replaced my 4071 with a 4081. the 4081 worked properly, therefore, the connection was fine. i replaced my 4071 with a new one. it worked fine..
why do ICs gets so easily damaged?
i finished the whole project just in time... i hope my friend will have a good grade.. and i'm pretty confident he would. 8) thanks you guys..
on the other hand, i learned a lot too.. he said the next project they have to pass is an AM radio receiver..
tahnks again for the help..
Similar threads
