Sequential LED circuit w/o timer 555 and decoder

Hi,

May I know how I can build a circuit using LM358 and some MOSFETs or BJTs to sequentially light up a row of LEDs?

Thank you very much.

What, exactly, do you mean by "sequentially" (sorry in advance if you mean that literally -- it's common on this forum for posters to not know the meaning of the words they use, so it's a necessary question ;)

Can you give me an example of the pattern you are looking for?

Also, is this a one time event, or will it repeat. And how will the pattern transition? All shut off and then sequentially, again, etc.?

And, how about timing? Even timing? How long is the delay between each LED transition? Guess that isn't important in terms of the method, as long as the frequency isn't too high or low.

let say, a row of 6 LEDs, and one will light up after the previous and at the end, all LEDs will be lighted up, then all 6 will blink in unison, until I switch off the circuit.

I have currently a square wave generated from a bistable multivibrator. timing of each LED transition can be 1sec now, for good reference.

You could just use a shift register 74HC595. this should work for you.

Whew...that's going to be difficult to do with the linear components you specified. Much easier with logic components or even better, an MCU.

ya i've seen many circuits online that can work this out, but this is a school project and we are only give opamps, MOSFETs and BJTs to play around with..

Is it possible to have a circuit to light up 3 LEDs first? then i can build on it further... thanks!

Sounds a bit odd this question Steve sequencially hmmm with Lm358 could be possible i suppose but very strange request Normally you would never approach this problem like this You would use a decade counter cd4017 and 555 or these days a micochip or a 7HCT4020 with cmos oscillator as clock source or cd4060

Thats the the way we normally achieve this with fets if you want high current applications

Yes thats possible 3 leds with flip flop and one extra stage in the counter possible

You can form an oscillator from the bjt but why would you if you have a 555 Something doesent make sense here at all in fact if you want the truth I think your teacher is trying to find out whos cheating Thats what this sounds like

An opamp you would use to form eithet a square wave oscillator or sine wave oscillator A bjt gives a triangular waveform and a 555 is either astable, bistable, triggered or pwm modulator

So there is only one answer to this its flip flop using fets with extra stages more or less the same as you would a transistor flip flop with additional stages with feedback

How about finding the circuitry of 555 timer and using op-amp and transistor to make a 555 timer?

If you want a really interesting method of achieving this circuit use a ring counter employing ldrs "LIGHT DEPENDENDANT RESISTORS AND LEDS AND FETS"

Here is a link in the meantime for fet flip flops

http://www.techlib.com/electronics/flipflopflash.htm

Here is another little clue for you see attached but you have to think a little bit on this one Think ring counter and think feedback

Weren't me that asked the question

Something like a ring oscillator that sets flip-flops (made out of transistors) ... at least for the first mode, but then, how to get it to switch over to all blinking in unison? I guess the last stage of the ring oscillator could flip the state some how -- perhaps turning on a bistable multi-vibrator that toggles all of the flip-flops at once ... just thinking out loud... well, bed time...

More tomorrow, maybe, unless someone else comes up with something.

OK, just got back from a nice hot shower. nothing like a hot shower to relax the body and allow the gray matter to work. It's so simple. I was expecting this to be horrendosly complex which scared me away from the simple truth,

Concept attached (left some work for you

BTW: R5 and R7 are there merely because I originally had them driving transistors to drive the LEDs, but then realized I needed some sort of two input gate there, so I decided to make it a "black box" for you to figure out (cuz I'm tired and need to get to bed ;)

Those resistors are inconsequential and depend on the type of logic/driver in the box.

thanks guys! you all have been a great help! i'll work on the few suggestions!