Hi all, I know this might sound beginnerish but I need a 'Non Microcontroller' circuit that will be like an LED chaser; but stacking the LEDs. It would be good if it could do this with about 9 or 10 LEDs per chip, but it doesnt matter, I want to drive 24 LEDs anyway; so the circuit needs to be stackable. So far im thinking shift registers, but i don't know. If anyone has done this before, or has some help for me, please help me out.
I have. That is, if you mean what I think you mean. I have done it several times using something similar to the enclosed diagram. ( note that this is not the actual diagram I used, it's one I've just thrown together to give you the idea )
Have the 555 as a clock pulsing the first 4017, counting from 1 - 6 then moving the second 4017 on 1 then resetting. When the second 4017 counts past 4, it resets. 4 x 6 = 24.
Put "555 4017" into google for example circuits of chasers.
Hey dch222,
Thanks for that. im not very good with shift registers, do you know any good sites? Is the 74HC595 what I need? Its the only shift reg. my supplier stocks.
thats good to hear, i will need power on reset. what is this? and how do i do it? any websites to help me out with shift register stacker? or just the chip itself?
thats good to hear, i will need power on reset. what is this? If you don't know what it is, then how do you know you need it?
I explained what it is in my post. It means that the LEDs will start in the all off state rather than a random state.
and how do i do it? any websites to help me out with shift register stacker? or just the chip itself? Just read the data sheet of the 74HC595. It explains how the IC works.
What I described is for 8 LEDs. So if you only need 5 as per your initial post, then take the output from Qe not Qh.
You will need 2 ICs, the 74HC595 and a 74HC14.
The 74HC14 will do the inverting and the oscillator functions. And if you really need "power on reset" then you will need a diode and a resistor wired as an OR gate and a capacitor and resistor for the timing.
for the whole thing, or the POR? I think ive got the POR figured out; can you read switcherCAD 3 files? (attached in SwCAD format) Either way, that would be really appriciated.
yeah, sorry; it was whatever I could throw together at the moment. I would have thought it would be good enough for this kind of application. Thanks anyway for the circuit. It really helps out.
yeah, sorry; it was whatever I could throw together at the moment. I would have thought it would be good enough for this kind of application. Thanks anyway for the circuit. It really helps out.
Well, I need 24 LEDs (3chips) I need them to be the high-intensity blue or green ones, but they will be driven at a very low current (~6mA). I need them about 5mcd.
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So I assumed you only wanted 5 LEDs.
But after reading your post above and your original post you said 24.
So do you want them to be as above but with 24 LEDs? In other words, you want to start at 0 ie. no LEDs lit, then 1, then 2 etc until you have all 24 lit?
To check, I suggest you connect one in series with a 330 Ohm resistor and connect it across 5 Volt and measure the LED voltage. If it is 3 Volt, then 330 Ohm will set the current at about 6 mA. Iled = (5 - Vled)/R
Attached is the basic circuit, configured for 4 LEDs. You may wish to build and test this one before making the full 24 LED version.
I have not included the POR. I have chosen C1 and the 10 M to make the oscillator frequency about 1 Hz. If you want a different frequency, change C1.