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Author Topic: First project: LED chaser....sort of  (Read 2082 times)

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First project: LED chaser....sort of
« on: October 16, 2013, 02:18:52 AM »
I have been seeing all these LED chaser kits and tutorials like this one http://www.youtube.com/watch?v=E_uPQ1oVaVs but none of them do what I want them to do. I am looking for a simple 5-LED light strip that will light each light one at a time till all the lights are lit then all go out and start the sequences again. I also want to regulate the speed they ascend. I have determined I need the following parts but am not sure what the final chip/s should be. I have see people mention a 74ls164 chip and the pic16f628a, but don't think those are what I need. I could be wrong but I am not sure where to go from here. Any advice would be greatly appreciated.

555 timer
1000mf capacitor
2n222a transistor
150om resistor
1200om resistor


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Re: First project: LED chaser....sort of
« Reply #1 on: October 16, 2013, 09:02:21 AM »
Hello ronhancock,

PIC is the ticket for you. Do you have any previous experience with PIC micros? They are programmed in C or assembly (usually) and you can do miracles.
You can still go with 74-series chips (like the one you mentioned) but you will need half a dozen of them to make your circuit (well maybe 2 or 3 actually).

Get a BCD counter (i used to work with the CMOS 4518). The timer of the counter goes to the 555 pulses. The same timer must be applied to the 74ls164 clock input. The D output of the BCD is 8 pulses HIGH and 8 pulses LOW. So you connect this output to the A and B inputs of the 74ls164. Your LEDs goes to the 8 outputs of the 74ls164 with proper resistors. Enjoy.

PS you may have to add a NOP gate between the 555 timer and the clock of the 74ls164. So that the CD4518 increases on LOW to HIGH clock, and the 74ls164 shifts on HIGH to LOW. Yeah, now that i think of it, add some NOP gate. Get a quad 2-input NAND gates. Connect the two inputs of each NAND together and there it is! You have a NOP gate.