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LED circuit board

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New Member

I'm new to this board. I do need some help with a small project using LED's.
I got this idea from a toy sword I bought my son at a circus. It had 18 LEDs soldier together in parallel ( one on top of another) looked kind of like a ladder. This sword worked on three AA 4.5 battery. It would just turn on and off. After my son had no interest in it I took it a part to see how it was design. I didn't see in resistor unless it was in the on/off switch. one wire run to the + and the ground to -.

Now, I'm making two small caution lights that can work on 3v or 4.5 using these lights. The LED are red and rated @ 2v each. I have carefully coiled the LEDs and hot glued them in a 4" lens with only have two wires going down into the project box to the battery pack. It will light up the lens very bright just like it did in the sword. I now want them to flash like a caution light at a road construction site. This is were my problem is. I have looked at a lot of 555 timer circuit but they are for one or two LEDs. I need a flasher board that will work these 18 LEDs wired in parallel and off 3v or 4.5.



Well-Known Member
Most Helpful Member
Three AA alkaline cells can provide 3A at 2V. If you have 18 LEDs and if they are exactly the same, each will pass 167mA which is way more than their max allowed current and some will burn out then the remainders will burn out. Current-limiting resistors are important.

The minimum supply for a 555 is 4.5V but the battery voltage will qhickly drop to less.
The minimum supply for a Cmos 555 is 1.5V and it can drive transistors to flash the LEDs.


New Member
I can use up to a 9v battery because it's small to fit my project box. I'm looking for a good easy design I can use to build a board from.
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