help still confused

Thread Starter


Joined Jul 21, 2008
hi all i have finished this circuit today but still a little confused
i have connected led's with current limiting resistor between the set of pins A and the gates on the irf630's is this correct ??? i would like to know what does the set of pins labled B do on the circuit ??
the circuit is working and the led's ar working in a chaser fashion but randomly has any one any idea why ???


Last edited:


Joined Jul 17, 2007
Those look mighty pointy and dangerous. Maybe you should use a hammer on them to flatten them out before someone gets poked? :)

No, don't do that. ;)

Seriously though, I vaguely remember you posting a slew of schematics when you were trying to figure out how to flash some LEDs in sequence, or something like that.

How about posting that schematic you built the board from, so that we don't have to guess?


Joined Dec 20, 2007
The output of each Mosfet is its Drain, not its gate. An LED connects from the drain to the positive supply with a current-limiting resistor in series with it.

Your CD4017 does not have a supply bypass capacitor so its supply voltage is probably jumping all over the place and randomly reseting the CD4017.


Joined Jul 17, 2007
Oh, the RESET pin is floating - that's why.

I'm guessing what you're calling "set b" is actually J4.

J3 is the single hole next to J4 that you circled in purple.

I'm not certain, because you didn't give a board layout, but the hole next to what I'm calling J3 is probably J15, which is connected to ground. If that is the case, and you want for all of the outputs to operate, you will need to connect J3 to ground, which is J15. If you want only a few of the LEDs to flash and then repeat, you need to select one of the J4 pins to connect to J3 - and in that case, J3 must not be grounded.

If you want to play it safe, connect J3 to J15 using a 10k to 50k resistor. That way you can just add a jumper from any J4 pin to the resistor on J3, and it'll reset whenever you specify.

Your "set a" is probably J4 through J14, the pins that will sink current from the LEDs.