Isolation blinking LED

galaxy_jason · Post by **galaxy_jason** » Wed Sep 29, 2010 3:48 pm

I am running 4 leds off of two small batteries as well as an LED blinker
from radio shack. When the LED blinks the others dim for an instant due to the inrush current. How can I isolate the blinking LED to eliminate this?

I assume a capacitor of some sort. Battery voltage is 3volts.

I should know this, I have a EE degree but its been a long time since I worked with analog

USS Atlantis · Post by **USS Atlantis** » Wed Sep 29, 2010 6:14 pm

Got a pic and/or schematic

Sounds like the two circuits are linked in some way you're not seeing

Maybe a common resistor

galaxy_jason · Post by **galaxy_jason** » Thu Sep 30, 2010 9:39 am

The only common point is the batteries. The four always on LEDs are connect in parallel, each with its own 100 ohm resister. Also in parallel are the power leads to the little flasher circuit....

http://www.radioshack.com/product/index ... Id=2062571

The blinky chip is on the same little board as the LED. I just cut the wires and istead of using the AA battery box I am using a pair of watch batteries (same voltage) so it will fit in the small model.

USS Atlantis · Post by **USS Atlantis** » Thu Sep 30, 2010 5:09 pm

What I'm thinking is that

1) Watch batteries are designed for constant, steady drain

2) You're introducing a variable current drain to the circuit

3) The watch batteries are suffering a minor overload, thereby causing the dimming effect noticed with the constant LEDs

Solution

Add another pair of watch batteries - 1 pair runs the constant LED's, the 2nd pair runs the blinking circuit

galaxy_jason · Post by **galaxy_jason** » Thu Sep 30, 2010 5:17 pm

I thought about that as well good suggestion. I think I have room, will have to check.

Thanks!