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LED Problem

Sounds to me like you are getting false triggering of the 555s due to noise on the power supply. There are a few solutions I might offer, none better than the other.

  1. A large (1000 uF or so) electrolytic capacitor directly across the battery.

  1. A small value (100 ohms or so) resistor in series with each 555 power lead bypassed on the 555 end with a moderate (100 uF or so) electrolytic capacitor.

  2. A small power diode (1N400x or similar) in series and a capacitor as in suggestion #2. With this one, you might be able to get away with only a single diode and capacitor and all three 555 power leads tied together.

Jim

Reply to
RST Engineering (jw)
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  1. A small Power Inductive Bead (330 ohms, 2mm x 1mm). We use them for on-board switching regulators. You might want to find something bigger in size.
Reply to
linnix

I am having a problem with a LED project I designed. I have 3 leds flahing at different rates. I am using 555s to do this. The circuit works fine by it self but the problem I am having is when I hook up a small DC motor to the batterry used as the power source. When I power the dc motor the Led blinking rate speeds up out of control. Is there anyway I can correct this. I would really like to use the 9V battery for the power source for the DC motor and 555 led timing circuit.

Your help is appreciated.

Randy Joseph

Reply to
Randy Joseph

You've got a couple of good replies already. Do you have an oscilloscope? If so, probing the power pins on the 555's might be worthwhile to help understand what kind of filtering would work best.

--Mac

Reply to
Mac

Will you people please stop top-posting? You can see how it screws up the continuity of the thread! (I used to top-post, but I've been *SAVED*! ;-P )

Anyway, I'd put some .001 uF (1 nF) or .01 uF (10 nF) capacitors from one motor lead to the other, and one from each motor lead to the motor frame, and I'd see to it that the leads, both power and ground, are separated right at the supply, so that the 555s and motor don't share any supply current paths.

All of those other suggestions are good, too. :-)

Good Luck! Rich

Reply to
Rich Grise

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