LED Pulsating\Dimming with 555 Timer

Wendy

Joined Mar 24, 2008
23,415
Try removing the cap on pin 5, leaving pin 5 open. It is optional anyhow. Voltages. Assuming the battery is 9V (bad assumtion, 9V batteries are pretty unstable over the long term, but the 555 is designed not to care), pin 5 is 1/3 Vcc, or 3V. Pins 2 and 6 (same point) are between 1/3 and 2/3 Vcc, and should be shifting, and Pin 7 is higher than pin 6, until it conducts (1/2 of the cycle) and it goes to ground. It is possible that pin 7, which is a switch, is blown, a common problem.

This article, CMOS 555 Long Duration Minimum Parts LED Flasher, shows how this oscillator works. Other than not having a LED resistor (which is a specific property of the CMOS 555 and low battery voltage) it is very similar to your circuit.
 

Thread Starter

Rudster816

Joined Aug 18, 2009
10
Somehow I got it to work. There blinking just like they should, the 555 isnt heating up, and I removed the .01uF cap from the circuit. :D

Now I just got to add the fading circuit back on and get that working. :)
 

Wendy

Joined Mar 24, 2008
23,415
I've heard more than one person talk about bad protoboards. Just be aware, and keep an eye out for shorts, possibly using a meter on a circuit without power to look for something like it on adjacent strips on the protoboard. Pain in the arse, but there it is. Knock on wood, I haven't seen it personally. I have noticed the quality of them is dropping on some makes/models (notably the smaller ones). The chips and parts just don't fit as snug as the older models.
 
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