Why is my 555 Timer not blinking?

[vk6kro]

That's right. There is a lot of interest in these chips.
Look at the views on the main page too. Currently 1061 views.
We covered some good fault-finding techniques, so hopefully it was educational, at least.

 

[ShadowPho1]

That question was asked way back in the thread. Yes it does.

Then something is horribly wrong with the chip, power supply or the breadboard. :)
Do you have a different 555 chip you can use?
How far do you live from Chicago? (I can test one and send you one if needed lol)

 

[vk6kro]

Driving to philly, I'll be back in 2 hours perhaps. (post #32 in this thread)

Guess this means Philadelphia. About 666 miles from Chicago.

It would be good if you could get the breadboard sent to you so you could tell us all what the problem was.

 

[Twinfun2]

If the chips get hot with just the supply voltage on them, then the chips are probably faulty. You can't fix faulty chips.

Good news about the Picaxe kit. Amazing chips and a great programming language. Which one did you get?

28X1

Ok, well as it seems by you guys that this thread is of high concern, I guess I'll keep on trying.

What I think I did was when I plugged in my new 555 timer into the approved circuit a few posts back, I had the same problem, in which I am sure has burned my new 555 timer. I am here left with 3 burned 555 timers. What I am thinking of doing now is trying to build a monostable circuit instead of an astable circuit; the monostable circuit I tried worked fine in driving a PnP Transistor to make a police siren. I will have to go to Radio Shack to get another timer, or maybe even try to turn in the 555 timer I just burned, saying that it came defective.

I'll try my best to get this to work!

 

[Redbelly98]

Since you have had a working monostable circuit, it sounds like a good idea to go back and build it again. After you get it working, I'll suggest:

Put your LED+resistor on the output of the monostable circuit, and make sure that works.

See if the LED monostable circuit works with just 3V Vs. If not, try 4.5V. Using a lower Vs will at least not heat things up as much, and might save on frying more chips in the future.

Then, leaving the chip in place, change the monostable circuit into the astable one.

Also, you might try buying 2 or 3 555's, instead of just 1. Don't know how much they cost or what your budget is like, so that's really up to you.

 

[vk6kro]

Probably, R... Shack have a bad batch and they are selling them to you already bad. There was nothing wrong with your circuit.

Could you get a couple from somewhere else or (better option) get the CMOS ones? They cost the same at Radio Shack and you can have resistors up to megohms in resistance.

With CMOS ones, you can have a simpler circuit. You leave pin 7 unconnected and take a resistor to pins 6 and 2 from the output pin, pin 3. Gives a 1:1 square wave so that is fine for a flashing LED.

Maybe get a 10uF tantalum capacitor. Electrolytics can be a bit leaky when used as timer components.

 

[chroot]

Well, most semiconductor companies keep their product output at a failure rate of less than 10 parts per million, so it would be literally incredible for an entire batch of parts from Radio Shack to be bad.

I strongly suspect something is just wrong with the breadboard, and the nets need to be ohmed out (tested for continuity) and the currents through the important pins need to be measured. With that info, we could positively identify the problem as a bad breadboard.

- Warren

 

[vk6kro]

I would have to agree about the reliability of semiconductors. I have never proven a new IC to be faulty although I did get some diodes that were marked the wrong way around.

However, chips that get hot when the power supply alone is connected are faulty. Do you buy more chips from the same place just to prove the point?

We have already suggested wiring up the circuit with soldered joints and not using the breadboard. That is what I would do and I'm sure it would be working in 10 minutes.