problems with 555 timer.

Post a link to your schematic, if possible (on a personal website).

Try building this circuit to test your 555 (maybe it's burned out?)

Michael

wrote

get

Then there is something wrong with the 555. As long as you have correctly identified pin numbers 1 and 8, then applying power should not result in a large current draw.

Check here:

everything

would

Try another 555.

Please send us your schematic.

Not the web site schematic, the schematic of the thing _you_ wired.

PS: maybe your in the wrong hobby.

Very little information to go on, but i'll give it a shot..

It does sound like something is shorting out. what schematic are you working from exactly? also make sure you have the capacitors connected the right way around as specified in the schematics. If you do have a picture of how you've wired it all together too, and can post it on the web somewhere that would be very helpful.

What light are you using (the one you want to blink) as its possible it's drawing too much current. A 1KOhm resistor in series with an LED on the output draws very little current and is a good indicator of wether it's working.

Is the chip the right way around, and also is your understanding of the pin layout correct, it should be as follows: _____ [1]| u |[8] (+) [2]| |[7] output==[3]| |[6] (-)=[4]|_____|[5]

there's a very basic circuit on my site for a 555 astable timer, although you've probably come across the design before (it's quite popular as a beginners model)

Although the schematic states 12V, the circuit should operate at any voltage in the range +5v to +15v

a good starting point is to use a 220uF capacitor for C1 and R1 and R2 as a 2KOhm resistor for R1 and a 5KOhm resistor for R2, that should give you an on time of about 1 second and an off time of about 0.7 seconds.

If all else fails, your 555 chip could be dead. do you have a spare to try it out with?

Regards, Mark

Naa, if your response to seemingly insurmountable, unexplainable problems is to keep trying then you're definitely cut out for electronics.

EEK! I put the (-) terminal in the wrong place. Should be:

also notice the little notch at the top of the chip

My bad!

Mark

This is the schematic... the basic astable 555 that I know and hate.

Maybe I shorted it out somehow, today I'm going to buy another 555 and try it again.

For now.. can you guys tell me if this should happen?

(-) 1 | u | 8 LED (+)

negative to pin 1, pin 8 to LED to positive. Nothing else is connected anywhere.

The LED turns on very bright... is this proof my 555 is toast?

Thanks for the help... if I have more trouble I'll post pics.

Thanks,

-sam

Since you probably cannot read a schematic, could you post a link to a close up photo of what you have built?

Luhan

Why are you connecting the LED to pin 8 (+)?

pin 8 should be the +v source for the 555 and should be connected direct to the +9v supply. If you put the LED where you said you have then the

In message , dated Mon, 14 Aug 2006, snipped-for-privacy@gmail.com writes

It's a very good site BUT it's far too comprehensive for a beginner.

Look at Figure 5, that is the thing to build. You can study all the rest AFTER you've got Figure 5 to work.

Yes, your 555 may be dead. They are difficult to kill, but it can be done.

Mark, this wasn't part of my schematic... I was wondering if this proves that my 555 is broken or not.

I am in fact new to electronics, but I don't expect the below schematic to magically cause an LED to blink.

-sam

Mark Fortune wrote:

The proper newsgroup for questions like this is sci.electronics.basics

Besides, if you are asking about timers here, the proper solution is generally a microprocessor.

Michael

In message , dated Mon, 14 Aug 2006, snipped-for-privacy@gmail.com writes

Probably, but without knowing how you have connected the other pins, we can't be sure.

You are getting some rather abrupt responses, which don't help much. This is because you are really in the wrong newsgroup. You should be in sci.electronics.basics

However, now you ARE here, we will try to help. Have you built that Figure 5 circuit? If so, tell us what happens.

In message , dated Mon, 14 Aug 2006, Michael Black writes

Oh, no! Not another one. 555 timer, what, 50 cents all up? Time to first blink 30 minutes maximum, if you don't goof.

Microprocessor timer 10 cents for the chip, USD100 for the development system and four weeks to learn to program it.

But then you can make it blink in Morse code!

I use both, but each in it's appropriate spot. If _all_ you need is blinky, a 555 is the way to go.

Not to mention that this "to 555, or not to 555" question may lead to a life-changing decision for a promising, heroic electronics designer eventually slipping away into the evils of software programming and the corrupting influences of its dark minions. ;)

Jon

If you were really good, you could make it flash in Morse code with some 555s! ;-)

You're right! When will people learn that you really do have to add some bleach when they wash their minions? ;-)

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