Astable multivibrator.

[bitem2k]

After hours of trawling the web, i have failed to understand how this works.
Could someone please explain it to me (in ultra simplified terms)?

Also whats the point of using a 555 if you can do this?

thanks very much


**broken link removed**

 

[fingaz]

try looking here, this explains in simple terms. . .
**broken link removed**

A 555 can be made to perform many different timing operations, not just flashing led's. try looking up 555 timer on www.google.co.uk to see how it can be used

 

[bitem2k]

Hi fingaz, thanks.
Unfortunately i allready looked at that site. Its the first one that comes up when i google.
I just dont understand the path that the current takes. I cant find anysites with good pictures.

I have looked at 555 timer sites, and have made several circuits involving the 555. Surely the circuit above can be employed for more usefull operations than just flashing leds?

I dont understand the differences between the two circuits.


thanks

 

[Andy1845c]

Try this- go here: https://www.falstad.com/circuit/ when the sim opens, select Astable multivibrator from the transistors menu.

 

[bitem2k]

Thanks mate, I was kind of hoping to get away with not installing the java runtime, ive only just formatted and re-installed everything, and its running sweet.

but ill give it a bash.

 

[bitem2k]

Mate, your a lifesaver!
that apps great.

Cheers

 

[fingaz]

The difference between the two is, the astable can perform only one function. . . to alternate between on and off at a rate determined by the resistors and capacitors.

A 555 can do this, but can do other things too, e.g. wait for a specified time, then turn on. Or turn on for a specified time, then turn off. Or etc etc

Basically, the 555 is more versatile (than the astable transistor circuit), and often just as cheap, or cheaper than using transistors to perform the same task.

 

[bitem2k]

niceone.
thanks for the info.