Are TS555's really supposed to suck this much?

Well, duh, it's a 555.

John

You're NOT looking at the data sheet for a _TS555_. You have the data sheet for a high-powered version.

No, the inadequacy of current drive stands out to all who can read ;-)

ONLY if you are using feedback from output.

Well, duh! TS555 is a MICRO power version. ...Jim Thompson

It's more that John Larkin is good at electronic design, and has recognised precisely how useful the 555 is - which is to say, not a useful device in most applications.

-- Bill Sloman, Nijmegen

I noticed that too, but did not want to alarm anyone.

Why then is it STILL one of the most widely used chips in existence?

Sloman, you should really get the f*ck out of these groups because your grasp of electronics hovers at just above nil.

Are 555s actually being designed into many commercial products these days? A 555 provides a very small amount of analog intelligence at the cost of a bunch of discrete parts. A 40 cent uP provides thousands of times more functionality with, usually, zero parts and zero cost per added function. Even things like toasters and time-delay relays are digital now.

I used a 555 once in my life, to run a little charge pump to make some negative voltage from +12. I ran the output back to the timing cap through one resistor, avoiding the usual extra parts in the charge/discharge path to get a square wave... something that I thought was obvious but not on the datasheet. I still don't see that configuration very often.

John

ns

ycle

Legacy design. It worked for specifc applications, back in 1971 when Hans Camenzind designed it, and people have been copying these circuits ever since. Not because there isn't a better alternative - there almost always is - but because finding out what the better alternative is, qualifying the new component and explaining to the boss why you've wasted your time solving a non-problem all take time, and while the time is usually well-spent, in the long term, lots of people have more immediate short-term concerns.

ur

Archimedes Lever, you really don't have a clue about electronic design, and you illustrate the point by slagging off people who do. I've got less fancy electronic design to my name than John Larkin, but you've just slagged off both of us for not knowing our business, on the basis that we've criticised the use of an obsolete part with a couple of embarrassing weaknesses.

-- Bill Sloman, Nijmegen

Responding to the entire thread:

Tim appears to be trying to do something that is not spec'd for the device. He should use the discharge pin to power the LED rather than trying to use the output if also using the output as a timing element.

Here is a schematic for him:

VCC = 5V 47 ___ VCC-|___|-. | TS555 V -> RED __ - 10k GND-o| |o-VCC | ___ .-------o| |o-----------' .---|___|----)-------o| |o-------. '------------+ VCC-o|__|o- | | | | --- 100u | | --- '--------------------' | | | GND

Cheap 1.45s period flasher, rcmonsen, Jan 2010

(created by AACircuit v1.28.6 beta 04/19/05

Nice things about TS555s:

Jimmy Neutron and the Fieldster appear to like it.

Bad things about TS555s:

Strange glitchy behavior, noisy on supply, long intervals hard to do, Larken and Sloman both agree that it is a pos (agreement may be a first).

So, decide for yourself.

Regards, Bob Monsen

The designation of "POS" is in the eye of the incompetent user. Some people just can't read a data sheet, then conclude anyway, based on their lack of reading comprehension, that it's not behaving as expected ;-) ...Jim Thompson

mA

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=A0 =A0 =A0 =A047

=A0 =A0 =A0 =A0___

=A0 VCC-|___|-.

=A0 =A0 =A0 =A0 =A0 =A0 |

=A0 =A0 =A0 =A0 =A0 V -> RED

=A0 =A0 =A0 =A0 =A0 =A0 -

=A0 =A0 |

=A0 =A0 =A0 =A0|

=A0 =A0 =A0|

=A0 =A0 ...Jim Thompson

=A0 =A0| =A0 =A0mens =A0 =A0 |

=A0 | =A0 =A0 et =A0 =A0 =A0|

=A0|

=A0 =A0 =A0 |

quoted text -

I just want to interject a tiny dose of sanity when it comes to relying on datasheet specs.

It doesn't happen very often, but I think we've all been burned by errors and omissions (some would say outright lies!) in manufacturer's datasheets. Last time it happend to me, I could not for the life of me figure out why an Atmel 8051 derivative's on-board oscillator would not start reliably. The datasheet CLEARLY said 30pF for the crystal caps at that frequency.

But Jim's point is valid. How does the saying go? "It's a poor workman who blames his tools." Substituting the nouns as appropriate.

"CD4001 will drive a damn LED"

Take a scope and check the damn CD4001 output loaded with LED.

I never use the same pin for load and feedback.