555 Easter Egg?

[Lancelot59]

I frequent the community around the Electronics Engineering Video Blog. Apparently the host Dave Jones found a neat little quirk.

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A member of the forum confirmed that it worked on the CMOS version, only if the voltage was 7.555V too.

What do you folks think?

[Antiphon]

A big load of BS.

[Lancelot59]

A big load of BS.
Any particular reason?

[Antiphon]

This is more astrology/numerology than circuit analysis. The 555 has way more than 5 resistors in it. And odd behavior at 7.555 volts? Come on. There isn't a bandgap reference on the planet that is that reproducible let alone a CMOS IC. Neighboring 555 chips sawed out of the same wafer don't have tolerances that would permit them to act funny at 7.555 volts but not elsewhere. And at what temperature? It would take more transistors than are in a 555 to make a circuit that could recognize 7.555 volts in a temperature-independent way. You're in crystal oscillator territory for accuracy (7.555/7.554=132 parts per million). No silicon chip is that tight.

Edit: I'd bet $100 that no two random voltmeters would agree on where 7.555 volts actually is unless they were both recently calibrated to same reference.

[Lancelot59]

This is more astrology/numerology than circuit analysis. The 555 has way more than 5 resistors in it. And odd behavior at 7.555 volts? Come on. There isn't a bandgap reference on the planet that is that reproducible let alone a CMOS IC. Neighboring 555 chips sawed out of the same wafer don't have tolerances that would permit them to act funny at 7.555 volts but not elsewhere. And at what temperature? It would take more transistors than are in a 555 to make a circuit that could recognize 7.555 volts in a temperature-independent way. You're in crystal oscillator territory for accuracy (7.555/7.554=132 parts per million). No silicon chip is that tight.

Edit: I'd bet $100 that no two random voltmeters would agree on where 7.555 volts actually is unless they were both recently calibrated to same reference.

Well the 7.555 was posted, but not shown by a member of the forum. All the video shows is one brand of the regular version.

[Blenton]

Possible that this was the reason for its naming?

[Lancelot59]

Possible that this was the reason for its naming?

That's the idea. Still needs to be checked though.

[Phrak]

YouTube video posted on April First

[uart]

YouTube video posted on April First
Well spotted Phrak. :smile:

I want to know what brand solder flux that guy is using and how much he's inhaling. :eek:

[UR_Correct]

I want to know what brand solder flux that guy is using and how much he's inhaling. :eek:

Holy jeez, I know! He is rather obnoxious.

[MATLABdude]

Like Glenn Beck (or any other really good showman): you control the interpretation, you control the message.

EDIT: Happy April Fooled!

[Averagesupernova]

April fools or not, the reason the 555 is so named is the 3 5K resistors that form a voltage divider to set a bias point on the latch to form the trip points of 1/3 Vcc and 2/3 Vcc.
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To think that something as ancient as the 555 would have an easter egg is beyond reason.