What is a CMOS 555? Different from ne555?

[Will.mendil]

Hi,

I would like to attempt the uglyface from home wrecker. They use a cmos555 chip. Is a ne555n (if I remember correctly) ok? What does CMOS stand for?

[Will.mendil]

http://www.super-freq.com/wp-content/uploads/2007/07/uglyface_mix.gif

[R.G.]

The 7555 and a few other versions use CMOS parts inside to do the same functions as the NE555 bipolar version of this timer. The reason the CMOS versions were developed is that the bipolar versions are power hogs, and cause big (1.2A or more~!) spikes on the power lines when they switch.

There are applications where the high power of the bipolar 555 is useful, but in general pedals are not among those.

[PRR]

I know this one!

> What does CMOS stand for?

Complementary Metal Oxide Semiconductor.

Rust that says nice things?

You can control current through a semiconductor either by putting a junction in the middle or with a control electrode on the side. If you really care, there are books.

The classic 555 is done in junction transistors which can dump BIG current to smack lamps or relays. It was designed without a customer or market, so it was built beefy in hopes someone would use it for SOMEthing. Maybe washing machine valve solenoids? (It turned out to be maybe the #1 or #2 most popular chip of all time, but was widely copied, and I don't think Hans ever got more than a few bucks from it.)

Commercial CMOS is tuned for low-low power, not as muscular.

Sometimes you can use one or the other.

Looking at that plan, there's a hint(!) that the CMOS part may be better.

[blackieNYC]

BTW, just pulled an uglyface of the breadboard and I'm stuffing a perf board now.  There are mods here you should consider
http://www.diystompboxes.com/smfforum/index.php?topic=68966.0;prev_next=next
Namely, changing the cap value in the freq pot circuit to a lower value for a lower oscillator. The threshold pot - I bagged it and will use a switch because it seems to dial up two states: oscillator on between notes, and oscillator off between notes. I added that 22k you'll see there, but I don't know wtf it does.  I need to add the .001 caps on the in and out as shown at homewrecker. I'm not adding the op amp LFO mod. 

[greaser_au]

From memory, the 555 was considered to be the first real integration* of analogue & digital electronics on a single chip. I reckon I have an older edition of this book:
http://www.amazon.com/Engineers-Mini-Notebook-Timer-Circuits-276-5010/dp/B000MN54A6  at my Mum's place.

I just love this:   http://www.evilmadscientist.com/2011/555-footstool/
david

*   <foghorn leghorn voice> that's a joke, son...

[Lurco]

http://www.diystompboxes.com/smfforum/index.php?topic=80952.0