View Full Version : 555 Timers

03-23-2010, 12:29 PM
Is there a difference in the 555 timers that are used in most projects? I was looking to purchase some and I noticed there are NE555 Timers and just 555 Timers.

I will probably be doing a lot of posting of questions over the next few weeks, I am having Titanium anchors put in my shoulder this week and will be out of work for a whike and can not do any heavy lifting, so I plan to be working on several projects that I had set aside because of a lack of time. Looks like I will have plenty of time to do some soldering and get some of my ongoing projects completed. Thanks for the help.

03-23-2010, 07:34 PM
On the bottom of the following link, it shows different ordering·designations for 555 timers. (Different packages, operating temperatures, etc.)


For example·you might want a less rugged chip (and less expensive) for use in someone's living room, but more rugged for use outside in the desert or on the north pole.

03-25-2010, 03:05 AM
XLNT info on 555/556 at http://www.kpsec.freeuk.com/555timer.htm

·"If you build it, they will come."

03-25-2010, 04:04 AM
And another...www.unitechelectronics.com/NE-555.htm (http://www.unitechelectronics.com/NE-555.htm)

- Stephen

Tracy Allen
03-25-2010, 05:44 AM
There is a dividing line in the 555 world, between the classic design with bipolar technology and ones made with CMOS technology. Basically the same circuit, same pinout, same functionality. You can usually distinguish the part numbers, because the CMOS versions have a "C" or a "7" before the 555, as in TLC555 or LMC555 or ICL7555. The web sites cited above probably mention those. The CMOS versions have a number of advantages, such as lower power requirements for battery power, and higher input impedance, and rail to rail output swing. Check the power supply ratings of whatever you buy. Some of these can operate over a wide supply range, as low as two Volts and as high as 20 Volts. Also look at the upper frequency limit if you plan to push it in that direction.

Tracy Allen
www.emesystems.com (http://www.emesystems.com)

03-25-2010, 12:10 PM
Hey, Thanks for all the great info. I see the one that the one that comes with the BoeBot is the LM555CN, so I "assume" that would be a safe way to go????