What is the schematic for building my own 555 timer IC?

Question

I Just need the schematic diagram and the component values to make this circuit for my digital class.

Answer 1

If you are looking to actually make a circuit equivalent to what is in a 555 timer IC, you will need a set-reset flip-flop (also called a J/K flip-flop), two comparators, some transistors, and some resistors.

This page shows the basic diagram of what is inside a 555:

http://home.cogeco.ca/~rpaisley4/LM555.html

Note that it also has a lot of circuits using the 555, so if you are looking more for a circuit design to build using the 555 then this will help you out as well.

This file shows how the internal comparators are hooked up in a bit more detail, it also has a lot of good detailed information about exactly what happens inside the 555 so you can make more sense of the diagrams:
http://www.fairchildsemi.com/ds/NE/NE555.pdf

Note also that the Flip-Flop shown in these diagrams assumes a logic HIGH to the SET and RESET pins to perform their functions -- if you use something like a 74HC74 flip-flop, the SET and RESET pins are active LOW so you may have to change the connections of the comparators to make it work right.

Now, if you want a really detailed schematic of the 555 there is one in this data sheet:
http://info.hobbyengineering.com/specs/LM555.pdf

but it assumes the availability of some types of transistors which normally are only available inside IC's, not as discrete components. Fortunately they are all parts of blocks which are the flip-flops or comparators so once you work out which is which, you will be able to eliminate them from the design.

Answer 2

For everything you ever wanted to know about the 555 timer, complete with the schematics for a dozen or so different circuits - you've just got to have the Radio Shack "Engineer's Mini-Notebook", Cat. No. 276-5010A.

For a quick list of specs:
Pin 1=Ground
Pin 2=Trigger
Pin 3=Output
Pin 4=Reset
Pin 5=Control Voltage
Pin 6=Threshold
Supply Voltage=4.5-15 Vdc

The Mini-Notebook contains schematics for everything from an infrared security alarm to a sound effects generator - and everything in between.

Answer 3

a 555 timer IC is an Integrated circuit used to time pulses in a circuit. It's called a 555 because that is number stamped on the outside of the casing.

Answer 4

Hello, Sorry. It is true that the 555 can be assembled using discrete components. I did so several times back in the late '70s and the early '80s.
If you find out the answer to your question (and mine!!!), let me know. Thanks.

Sincerely,
[e-mail]

A few trans. caps, resis, and 8 points is all I remember.

Answer 5

Look in Wikipedia for pictures, and links to data sheets.