square wave oscillator

This is a simple square wave oscillator using a 4011 NAND chip, you could of course use the TTL equivalent as well.

Adjusting the resistor values will adjust the mark/space ratio of the square wave output

Schematic

Sqaure Wave Oscillator

Parts List

QTY  PART-REFS           VALUE                           
---  ---------           -----                             
Resistors
---------
1    R1                  100k                                              
1    R2                  22k                                               

Capacitors
----------
1    C1                  10nF                                              

Integrated Circuits
-------------------
1    U1                  4011                                              

Diodes
------
2    D1,D2               1N4148