Hi, newbie here, madmen can i have you full circuit diagram? i would like to build also a tacho for my bike. Thanks

 

Welcome to the forums.

You grabbed an old thread - http://forum.allaboutcircuits.com/showthread.php?t=16291 - so now you have your own.

There are several schematics in that thread. The original intent was for a voltage indicator. Maybe you could tell us what your specific interest is?

 

What type of bike are you trying to attach the tachometer to?
Are you replacing a tach, or is this from scratch?