car RPM meter 2

[ido2]

Hello,


There's this post from Cobra' :
http://www.diyaudio.com/forums/showthread.php?postid=737616#post737616



However I couldn't find the schematics for it, could anyone please help with that ?


Thanks in advance,


Ido

 

[Ron E]

possibly?

http://www.national.com/ds.cgi/LM/LM2907.pdf

 

[ido2]

Thank you for your quick reply.

I have gone through that manual, however I am new to electronics, and Since that schematics over there differs from others I have found on the net, it just gets me confused on how to wire the tach..

I'm currently building by this schematics:
http://www.rollmeover.com/bronco_fab/odds_n_ends/digi_tach_schematic.jpg
but will use only one 3914..

hope it works well.


Also, the person at the electronics store gave me a 2907N instead of a 2917, he said it should also work.
By the datasheet, the difference is a builtin diode. would it also work for me ?