I am trying to find a circuit diagram for a LED tachometer. I want to have a led light up for every 1000 RPM’s. Anyone know were i can find one?

 

that might be cool if you can mount round LEDs right at each 1K mark on the stock tach.

I could thumb through some of my basic digital and analouge text books and jog my memory a little.

a little 'backwards engineering' and I'll have your plans sometime.

 

i would like to do this also but in 100-500 incraments.

Anyone??


Jeremy

 

Palmer, MA? I have family there...

let's start with the tach signal....what is it (electrically)?

 

After searching the web I found 2 designs:

http://www.t-r-j.com/Auto/Tach/tachometer.htm
http://www.niksula.cs.hut.fi/~mdobru...cho/tacho.html

They are both based on LM2917 / LM2907 which is a frequency to voltage converter.

 

cool, no sense in designing something if someone already has.

both designs seem reliable....so, who's going to build it?

 

read the disclaimer on the second link:
"I apologise if the above circuits are not shown correctly. I have checked my design both with the made circuit and the data sheet of the LM2917. If you have any problems then please mail me, but you may find the answers are in the LM2917 data sheet. I was planning on showing the output verses input graph but my circuit doesn't want to work today - the chip seems very easy to blow up and I have had a long day :-(. I'll put up the results when I have obtained them. "

Both designs have not been tested. The first one seems like it would work, may need slight tweaking

 

I'd use a counter and do it digitally instead of messing around with all that analog frequency-to-voltage crap.

 

well, whatever....what's the worst that happens? just start putting it together, if it burns, it burns!


he obviously isn't with it, what a discrace. he does have a parts list and a 'plan' though. Isn't he the one who recomended the potentiometer?

I do remeber one of them mentioned 'common sense' so that plays a big part as well, in any electronic endevour.

I would need to see more info on those components to make it work'on-paper'. So, who's going to brave this project? I don't have any cash so I won't be involved other than to offer comentary.