Building a tachometer for the 250r

Halcyon · February 27th, 2017, 02:47 PM

Hi, all. I'm working on making my 250 into a streetfighter, and would like to design some gauges for them. I know the 250 puts out a 12v square signal, but is it positive, or grounded? Detecting a positive signal is easy enough, but if the 250 puts out a grounded signal, how would I detect it?

MauR · February 27th, 2017, 08:09 PM

If I understand the diagram it is negative signal.

Triple Jim · February 27th, 2017, 08:28 PM

Put a scope on the tach wire and see exactly what it's sending to the tach. It seems to me that when I calibrated my tach, I just put a low voltage square wave on the tach input. The tach is probably AC coupled, with a capacitor on its input, but you should be able to look at the tach circuit board and see for sure. I don't remember it being more than a through-hole board with big, easy to follow traces.

February 27th, 2017, 02:47 PM	#1
Halcyon ninjette.org newbie Name: N/A Location: Virginia Join Date: Apr 2016 Motorcycle(s): ninja 250 Posts: 4	Building a tachometer for the 250r Hi, all. I'm working on making my 250 into a streetfighter, and would like to design some gauges for them. I know the 250 puts out a 12v square signal, but is it positive, or grounded? Detecting a positive signal is easy enough, but if the 250 puts out a grounded signal, how would I detect it?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Ninja 250R tachometer problem. Please help	kabanashvili	2008 - 2012 Ninja 250R Tech Talk	2	August 13th, 2016 03:07 PM

February 27th, 2017, 08:09 PM	#2
MauR ninjette.org member Name: Mauricio Location: Mexico City Join Date: Aug 2015 Motorcycle(s): 250R Posts: 84	If I understand the diagram it is negative signal.

February 27th, 2017, 08:28 PM	#3
Triple Jim Guy Who Enjoys Riding Name: Jim Location: North Carolina Join Date: Jul 2016 Motorcycle(s): Ninja 250 Posts: A lot. MOTM - Oct '18, Aug '17, Aug '16	Put a scope on the tach wire and see exactly what it's sending to the tach. It seems to me that when I calibrated my tach, I just put a low voltage square wave on the tach input. The tach is probably AC coupled, with a capacitor on its input, but you should be able to look at the tach circuit board and see for sure. I don't remember it being more than a through-hole board with big, easy to follow traces.