Noisey tach signal

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fvracer27
Posts: 247
Joined: October 25th, 2009, 8:40 pm

Noisey tach signal

Post by fvracer27 »

Anyone running Data systems having any problems with a noisey Tach signal?
Mark Filip
NER #27
Womer EV-3
FV80
Site Admin
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Joined: June 27th, 2006, 9:07 am

Re: Noisey tach signal

Post by FV80 »

They're ALL noisy. I installed a magnetic pickup on the front pulley and .. amazingly it was JUST as noisy as the original signal from the coil. I also added the "filter pack" from AIM - guess what .. Still the same noisy. Digital filtering (in AIM) helps, but it's still messy. MPH looks pretty good comparatively.
I've learned to average "in my mind" :mrgreen:
Steve, FV80
The Racer's Wedge and now a Vortech, FV80
To sign up in the FV Registry for updates about SCCA Formula Vee, please send me an email or PM with your name, location (city/state), make/model of car, phone # and any other appropriate info.
fvracer27
Posts: 247
Joined: October 25th, 2009, 8:40 pm

Re: Noisey tach signal

Post by fvracer27 »

FV80 wrote:They're ALL noisy. I installed a magnetic pickup on the front pulley and .. amazingly it was JUST as noisy as the original signal from the coil. I also added the "filter pack" from AIM - guess what .. Still the same noisy. Digital filtering (in AIM) helps, but it's still messy. MPH looks pretty good comparatively.
I've learned to average "in my mind" :mrgreen:
Steve, FV80

Steve I have a magnetic pickup I was going to put on the front pully as well but I wanted to ask first. Under acceleration it's pretty good but as soon as I lift off the throttle I get spikes of 8k to 9k. I put a AIM filter cable on and it filtered the entire signal out and I had not tach reading. I was hopping the magnetic pickup type would work. Care to share how you installed the pickup to the engine and the magnet to the pully?

thanks
Mark Filip
NER #27
Womer EV-3
brian
Posts: 1348
Joined: June 26th, 2006, 12:31 pm

Re: Noisey tach signal

Post by brian »

every filter is specifically designed for the system involved. The AIM works best for AIm systems. If you use a mag halo system off the pulley install a 450ohm resistor between the positive and negative leads and it will steady the sytem down. The halo system works best with a constant load.

I always use noise suppression plug wires. Buy a good quality v8 set and do two motors.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
FV80
Site Admin
Posts: 1168
Joined: June 27th, 2006, 9:07 am

Re: Noisey tach signal

Post by FV80 »

fvracer27 wrote:
FV80 wrote:They're ALL noisy. I installed a magnetic pickup on the front pulley and .. amazingly it was JUST as noisy as the original signal from the coil. I also added the "filter pack" from AIM - guess what .. Still the same noisy. Digital filtering (in AIM) helps, but it's still messy. MPH looks pretty good comparatively.
I've learned to average "in my mind" :mrgreen:
Steve, FV80

Steve I have a magnetic pickup I was going to put on the front pully as well but I wanted to ask first. Under acceleration it's pretty good but as soon as I lift off the throttle I get spikes of 8k to 9k. I put a AIM filter cable on and it filtered the entire signal out and I had not tach reading. I was hopping the magnetic pickup type would work. Care to share how you installed the pickup to the engine and the magnet to the pully?

thanks
Mark,
I no longer have it installed... but I drilled/tapped a hole in the pulley and screwed a magnetic 'puck' into it (with a lock nut behind it). My battery is mounted (more or less) just in front of the pulley, and I have a CLAMP (BIG hose clamp) to tie the battery down. I loosened the clamp and slid a small piece of 1/8" plywood between the clamp and battery. I mounted the mag sensor on that piece of plywood and "adjusted" it so that the clearance between the magnet and sensor was "appropriate". It worked OK .. until I went off track or something and JARRED the >***> out of the car, sometime creating an "interference fit" between the 2. I never tried filtering the Mag input - just the one from the tach. In the end, the results did not seem to justify the effort, so I took it all out. In my case, I ADDED the mag input so that I could compare it to the coil signal. There was not enough difference to justify the effort. I decided that I just couldn't rely on the 'max/min numbers .. so I just run an average in my head when I look at the data.

Steve, FV80
The Racer's Wedge and now a Vortech, FV80
To sign up in the FV Registry for updates about SCCA Formula Vee, please send me an email or PM with your name, location (city/state), make/model of car, phone # and any other appropriate info.
AJP
Posts: 41
Joined: February 20th, 2008, 9:10 pm

Re: Noisey tach signal

Post by AJP »

Mark,
We solved the noisy tach signal problem with a magnetic sensor as well. In our case it worked very well. Fabbed a bracket that attached to the case and hung the sensor in front of the pulley, spaced properly from the magnet installed on the pulley.
The sensor is also the same as a wheel speed sensor that some folks already use.
http://www.digikey.com/product-detail/e ... -ND/280930
You should at least try the one you have.

I'll be using the EVO4 in the future so I'll let you know how it goes as I plan on using the same sensor.
The RLC dash/data unit I was using crapped out and they wanted too much to fix it. I've never been really happy with it and figured I would put money towards a company that offers real support for their customers. Got a used EVO 4 and am now looking for a display. (not that you should care:))

-Andy P.
fvracer27
Posts: 247
Joined: October 25th, 2009, 8:40 pm

Re: Noisey tach signal

Post by fvracer27 »

Thanks for the input guys

Andy I use a evo4 with a mycron display

I spoke with Dave from Veracity Racing Data he has a mag sensor with a resistor in it to make it work so I'm going to try and fab a bracket this week and hopefully Ill get a good reading.

Ill report on results
Mark Filip
NER #27
Womer EV-3
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