Tach filter
Thread Starter
Drifting
Joined: Jun 2000
Posts: 1,476
Likes: 1
From: Mt Juliet TN
Tach filter
While I was dinking with my intake this weekend trying to figure out another problem my tach stopped working. I think I fried my tach filter. It wasn't bolted in right and it probably got too hot. Can I just bypass the thing? I know they don't make replacements but is it really needed with shielded plug wires. How bout an msd? Is there a way to plug it into the tach output of an msd6a? Just curious.
Le Mans Master
Joined: Aug 2000
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From: Semper ubi, sub ubi
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Re: Tach filter (TTop Tony)
The tach filter isn't there just for shielding from stray ignition sources. It is a capacative filter designed to take out spikes from the tach source. They are available from several sources but sort of expensive. You can build your own for about $4.00 and 20 minutes of time. They are very simple circuits. I am going to attach a schematic, that was originally posted by Zwede(I think!!) I have built several filters for people and they work great. One fellow I work with built one small enough to fit in the original case, he then filled the ends of the case with epoxy and it is indistiguishable from the original. He drilled the old case out with a dremel tool. Good luck.
Thread Starter
Drifting
Joined: Jun 2000
Posts: 1,476
Likes: 1
From: Mt Juliet TN
Re: Tach filter (Smokehouse69)
Interesting I thought it was literally just a filter. I'll give it a shot I'm not an electrician but the parts seem cheap enough to give a shot. Thanks smokehouse.
Le Mans Master
Joined: May 1999
Posts: 6,692
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From: Texas
Re: Tach filter (TTop Tony)
OK, could somebody read the above schematic for me and tell me what sort of resistor I should buy at Radio Shack if I wanted to fabricate my own filter. And, the epoxy that the resistor should be encased in - is that any special type of expoxy or would something like JBWeld do OK.
Thanks. Glad I could keep this topic alive :crazy:
Thanks. Glad I could keep this topic alive :crazy:
Thread Starter
Drifting
Joined: Jun 2000
Posts: 1,476
Likes: 1
From: Mt Juliet TN
Re: Tach filter (Larry82)
Unfortunatly I'm not an electrician so I can't be of too much help. I found someone who's going to try and resolder the ends on mine and hopefully it will be OK. Otherwise I'm in the same boat. I was hoping the guys at radio shack could help out. Just print out the schematic and show it them. You never know.
Instructor
Joined: Jan 2000
Posts: 163
Likes: 0
From: Fullerton CA
Re: Tach filter (TTop Tony)
When my turn signals are activated, I've noticed that my tach needle bounces 100 RPM to the rhythm of the turn signal blinking. Is the problem that this filter is bad?
Le Mans Master
Joined: Aug 2000
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From: Semper ubi, sub ubi
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Re: Tach filter (Smokehouse69)
Okay,
Here's the parts list, spelled out and explained.
You need two capacitors as follows...
1 .10 Microfarad
1 100 Picofarad
You need two resistors
1 5.6 Kilo Ohm
1 10 Kilo Ohm
Actually these are very forgiving circuits, if you can't find the exact values for the parts, you can substitute others of a fairly close value. If all you can get is a .20 or .30mfd capacitor, get it, it will work. The same thing goes for the other parts.
In fact this circuit is really a little overkill, an even simplier single capacitor design would probably do just as good a job.
Good luck!
Here's the parts list, spelled out and explained.
You need two capacitors as follows...
1 .10 Microfarad
1 100 Picofarad
You need two resistors
1 5.6 Kilo Ohm
1 10 Kilo Ohm
Actually these are very forgiving circuits, if you can't find the exact values for the parts, you can substitute others of a fairly close value. If all you can get is a .20 or .30mfd capacitor, get it, it will work. The same thing goes for the other parts.
In fact this circuit is really a little overkill, an even simplier single capacitor design would probably do just as good a job.
Good luck!
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Thread Starter
Drifting
Joined: Jun 2000
Posts: 1,476
Likes: 1
From: Mt Juliet TN
Re: Tach filter (Smokehouse69)
You know smokehouse you have always been a virtual cornicopia (sp) of information. It seems like every stupid post I've ever made you've been there with a more then helpful response. I'm not kissing up I just thought I'd let you know I for one appreciate it.