Topic: Electronic Tachometer filter
in Forum: C3 Electrical
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WOW!!
I'm curious as to where you found that! (Besides CF, that is...)
That appears to be an original spec drawing for GM...
I'm curious as to where you found that! (Besides CF, that is...)
That appears to be an original spec drawing for GM...
Joel Adams
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Yelm, WA - USA
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Vette(s): 1979 L82 4 speed Scat 383 crank 190 cc Procomp Aluminum Heads 202 160 stainless valves GM Powder metal rods Speedpro H860CP Hypereutectic pistons 280 cam hydralic HEI Pro comp 1.6 roller rockers Mighty Demon 750 Sanderson CC1AP Hedders.
[QUOTE=Adams' Apple]WOW!!
I'm curious as to where you found that! (Besides CF, that is...)
That appears to be an original spec drawing for GM...[/QUOTE]
I'm curious as to where you found that! (Besides CF, that is...)
That appears to be an original spec drawing for GM...[/QUOTE]
Gotta love the internet! 
I just googled corvette tach filter schematic and bam!
I just googled corvette tach filter schematic and bam! Former Member
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Charleston AFB, SC - USA
Joined: 10/31/2007
Posts: 111
Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
Holy crap Ecklers charges $30 for that 
defsegx 2007-12-30 10:26:54
I could make 30 of those for $3 with parts I already have here. Actually my tach just started bouncing, I'm gonna make one for myself anyway.
[Quote]
I found a schematic online for a tach filter but I'm also gonna get the cheap one from ecklers and disect it. If all it is are too resistors inline I'm gonna be upset for paying 30 bucks for one, but if that's the case I will probably start making my own and selling them if anyones interested.
[/quote]
It's more than just 2 inline resistors, but not much. If you look at the schematic, it's just 2 low-pass filters inline on the dist->tach path.
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Yelm, WA - USA
Joined: 7/12/2007
Posts: 356
Vette(s): 1979 L82 4 speed Scat 383 crank 190 cc Procomp Aluminum Heads 202 160 stainless valves GM Powder metal rods Speedpro H860CP Hypereutectic pistons 280 cam hydralic HEI Pro comp 1.6 roller rockers Mighty Demon 750 Sanderson CC1AP Hedders.
Two capacitors and two resitors right? It's been a few years since I've done any work off schematics and being in the Army the last 6 1/2 years hasn't helped me out in the brains department much. But your right it's seriously pocket change for the parts! I didn't even know about the cheapy Ecklers one untill I found this thread so I was looking at the 50 dollar replacement variety
I was also under the impression that you needed this part otherwise your tach would burn up. My tach wasn't working anyways, I was just curious about what this component actually did and why it cost so much. I'm all about helping others so hopefully this will save someone some heartache.
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Charleston AFB, SC - USA
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Vette(s): 1979 Cream Beige Coupe w/383 & 700R4
Yep, that's it exactly. You can get 1/2 watt resistors and those capacitors by the dozen for super cheap. I do a lot of electronics work so I keep them handy anyway.
I think I figured with my cost on things, it would cost me <$5 to make 10 of these. And Ecklers sells them for $30 each
Just to help make the schematic more clear
5.6kohm 10kohm
Dist <---------- ^v^v^v-----------^v^v^v-------------------------------> Tach
| |
| |
0.1 microfarad cap = = 100 picofarad cap
|_____________|
|
|
V
Ground
My super fancy text art at work there :)
There was a dude on CF making those filters about a year ago. I talked with him briefly about where to get the parts. He told me Radio Shack. So I went there and bought the parts. When I get time I'm going to make one up for mine and test it out. The parts have only been laying around the shop for the past year now. 
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