Tacho tech

[joecoolmk2]

i was just about to ask about using a 4cyl tacho on one 1uz coil, but it's been said and now i am happy they are voltage spike right? +rep btw

[LiTTLe_DRaGoN_HuNTeR]

I found this on club4ag, but not sure if it's similar to modifying the hardware part in "- New engine/ECU outputting 5V square wave mating to voltage spike tacho"...

http://www.club4ag.com/faq%20and%20t...considered.htm

[fester]

Hey guys I know this is an old post but I came by it from a google search. I haven't been on this forum since getting my 20 valve up and running in my MG Midget but now I'm hoping you can help me with another project even though it's not Toyota related.

I am looking at putting a late model fuel injected instrument cluster into an older Ducati which is carbed. So I think I need to do pretty much the opposite of you guys. I'm assuming the Ducati tacho also would use a square wave signal so I will need to convert the voltage spike to a square wave.

I not sure yet exactly waht signal the new tacho takes as I haven't bought one yet. I need to make sure I can get it to work before shelling out. Problem is I don't know anyone who can test their tacho to tell me exactly what signal they require. Also don't know how to test the signal.

Hopefully I can find some workshop overseas somewhere that can confirm the signal but being late model 2001 or newer I would be surprised if they do nto use the same signal format as most modern cars.

So anyway can anyone lead me towards a kit or product (preferrably cheap) that will convert voltage spike to square wave.

Gavin

[CrUZida]

http://toymods.net/forums/showthread.php?t=3710


EDIT: Wait, maybe not, but it may be helpful none-the-less.

[Sam_Q]

A .pdf guide for modifying the hardware in an AE86 dash to overcome this problem (and accept twin coils too) is provided HERE

this link no longer works does someone have it handy?

[mr2gze]

this link no longer works does someone have it handy?

http://members.iinet.net.au/~awcabren/ae86gzetacho.pdf

[Sam_Q]

thanks for that

maybe you or someone else can help me with this problem, I have a waste spark setup on my 20V with a custom DLI converter, two generic coils and magna ignitors, I want to take a signal directly off the coils if possible, can I do whats shown in this diagram?

[Duk]

- 6cyl engine mating to 4cyl dash (or other combinations)
The tacho will read 50% too high for a 6cyl engine -> 4cyl dash. Hen

Actually, it will read 33% (1/3) too high. If you used a 4 cylinder engine with a 6 cylinder tacho, then you would have to increase the signal by 50%.
Either/Or, excellent write up

[Talasas]

Yeah I like this writeup, I love reading this sort of tech stuff, but I always want to go deep beyond the scope, like:

In this case the tacho just monitors the frequency of these spikes and converts that into a needle movement.

How it does this exactly would greatly interest me. There are a few issues the need to be overcome and I'm not sure how they do it.

Anyway, this is a good thread, pity I didn't see it when it was originally posted.

[wilbo666]

Yeah I like this writeup, I love reading this sort of tech stuff, but I always want to go deep beyond the scope, like:

How it does this exactly would greatly interest me. There are a few issues the need to be overcome and I'm not sure how they do it.

Usually they use a frequency to voltage IC.

And the needle is a Galvanometer...
http://en.wikipedia.org/wiki/Galvanometer



Cheers
Wilbo

[Stefan]

http://members.iinet.net.au/~awcabren/ae86gzetacho.pdf

Has anyone tried this? Wondering if it will work for an xA6x analog tacho...

[Nic19]

i have a microtech LT10s running my 4agte with x4 box and 4 bosch coils. what do i need to do to get this to work with my stock ae71 tacho dash? If its some kind of booster, who can make it for me and how much will you charge.
cheers
nic
im not very bright wen it comes to this sort of stuff lol

[timbosaurus]

Do you know what signal the AE71 tacho is expecting to see?

Is it a 0-5V or 0-12V square wave sent from a factory ECU?
Or is it designed to trigger off the ignition coil flyback? (ie: factory carby engine)

sorry, I don't know what 4A the AE71 had.

[WiLo]

AE71 came stock with 4ac so i imagine it would be a coil triggered

[dfunkt]

Or is it designed to trigger off the ignition coil flyback? (ie: factory carby engine)

sorry, I don't know what 4A the AE71 had.

4A-C, Carby.

EDIT: what he said...