Finished my electronic tach project

[Sarastro]

I finally finished my ongoing project to replace the mechanical tach with an electronic one. This is my own design, not just a later electronic unit. Part of the reason for the tach replacement is that I might want to replace the generator with an alternator, which would eliminate the mechanical tach drive.

I wrote up a description of the project and posted it in my web page. It can be accessed here., along with reports on my other odd projects. (Scroll down to the bottom of the page.)

 

[drooartz]

Nice work. Good to see smart folks out there figuring out this stuff.

I'd like to do something similar some day, but I'm not electronically intelligent enough to go to the level that you did. My hat's off to you!

 

[Bruce_B]

Steven,
Just looked at your web site and I now have an overwhelming urge to paint my car RED! Beautiful looking car in great shape.

Some or your solutions/improvements while seeming simple require years of experience.. That's the problem with you 'EE' guys...you make it seem to simple.

Look forward to reading about more of your inventions. Additional kudos for your great documentation.

 

[jlaird]

Man Steve, that stuff is awsum. Miss Agatha is in the post comming your way for these mods. I don't think I could do them. Impressed, yep and the write ups are outstanding.

All this stuff should have been standard.

Now where are these write ups going to be saved for future generations?

 

[racingenglishcars]

Good work. I can see you are retired. The point about single-point failure is all too true. Those things were notorious for failing causing no-start situations, and even sometimes causing sudden engine stops while driving.

I took a slightly different route. Spitfire mechanical tach and a TR5 / TR6 distributor converted to 4 cylinders. Those distributors have a mechanical tach outlet near the base and are only a centemeter or so longer than a standard unit.

 

[racingenglishcars]

Oh yeah, I of course changed the dial on the spitfire tach to an original sprite unit I got from the breakers.

 

[dklawson]

I've downloaded a copy of your PDF. Excellent work. Theo Smit is another LBC person who designed his own board like you did. Check out his web site when you get a chance:
https://members.shaw.ca/tsmit/tachmod/tachmod0.html

Being a mechanical engineer, I chose not to design my own circuit for conversions but to use the electronics from donor tachometers to power the Smiths movements. So far I've been lucky enough to only need to add a calibration potentiometer to the donor electronics to get the calibration to match. My PDF about this approach can be found at:
https://home.mindspring.com/~purlawson/files/Smiths%20Tachometer%20Conversion-R1.pdf

 

[Sarastro]

Thanks for your comments. I have to confess that I'm an electrical engineer, and have been messing with electronic stuff since I was about 8 years old (like, 50 years ago!) I think that anyone with an electronics experimenter's knowledge of the subject could reproduce what I've done--the hard part, actually, was all the mechanical stuff, getting it to fit and work together, with all the mixing and matching of parts.

I have seen Doug Lawson's article, which seems like a reasonable approach. Also, I can't quite make out the markings on the ICs in Theo Smit's circuit, but the big IC is a voltage regulator, like mine, and I'll bet anything that the smaller one is a 555 timer, which I used. It's pretty much the logical way to do this.

And, no, I'm not retired. Just potty about LBCs. Project like these keep me sane, although that may be in dispute...