I need an electronic tachometer to run with a 4 cylinder engine that uses a magneto rather than coil ignition. I'm told that a standard electronic car tacho won't work. The one that I have gathering dust works off the main coil HT lead anyway (which a magneto engine doesn't have)
There must be a solution but it's eluded me - quite a lot does. Any of you knowledgable types know where to find one?
Thanks
Charles
Inductive pickup works. Depends on the trigger voltage requited to the tacho though.
Have done this with wire wrapped around one of the HT leads.
I think the Vellemann digital tacho available as a kit from Maplins will work with a low enough trigger voltage.
Wayne...
Could you not mount a 'sensor' (proper term alludes me) on the flywheel a la modern machine tachos? Are we talking about pre'28 Austin Seven engines? Where's Tony Jeffree when he's needed! --
Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"
You know me too well Chris. Because it's for an old car it needs to be disguisable in an original analogue type casing.
Charles
Rules out my digital tacho then ;-)
Regards, Tony
Get a standard Lucas tacho off a 1960's - 70's vehicle, of the sort that uses a turn of wire wrapped round a post on the back of the instrument, and wire the loop in series with a load resistor and inductive proximity sensor suitably and subtly placed to avoid sight.
AWEM
Crank 'Tachometer' into the e-Bay search box, there are a couple of items buried in the hundred or so hits that you might be able to adapt. I think you need a ' non-contact' type of sensor. Have a look at Items
150052944157 and 190047192212. Perhaps one of these might be adapted? A --Chris Edwards (in deepest Dorset) "....there *must* be an easier way!"
I made one of these a few years back for a boat - it worked straight off, but suffered from a lack of high voltage components - I'll scan the schematic for you if you are interested, pretty simple.
Steve
Andrew
Thanks for the tip. However as you know cars of the 60's and 70's are a bit modern for me. Come to think of it hydraulic brakes are way ahead of my garage. Would you care to point me at a model or spec that would suit. I've scouted through Ebay and can't see one that matches your description of the "wire wrapped round a post".
Ta
Charles
My fork truck would gladly appreciate at least one brake.
.-- Regards,
John Stevenson Nottingham, England.
Visit the new Model Engineering adverts page at:-
standard
sight.
Charles,
The one used on my Austin Healey 3000, and was used from about 1960 onwards, has a plastic block with a hole in it held on with a screw on the rear, and the block is encircled with a steel strap. This strap forms the laminations of a transformer whose primary is a loop passed through the hole in series with the ignition coil primary, and whose secondary drives the pulse averaging circuitry. Same basic tacho used on MG's and Triumphs - here is an article about them:
Andrew
John, you haven't lost the brakes again!, after you loaded the mill I definitely left them propped against the wall. Perhaps someone has borrowed them for their bonfire or have you been throwing them at next door's cat again?
Regards
Keith
On or around Fri, 03 Nov 2006 16:10:17 +0000, Charles Ping enlightened us thusly:
some of the modern ones work from a tapping on the AC on the alternator. They're not particularly accurate though.
I don't know whether you have solved your problem, but if not try
They are located in Sheffield, phone number on web site. They make tachos for racing bikes, 2 stroke or 4 stroke. Pick up from HT lead. Phone them and I am sure they will have one to suit you, but they aren't cheap.
--=20 brightside S9
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