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Electronic rev counter on an Atlas

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I have an electronic rev counter off a Rotary that I want to fit on my Atlas fitted with a twin output coil, also has electronic ignition. It's simple Negative coil feed and earth but doesn't work. Anyone any advice on testing it or fitting it before I junk it.

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The Atlas is positive earth (yes we all know that!) So you will have to change the earth polarity of one to get it to work. I can advise how to change the Atlas to Negative earth. But the unknown rev counter ?? The other major point to ponder is the pulses per rev between the two engines?

It MIGHT be possible to fit a negative earth device to a positive earth bike-BUT you have to understand what is going on and take a lot of care BEFORE circuits are powered up. I might be able to test this rev counter?

By way of an update the rev counter works. Using a 50Hz battery charger it reads 1000rpm, polarity is negative so the bikes electrics will need changing to negative earth at the same time I'll replace the Lucas Zener diode and rectifier for a solid state 4 wire regulator/rectifier and add a fuse holder. 

I was going to replace the 2 separate gauge mounts for the 'correct' single plate and move the 88sa switch from the back of the headlight, that was in the warning light hole, to its correct position but will now make a custom plate to take the existing speedo and switch as well as the electronic rev counter.

The tacho may work but not on the Atlas. A reading of 1000rpm at 50Hz (100 pulses at full wave rectification) confirms that it would be only suitable for a 6 cylinder piston, or a twin rotor Wankel engine and with no way to reset it externally its surplus to requirements.

So now to find a suitable electronic tach that will work on a single (Atlas is fitted with a twin output coil).

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I fitted a Skitsu one, wired to the pilot light.  The Smiths electronic 'copy chronometric' speedos look the part, but seem to possibly not work with a magneto.  Does that apply to tachos also?

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You could always get:-

https://www.rgmnorton.co.uk/buy/electronic-analog-tachometer_3703.htm

 

Tony

 


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