Modern Vespa

Hello all,

I have a koso CHT guage that I am trying to get working. I installed it, and wired it up to the 12v output of my bgm voltage regulator.

The guage lights, but no reading on the screen. something flashed up when I revved up but then nothing.

tested the output of the regulator 12v pin and it's like 3.5v dc.

do I need to get a new voltage regulator and wire it to the 12v ac wires or is there something else I can do better? I have a no battery p125x electro ignition vespa.

thanks
chief

Which Koso do you have? I'm pretty sure they all require 12V DC, so you're going to either switch to DC or get a regulator that has a DC output, too.

it's a cheapo with 12v dc requirement. But, my regulator apparently has a 12v dc output. the problem is that it only really outputs 3.5v when measured.

I guess not enough coming from the stator?

Sounds like it.

Do your lights work?

Is it a DC or AC system?

Hey,
thanks for chipping in. I think I may have worked things out.

I was confused as I have a bgm regulator and instructions say I should get a 12v dc out of it. I don't it only supplies 3.5v, which varies based on the revs.

I checked the other output, which is AC. that was 12v even when idling.

So, I need one of those small regulators to attach to the 12v AC to make it DC for the guage.

thanks

You will not get a reading of 12v from the bgm dc output. It's only a half wave rectified output so, on a voltmeter, will measure just under a third of the peak positive pulse. Best off using it to charge a battery, or you may get away with fitting a capacitor.

Well that's the confusion for me then. I thought I remember seeing the instructions say that you could run 12 v gear off it if there was enough juice coming off the stator.

Well the marketing for them is a bit hyped as I believe these are rebranded Asian regs in an expensive box. I also remember asking bgm about the so called sense function, which they couldn't answer, as I believe that to be false also.
However it is a half wave pulse of about 17v peak, so will adequately charge a battery to run momentary loads and that is what these regs were designed for.

Thanks for sharing. I'm pretty lame at anything electrical. I couldn't get past op amps at college which has hindered any further development.

However, I share some of your experiences. I'm on my second vespa now and i seem to spend more time returning inaccurately described parts so various suppliers. I also see reuse of 7 year old reviews for newer parts as well as removal of reviews that are not positive.

Having said that it's still a pleasure to have such a hobby and learning from others experience in places like this is also very rewarding.


Thanks again