The definition I know of a transducer is it converts one kind of energy to another... like a piezo electric crystal that turns the energy of a mechanical shock into electric energy... push button spark lighter on bbq... or does something like turn heat energy into electrical energy... thermocouple...

Your system is 6 volts... Incandescent light bulbs work fine on AC or DC power. Battery is there because US laws require certain lights to stay on without engine (taillight primarily) and the AC versions of turn signal flashers and horns are expensive and don't work well.

A rectifier is not a transducer or a regulator. Yamaha rectifier (it's simply a single heavy duty diode) takes AC voltage and blocks the negative pulse of the AC sine wave so the (required by law) DC battery can be charged. Headlight runs on AC right off the magneto.

Magneto is not smart. It's fixed output due to fixed magnetic field. Will not put out more or less. System without regulator is balanced. Load of bulbs and battery charge (amps) is matched to mag output power to keep voltage within safe limits. More load equals less voltage. Less load equals more voltage.

Analogy is having a truck stuck at one throttle setting (constant power output) full of bricks driving up an endless hill... you don't want truck to exceed 60 mph or the tires will explode so you keep adding bricks until load on engine won't allow it to go over 60.

Yamaha factory single wire regulator is like an electronically regulated "variable load" connected to the AC circuit. If electrical load is too low to keep voltage within limits, it adds load to keep things in balance.

Most importantly... a 1982 DT100 should have a voltage regulator from the factory. It's in the parts list. I've bought used DT100 regulators before from ebay... DT100 got regulator in 1982 according to parts lists. Larger Enduro models got it in 1976 or so.

www.partzilla.com/catalog/yamaha/motorcy.../electrical-1-dt100j

P.S. The newest wiring diagram I've seen for the DT100 is 1980. 1980 parts list does not show a regulator. 1982 does.

MarkT,

Thanks for your input. I will be buying the newer Clymer since there are differences for the 1982. I was assuming that the manual I have (covering 1977-1981) would be good, since pretty much everything else I have traced out so far matches up...but obviously there were changes since the 1981 model.

So...if I have a regulator, then I should be OK without a battery functionally....just not if a cop makes me try to turn my lights on with the bike off.

I still don't get (and this is why I didn't become an electrical engineer) why the rectifier isn't enough...since it ONLY puts out 12VDC; no more, no less. That seems like "regulation" to me. I will be reading your explanation over (and over) again, till maybe the light shines on me.

Best to you,

Pink

MarkT,

You said "headlights run on AC straight from the magneto." If I am reading the wiring diagram correctly (and this is for the 1981), the AC from the Magneto goes into the rectifier (white) and what comes out is the DC. This goes two places...to the + terminal of the battery (red) and to the ignition switch (red). When the ignition switch is made the DC power goes out (brown) and this traces to all of the lights.

I will be interested to see how the regulator in the 1982 wiring comes into play.

Best to you ,

Pink

You will probably be wasting your money on a newer Clymer? Probably insignificant differences between 81 and 82 and still migh not have the correct wiring diagram?

You are reading somebody's blog or something that is not about your bike or your electrical system. Again, yours is 6 volt, not 12. You have a simple rectifier. Not a rectifier/regulator like newer bikes have.

Again, the rectifier on your bike is only a single diode. It's the simplest form of converting AC to DC. A diode is like an electrical one way valve. It only allows the + part of the AC sine wave through to the + side of the battery. With the single diode you get what they call "half-wave" rectification...

What comes from the stator is AC like this where the straight line is "zero volts", the curve above the line is positive volts, and the curve below the line is negative volts:



That negative voltage is not compatible with a battery... so the rectifier (diode) is installed to block it. After the rectifier you get this:



Really basic way to charge the battery... nothing fancy.

So now take another look at your wiring diagram. The brown does not go to all the lights. It only runs the battery operated lights.

There is a wire directly from the mag to the headlight high/low beam that does not go through the rectifier or to the battery. This wire is not switched because it only had AC power with engine flywheel spinning when engine is running and the US has an "always on" headlight law for motorcycles built after 1978 or so. That wire runs the headlight and the gauge illumination lights on AC power only when engine is running.

The Yamaha single wire regulator simply tees into the wire from the magneto to the dimmer switch. Case of regulator must be grounded.

Here is the Yamaha regulator on a 175 diagram of that vintage. Wire from magneto goes straight to dimmer switch on bars. Voltage regulator simply tees into that wire. That's what your bike has. Difference is I think your color wire from mag to dimmer is marked "L" (or blue) in color instead of the Y or Y/W (yellow or yellow/white) color the larger bikes use.



(If you want to see the unadulterated diagram it's from the 1981 DT125/175 supplement in the tech library.)

Not feeling well and bored so here's a 1980 diagram modified to show the factory voltage regulator wired in

Red line from my (poorly drawn) OEM Yamaha one-wire voltage regulator that simply tees into L or blue wire from stator. Black line out of regulator is showing regulator case is grounded. Yamaha often used a wire to one of the regulator mounting bolts that goes a good frame ground to make sure regulator case is grounded.



... hope this helps.




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MarkT…..WOW! That helps a bunch. Really filled in the gaps for me. BTW..I know it is 6V...just so used to 12V.

Didn't mean to seem like I was saying you don't know the voltage of your bike... My point was that wherever your were getting your information about the rectifier ...and if it also regulated the voltage as you quoted it was actually a rectifier/regulator combo unit that most newer bikes with magnetos have these days... was about a different more modern system.

Electronics have come a long way since these bikes were new. Even simple components like a diode were not cheap or readily available.

Take a look at this ebay ad for the rectifier that Yamaha used until the early 1970's... it was a selenium plate-type rectifier that's MUCH bigger than a modern silicon diode rectifier.



A car alternator needs diodes to convert AC to DC just like your magneto. Cars went from generators to alternators only after the compact high power silicon diode rectifiers were developed... the selenium plate rectifiers that were available were just way too big!

And that's why Yamaha and other bikes used a "balanced" system to keep the voltage in check. Bulb load was matched to stator output and a lead acid battery is sort of a natural "regulator-buffer" that helps keep voltage from getting too high... high voltage to a battery will make it heat up and making heat uses energy which adds load to system and keeps voltage down.

It wasn't until the later 70's that the voltage regulators were practical and Yamaha started using them... and not long after that the combo rectifier/regulator came out and made the "balanced" and "split" AC/DC systems of these early bikes obsolete.

MarkT,

Thanks again.

I think I have found my answer and gained a lot of valuable information in the process.

What I surmise is my answer: Since my 1982 DT100 has a regulator in the system I do not need the battery to perform the "buffer" function. I do need a battery if I am to meet the requirement to have lights when the motorcycle is not running.

Since Partzilla has batteries for under $15...I will likely get one. But, in the meantime, I will know there is no harm to the bike if I run without one. I have a few other things to buy first....like battery powered gloves, so I can keep riding to work this winter!

Pink

Without a good battery and with no regulator my bulbs have always blown... sucks especially if out on a ride and it's getting dark. I've had the standard batteries fail which is why I now run AGM batteries like the Motobatt (high end) or a 6v alarm battery. I still have an old UB645 alarm battery that's several years old and works fine. It was less than $10. I've had other alarm batteries since fail very quickly... I think the quality is suspect these days. There's a thread here on the Yuasa brand alarm battery which is probably the next one I will buy... Yuasa makes good stuff and I think they were under $20

I've had a battery fail while riding (which would normally blow bulbs) but with the regulator, they were fine. That was a temporary situation... running all the time without a battery could possibly overheat the regulator and cause it to fail? I don't know.

Hello, if going without a battery is it a good idea to still have a fuse, so you would have to connect the battery connectors but without the battery in the middle, or not ?