Daytona Sprinter 50cc DIM HEADLIGHT

[Tankie]

What are the capacitors for? to act as a battery , or just a buffer
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Always learning, everyday is a school day

[Elektroniker]

[Tankie]

Your thinking far too hard, this is the item you need

https://www.ebay.co.uk/itm/ROYAL-ENFIELD-BULLET-4-PIN-12v-VOLT-AC-REGULATOR-RECTIFIER-112242-SWISS-790/222106244557?hash=item33b69055cd:g:EwcAAOSwiYFXKKpE:rk:2:pf:0
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Always learning, everyday is a school day

[Elektroniker]

[WD Forte]

12v is just a nominal value.
Bikes/cars etc have an actual working voltage closer to 14V

Both of those above would work and be set to regulate at around 13.8V DC
They're basically bridge rectifers with a voltage controlled shunt to ground to prevent over voltage
larger bike rectifier regulators work the same way except they use
3 phase stators and rectifiers
( unless they have exterior alternators)
____________________
bikers smell of wee

[Elektroniker]

[WD Forte]

[Tankie]

This man know what he is talking about, the theory is called " applied electronics"
____________________
Always learning, everyday is a school day

[Elektroniker]

Thanks, WD Forte.

Do you know of an internal circuit diagram for one of these bridge rectifier/shunt "regulators"?

For the shunt to work, I'd guess there's a low value, high wattage resistor to drop the voltage (and avoid overloading the magneto coil), right?

[WD Forte]

Internal circuitry will depend on many things but whatever the bike
It will still have two main functions
1 Rectify ( AC to DC)
2 Regulate output voltage

older ones were crude but effective and were little more than rectifier diode/s and a zener
in a heat sink which was bolted to the frame.
Some later ones mixed and matched by using AC for the headlamp and DC for other circuits.

Most RRs still use silicon rectifer diodes but have extra components in a feedback control loop
with a zener for a reference voltage and transistors switched on and of to do the heavy lifting re regulation.
Some may have an SCR linked to one phase to momentarly short that phases power to ground when the output voltage exceeds the
reference voltage.

Some modern RRs use mosfets in a more complex 'zero switching' circuit to switch the AC on and off
which is more efficient than the common linear types.

Last year I fixed up an old moped for a guy and played around with its basic unregulated AC system to get a a more consistent
output so I could fit led lamps to it as although as was nominally a 6V system, he said it even blew the 12v bulbs he put in.
It's still working BTW

https://www.bikechatforums.com/viewtopic.php?t=324407
____________________
bikers smell of wee

[Elektroniker]

Thanks for your comments.
The "universal" regulator arrived today. I removed the plug, which didn't suit my connections, and crimped 1/4" spade (male Lucar) connectors onto the four wires. It works fine and even charges the battery when the lights are on. However, the voltage still goes above 15 volts so I need to do something about that. Maybe a low value resistor and a thumping big zener, both on a heatsink?

Another problem has arisen. Please refer to the carburettor photo near the bottom of this page:
https://www.DuckPoo.com/daytona/
We had a week of rain, after which the bike wouldn't start. I traced the problem to a float chamber full of water! I'm not sure how it got there but, as you can see in the photo, the air filter is a basic wire mesh device, which is immediately behind the front wheel. I suspect that the plastic faring above it fills with water spray every time I ride on a wet road. The air filter probably sucks in water. I don't see how it would get into the float chamber but I'd like to protect the carburettor from water anyway. The gap between the air filter and mudguard is only about 1.5 cm. I guess, for starters, I'm looking for a rubber inlet hose with air filter box that could be mounted higher.