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Tankie |
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Tankie Crazy Courier
Joined: 24 Feb 2017 Karma :
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Elektroniker |
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Elektroniker Derestricted Danger
Joined: 16 Dec 2018 Karma :
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Posted: 20:25 - 14 Feb 2019 Post subject: |
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Tankie wrote: | What are the capacitors for? to act as a battery , or just a buffer |
The output from the single-phase magneto is AC. Approximately a sine wave, such as you'd get from a basic mains transformer, except that its frequency changes with rpm. (Also the voltage increases with rpm.)
The 13.8v regulator requires a fairly smooth DC input so, to achieve that, I used a bridge rectifier followed by the two 4700µF reservoir capacitors (connected in parallel to make approx. 10,000 µF).
See a good explanation here:
https://www.electronics-notes.com/articles/analogue_circuits/power-supply-electronics/capacitor-smoothing-circuits.php
The reason for using the specific 13.8v regulator is that it works from 9v to 36v input, meaning that the battery is still charging at low rpm. Almost down to tickover speed, in fact.
Unfortunately, I miscalculated. The capacitors that I used were rated at only 25 vDC and also their ripple current rating was only around 1 Amp. As a result, they worked fine for about 5 minutes then overheated and exploded! That wouldn't have mattered so much but it meant that the regulator was now being fed full-wave rectified AC, which it didn't like, so it failed.
So, I have new capacitors and regulator on order (up to 7 weeks from China) so the bike is running with the old regulator once more.
I've realised that bike manufacturers save money by NOT using a proper regulator system. Instead, they use just the bridge rectifier with maybe some component to limit the peak voltage to protect the battery. In my case this latter item seems to have failed and the battery is seeing up to 15.5 volts, which will kill it fairly quickly.
So I'm toying with the idea of making my own version of this system, which doesn't require expensive, unreliable reservoir capacitors. The regulation won't be as good but I can live with that. Something like this:
https://www.circuitstoday.com/10a-adjustable-voltage-regulator |
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Tankie |
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Tankie Crazy Courier
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Posted: 09:02 - 15 Feb 2019 Post subject: |
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Elektroniker |
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Elektroniker Derestricted Danger
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WD Forte |
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WD Forte World Chat Champion
Joined: 17 Jun 2010 Karma :
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Elektroniker |
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Elektroniker Derestricted Danger
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WD Forte |
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WD Forte World Chat Champion
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Tankie |
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Tankie Crazy Courier
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Elektroniker |
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Elektroniker Derestricted Danger
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WD Forte |
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WD Forte World Chat Champion
Joined: 17 Jun 2010 Karma :
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Posted: 22:56 - 16 Feb 2019 Post subject: |
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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 |
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Elektroniker |
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Elektroniker Derestricted Danger
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Posted: 20:38 - 22 Feb 2019 Post subject: |
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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. |
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Old Thread Alert!
The last post was made 5 years, 57 days ago. Instead of replying here, would creating a new thread be more useful? |
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