Alternator rotor Inductive Kickback

The way I read budget meters, when doing diode tests, meter test knob in the diode symbol position (usually in the lowest resistance position), is to read the ohms as millivolts. That's the Vf (forward voltage breakdown). Values of 300-1200 can be found, ideal is around 600. Depends on the meter, and the leads. When a diode fails, you'll usually get a reverse or "dead short". It'll blow a fuse.

All your readings look ok.

Paul Sutton said:
I just ordered a 10 pack of 1N5408 Diodes at £1.49 including p+p. Now what do I do with the 9 leftover???
Click to expand...

Maybe your UK buds would like to get in on this?

Http://www.xs650.freeforums.net
 
Last edited:
TwoManyXS1Bs said:
What I plan to use is a 1000v, 6-amp, 0.7v forward-volt, 9mm diameter radial-lead rectifier diode, an 89¢ Digi-Key item.
Click to expand...
Oops missed seeing the rest of the thread when viewing a linked post. Mention was made of a reversed neutral LED flashing, could an LED be used as the "bleed off diode"? everyone likes to see confirmation a doodad is working....
 
Last edited:
gggGary said:
...Mention was made of a reversed neutral LED flashing, could an LED be used as the "bleed off diode"? everyone likes to see confirmation a doodad is working....
Click to expand...

I suppose you *could* use an LED (one designed for 12v), attached backwards between switched power (brown wire) and ground, temporarily as a test device. If it "glows" a bit right after switching off the bike, then you've confirmed that there's the threat of "inductive kickback" on your bike. With the catch diode installed, it shouldn't glow.

The LEDs used on 12v systems have a built-in current-limiting resistor, in series, somewhere around 470 ohms, since LEDs usually run on only 2-3 volts. This would prevent bleeding off the instantaneous high-voltage spike, so wouldn't be an effective catch diode. Plus, the bleed-off time of an effective catch diode is too quick to be seen.

On further thinking, any bikes that have the headlights always "on", the current drain thru those low-resistance headlights (and taillight) *could* be enuff to bleed-off the rotor's inductive kickback to safe levels. So, this mod is more appropriate to older mechanical regulator bikes that have the headlight on/off switch. I guess that would be the 70-75(?) models, or customs with a similar setup.

Now, a fun project would be to use high-voltage/high-current CREE LEDs for the alternator's rectifier diodes. You'd know pretty quickly if your charging system is failing, plus other interesting diagnostics...
 
Last edited:
dso-nano-dso201-jpg.56817


That's not an O-scope...

image027.jpg


THIS is an O-scope! Many, MANY hours in front of a Tektronix 535 in my days as a Navy tech.

R390ACollins.jpg


Usually working on these...
 
When I was kid, I remember my dad opening up the back of the (black and white) TV, taking the vacuum tubes out, and going to the 7-Eleven to test them. After further thought, I wondered "is that possible? The 7-Eleven?" So I Googled it, and sure enough:
aa.jpg


aaa.jpg
 
^I've used one of those, last time in the 90s. Look the tube up in a book and turn the dials to what it says and plug it in the socket it says, then hit the button. It was in the basement of a dept store, and down there was a room with a big bench and there was an overflow of tv technicians working! Last time I went there, there was possibly one guy left downstairs. Years later I went into a vintage guitar store near my house, and it was in there! The owner said the dept store was throwing it away so he picked it up. In the 80s I bought a tabletop FM tube radio for my brother, which is screwing up now, so I could use it again...
 
Last edited:
First school I went to in the Air Force was "basic electronics." 20 wks. It was 1972.... at the dawn of the digital age. It was all about tubes and transistors. After graduating from that I went to 18 wks. of "digital electronics" school. Then to "instrument/autopilot" school. We learned to fix and tweak F-4 autopilot amps, among other stuff. Don't remember the exact amount... but about 15 tubes inside it.

Been so long ago.... now I'm just a hack. :rolleyes:
 
Last edited:
^My first introduction was my uncle gave me a big stack of electronics magazines when I was a kid. I would read them and not have a clue but read them anyway and I remember the point where some kind of light came on and I got it.
 
I spent most of my first two years in the Navy in school. BE&E (Basic Electricity and Electronics) was something like 8 weeks, followed by 54 weeks of Electronics Technician Class "A" school, followed by 18 or so weeks of Crypto Repair School.

I can tell you I was THOROUGHLY tired of sitting in classrooms by the time I hit my first actual duty station.

Like Jim, mostly tubes, a little transistor stuff. The first Crypto School was all tubes, the second was "potted modules" which was transistors and discrete components cast into a resin block that soldered into the board with pins like a vacuum tube.

kg13_int_small.jpg


I went back to school not quite 10 years into my career and spent ANOTHER year sitting in classrooms. All digital, and my introduction to digital computers.

Also like Jim, it was all a VERY long time ago and I'm barely qualified to wire an outlet these days.
 

Similar threads

gggGary
Protecting electronics on the XS650 from voltage spikes.
2
Replies
35
Views
5K
TwoManyXS1Bs
TwoManyXS1Bs
E
Question about rotor and charging.
2 3
Replies
41
Views
2K
Eric12171
E
J
Balanced components of an electrical system
Replies
3
Views
466
650Skull
650Skull
Paul Sutton
Voltage Spikes
Replies
19
Views
2K
TwoManyXS1Bs
TwoManyXS1Bs
C
Electrical gremlins - blown main fuse, melted connectors, bad neutral switch, and dead turn signal
Replies
6
Views
497
5twins
5twins
Back
Top