Zeners on AC

For the three and more legged things
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pre65
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#1 Zeners on AC

Post by pre65 »

If you had (for example) a 9v Ac generator, would putting a 6V Zener diode in each wire give you 6V AC or a very rough DC ?

This is for an old autocycle to work the lights.
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Mike H
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#2

Post by Mike H »

I think I see what you mean, best is problee 2 end to end in reverse polarity to each other, across the alternator, this will knock off the surplus Voltage, but they'd have to be big barstewards to take the current they sink. Depends what power the alternator can put out.

Same idea as the old Triumph "regulator diode" :D
 
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#3

Post by pre65 »

Mike H wrote: best is problee 2 end to end in reverse polarity to each other, across the alternator, this will knock off the surplus Voltage,:D
I'm not sure I understand how you would do that. :?
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Mike H
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#4

Post by Mike H »

Two diodes? Put them end to end? In series? But connect the cathodes together, or the anodes together. Then the 2 free ends across the alternator output.

Coincidentally was looking at big metal power Zeners on RS just the other day, for no obvious reason except "cor they do them as well". Remember using things that size years ago for transistor amp PSU's. Most of the time only cos that's what was most readily available.
 
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#5

Post by pre65 »

Mike H wrote:Two diodes? Put them end to end? In series? But connect the cathodes together, or the anodes together. Then the 2 free ends across the alternator output.
I'm getting your drift. :)

EDIT

perhaps I'm not. :?
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#6

Post by Cressy Snr »

pre65 wrote:
Mike H wrote:Two diodes? Put them end to end? In series? But connect the cathodes together, or the anodes together. Then the 2 free ends across the alternator output.
I'm getting your drift. :)

EDIT

perhaps I'm not. :?
Does back-to-back make it any clearer?
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#7

Post by al newall »

Last edited by al newall on Fri Dec 23, 2011 10:17 am, edited 1 time in total.
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pre65
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#8

Post by pre65 »

That link won't work but I found the Zener page and read up about Square wave signal.

http://www.electronics-tutorials.ws/diode/diode_7.html

Personally I might use a rectifier and then a Zener on the DC. :wink:
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#9

Post by Mike H »

Ah back to Triumph m/cycle way of doing it....
 
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#10

Post by Mike H »

You need to know how much current the alternator can put out then that determines the Zener current if no lights are on. Then it's Ohms law to find the power rating required. As it's 9VAC, maybe a small value dropper resistor may be required as well.
 
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#11

Post by pre65 »

I use a Boyer "Powerbox" on both my classic scramblers. :)
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#12

Post by Mike H »

Show-off :lol:
 
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