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Please help me with this simple circuit. i cant do it alone!

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nate

New Member
hello, i hope you can help me as i am not able to figure this out on my own.

i have a 61 vespa motorscooter. it has a stator (magneto) which outputs 6VAC i would like to set up a circuit which converts the 6VAC to 12VDC
i would like to set it up without a battery. the 6VAC comeing off the stator is not regulated and so this circuit will have to have a regulator.

i heard something about useing a bridge rectifier and a diode clipper to do this.

a simple diagram and radioshack part numbers would be awesome!

i hope you can help me. thanks,

nate.
 

kinjalgp

Active Member
Use 1:2 ratio transformer to first convert 6VAC to 12VAC and then use rectifier and capacitor filter (around 1000uF/35V) to convert it to 12V DC unregulated.
If you want regulated output, use 1:3 transformer to convert 6VAC to around 18VAC and then use Bridge,Filter and IC 7812 which is a 12V/1A series regulator.

Please note that this is one of the way to step up the voltage. There are numerous ways to do it.
 

nate

New Member
thank you so much for your reply!

where can i buy all these parts to do the second method? i cannot find the 1:3 transformers on radioshacks website. are they called something else?

do you have a place you can suggest, where i can purchase all these components on-line?

also what are all the exact parts called and do you have part numbers?

i have searched the web all over and can only find transformers with an imput voltage of 85 and up.

could you please give a detailed explanation of how to build this power converter? in laymans terms. also a diagram would be so very nice!!!

please help me. i really want to learn how to build this. it would help me so much to have a circuit which could convert 6vac unregulated to 12vdc regulated.

this would help me and my friend so much as we both have vespas which we want to be capable of running 12vdc lights and accessorys.

here is more info on the vespas power output fron the stator-

it outputs 6vac unregulated, and it spikes as high as 10vac. and drops as low as 2vac. the stator ghenerally produces only enough power to run three 6vac 5w bulbs, and a 6vac 25w headlight. i have been told that combined wattage of all accesorys should not exceed 50-55watts.

i hope this is more helpful info. if you have other questions please just ask.

i hope very much that you can help.

sincerely,
nate.
 

nate

New Member
so after more web research... and reading kinjalgp's reply
i have figured out that the first thing i need to do is-

step up the unregulated 6vac to 18vac useing some sort of transformer.
then i can convert the 18vac to 12vdc, but what do i use?
then i need to add a regulator.

after thinking about this situation i realised that
if W/V =A then i need to have this setup capable of outputting 60 watts at 5 amps.

that would be 60watts (all combined accessorys running at once (worst case scenario)) devided by 12vdc = 5amps.

so the whole system needs to be able to hancdle 5 amps.

any ideas folks???

i would likle to put it together with inexpensive, dependable components.

thanks,
nate.
 

kinjalgp

Active Member
Oh yeah, i remember other simple method to multiply voltage. This is using Cockroft-Walton Ladder Network which makes use of Diodes and Capacitors. If you have the circuit implement three stages in the ladder and you'll get 18V from 6V. if you don't have the schematic let me know I'll give it to you.
 

pebe

Member
kinjalgp said:
Oh yeah, i remember other simple method to multiply voltage. This is using Cockroft-Walton Ladder Network which makes use of Diodes and Capacitors. If you have the circuit implement three stages in the ladder and you'll get 18V from 6V. if you don't have the schematic let me know I'll give it to you.
The problem with a Cockcroft is that to provide 5A would mean *very* large capacitors.

Even running at 10KHz and with a ripple of 3v, a tripler's caps would need to be one third of a Farad!
 

kinjalgp

Active Member
He has not mentioned the current capacity required and if it is less Cockroft ladder will suit his requirements.
 

pebe

Member
kinjalgp said:
He has not mentioned the current capacity required and if it is less Cockroft ladder will suit his requirements.

nate said:
"...after thinking about this situation i realised that
if W/V =A then i need to have this setup capable of outputting 60 watts at 5 amps.

that would be 60watts (all combined accessorys running at once (worst case scenario)) devided by 12vdc = 5amps.

so the whole system needs to be able to hancdle 5 amps. "
 

kinjalgp

Active Member
I found a good document on various combinations of cockroft walton ladder. It can be used for both high current and high voltage requirements.
Any one interested can download it from: **broken link removed**
 
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