Roll Your Own CDI

Are You Going to Roll Your Own CDI?

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Ok, the 1st attachment is Professor Daves using component values he had at hand, basicly same circuit tho. The second attach is Rohmells redraw of my hand drawn (post 422) tho the redraw has 1 error in kathode circuit. My rough hand draw is correct, go to last page of "Modified CDI & CR80 Coil" hi perf tips section posts #193 & #194 & I give values to bring it to the Jag spec. Cheers
 
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Hello,

Can someone lend a hand here please.

What SCR should I pick up? There is a lot of then in the list from this supplier:

http://www.farnellnewark.com.br/sea...cerangestart=1&nupricerangeend=9999999&type=2

And for coil? Does it matter it the coil are two ou four stroke? Or only matter if it does have two terminals?

Here are some options I do have at the local market (I'm in Brazil).

4 stroke scooter coil:

http://produto.mercadolivre.com.br/...ignico-pscooter50ccjonnyaugurimaxfoxbrava-_JM

Yamaha RD 135 two stroke motorcycle coil (just one terminal)

http://produto.mercadolivre.com.br/MLB-245055832-bobina-externa-ignicao-rd-135rdz-135-magnetron--_JM

Thanks a lot!

Felipe Cobu
66cc China Girl/ Beach Bike
Brazil
 
rohmell said:
For those who will use a TO-220 cased SCR, here is the assembly diagram:
Click to expand...

im building this circuit but im having a littletrouble withparts.

for SCR i have 3 options

7812: +12vdc
Voltage regulator
1A
_____
l-LM--l---output
l7812cl---gnd
l_____l---input

LM317T - positive
Adjustable Voltage Regulator
l-LM--l---input
l-317-l---output
l_____l---ADJ


full-wave bridge rectifier
4A 400v
_____________
/-GBL04---0408 l
l---------------l
l__+___AC___-_l
---ll---ll--ll---ll--
---ll---ll--ll---ll--
Also for capacitor i have
2 of:
1.0uf
Metalized-Film capacitor
250WDC max
__________
l----MF----l
l---250v---l
l___1.0k___l
ll----------ll
ll----------ll


also im having trouble determining the proper resistors, can please send me the info and color codes for the resistors??

A diagram similar tothe one iquoted would be awesome pleaseand thank you
 
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moosinatrix said:
im building this circuit but im having a littletrouble withparts.

for SCR i have 3 options

7812: +12vdc
Voltage regulator
1A
_____
l-LM--l---output
l7812cl---gnd
l_____l---input

LM317T - positive
Adjustable Voltage Regulator
l-LM--l---input
l-317-l---output
l_____l---ADJ


full-wave bridge rectifier
4A 400v
_____________
/-GBL04---0408 l
l---------------l
l__+___AC___-_l
---ll---ll--ll---ll--
---ll---ll--ll---ll--
Also for capacitor i have
2 of:
1.0uf
Metalized-Film capacitor
250WDC max
__________
l----MF----l
l---250v---l
l___1.0k___l
ll----------ll
ll----------ll


also im having trouble determining the proper resistors, can please send me the info and color codes for the resistors??

A diagram similar tothe one iquoted would be awesome pleaseand thank you
Click to expand...

None of the above you listed are SCR's
 
moosinatrix said:
maybe thats why i cant get working?? what is an SCR and why couldnt i find it at radioshack??
Click to expand...

I must say, at this stage of the game if you are asking "what is an SCR?" you have not done your homework before embarking on this project.... You should go back and do some reading about what you are actually building to get at least a base line level of understanding what you are working with.
An SCR is a Silicon Controlled Rectifier, a device that is kind of an electronic switch in the most simple terms. Try using GOOGLE or WIKIPEDIA, search SCR and do some reading. Maybe GOOGLE "CDI" or "CDI DESIGN" and do some reading, or just read through this thread and others in this forum. I know there has been mention of the various SCR's that others have been using here in this thread by part number, which you can look up and purchase from various sources, mouser, digikey, radioshack (perhaps), ebay etc.
So my advice is take a step back, do your homework and then take another stab at it with a proper SCR....

PS the reason you didn't find what you were looking for at RadioShack is basically because they have pretty much become a phone store in the last decade, and don't really carry much electronics supply any more....
 
i know enoug ht read a schematic and find parts according to part number. I have everything but the SCR atm all soldered up, i just need the correct SCR and i should be good.


That is unless the 1/4w 5% tolerance resistor i have
(same colorcoding as pictured in the rohmell CDI) dont work
once i get the last part and everything all cleaned up ill take pics and post schematics.
 
the SCR is a to-220 400v 4a thyristor correct?? for the rohmell coil??

also, think i might be able to find what i need in a computer power supply??
 
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moosinatrix said:
i know enoug ht read a schematic and find parts according to part number. I have everything but the SCR atm all soldered up, i just need the correct SCR and i should be good.


That is unless the 1/4w 5% tolerance resistor i have
(same colorcoding as pictured in the rohmell CDI) dont work
once i get the last part and everything all cleaned up ill take pics and post schematics.
Click to expand...

Ok man, I wish you luck....
Since you were asking someone to give you color codes for the resistors and were trying to use a voltage regulator in place of an SCR I figured you were a bit behind the learning curve for this project and could benefit from doing a little reading.
I'm pretty sure the couple schematics that have been posted here include written values for the resistors including wattage requirements for them, as well as voltage ratings for the caps and part numbers for the SCR and diodes. That said, you should know that other than size considerations you can always use a resistor that is rated at a higher WATTAGE and capacitors that are rated for higher voltage. So if you are worried about wattage of the resistors order what is listed on the schematic, and perhaps order a set of resistors the next wattage up just in case you burn one of the smaller ones. In the 1/4 to 1/2 watt range resistors are very small and cheap so its not a tough call to make.
 
moosinatrix said:
the SCR is a to-220 400v 4a thyristor correct?? for the rohmell coil??

also, think i might be able to find what i need in a computer power supply??
Click to expand...

The definition of a Thyristor is a bit broader than just SCR's, but yes, a 400v 4A thyristor sounds about right from my recollection....

PS I don't think they use a thyristor in a computer power supply, maybe a garage door opener or something like that might have one. Something that needs a fairly sturdy current demand that needs to be electronically switched on and off would be your most likely donor....

Take a look at Mouser.com for parts, they will have everything you might need. SCRs range from 70 cents to a couple bucks each, so no real reason to scavange if you have a couple dollars. You can get SCR's on ebay too.
 
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yeah im just tired of waiting on **** to be shipped, i have been waiting for parts for 2 and a half weeks now...im getting very impatient

well a trickle of parts extending over 2 and 1/2 weeks...
 
so i took apart a CDI for my 185 yamaha and took the SCR out of it, still no go. Rohmell if you would be interested in selling me one of yours??
 
I built the basic cdi, look at post 475 and 477 for the components I used. On some rectifiers the voltage required to fire the gate is a problem with our little magneto system. A different scr was all mine needed.
 
im trying, but findin component around here isnt very easy, i can build it according to a schematic. if any of you would be interest in selling a kit, that i can just solder up and slap on my bike i would greatly appreciate it!!!
 
ok so i tore aprt all the unused/unwanted/broken electronics i have (computer monitor, comp power supply, car audio amp, 3 disc dvd player, home theatre reciever)
not one of them has an SCR in it, all im finding is transistors.

also i been doing some googling and have found a couple of part numbers that i think meet the criteria

but im wondering what the difference is bettween them

C106D SCR 4a 400v 200uA Thyristor
http://www.taydaelectronics.com/c106d-scr-4a-400v-200ua-to-225-3-c106dg.html?___SID=U

T106d1 SCR 4a 400v 200uA TO-202-3 T106D1
http://www.taydaelectronics.com/t106d1-scr-4a-400v-200ua-to-202-3-t106d1.html


Also i just realized SCR stands for Silicon controlled rectifier. lol that should help some
 
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moosinatrix said:
ok so i tore aprt all the unused/unwanted/broken electronics i have (computer monitor, comp power supply, car audio amp, 3 disc dvd player, home theatre reciever)
not one of them has an SCR in it, all im finding is transistors.

also i been doing some googling and have found a couple of part numbers that i think meet the criteria

but im wondering what the difference is bettween them

C106D SCR 4a 400v 200uA Thyristor
http://www.taydaelectronics.com/t106d1-scr-4a-400v-200ua-to-202-3-t106d1.html

T106d1 SCR 4a 400v 200uA TO-202-3 T106D1
http://www.taydaelectronics.com/t106d1-scr-4a-400v-200ua-to-202-3-t106d1.html


Also i just realized SCR stands for Silicon controlled rectifier. lol that should help some
Click to expand...

Apparently you didnt read post 489 I made some time ago which explained what an SCR is? I also gave you a good idea what types of circuits may contain and SCR, like a garage door opener, or something that needs to turn on and off a fairly hefty amount of current. Nothing you listed remotely fits that description, and as you see, no SCR to be found there....

The main specs for an SCR are the Voltage and Current, which tells you the limits to how high the voltage can go on the SCR and how much current the SCR can pass. You also want to note what case style/package the SCR is built in. There are some specs on triggering etc that are more complex, but if you look at the available SCR's that meet the voltage, even suppliers that sell millions of different parts only have a few SCR's to choose from that fit the bill, and they only cost about a buck apiece. So grab a few and give em a try, or stick with the components others have used with success if you don't want to screw around. You might find the exact component or a cross referenced substitute which should do the job.....
 
ill go back and read your post, im still trying to wrap my head around all of this.

so the 2 i linked are they not gonna work for this application???
 
You may want to use 1w resistors, if you read this thread or have been following it all along there has been overheating on 1/2 w resistors. I used 1w 18 ohm and 2w 82 ohm. I used scr 's from gas heater igniters and from battery chargers. I hope this helps.
 
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