If you build the basic cdi use higher watt resistors, I used 1w 18 ohm and 2w82 ohm. The 1/2 watt resistors have overheated on some.
Roll Your Own CDI
- Thread starter rohmell
- Start date
Cool will do, found some from the same supplier for the same price lol.
Everything else looks good otherwise then?
Think i'll give the basic one a go first before getting any more complicated hehe
Evertything else should work, on my first cdi the scr required too high of a voltage to fire the gate making the bike sluggish at low rpm. With a different scr it worked correctly.
cdi=more to to wrong.. parts burn out.. id hate to be 20 miles out on my motorized bike and it fail... go the normal route.. unless its a cdi designed for a honda bike like a regular motor cycle ..
Wow!
I was heart broken when I saw the prices of MPF capacitors, until I saw your links.
You are saving me a crap-ton of bux.
And the 1n4007's
(I put these 2 things on my ebay watch list so far.)
Going to look at the rest of what you found.
Thanks.
PS, I read the whole thread yesterday and today! Some of it twice!
I would like a second opinion on this one.
This is good? No?
Triac, does that mean, three prong, or leads?
One other question:
Can I mix 1W and 2W resistors? I can only find 2W 18ohm resistors at the quantity and price I want.
Can I mix 1W and 2W resistors? I can only find 2W 18ohm resistors at the quantity and price I want.
2W resistors will be fine as the W(watt) value only means how much power they can handle. The higher the W value the more power(heat) they can soak up. You can go up in watt value but never go down in the value. So if a circuit calls for a 100 ohm 1W resistor you can use a 100 ohm 2W or even 3W resistor in its place. But do know that the high the W value the more it will cost for the part many times.
I am quite interested in that, but first things first. I'll make the simple one for now. It'll be an improvement.
It's been awhile since I've done electronics projects, I'm a bit rusty.
But compared to 22 years ago, electronic parts are so much easier to find.
I think that as RPMs go up, you would want to advance the timing, in other words, have the spark occur earlier.
Yes, during one half cycle, all the current is flowing through the resistors, so they should be rated at a higher wattage.
2 strokes are weird compared to 4 strokes.
Folks here who have experimented with adjustable ignitions on these HT engines have found that retarding the ignition as the RPM's go up proved better than advancing it.
I still gotta agree with you though, it makes no sense to me either.
Apparently this is a triac and it is different as pointed out to me by:
Opinions on this, I assume it's just fine:
5P4M-SCR-400V-5A-NEC-THYRISTOR-
A lot of the buying leads on the SCR's that Rohmell posted from ebay are out of date and not available and/or at a good price.
Screw it, I just bought 5 for under 7 bux S&H included, they are rated -40C
5P4M-SCR-400V-5A-NEC-THYRISTOR-
A lot of the buying leads on the SCR's that Rohmell posted from ebay are out of date and not available and/or at a good price.
Screw it, I just bought 5 for under 7 bux S&H included, they are rated -40C
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If anyone wants a better understanding of how a SCR works in a circuit,
this video is not bad only problem is the not-stellar sound quality and the Indian accent.
What a sound quality combo that is!
this video is not bad only problem is the not-stellar sound quality and the Indian accent.
What a sound quality combo that is!
I've read through this post with some interest. I have to say there is much more going on with this seemingly simple system then meets the eye. You firstly need to go way back to basics and understand how the points magnetos work. You need an SCR not a triac for this to work, when you know how the magneto works and how the SCR functions you'll realise why.
We manufacture direct fit replacement CDi units for 70s machines, as well as a few of our own design (google rex's speed shop)
Going down the road you guys are isn't going to give you the system you want.
We manufacture direct fit replacement CDi units for 70s machines, as well as a few of our own design (google rex's speed shop)
Going down the road you guys are isn't going to give you the system you want.
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I am really no salesman, but I'm a developer.
Read here to understand how SCRs, Tyristor and Triac work. And read carefully.
http://de.scribd.com/doc/42776869/scr-traic-diac-Report
Then take your Osco and look which polarity reaches the capacitor and the gate. Then you know, which kind of device you have to choose.
I have developed my own programmable digital CDI in 2010. My wife has got one, about ten of my friends have got one and we all use it in our 30cc Saxonette. It is a magneto ignition without pickup and without battery, just like in our HT motors. I have build a lot of analog CDIs, which are very simple compared with the digital ones.
Professer Dave wrote somewhere in this thread, that he wanted to start developing a digital ignition. That was about May 2012. Doesn't matter, that he hasn't finished yet. All in all my lasted 18 months. And I'm proud of it.
Multipaul
Read here to understand how SCRs, Tyristor and Triac work. And read carefully.
http://de.scribd.com/doc/42776869/scr-traic-diac-Report
Then take your Osco and look which polarity reaches the capacitor and the gate. Then you know, which kind of device you have to choose.
I have developed my own programmable digital CDI in 2010. My wife has got one, about ten of my friends have got one and we all use it in our 30cc Saxonette. It is a magneto ignition without pickup and without battery, just like in our HT motors. I have build a lot of analog CDIs, which are very simple compared with the digital ones.
Professer Dave wrote somewhere in this thread, that he wanted to start developing a digital ignition. That was about May 2012. Doesn't matter, that he hasn't finished yet. All in all my lasted 18 months. And I'm proud of it.
Multipaul
eh, we will see how it goes before I get to the parts store, I found stuff with plenty of boards
Parts on ebay are dirt cheap, still waiting for my SCR's and tantalum capacitors though, then I can build this one:
It's retarded.
Then I will consider the modified jag clone.
It's retarded.
Then I will consider the modified jag clone.