jephilp
commented
8 months ago I'll do my best to answer all your questions here, I'll be adding images as well for clarity sake.
Here is the schematic for the CDI, I have also added it to the respective tuning section.
To start, you got fairly close in figuring out what the actual schematic with labeling was which I applaud and is very impressive! I did purposely change a lot of the designators to obscure them from people looking to copy my designs, but since this appears to now be an issue it is time that I release the schematic to make everyone's life easier.
This should answer your questions as you can see they are not typos, just me referencing the schematic directly without showing it. If it is still confusing to have them all different we can look at changing ALL the designs to have a common reference designator between them.
exokinetic
Firstly, I would like to thank you for making this project public and open source under GPL liscence!
Secondly, I would like to thank you for sharing your research with regards to the block diagrams from the "previous art" CDI's that have been available to us up until now.
Thirdly, I would like to thank you sharing the circuit design principles so that others can follow along with the work!
Before I dive into the juicier details of the actual circuit design, and EXACTLY what is going on within;
I believe there are a few typo's between the block diagram and the tuning page, allow me to explain....
RV1 has a "stock value" of 16 Ohms.
RV1 is a 0-50 Ohm Pot on the DevPot V2 Block Diagram.
There is a 33 Ohm Resistor in the Jaguar CDI Block Diagram at exactly that location.
The images on your tuning page come from the Jaguar dragonfly45.com website.
The "16 Ohm" Pot is the one that is adjusted to move the whole curve up/down 1 degree per 1 Ohm of value change.
+1 Ohm on the 16 Ohm (stock setting) Pot should yield +1 Deg for EVERY step on the curve, based on the image you have on the "tuning" page which is following the JAGUAR CDI design principles; as the image is coped directly from his website.
The 16 Ohm Pot is on ONE SIDE of the "Voltage Divider" (you call it a 'resistor divider', but technically its called a VOLTAGE divider, and the distinction is important, as it explains why it effects the entire curve by the same amount)
Which side of the voltage divider the "higher resistance" is on is quite important in the effect it has on the voltage passing through it, as the equation for the voltage divider is thus:
V(out) = V(in)*((R2/(R1+R2))
Where R1 is on the "positive"/ "voltage source" side of V(out) and R2 is on the "negative"/"ground path" side of V(out).
As you can see, unless R1 is exactly equal to R2, it matter's what side its on. This is called the "Resistor Ratio" of the "Voltage Divider".
In the Jaguar CDI Block Diagram the 16 Ohm resistor is in the "RV3" position of the DevPot V2 Block Diagram, NOT the RV1 position.
The DevSnapLock Block Diagram appears to CORRECT this error, placing the 16 Ohm SnapLock resistor in the exact same position as the Jaguar CDI. Now called the R2 position on the DevSnapLock Block Diagram, and would correspond to the "RV3" position of the DevPot V2 Block Diagram.
Can you please confirm the location of the "16 Ohm Stock Setting Potentiometer" for the DevPot V2 design?
Is it INDEED in the RV1 position?
Or is that a typo, and its actually RV3 that is the "16 Ohm Stock Setting Potentiometer" (which would match the Jaguar CDI design)
RV3 has a "stock value" of 760 Ohms.
RV3 is a 0-50 Ohm Pot on the DevPot V2 Block Diagram.
There is a 16 Ohm Resistor in the Jaguar CDI Block Diagram at exactly that location.
How -exactly- do you set a 0-50 Ohm Pot to 760 Ohms?!
This is clearly a typo somewhere.
The most likely "correct" labeling/ stock settings in my opinion is that RV3 is -ACTUALLY- the "16 Ohm" stock setting position.
There are only -TWO- Potentiometer's in the DevPot V2 Block Diagram that are OVER 0-500 Ohm Pots.
RV2 is labeled as a 1k Pot RV5 is labeled as a 1k Pot
Based on on the fact that the Jaguar CDI has a 680 Ohm Resistor in the RV5 position, I think it is most likely that "760 Ohm" is the stock setting for RV5, and NOT RV3.
Can you confirm exactly what is correct here, as it is not possible that RV3 has a stock setting of 760 Ohms.
RV4 has a "stock value" of 390 Ohms.
RV4 is a 0-500 Ohm Pot on the DevPot V2 Block Diagram.
There is a 470 Ohm Resistor in the Jaguar CDI Block Diagram right around that position.
This actually seems correct.
Can you please confirm that this is correct?
RV5 has a "stock value" of 33 Ohms.
RV5 is a 0-1000 Ohm Pot on the DevPot V2 Block Diagram.
Why a 0-1000 Ohm Pot if the stock value is so low...?
There is a 7.5k and a 680 Ohm Resistor in the Jaguar CDI Block Diagram at exactly that location.
There is also a 33 Ohm Resistor in the Jaguar CDI Block Diagram at exactly the RV1 position on the DevPot V2 Block Diagram.
It seems MUCH more likely that RV1 should have the "stock value" of 33 Ohms and that RV5 should have the "stock value" of 760 Ohms.
Can you confirm exactly what is correct here?
Image for Reference:
I am excited to begin discussing the actual design of the circuit, and what adjusting the various resistor/ capacitor locations should do to the resulting spark curve, and WHY that happens based on basic circuit design principles. Ohm's Law, Farraday's Law, Len's Law, etc, etc.
Thank you again!
-Sean Davis