POST ISSUE DRAFT 8 of 2017_01_26
Hi K01,
I can't resist anything involving motor bikes so I had a look at the original circuit in post #1 and worked out a universal trigger input that would just connect to the 'CB' terminal on the coil, regardless of what type of ignition: traditional Kettering, solid state assisted, CDI. I also improved the accuracy and tolerances by changing a few components here and there and specifying component types that would improve the accuracy, the 100nF timing capacitor being the most significant.
But I also looked at other circuits, and on balance, the circuit shown below may be worth considering.
I assume that the engine on your bike produces a spark every revolution of the crankshaft and that the maximum engine speed is 10,000 RPM.
Do you have any idea, at this stage, what meter you are going for. I have assumed a moving coil meter with a maximum full scale current of 1mA.
spec
SCHEMATIC TO BE POSTED
NOTES
(1) The timing capacitor is a polypropylene type for high stability and zero leakage
(2) All resistors are 1/4 W (250mW) or more, 5% or better, metal film, Except the input resistor which is 1/2 W (500mW) or more, metal film, 10% or better with a 500V minimum rating.
(3) The capacitors are critical to the design and must be the type shown.
(4) The physical layout must be compact, using short wires and component self leads.
(5) The deign is suitable for both 6V and 12V systems.
DATASHEETS & SUPPLIER
(1)
CD74HC4538: https://www.ti.com/lit/ds/symlink/cd74hc4538.pdf
**broken link removed**
(2) LP2950-5:
https://www.ti.com/lit/ds/symlink/lp2951-n.pdf
https://www.digikey.com/product-det...r/LP2950ACDT-5.0G/LP2950ACDT-5.0GOS-ND/918530
(3) IRLML6302TRPBF:
https://www.infineon.com/dgdl/irlml6302pbf.pdf?fileId=5546d462533600a4015356688c702627
https://www.digikey.com/product-det...ogies/IRLML6302TRPBF/IRLML6302PBFCT-ND/812510
(4)
47nF polypropylene capacitor: https://www.vishay.com/docs/28128/mkp416to420.pdf
https://www.digikey.co.uk/products/...=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25
(5)
1uF ceramic capacitor: https://www.vishay.com/docs/49363/49363_vmn-pt9161.pdf
https://www.digikey.co.uk/product-detail/en/vishay-bc-components/K104K10X7RF5UH5/BC2665CT-ND/2356879
(6) 10uF, tantalum capacitor:
https://www.vishay.com/docs/40080/tr3.pdf
https://www.digikey.co.uk/product-detail/en/vishay-sprague/TR3C106K025C0500/718-1769-1-ND/2260014