Red 6-volt DC Coil compared to Green 6-volt AC Coil
Posted: Sun Nov 12, 2023 10:22 pm
I've been asked what the static resistances are for both the Ducati AC green coil and DC red coil.
I was able to find both style coils among my spare coils. I have coils with Ducati labels assuring me that two types of coils and I am not reading coils made for another brand.
I have no way to assure these coils are good, but given that there is measurable resistance through both internal coil windings it is likely that the coils are good.
I checked my multimeter by measuring a known resistance before making these measurements.
Each "coil" has two coils inside the can, The first coil winding (the primary) is measured across the two threaded terminals on opposite sides of the Bakelite top.
My green coil measured 3.8 ohms of primary winding resistance across the two threaded terminals. The secondary winding is measured from the terminal that the black wire connects to and the center contact under the cap, where the high voltage wire connects. The secondary winding measured 11K ohms (That's 11,000 ohms.)
My red coil measured 1.7 ohms of primary winding resistance across the two threaded terminals. The secondary winding measured 600K ohms (That's 600,000 ohms.)
Worth noting is that the black wire's terminal on either version exhibited no resistance to the coil's metal can. This is why it is necessary to ground the black wire to the frame. Clamping the coil's metal can to the frame does not provide the required electrical connection to the frame.
I was able to find both style coils among my spare coils. I have coils with Ducati labels assuring me that two types of coils and I am not reading coils made for another brand.
I have no way to assure these coils are good, but given that there is measurable resistance through both internal coil windings it is likely that the coils are good.
I checked my multimeter by measuring a known resistance before making these measurements.
Each "coil" has two coils inside the can, The first coil winding (the primary) is measured across the two threaded terminals on opposite sides of the Bakelite top.
My green coil measured 3.8 ohms of primary winding resistance across the two threaded terminals. The secondary winding is measured from the terminal that the black wire connects to and the center contact under the cap, where the high voltage wire connects. The secondary winding measured 11K ohms (That's 11,000 ohms.)
My red coil measured 1.7 ohms of primary winding resistance across the two threaded terminals. The secondary winding measured 600K ohms (That's 600,000 ohms.)
Worth noting is that the black wire's terminal on either version exhibited no resistance to the coil's metal can. This is why it is necessary to ground the black wire to the frame. Clamping the coil's metal can to the frame does not provide the required electrical connection to the frame.