amazingly…cheaper for 4 !!

[vintin]

I’m quite sure you can not use the ratio of the primary and secondary coil resistances to figure voltage step up in a transformer/coil.

It is the ratio of the winding count that should be used in the calculation. I believe at this point the winding ratio and count is unknown.

EDIT: Likely the wire gauge is unknown. Even if the gauge of the wire were known we’d still have to know the windings ratio.

I ordered 4 yesterday.

[fisherman6]

I agree Dan. It is the ratio of the windings that matter in the step up/dn calculations of a transformer or a coil. Using resistance to estimate that truly leaves too many variables unknown. The wire gauge is unknown as well, but knowing that wire gauge determines the amount of raw material used to produce the coils, I’m willing to bet it’s quite small. If we knew it, we may be able to predict the windings ratio more closely, but it would still be only an estimate. I’m going to try them in another motor sometime hopefully fairly soon and see if I get the same results again. All this said, I still ordered some more to have on hand.
-Ben

OldJohnnyRude on YouTube

[outbdnut2]

Yes – The laws of magnetic inductance are confusing. I’m a retired electrical Engineer and can confirm there are many factors that will affect current through the points and output voltage and current. Here is a list of all I can remember:

-DC Resistance Primary winding
-DC resistance Secondary winding
Note DC Resistances of copper windings are affected by temperature, and wire size.
– Permeability of the iron core (symbol is greek letter "u" pronounced "mew") Iron cores must be a special steel to have no permanent magnetization carryover – what is known as a square hysteresis curve is undesirable.
– Inter-winding capacitance
– stray capacitive coupling from windings to core
– How close to core saturation the core is driven.
– Mutual inductance of the device (varies some with load)
– inductance of primary
– Inductance of secondary
– stray eddy currents in the core (insulation coatings on iron laminations reduce eddy currents)
– number of winding turns primary
– number of winding turns secondary
Probably the most reliable number is the ratio of number of winding turns in the primary vs secondary for voltage step up. This also affect current via the Amp-turns ratio.

All of these things come together to give complex impedances.

Note inductances are affected by how close to the iron core the windings are wound – affected by insulating spaces and thickness of enamel insulation on the winding wire.

The capacitance of the condensor also affects erosion of the points.

OK – so all this being said, the message here is each manufacturer’s ignition coils will be a bit different because there are just too many variables. So even if you have a you have a lot of lab electronics equipment (impedance bridges, etc,) you have to put them in a motor and see how they perform.

I’ve seen electronic inductors from different vendors that have identical spec sheets perform different in some circuits I’ve designed.
Dave

[crosbyman]

Now you know why I quit Tech school to move on to a successful career 30 years for the phone company who treated me well, salary wise, promotions, trips, conferences, skills development, management course until 30 years later some jerk head cutter came around telling the experienced employees our knowledge and skills would no longer be required for the "new Bell "… 😯

I waited a few weeks signed myself out….with my pension… quit on a Friday and went to work for the competition ( cable company) who had no real experience in Telephony and…communications fraud. Next Tuesday after I quit I started working for another 10 years to work and migrate thousands of Bell clients per week……over to IP Telephony over cable while stopping the crooks from migrating over ….

it was all fun but oldies are fun to 🙂

Joining AOMCI has priviledges 🙂

[outbdnut2]

There were a few times during my 28 years designing medical electronics when I needed custom transformers for my circuits – I took a circuit prototype "breadboard" to a local small company that designed and manufactured inductors and transformers and told them what the inductor had to do in the circuit and let the experts there design them to work in my circuits. I wasn’t going to pretend to be a transformer designer! That strategy worked great!
Dave

[garry-in-michigan]

It is all in the turns ratio, As the voltage goes up. the amperage goes down, Less amperage allows the use of smaller wire. That is why very high voltage is used on long distance electric lines. . . 😎

[Author]

Posts