Ohms addition / subtraction

[Al]

Does a pair or 1.5 ohm (Brown / Red) Dyna coils sum to 3 ohms when wired in series?

Or is resistance not an addition process but an iterative one?

This is for a four coil setup on a bike with an 8 plug head running Dyna 'S'.

I believe the correct resistance should be 3 ohms for Dyna 'S' but with four coils (1.5 ohms each) i need to check the value of 2 times 1.5 in series.

Reason for asking is i have seen it done with four Grey Dyna coils of value 2.2 ohms.

AL

[london calling]

Resistance in series is added together,eg 2=2+4
In parallel it's the reciprocal of the reistances combined,then reciprocated again.
This means the overall resistance is always less than the smallest resistance.

[KeithZ1R]

connect em up and measure it although from my dim and distant classroom days coils are measured in inductance so it may not be that simple although as Jack has pointed out series is summing parallel is reciprocal summing

[ZedHead]

Resistance in series is added together,eg 2=2+4
In parallel it's the reciprocal of the reistances combined,then reciprocated again.
This means the overall resistance is always less than the smallest resistance.

Correct

Resisters in series R = R1 + R2 +R3 etc

Resisters in parallel = 1/R = 1/R1 + 1/R2 + 1/R3 etc

[garyd]

Resisters in parallel = 1/R = 1/R1 + 1/R2 + 1/R3 etc[/quote]



A different way to write it if you understand maths


Resisters in parallel = R = 1 / ((1/R1) + (1/R2) + (1/R3))

[Al]

Outstanding gents, thank you all.

AL

[Taffus]

connect em up and measure it although from my dim and distant classroom days coils are measured in inductance so it may not be that simple although as Jack has pointed out series is summing parallel is reciprocal summing

You're thinking of dynamic impedance
Zo

[KeithZ1R]

thats the one what a bastard equation that was

[Taffus]

1 over 2 pi root lc that is the resonant frequency.......
is that my anorak?

[Z1parR]

For gods sake you sparks , glad i'm a mechanical fitter
What was it again about the East coast line engine that pulled the 8 carriage and buffet car

[KeithZ1R]

nope just a better memory now without google the transformer efficiency equation please

[Taffus]

nope just a better memory now without google the transformer efficiency equation please

or the square root of -1