Ohms addition / subtraction

Al · #1 PostAuthor: Al » Sat Oct 06, 2012 9:32 pm

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 · #2 PostAuthor: **london calling** » Sun Oct 07, 2012 4:44 am

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.

#3 PostAuthor: **KeithZ1R** » Sun Oct 07, 2012 6:53 am

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 · #4 PostAuthor: **ZedHead** » Sun Oct 07, 2012 7:08 am

london calling wrote: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 · #5 PostAuthor: **garyd** » Sun Oct 07, 2012 8:06 am

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 · #6 PostAuthor: Al » Sun Oct 07, 2012 8:33 am

Outstanding gents, thank you all.

AL

#7 PostAuthor: **Taffus** » Sun Oct 07, 2012 3:14 pm

KeithZ1R wrote: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

#8 PostAuthor: **KeithZ1R** » Sun Oct 07, 2012 7:04 pm

thats the one :lol:

what a bastard equation that was :evil:

#9 PostAuthor: **Taffus** » Sun Oct 07, 2012 7:39 pm

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

Z1parR · #10 PostAuthor: **Z1parR** » Sun Oct 07, 2012 7:49 pm

For gods sake you sparks , glad i'm a mechanical fitter :lol:

What was it again about the East coast line engine that pulled the 8 carriage and buffet car :wink:

#11 PostAuthor: **KeithZ1R** » Sun Oct 07, 2012 7:49 pm

nope just a better memory :roll:

now without google the transformer efficiency equation please :lol:

#12 PostAuthor: **Taffus** » Sun Oct 07, 2012 8:18 pm

KeithZ1R wrote:nope just a better memory now without google the transformer efficiency equation please

or the square root of -1

Ohms addition / subtraction

Ohms addition / subtraction

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