Topic: What wattage resistors to use on 3 ohm coils?

[Duke McDukiedook]

What wattage resistors should I use on my 3 ohm coils to raise the impedance to the coils?

I'll be buying some CL-80 thermistors for my tube amps and preamps and some other electronic parts I need to buy and I did not know what wattage Hondaman used in his resistor packs.

[luap]

http://sohc4shop.com/catalog/product_info.php?products_id=44
thats got good info.
"The Dyna (Green) coils and ACCEL performance coils have 3-ohm primaries: these require a 1 ohm Resistor Pack to match these bikes' wiring (and charging) systems to those coils"

[Duke McDukiedook]

Well, I have the original points still but I hooked up a dyna-S system with 3 ohm coils and burned up the kill switch a good while back before I knew any better. 
I just want to get it close to 5 ohm coils without wasting money on a whole set of 5 ohm coils.

I figured 10 watts is about what I would want but was unsure I would get 1 ohm or 2 ohm resistors until I actually measured the resistance on my current 3 ohm coils.

2 0hm
http://www.digikey.com/product-detail/en/RH0102R000FE02/RHRB-2.0-ND/1166282

1 ohm
http://www.digikey.com/product-detail/en/RH0101R000FE02/RHRB-1.0-ND/1166277
 

[Duke McDukiedook]

From that link you provided it looks like Mark uses 25 watt resistors, that would give a pretty healthy FOS as long as they fit and it looks like they do.

http://www.digikey.com/product-detail/en/RH0251R000FE02/RHRC-1.0-ND/1166295

[scottly]

P=IR²
1x1 = 1, 1x 3 = 3 Watts dissipated by the resistor when one coil is left on or two coils are operating alternately through the same 1Ω resistor.



Cheers,

P=I squared x R. 3x3=9, 9x1=9 watts dissipated by the resistor. The power dissipation would be less with the motor running, depending on the duty-cycle, or dwell, of the Dyna. For example, a 180 degree dwell would equal a 50% duty cycle. .5 x 9= 4.5 watts.

[TwoTired]

P=IR²
1x1 = 1, 1x 3 = 3 Watts dissipated by the resistor when one coil is left on or two coils are operating alternately through the same 1Ω resistor.



Cheers,

P=I squared x R. 3x3=9, 9x1=9 watts dissipated by the resistor. The power dissipation would be less with the motor running, depending on the duty-cycle, or dwell, of the Dyna. For example, a 180 degree dwell would equal a 50% duty cycle. .5 x 9= 4.5 watts.

Dyslexia strikes again.   

[scottly]

I know the feeling! LOL

[HondaMan]

I use 10 watt resistors: the picture on my website shows the ones (25 watt) that I had to use during 2008 and 2009, when the entire world's inventory of 10 watt aluminum resistors in 1.0 and 1.2 ohms was gone, and no one was planning on making them soon(!). I used all those up, back to the smaller 10 watt units again. Thank goodness for Ohmite stepping back up to fill in the gap!

[Duke McDukiedook]

Thanks guys, I would buy them from you Mark if I wasn't buying parts for some audio vacuum tube equipment I am recapping for some rebuilds.
Time does not wait for electrolytic capacitors. 

[Duke McDukiedook]

Is my assumption correct to connect the resistors to the black wires and then to the coil from the positive side of the battery?