Help confusion Constructing Nichrome Dew Heaters

[lifeonmars]

Hello Everyone Just been reading Ron Keatings Method of constructing Nichrome Dew Heater strips at Dewbusters.com,great write up and very informative.

One thing I am struggling with is in step one you measure the circumference of your scope and then divide 190 by the circumference of the scope to give you the resistance of your heater to give you .76 watts /inch great so far and no probs.

Step 3 and 4 get you test by moving crocodle clips along the wire whilst applying a 12 volt supply to establish minimuim length to provide a gentle heat and the measure the resistance between the two points ,great I am ok with that.

step 5 and 6 start to confuse me,in step one we establish the required resistance(5 ohms) but in step 5 and 6 we times it by 3 to get 15 ohms,if we cut three strips at 15 ohms isn`t it going to be way over the 5 ohms we established in step one, to be adequate to heat the scope in the example.

Can anyone clarify what I am missing here ,and I hope I have not confused matters more !!Sorry if I have created more confusion!!!!

[Gina]

Three 15 ohms in parallel gives 5 ohms.

[lifeonmars]

Thank you very much for that Gina I am afraid my electrical theory just about stretches to Ohms law so your help is much appreciated and helps me advance my project.

Thanks Frank