Microcoils and a question about Ohm's law

[dannyw14]

Just had a second attempt at a microcoil on a kanger head. I used 8 wraps of .32 kanthal and cotton.
Ended up with a resistance of 1, couldn't obviously try it on the vamo so I had a go with a spinner and it worked well to start with but then dried out pretty quickly and tasted like it wasn't wicking.

Is it probable that the coil was too small? As that would explain the low resistance and lack of wicking?

Could someone also point me in the direction of a simple explanation of Ohm's law or just tell me if this is correct.


A 2 ohm coil ran at 8 watts would produce 4 volts, and to get 4 volts from a 1.5 ohm coil, it would need to be ran at 6 watts.

Thanks in advance

[Super-Shiny]

Have a look at this what i knocked up:

[meeee]

My Coil setup is No.10 which works well for me.

[dannyw14]

Thanks that's really useful, so the resistance is increased by increasing the coil diameter and number of wraps, and decreased by the wire guage? Is that right?

[Deleted]

dannyw14 the relationship between watts, voltage and resistance is watts = (volts x volts) / resistance so if you wanted 4 volts using a 1.5 ohm coil you would need to set your watts to 10.7 ...... watts = (4 x 4) / 1.5 = 10.66

[Deleted]

Thin wire = high resistance
Thick wire = low resistance
A 1m length 0.25mm wire has a resistance of approx 28ohms
A 1m length 0.32mm wire has a resistance of approx 18ohms.
Whatever gauge wire you use for making a coil, the longer it is the higher the resistance. Obviously the coil dia and number of wraps dictate the length.

Look at No 4 & 13 on the chart posted by Super-Shiny  Same dia coil, both 10 wraps but the thin wire is 1.6 ohms and the 0.32mm is only 1.2 ohms


This coil calculator found by Super-Shiny is excellent

Use this Ohms law calculator in conjunction with the coil one and your all sorted

[surfatwork]

A 2 ohm coil ran at 8 watts would produce 4 volts, and to get 4 volts from a 1.5 ohm coil, it would need to be ran at 6 watts.

2ohm coil at 8W would produce 2V, because power = v * v/r, so 8 = (V*V)/2 => V = 2V
to get 4V from 1.5ohm, you would need 4 * 4 /1.5 = 10.6W, as @yinyang said.

The basic laws are
P = V*I
I = V/R
where P=power, V= volts, I = current in amperes.

[Deleted]

'2ohm coil at 8W would produce 2V,'

Something's wrong there surfatwork 2v @ 2ohms is 2w.

[Deleted]

Jun 5, 2014 21:49:41 GMT @scooby said:

'2ohm coil at 8W would produce 2V,'

Something's wrong there surfatwork 2v @ 2ohms is 2w.

A 2 ohm coil at 8 watts would produce 4 volts

[Clivia]

I use 0.25 kanthal and get with 8 ( tight blowtorched wraps ) 1.9 ohm - which is fine for me - but not like in the chart ???

edit inside diameter 2mm - if I do 9 wraps I get about 2.3 ohm

[Deleted]

Jun 6, 2014 5:25:31 GMT @yinyang said:

Jun 5, 2014 21:49:41 GMT @scooby said:

'2ohm coil at 8W would produce 2V,'

Something's wrong there surfatwork 2v @ 2ohms is 2w.

A 2 ohm coil at 8 watts would produce 4 volts

Yep, just a slip with his maths. 

[surfatwork]

oops, sorry, yes 8W into 2ohms would need 4Volts.

[hijack]

dannyw14 I know this is a late response to your thread but when I read it I thought you might like to take a look at this vv/vw guide. Your probably ok with the concept of vv/vw, but at the bottom of the guide I discuss Ohms laws and how it can be used to work out the bits we need it to. you may find the chart there useful.