Maker Pro
Maker Pro

Graphite painted cards and varying resistance

123456789a

Mar 2, 2013
21
Joined
Mar 2, 2013
Messages
21
hello I had been making cards painted with graphite and due to uneven distribuation of the paint, some parts of the same face on the card will have different resistance (ranging from 30Ω to 100Ω) so how will this effect the resistance when connected in paraell? Will it treat them as invidual resistors when they are on the same face on the card?
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
Joined
Nov 28, 2011
Messages
8,393
What do you mean by "connected in parallel"? Do you mean that the two cards will be placed face-to-face? And how are you measuring the resistance? Can you describe what you're doing?
 

Arouse1973

Adam
Dec 18, 2013
5,178
Joined
Dec 18, 2013
Messages
5,178
I think it all depends on where you make your connections. Mark two points on the card and measure the resistance, if you then use these same points for your connection then this will be the value of resistance across your connections. These points will then behave as a resistor and you can treat them as such. How good a resistor they will be is another matter.
Adam
 

Gryd3

Jun 25, 2014
4,098
Joined
Jun 25, 2014
Messages
4,098
Something else to consider...
As Arouse1973 stated, marking two points, measuring and using the same two points will result in a resistor of that value. Adding additional card that are prepped the same way will be like adding resistors in parallel.

Measuring from multiple points on the same sheet of painted graphite will not result in a parallel resistance equation when you use all of the points at the same time, unless you have painted or cut lines into the card to electrically separate the path between the points you wish to use.

A picture is worth a thousand words, can you please upload a sketch, picture, render... etc?

Give us some idea of how these will be used and how you are measuring them with specifics as if you were instructing someone over the phone to do the measurements for you.

Edit: http://en.wikipedia.org/wiki/Sheet_resistance
Because the the material you are working with is a non-uniform thickness, the examples here do not 100% apply, but even if it did this subject could get potentially complicated.
We await some additional details to help us determine what we are dealing with.
 
Last edited:
Top