C11G (Rev. 8.2) User Manual
Revision: 01/27/2010 http://cnc4pc.com/TechDocs/C11GR8_2_User_Manual.pdf 15/21
Calculating the R1 value.
Note:
Rx is the unknown resistor value.
R
X
= V
EX
.(R/V) - R (1)
Where:
V
EX
is the external power supply voltage
V
is the voltage across the R resistor
An external resistor and a voltmeter are required to calculate the internal resistor (Rx)
value.
Note. The user should know the R value to do this operation. A 4.7KOhm @ 1/2W is
recommended.
SAMPLE: if you are using a 12V power supply (V
EX
), and using a 4.7KOhm as
external resistor (R), then the voltage across R should be 6V, using the equation 1,
the Rx value is 4.7KOhm.
