8
•
Customize the Current Limit Resistor
Appendix A.
Customize the Current
Limit Resistor
The ACLD-9182 contains 16 identical opto-isolated control input
channels. The circuit diagram of the isolated input channel is shown
below. The digital input is first routed through a photo-coupler (PC-
814), so that the connection are not polarity sensitive whether used on
AC or DC voltage.
In addition, a single-pole filter with a time constant about 5ms is used
to filter when the AC inputs passed through.
V
IN
1.2k
Ω
Ri
4N-35
(opto-isolator)
I
F
The normal input voltage range for high state is 3 to 24VAC or DC.
The normal input range can be extended by changing the resister (Ri)
to limit the current (
I
F
)through the PC-814( opto-isolator to about
10mA . The exact resister value to replace the original resister Ri
(1.2K
Ω
) can be calculated by the following formulas.
Vin =
I
F X
Ri
Pw = Vin X
I
F
For example,
if the input voltage is 110V, then the Ri should be
replace by
Ri = 110 (V) / 0.01 (A) =
11 K
Ω
Pw = 110 (V) X 0.01 (A) =
1.1 W
