Changing the Resistance of Your PhotoCells
Note 1.	Test Results using the same PhotoCell each time in controlled "Bright"/"Dark" conditions.
Note 2.	To trip the Trigger Point of the LPT port,
	"Bright" Resistance must be less than Trigger Point and
	"Dark" Resistance must be greater than Trigger Point.
Note 3.	All measurements below are in OHMs, your measurements will vary
Adding a Resistor in Parallel
	Parallel	"Bright"	"Dark"
Case	Resistor	Resistance	Resistance
1	0	1,640	7,500
2	10,000	1,440	5,700
3	4,700	1,240	3,560
4	2,200	944	1,934
5	1,000	616	940
6	470	364	452
7	100	91	96
Example: If Trigger Point is 1,000 then about 2,000 ohms resistance needed in Parallel.
Adding a Resistor in Series
	Series	"Bright"	"Dark"
Case	Resistor	Resistance	Resistance
1	0	1,640	7,500
2	1,000	2,630	8,000
3	2,200	3,800	9,000
4	4,700	6,320	12,000
5	10,000	11,630	17,250
6	15,000	16,470	22,000
7	100,000	101,200	106,300
Example: If Trigger Point is 15,000 then about 10,000 ohms resistance needed in Series.
Summary
Problem = Can't get PhotoCell Bright Enough to reach Trigger Point
Solution = Add resistor in Parallel with PhotoCell
Problem = Can't get PhotoCell Dark Enough to reach Trigger Point
Solution = Add resistor in Series with PhotoCell
HINT 1.	Instead of using a standard ceramic resistor, you could use a variable resistor
	(referred to as a Potentiometer) which would allows you to adjust and
	fine tune resistance with the twist of a knob.
HINT 2.	Use CHITI.EXE as a visual reference for your fine tuning.