TC33B Model TC33B is a low profile, bottom adjust only 3 mm open-frame trimming potentiometer. This trimmer was specifically designed for, but not limited to, LCD applications. Its low profile and bottom adjust features make it suitable for space restricted applications. Refer to Figure 1 for an example of a trimmer in an LCD application. The trimmer is connected as a voltage divider and its function is to vary the contrast of the LCD monitor. The bottom adjust feature is necessary for ease of adjustment. LCD monitors have the control circuitry on a thin flexible PCB that is folded up Vcc against the screen. The trimmer Vcc 74LS174 LCD cannot be adjusted, unless a 10 K 16 Vcc 1 - Gnd small via is placed on the bottom 1Q 2 0.1 µF 2 - Vcc 2D 4 of the PCB. Figure 2 shows the 3 - Con Vcc 2Q 5 4 - RS 1 - Clr location of the via in the PCB. The 3D 6 5 - RW 3Q 7 3 - 1D 6 - E via allows the operator to vary Data 4D - 11 7 - D0 9 Clk 4Q 10 the contrast without having to 8 - D1 Clock 5D - 13 9 - D2 disassemble the LCD monitor. 5Q - 12 10 - D3 8 - Gnd Other applications involving space limitations in the end product may find the TC33B to be a suitable solution. 6D 6Q - 14 15 1K IN914 11 12 13 14 - D4 D5 D6 D7 Figure 1: LCD Monitor Schematic Applications: • Pilot headset • Door intercom • Rotary encoders • Miniature sensors Figure 2: LCD Monitor Printed Circuit Board Americas: Tel +1-951 781-5500 Fax +1-951 781-5700 Europe: Tel +41-(0)41 768 55 55 COPYRIGHT© 2007 • BOURNS, INC. 04/07 e/T0729 “Bourns” is a registered trademark of Bourns, Inc. in the U.S. and other countries. Fax +41-(0)41 768 55 10 Asia-Pacific: Tel +886-2 256 241 17 Fax +886-2 256 241 16