Figure 1. Board-mounted “DIP switches.” Left group, front to back and left to right (all are SPST): single station side-action toggle; three-station side-action, two-station rocker, and single-station slide; eight-station slide (low-profile) and six-station rocker; eight-station slide and rocker. Middle group (all are hexadecimal coded): six-pin low-profile, six-pin with top or side adjust; 16-pin with true and complement coding. Right group: 2 mm×2 mm surface-mount header block with movable jumper (“shunt”), 0.1"×0.1" (2.54 mm×2.54 mm) through-hole header block with shunts; 18-pin SPDT (common actuator); eight-pin dual SPDT slide and rocker; 16-pin quad SPDT slide (two examples).
D. PC-mounting switches
It’s common to see little arrays of switches on printed circuit (PC) boards, like the ones shown in Figure 1. They’re often called DIP switches, referring to the integrated circuit dual in-line package that they borrow, though contemporary practice increasingly uses the more compact surface-mount technology (SMT) package. As the photograph illustrates, you can get coded rotary switches; and
because these are used for set-and-forget internal settings, you can substitute amultipin header block, with little slide on “shunts” to make the connections.
E. Other switch types
In addition to these basic switch types, there are available various exotic switches such as Hall-effect switches, reed switches, proximity switches, etc. All switches carry maximum current and voltage ratings; a small toggle switch might be rated at 150 volts and 5 amps. Operation with
inductive loads drastically reduces switch life because of arcing during turn-off. It’s always OK to operate a switch below its maximum ratings, with one notable exception: since many switches rely on substantial current flow to clean away contact oxides, it’s important to use a switch that is designed for “dry switching” when switching low level signals; otherwise you’ll get noisy and intermittent operation.
|Engineer.Labs | Hardware Design Engineer (Freelancer)||
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