Coin Slot Magazine - #087 - 1982 - May[International Arcade Museum]
are also referred to as 'NO' or 'Form A' and 'normally
closed' switches as' NC or' Form B.' The SPDT switch
is actually a 'normally closed' switch and a 'normally
open' switch sharing a common switch blade. It can
have used switches on a relay (as shown in Figures 2A
and 2B) to illustrate switch operation, the exact same
ideas apply to switches operated by any other device
(such as score motor cams, playfield scoring devices,
easily be seen by referring to the lower switch (the one
with three blades) in Figures 2A and 2 B, that the center
stepping switches, etc.) when you consider the'normal'
blade is the 'common blade,' the upper blade forms a
'normally closed' switch with this common blade, and
the lower blade forms a 'normally open' switch with it.
to the 'unenergized' and 'energized' states of the relay
The dots placed to the left of the solder terminal end of
the switches in the figures illustrate that when this
switch is in its'normal state' (figure 2A) current flows
between the'common blade' and the'normally closed'
blade of the switch. When the switch is in its 'operated
state' (Figure 2B) that circuit is opened (no current
flows) but current now flows between the 'common
blade' and the 'normally open' blade. This illustrates
the action of SPDT switches and should be thoroughly
understood.
Another type of switch sometimes found in games is
what I call the 'Normally Open-Normally Open' (or
' NONO') switch. It has three blades, the contacts on all
of which are normally open. When the switch is actuated
the contacts on all three blades touch thus electrically
connecting all three circuits connected to them. This
configuration was used on relays and some playfield
switches on older (mostly pre-war) games and occa
sionally on playfield targets on later machines.
The symbols used on schematic diagrams for the
various types of switches discussed above were shown
in Figure 1, which was with Part 1 of this series of
articles Schematics often used abbreviated terminology
such as NO, SPDT, etc. mentioned earlier. Often the
abbreviations'OWE'(open when energized) and'CWE'
and 'operated' states of these devices to be equivalent
respectively.
SWITCH APPLICATIONS
Switches in games provide three basic functions.
The switches which are operated by'playfield scoring
devices' (bumpers, rollovers, etc.) act as'sensors;' they
sense the occurance of some playfield event (such as
a ball striking a bumper) and pass this information on to
the game's internal circuitry. Switches on relays provide
'control' functions; they pass on information regarding
one event to control another. The third basic switch
function is that of'feedback' The'end-of-stroke' switches
connected with some solenoids are a good example of
this as they provide information to indicate that an
action (the pulling in of the solenoids plunger) has
been properly accomplished. Other examples of this
function would be the 'zero switches' on stepping
switches and 'score reels' which indicate that these
devices have been successfully 'reset' to zero.
The applications of switches on 'score motors' were
covered in last month's article. Switches on relays
were also discussed in a previous article. The functions
of these switches vary, but usually provide 'control' of
other circuitry as mentioned above. The discussion of
an example of typical game circuitry in a future article
will provide a better understanding of the functions
performed by relay and score motor switches.
(closed when energized) were used next to switch
symbols. This was normally used when a switch was
operated by a solenoid coil, 'energized' referring to the
condition where that coil had current applied to it. The
terms 'OWP (open when in) and 'CWI' (closed when in)
This discussion of switches will be
continued in the June issue
were used to refer to switches operated by the movable
'shuffle panel,' found on older games, which moves'in'
when the coin chute was pushed in at the start of a new
covering stepping switches,
playfield switches and
switch maintenance.
game.
At this point, it should be pointed out that although I
SWITCH "STACK'
INSULATING ACTUATOR
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FIGURE 2A
RELAY "UNENERGIZED'
© The International Arcade Museum
May, 1982
FIGURE 2B
RELAY "ENERGIZED'
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