b) P u s h - b u t t o n Switch
A switch IN which a b u t t o n must be depressed each TIME
t h e contacts are to be opened or closed. Microswitch and
tact switch, however, are excluded from this category.
P u s h - b u t t o n switches can be classified by uses, number of
keys, and mechanisms as shown in Table
2.
Nonlock (momentary or press-to-talk) type opens or closes
A
circuit only
I N
the period a key is depressed. Releasing
the key deactivates the switch.
Power switches employ press mechanism and signal selec
tors employ sliding mechanism. A signal selector has gener
ally two contact points for two to eight circuits.
Table 2 Push-button Switches.
Lock/release (interlock) type locks the newly depressed key
releasing other keys.
Self-locking (latching) type locks by the first press and
releases by the second irrelevant to the state of the other
keys.
Lock/release type can contain m a n y switches, deals with
m a n y circuits and does not require to pass unwanted con
tact points to reach the desired point unlike the r o t a r y
switch. With these features multi-gang push switch of l o c k /
release type is suitable for selecting functions. Switches of
single and multi-gang self-lock types are used in m u t e r s ,
filters, tape m o n i t o r s , etc. and those of nonlock type are
used in tape deck R E C muters, key inputs of digital cir
cuit, etc. Instead of push switches many tact switches dis
cussed later are being used in digital key input circuit.
Multi-gang push switch has all functions of lock/release,
self-lock and nonlock types. P h o t o 3 shows typical push
switches.
Photo 3 Push Switches
5
Push s w i t c h
Power s w i t c h
Signal selector
Multiple Key
Single Key
Lock/release
Self-lock
Nonlock
Self-lock
Nonlock
