How can a single pole, 3 position selector switch be created from standard 22mm Harmony parts?
The parts listed are based on the metal bodied ZB4B 22mm range but could also apply to the plastic ZB5A equivalent parts.
The 3 position switch* has 2 plungers. In the left position the left plunger operates a contact block in the left and centre. In the right position the right plunger operates a contact block in the right and centre.
KEY; Black square = contact closed. White square = contact open.
Thus to obtain 3 separate circuits, one of which will active (logic state 1) in each of the 3 positions, then 3 contact blocks will be required as follows;
Left position; ZBE101 (N/O) Contact only closes (makes circuit) in left position.
Centre position; ZBE102 (N/C) Contact only closed (makes circuit) in centre position, when switched to left or right the contact is opened.
Right position; ZBE101 (N/O) Contact only closes (makes circuit) in right position.
The above can be specified as a ZB4BD3 (3 position head) + ZB4BZ103 (body with 2 N/O contacts) + ZBE102 (N/C contact block)
*Important note; This information is based on the newer (as featured in current catalogue) design of 3 position selector switches (e.g ZB4BD3) that have a revised design of plunger.
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