COSMAC Elf switch panel using PCBs

Mike Stein mhs.stein at
Sun Apr 24 02:26:35 CDT 2016

----- Original Message ----- 
From: "Eric Smith" <spacewar at>
Sent: Sunday, April 24, 2016 1:38 AM

> On Sat, Apr 23, 2016 at 8:18 PM, dwight <dkelvey at> wrote:
>> You'd need to decide, LOAD is switch up or
>> LOAD is switch down.
> Which still doesn't explain how a toggle (not momentary) can be said
> to have NC and NO pins.------------

It kinda does, if you think of 'normal' not as a fixed function of the switch but its logically inactive state, usually relative to its (possibly implied) label and function. If a push button is labelled 'RUN' then the 'normal' state is opposite and away from that label, i.e. out or up; similarly, when a toggle switch is labelled 'RUN' then its 'normal' position will be opposite that label and like the momentary switch in that NORMAL state it can be either OPEN or CLOSED (with a complementary contact if it's a DT switch).

Schematics will usually determine and indicate the 'normal' state and the switch should be mounted, labelled and connected accordingly.

The on/off light switches in your house would be considered NO; by convention toggles (if any) should be UP to CLOSE and turn on the light  and the 'normal' state would be OPEN and pointing DOWN.


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