May I add that the switch you seek should have a 'break before make' not the 'make before break' type circuitry.
Here are the make before break/break before make definitions:
In a make before break type, a contact will not open it's primary output circuit until it has closed it's secondary circuit. Conversly, in a break before make type a contact opens the circuit to one output before it closes the circuit to a second output.
Also a DPDT with a "OFF" center position will work.
Here are the make before break/break before make definitions:
In a make before break type, a contact will not open it's primary output circuit until it has closed it's secondary circuit. Conversly, in a break before make type a contact opens the circuit to one output before it closes the circuit to a second output.
Also a DPDT with a "OFF" center position will work.