I have several commercial circuit boards in my project which will run on individual 9-volt batteries. (And no, the discussion here is not on whether I could or should run them off a single battery. Current requirements require that each board have its own battery.) Anyway, the type of switch I'm using on each one is one of those 4-contact rotating switches that are marked "110" and "220" at the two switch positions. This switch is commonly used by rocketeers to power up their onboard electronics with a screwdriver, because the switches have a good positive snap into position and because they're low profile. For those who aren't familiar with these switches, there are four contacts (call them 1-4) in 4 out of 5 equally spaced positions around the body of the switch. Let's call the vacant fifth position 0. The connections in the two positions look like this (unrolled out flat):

220: 0-1 2-3 4
110: 0 1-2 3-4

So I want to wire the battery leads to 1 and 4, and the two power leads into its circuit to 2 and 3. So in the 220 position, both leads of the battery are disconnected, and the power leads into the circuit are shunted. In the 110 position, the shunt is absent and both battery leads are connected. Oh, the switch contacts are break-before-make.

My question is, are there unforeseen consequences from shunting the power input when switching the circuit off?

 

What are the two circuits? You may want to add a protection diode to each battery input

 

There are three circuits. Two are commercially available altimeter boards used for the recovery systems of sport rockets. The third is a BASIC Stamp Carrier board.