Electronic SPDT signal selector
simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. CMOS two-way switch.

With the sparse details supplied in your question I think that this circuit may satisfy your requirements.

A CD4066 quad CMOS switch can be used to switch analog voltages. Check the datasheet for details of on-resistance at the voltage you are operating on and pay particular attention if you are switching voltages which go down close to zero or the supply voltage.

How it works


With CONTROL low SW1 is off and its output is high. This turns on SW2 and connects SOURCE1 to OUT. Meanwhile SW3 is open and SOURCE2 is isolated.
When CONTROL is high SW1 turns on pulling the bottom of R1 to ground and turns off SW2 which isolates SOURCE1. Meanwhile SW3 closes and SOURCE2 is connected to OUT.


The trick in this circuit is using SW1 as a logic inverter, keeping the parts count low.