The sound card is suitable for battery powered locos in the range 7.2 to 30 volts, with or without radio control.
The diagram below shows how the sound card can be connected to a loco with a manual speed control.
Note that the horn/whistle is shown as a negative (ground) input connected to terminal H1. A positive horn/whistle input should be connected to terminal H2.
Again, the horn/whistle can be operated by means of a switch or pushbutton mounted on the loco, by means of a reed switch operated by trackside magnets or by a simple wireless device such as a door chime or garage door actuator. In battery powered locos, the horn/whistle works on a momentary basis ie. it starts when you close the switch and stops when the switch opens again.
