@BOB WALKER posted:The DIP sized relays I have used in a number of projects are pretty small and work fine.
I wouldn't be firing O-gauge couplers with a .5A rated relay.
@Norton posted:I am sure there are some smaller than one I use but they are only a buck apiece. They used be 50 cents and they are DPDT. 28ma coil current and can switch 2 amps.
Pete, for a bit shorter package, try the IM06 relays, the IM06D switches 5A and is shorter with the same size base.