and besides the SW1, it picked up a trio of Alco HH660s, and a pair of Baldwin VO660s. The Alcos eventually spawned a larger order of 1,000 horsepower S2s and S4s, and 900 horsepower S6 switchers ...

KEY1 enables the charging of the capacitor (the camera ON switch) and SW1 is located under the shutter-release. Now all he had to do was replace SW1 with an electronic trigger from his DSLR.