Relay Operation Simulator

Micro Trainer Relay
Control current Load current Load circuit Switch — click it Dots show conventional current: B+ → load → ground
Master The MASTER slide switch feeds B+ to the whole card. With it off, there is no B+ at pin 86 or pin 30 and nothing can run.

Terminal numbers 30, 85, 86, 87, 87a come from DIN 72552, the German standard the industry settled on — SAE has no equivalent numbering, and no formal designation for the two sides. Control side and load side are the working terms. SAE’s relay standard, J1744, specifies the 280 footprint the part plugs into, not what the terminals are called.

Battery (one 9 V cell feeds both relays)
What if — applied to the whole card