There are 10 relays DPCO(dual pole change over), which are activated using a 12V supply, and around 60mA current.
Note that the diode D1 is there to protect the rest of the circuitry (the buffer) from the current which flows once the relay is switched off. The current is produced because the relay coil builds a back emf to counter act the magentic field built across it. When the buffer is switched off, the magnetic field will still exist and will need to discharge via the coil . The diode enables the current to flow in a loop without damaging the circuitry.
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