I would think TheLongBuild has described how it works accurately.
The 2 chips are:
IC1 is an 18 pin PIC chip - this is the brains of the board that is connected to the single channel radio control receiver input signal. It will continually analyse the RC receiver pin it is connected to to see what the "state" is - (probably Full / Zero stick but could be Full/Mid/Zero Stick). It sets it's digital, very low current output pins high or low to switch the transistors on and off in IC2 (Darlington Array)
IC2 is a seven channel Darlington Array - this uses the very low current logic pins (on/off) from IC1 to switch a much higher current that is used to energise the relay coils.
Note the 2 screw connectors for each relay are a seperate circuit to the power for the PICswitcher board, and are isolated from any of the electronics on the board.
You insert the relay connections into the circuit you wish to control (switch) and according to the specification printed on top of the relay you can switch upto 110vac or 24vDC at 3 amps. As you have 5 relays on board you can switch 5 separate circuits all at different voltages so long as you remain within the relay operating specification.
The black slide switch ("setup / operate") is likely to allow you to set/calibrate the radio control transmitter stick positions most likely just for the OFF state. Off state =(zero stick or maybe neutral (half/mid stick). Remember to return the switch to the "operate" position once calibrated
As TheLongBuild has described each time you "flick" the stick corresponding to the receiver channel you are connected to the next PICswitcher 5 relay will be energised/de-energised, a little experimentation will be required in the absence of operating instructions but the PICswitch 5 will operate pretty much as described.
C-3PO
