The Shield consists of four push buttons, a digital to analog converter, a negative supply, a rail to rail operational amplifier, two input and output jacks, a control LED and some pole connectors, resistances and capacitors.
Arduino and shield can be powered by USB or a 7.5 to 12 V mains adapter. The red and black plugs on the front lead to the test voltage. The BNC plugs on the right are connected to the oscilloscope. The black wire to the trigger source, the yellow one to an arbitrary channel.
The upper buttons decrease and increase settings. SE button starts settings and switches through them. A short press on F starts or stops tracking, a long press on F deletes the current tracking curve.
The LED stays dark in setting mode, blinks while tracking and will light constant when tracking is stopped.
The oscilloscope does not have to run during tracking and can be switched on and off at any time, without loss of results.
For proper presentation the oscilloscope should be set 10 ms horizontal and 2 V vertical.
All settings are stored persistently in Arduinos EEPROM.