The new SD modules now run with new electronics. A custom PCB hosts an Arduino Micro (RS 771-7667) and controls three Darlington transistor arrays (ULQ2803A - RS 168-8906 - datasheet) connected to the total of 20 Arduino output pins (digital + analog). The arrays can pilot up to 500mA per transistor which is enough to control N20 motors (aliexpress - 200rpm - 240rpm, 25 mA at 4.8Vdc), valve solenoids (aliexpress - 260 mA at 5Vdc) or, of course LEDs. The PCB was designed for the Air/Gas/Odour delivery device and it can pilot up to 20 non-PWM outputs. It's normally meant to be used with 10 motors (M1-10, 5 on each side) and 10 valves (V1-10, 5 on each side). LEDs or other types of solenoids could also be used in principle: anything that draws less than 500mA. Power for the motors can be drawn directly from the Arduino 5V for low current use (e.g. for LED) or it can be drawn from an external power source - the external power source could also be used to power the Arduino. Jumper J1 (shorted by RS 251-8503) optionally regulates these behaviors.
A drawing of the PCB. Size is 78 mm by 54 mm. Order as double-layer, 1.6 mm.