As of June 2020, the ethoscope modules changed to be more modular in nature (onshape workspace). The SD module is the first one to be redesigned, together with the The solenoid AGO . The advantages of the new systems are discussed below.
The system has a modular structure, meaning that it can be expanded in the future by piling different modules into one.
Sample assembly of the new dynamic SD module - the module itself consists of a motor holder, a base for the electronics, two interchangeable covers that hold down the motors and can be replaced if needed (for instance to add holes for access to the tubes or to add 5 more motors)
The overall footprint of the modules is smaller so that they will take less space in the incubators
The overall distance between the motors and the floorplate is now35 mm - 7 mm shorter than it used to be
As a consequence of the above points, printing time is reduced. The holder for the N20 Motors and its regular base can be printed at 0.20 mm definition in about 4 hours each. The valve base is best printed at 0.15 and it prints in ~9 hours. Everything prints with very limited support (mostly no support at all) so post-printing clean-up is minimal.
The motors are now positioned laying on their long side, flipped by 90 degrees. This eases stress on the wire soldering and should help with another previous annoying issue (wires coming undone). The motor wires fold into the holes just underneath and from there they go directly in the base where they connect to the PCB board.
All the parts sit on top of each other and screws can be used to secure them in that position. Use 4x M3 threaded inserts (RS 138-893) that clip into place on four corners of the base or simply fit M3 nuts through a side slot (RS 837-262). The latter option is better suited given the force vector in place. M3 Hex socket cap screws are recommended for fastening: either M3 x 16mm (467-9818) or M3 x 20mm (467-9824). Longer screws (M3 x 35mm) could be used to connect to another module further down if needed. Because we try to save space, things can get easily cramped inside the module for some uses, so if you need more room you can distance the two components using M/F M3 standoffs (RS 606-686 for 10mm or RS 806-6607 for 5mm).
The new SD modules now run with new electronics. A custom PCB hosts an Arduino Micro (RS 771-7667) or Arduino Every (RS 192-7586) and controls three Darlington transistor arrays (ULQ2803A - RS 168-8906) connected to a 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 (5 on each side) and 10 valves (5 on each side). LED or other solenoids could also be used in principle or 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.