Ball detector module.

thingiverse

Ball detector module. Can be used to count or detect the number of balls. Works seamlessly with a hall chip built right into the module itself. A small Neodym magnet is cleverly integrated into a rotating anchor, which is essential in order to measure a series of balls properly. To ensure accurate measurement, a brake zone has been carefully designed and built in. Without this braking zone, the anchor would otherwise not have enough time to move back. The anchor features two extra holes of 4 mm that can be used to add small steel axles as additional counterweights. However, I've found that it works perfectly even without these extra weights. The first hole of 4mm also serves a second purpose - it allows you to easily pull out the small magnet if you accidentally attach it with the wrong polarity. To avoid any confusion, I created a reference setup so that I can ensure the correct polarity before attaching the magnet. In order to make the module even more versatile, extra height has been kept free to accommodate Fischertechnik blocks. These are clearly indicated on the drawing itself. Original Fischertechnik parts are always easier to connect with other parts, which is why they're used in this design. The necessary blocks for making a straight connection or a 180-degree connection are also shown in the drawing. For the hall connection, I use a standard 3-pin female connector. The wires of the hall can be easily connected without any additional printed circuit board (PCB). I swapped the two power pins of the hall output to the connector so that it has a standard connection: Output, +VCC, GND. This wiring is identical to that of a servo connection. The hall chip itself features an open collector output, making it easy to use with any kind of interface. Its power supply can range from 4V to 24V, although the most commonly used voltage is 5V. A drawing is also included with the timing results for a burst of 5 balls. It's essential to note that sometimes the speed can be quite high (pulses about 25 msec), so you may need to adjust the brake zone (input) to ensure that the ball just passes through. This may be necessary if your controller cannot handle this speed, as is the case with the TXT Controller Fischertechnik. I use my FPGA controller to read the pulses and it has never had any issues with speed. All parts are printed using a Flachforge Finder 3D printer. The filament used is PLA 1.7mm, 210 degree, Raft and Brim enabled, Infill 25%. Update: I forgot some crucial details earlier. As the pivot shaft, I use a part of a nail with a diameter of 2.15mm. In the body, I drill a hole with a diameter of 2.2 mm, while in the cover plate, I use a diameter of 2.3 mm. This allows the nail to securely clamp into the body and can be easily removed again if needed. If you want to add counterweights to the anchor, simply drill them out with a 4mm diameter, which is the same as the Fischertechnik steel shafts. The small spacers rings are 0.5mm thick and must be securely mounted so that the anchor can move freely. There's still enough clearance left in the body for you to make adjustments as needed. Of course, you can use a different diameter for the spindle - just adjust the drill diameter accordingly. The Neodym magnet integrated into the side of the anchor is D2x3mm. To make it easier to press the magnet in, I first drill out the hole with a 1.9 mm diameter and then with a 2.0 mm diameter 1.5mm deep. If you don't have a D2x3mm Neodym magnet, you can also use a D3x3mm one - just adjust the holes accordingly. Update 20181107: I've added the "a181106 cover 3pin.stl" file for the cover with three pins connector.