ASSEMBLY Resistors/transistors are SMD parts of reasonable size and easy to hand assemble. LED emitters/phototransistors and the small header are TH (through-hole) parts. Inclinometer vial is held in place by a pair of TH AA battery clips; squeeze them a little for a tight fit. Recommend a little silicon rubber between the vial and the clip to secure it after test.
CIRCUIT OPERATION (Schematic is a KICAD file: YAW_BOARD.sch) Designed for 5V supply, 3.3v - 6V acceptable. Any reasonable voltage will work, with appropriate resistor value changes. There are three detector sections: left, center and right, which refer to the locations of the LED/phototransistor pairs, as seen by looking at the component side. The output transistor for each section is connected to a header pin. If the ball is located between the emitter and it's respective phototransistor the output drops to a logic LOW; otherwise it's a logic HIGH. Any tilt exceeding about 5 degrees will cause the ball to slide over to the left or right detector. This can also result from "skidding" forces generated during a turn in a car, aircraft, drone etc. Test is very simple: Just apply power and tilt the board to position the ball as desired, ensuring that the correct switching action is observed. NOTE: Output pull-up resistors are included on the board; as a result, none are required at the input ports of microcontrollers or other devices, for example.
BOARD PHOTO This is the upper board in the photo, a little blurry, but should convey the overall appearance.
|PART NO AND DESCRIPTION||PACKAGE||VALUE||QTY||REFERENCE||REMARKS|
|PCB G76294 (PCBWAY ORDER NO.)|
|EMITTER IR HONEYWELL SEP8506-003||RADIAL||935nm||3||LED 1, 2, 3|
|PHOTOTRANSISTOR, HONEYWELL, SDP8406-002||RADIAL||935nm||3||Q1, 4, 7|
|TRANSISTOR, BC849||SOT23||NPN, 45V||6||Q2,3,5,6,8,9|
|RES, SMD, 5%, 1/4W||1206||140 OHM||3||R1,7,13|
|RES, SMD, 5%, 1/4W||1206||3.9K OHM||6||R4,6,10,12,16,18|
|RES, SMD, 5%, 1/4W||1206||1K OHM||9||R2,3,5,8,9,11,14,15,17|
|CONN, MOLEX, KK-6410-05||TH, 5X2.54mm||1||J1||“OR EQUAL” OK|
|VIAL, P/N 601-301-028, W.A. MOYER CO., EMPORIA KS, USA||NA||NA||1||NA|