Modulated Reflectivity Sensor Driver V2
author: dewhisna
2 layer board of 2.11 x 2.23 inches (53.5 x 56.7 mm)
Uploaded:
September 05, 2017
Shared:
September 05, 2017
Total Price:
$23.45
DO NOT BUILD This circuit has serious design issues rendering it virtually useless. The biggest problem is that the sensor input circuit’s filter time-constant is greater than the PLL frequency, causing it to never detect lock. It comes closer to working without C2 and C7 installed, but even then has such a small window of detection that it’s useless.
A better variation would be to remove C2 and C7, ditch the entire HC7046 PLL and 74LVC1G123 debounce circuit, tie the input side of R8 and R15 to +5V, and just use the 74HCT14 output signals directly. But that basically means throw this board away and just use the sensors with a couple of schmitt trigger inputs for filtering.
For a usable version of this circuit, see the original Modulated Reflectivity Sensor Driver instead.
DO NOT BUILD This circuit has serious design issues rendering it virtually useless. The biggest problem is that the sensor input circuit’s filter time-constant is greater than the PLL frequency, causing it to never detect lock. It comes closer to working without C2 and C7 installed, but even then has such a small window of detection that it’s useless.
A better variation would be to remove C2 and C7, ditch the entire HC7046 PLL and 74LVC1G123 debounce circuit, tie the input side of R8 and R15 to +5V, and just use the 74HCT14 output signals directly. But that basically means throw this board away and just use the sensors with a couple of schmitt trigger inputs for filtering.
For a usable version of this circuit, see the original Modulated Reflectivity Sensor Driver instead.
