Share your experience in debugging infrared thermometer
1. The use of digital oscilloscopes, such as data reading and adjustment, has not reached a certain level in hardware debugging, and lacks sufficient ability to analyze and reason about the source of problems. Oscilloscopes are a key tool. In the use of an oscilloscope, ① use the appropriate gear, such as using the AC gear to measure the ripple of the power supply. If using the DC gear, there will be little reaction when a small AC signal is superimposed on the DC; ② During testing, the grounding must be close to the testing point.
2. Truly understand some of the working principles of RC filtering circuits. RC circuits are used in different places and have different purposes. In terms of this circuit, the RC at the detection head generates oscillations, and later we don't want these oscillating waves. We can use RC circuits to filter out these waves, with a frequency of f=1/2 ∏ RC, which is the passband in the frequency selection circuit and the clutter in this frequency band in the filtering circuit.
3. The capacitance issue of diodes is often overlooked by most people when using diodes, especially PIN diodes, which have stronger capacitance due to the presence of some intrinsic semiconductors in the PN junction. They can be equivalently connected in parallel with a considerable capacitor, and this capacitor and feedback resistor form an RC oscillation circuit, resulting in problem three - a 15 ℃ jump around 900 ℃, and the temperature display does not stabilize after the jump.
