LM358 is the core two-stage operational amplifier, which can amplify DC weak signals, such as DC voltage signals and DC pulse signals, and can amplify millivolt or even weaker signals. There are two potentiometers for the first and The second level is for single-level magnification adjustment, but the total magnification is the product of the two-level magnification, so the magnification will be adjusted to a very large value. If the first level is adjusted to 20 times magnification, then if the second level is adjusted to 100 times, then the total magnification is 2000 times. Board parameters: 1. Power supply voltage: 3.5-24V DC power supply 2. Current output: maximum 15-20MA (non-linear) 3. Voltage output: output = input voltage signal * magnification 5. Board size: length 45.3mm width 16.2mm