In DC, differential amplifier can be use to detect the voltage different between two point. Its like a mini voltmeter or current meter. You can interface it with microcontroller in order to read voltage different at certain point.
Current to Voltage Converter - Transimpedance Amplifier
Current to voltage converter usually coupled with photo diode or phototransistor. This photo device convert light to current. By using transimpedance amplifier, it will convert small amount of current to significantly measurable voltage.
This circuit will limit current to the limit set by Iset. If you do not want your load to exceed certain value of current, you can use this circuit in order to limit the maximum current. You can use this circuit with microcontroller to digitally control the maximum current.
This circuit is use to regulate an input voltage to a certain value set by Vset. Its like LM317 adjustable voltage regulator but using this circuit, you can interface with microcontroller to digitally control the voltage regulated.