If you are designing your own intelligent “Graden Computer” with an optional digital plant moisture sensor/water pump controller that lights an LED to alert the user when it is time to water a potted ...

A previous Design Idea describes a circuit that uses an astable multivibrator to drive an LED (Reference 1). The circuit in Figure 1 uses a simpler alternative approach. The circuit uses a 2N3904 NPN ...

A versatile signal-conditioning circuit for use with with programmable logic converters or controllers that can accept only one input polarity. Matching a sensor interface with a programmable logic ...