Consultancy has designed a simple board called the Pico Indicator to add LEDs to the GPIO and power pins of the Raspberry Pi ...

This paper introduces a novel high-sensitivity readout circuit that leverages the resonant amplification effect of the LC network in an oscillator to generate high-voltage excitation signals. By ...

Then knowing he needed 4 mA to power each LED for backlighting he used some 1978 vintage current limiting diodes designed to ... constructs a current limiting circuit using a JFET and feedback ...