Reverse biased base-emitter junctions are effectively used as noise sources, with a great amount of ENR (Excess Noise Ratio) originating from the intrinsic behavior of avalanche and zener operation. This article is a compilation of measurements in a noise source prototype - designed for evaluation of a subcircuit for another
Active probes are a must when designing high frequency topologies. This article covers a modification procedure to adapt HP 1152A active probes into modern oscilloscopes. The HP1152A is a 2.5 GHz active probe, with 100 kΩ @ 0.6 pF input impedance. This old design utilizes an old version of
Remote controls for garage doors are designed as low-cost devices, using very low part counts, and with small size for portability. These constraints commonly reflect in an RF system with low performance (low range and/or low battery life). This article explains the RF section of a remote control and
Blocking Oscillators were the standard method for creating oscillators and pulses in the Vacuum Tube era. Fast rising/fall times with long pulse repetitions came from a positive feedback topology and from a complex interaction between the pulse-transformer, the grid capacitor, grid resistor and the characteristics of the tube. The
This article describes the development and working principles behind a discrete Spread Spectrum BPSK beacon. The designed system consists of a reference oscillator, frequency multiplier, binary phase-modulator and digital microcontroller, integrated on a single PCB. The presented architecture could easily be implemented in CubeSats or for terrestrial monitoring of distant