The pulse generator itself is the single 2N3904 on the right. When you are a Hackaday writer with some oscilloscope bandwidths to measure, you need a picosecond avalanche pulse generator ...

Making an oscilloscope is relatively easy ... Clever tricks abound, such as using the diode pair to cancel out pulse leakage finding its way back to the source. To complete this black magic ...

Rohde & Schwarz Oscilloscope Days 2025 provides expert knowledge for day-to-day testing challenges. Source: GTY/Westend61 ...