This is a PCB-design + Arduino firmware for an Ethernet-controlled 1:8
RF-multiplexer (SP8T). It allows selecting as output one of eight
input-channels, as commonly used e.g. in timing-laboratories when one
wants to measure many RF-sources (clock outputs like 1PPS or 10MHz) with
a single instrument (frequency or time-interval counter). The unselected channels are terminated at 50 Ohms. The design is for two independent MUX-boards to fit in a 1U 19” rack enclosure together with an Arduino MKR ZERO microcontroller with Ethernet interface. The firmware allows for simple control over http with a browser or e.g. the python requests library.
Revise schematic to note that MCP23S17 io-expander address bits A0, A1, A2 must be externally driven (not left floating)
Revised front-panel with pushbuttons B1 and B2. From S/N 4 onwards (2019-11).:
Internal view of S/N 4. Rightmost is the MKR ZERO Ethernet shield, followed by the MKR ZERO, and the carrier-board which takes +5VDC input and has two 10-pin IDC ribbon-cables to the MUX boards.
3x1U MUX-units for a 40-channel 1PPS measurement system. Installed at the VTT MIKES UTC-laboratory in March 2020. The boards are connected (cables not shown) in a tree configuration. One 8-channel MUX-board is used as the root node, where each channel connects to a leaf-MUX. This provides a capacity of 8x8= 64 channels, if seven leaf-MUXs are used. Here we only have 6 MUX-boards in 3U, so 5x8= 40 channels. This system is in continuous 24/7 use with all channels measured every 600s (10 minutes).
Transmission bandwidth test on S/N 4. Note Y-scale is 3 dB/DIV. Bandwidth is >1 GHz.