b'FeatureDIY geophysicistRMS amplifier to put out all types of useful transducer-groundTwo developments are here to assist the DIY geophysicist stimulus. I am currently using a Pyboard and class-D amplifierwho needs to communicate between nodes and send power to control an electromagnetic shaker system for shallow seismicwith wires: 10BaseT1L ethernet, and communication over applications (Figure 4, like Dean etal. 2018(a)). Plus, I have beenpowerlines IC (e.g. smart metering) such as the THVD8000. experimenting with the TPA3255 system driving the output viaEthernet has a lot of software/processing overhead, but many a 300 VA toroidal transformer to increase the output voltageIC makers have incorporated much of this into hardware and (and coupled power) with programmed random waveforms forthere is a lot of software support of ethernet protocol stacks, resistivity and find that even with 12-bit ADCs (measuring outputincluding MicroPython. Ethernet using10BaseT1L is fairly new current and sensor voltage) I can obtain very high precisionand evaluation boards are a bit hard to obtain, but if you need and sensitivity (and perhaps even IP, not tested) with a modesta robust full duplex (both directions simultaneously) 10Mbits outlay in equipment and monies. Such an approach could alsoa second over two wires up to a kilometre between nodes that work as a broad-band EM system providing both frequencyuses far less power than Wi-Fi, then this technology is for you. domain and time-domain responses when processed later.Look for EVAL-ADIN1110EBZ and DP83TD510E-EVM for testing Possibilities that were once merely theory are now tangible. Noteand the related ICs.that using the same set of ADC channels to measure the sensors and the current/voltage into the excitation source/transducerCommunication over powerlines has been around for a long compensates for various changes in ADC and excitation sourcetime and is either geared towards running Ethernet via the wall-properties. plug through the house with fiendishly complex circuits placed into chips with over two hundred pins and proprietary code information, or low data rate modems of less than 10 kbaud. Communication between nodes I bring your attention to the Texas Instruments THVD8000 instead, a tiny 8 pin IC that you use a simple UART interface to What if we want to have an array of sensors? Or have a remotean embedded microcontroller to send OOK (on-off modulation node that measures and another that processes, stores andencoding) as simplex (one directly at a time data transfer) over passes the data onward for real-time quality control. Theretwo wires 30kBd to 1 Mbaud. Dr Christian Dupuis and Masters are two practical solutions: a data logger with no real-timestudent Andre Mercier, at the University of Laval, has used communication and then harvest later or use wires to sendthis IC for borehole communication and power over a 500 m power and communicate in real-time. I will say right nowsingle (poor quality co-axial) wire winch for a VSP tool stack that I dont tend to use Wi-Fi, or wireless, unless I really must.(https://github.com/Geophysical-Instrumentation-Group-UL/After watching more than one thousand Wi-Fi nodes trying toGeophysical-Open-Seismic-Hardware). The THVD8000 is a very download data to a central repository, I can say that it isnt a verynice balance between simplicity in use and to implement on practical solution for most field measurement and expensivelyany pair of wires in a cable - bits in one end and bits out the complex to implement well. Wireless requires batteries andother end - with good throughput performance with low power then drains these quickly. Wires are not cumbersome whenconsumed.the nodes are close together and they carry power with high data throughput-bandwidth and communication is easier to implement in code. If your measurement node is down aMaking it from scratchborehole, then wireless isnt practical anyway. If you cannot buy exactly what you want, then you can still design and make it yourself. The IC datasheets and CAD-CAM files made available by the microcontroller and IC manufacturers can be used and reworked sightly. When making a daughter-card for plugging into one of the embedded microcontrollers it is a very useful approach, especially if you want the best in performance, size and capability, or you wish to manufacture many sensor nodes. I have done this for the Nucleo H743 board to allow buffering, amplification and voltage isolation into the 16-bit ADCs with level shifting via signal transformers (Figure 5). Another example, combining the CAD files for the Pyboard 1.1 and ADS131M04EVM would make a very capable, generic 4 channel data acquisition system for a nodal resistivity, 3-C seismic or EM system, such as that described by Dean et al (2018(b)). KiCad (https://kicad.org/) is freeware for PCB design and can be used to create electrical schematics to producing the Gerber files and CNC drill files for quite complex and useful parts. It is relatively easy to learn and very powerful in its functions. Templates for the integrated circuits and parts number in the many thousands (from major parts supplier such as Digikey and Mouser via SnapEDA and Ultra Librarian links) so time is spent designing not creating footprints and other basic work. Another free product, Altium Figure 4.This photo shows an evaluation board for class D audio amplifierCircuitmaker (https://www.altium.com/circuitmaker), is loosely using a TPA3255 chip (under the black heatsink. It will send out 300 W of powerbased upon the industry standard Altium PCB design software into a 4 Ohm load all day without overheating at 95% efficiency with less than 10% distortion, or 100 W with less than 1% distortion. Complex waveforms suchpackage. The caveat is you must share your designs. I have not as uniform random noise can be transmitted into the earth or transducer andtested it, but for public good and education projects it seems then correlated with sensor data to provide high signal-to-noise. a good option. To transition to proprietary designs the Altium DECEMBER 2022 PREVIEW 54'