# Automated Low Investment Cost Evaporometers (ALICEs)
## 2 Materials and Methods
### Electronics  
The electronic part of the device was a hybrid of a custom-made circuit board and three commercial sub-boards. This approach was chosen because of the manufacturing ease. All electronic parts soldered on the circuit board were through hole mounted, including resistors, capacitors, wires, and connectors. Paths were created by drawing with a path-drawing pen and subsequently etched. Sub-boards were made commercially, and electronic components were mainly mounted by surface mounting. This is almost impossible to do by hand. Commercial sub-boards are manufactured precisely, tested, and standardized. These sub-boards are easy to use for people without an electrotechnical background, like environmental engineers.  
The circuit board was made of one sided EPCU120X80 sheet. Copper thickness was 35 \(\upmu\)m, dimensions of the board were 120 by 80 mm, and the thickness was 1.5 mm. The material of the dielectric was glass fiber laminate. The manufacturer of the board was Bungard. Electrolytical radial capacitors CE 10 u/100 V HIT-ECR 6,3x11 RM2,5 BULK were used, made by Hitano. Metal oxide resistors, size 0204 with 1% accuracy were used, with values of 10 k\(\Omega\) and 200 \(\Omega\). As a transistor, we used a bipolar transistor, PNP, THT, 45 V, 0.8 A, 0.625 W, TO92 BC327-40. All the components were supplied by a local vendor that specializes in electronics, tools, and electronic components. The microcontroller Original Arduino Nano R3 and shield ATMega328P and real-time clock DS3231 AT24C32, microSD card module SPI were attached to the circuit board. We decided to use these premanufactured elements to simplify the circuit board. The Arduino board and shields were bought from a specialized e-shop. Figure 1 shows the scheme of the electronic part of the device.  
Manufacturing the circuit board started with cutting the raw circuit board into suitable dimensions. This dimensionally corrected sheet was then thoroughly cleaned. The circuit board jig (Figure 2E) was placed on the raw circuit board and fixed by clamps. The location of the through holes and the corners of the circuit were then drawn using a jig. The jig was then removed, and the circuits were finally drawn using a circuit board-drawing pen. After sufficient drying, the drawn circuit board was submerged in the etching solution. Premixed Circuit Board Etching Solution was used, and while the etching board was checked for possible errors, the solution was slowly mixed using a soft brush. Brushing the etched surface also speeds up the process. After sufficient etching, the circuit board was thoroughly cleaned. The circuit board jig was then again clamped onto the circuit board, and this assembly was performed with a vertical drill, and the through holes were made. The jig was then removed. Burrs were then removed by gentle brushing with smooth sandpaper. In this way, the circuit board was prepared for soldering the electronics. Lastly, a circuit board with electronic parts soldered on was set up on the electrode positioning jig (Figure 2D). The electrodes were inserted into the drilled holes, secured in place with heat glue, and their connection wires were soldered to the circuit board. The position of the electrodes was then finally checked against the positioning jig. After the RTC, the SD card reader and the Arduino Nano board were attached, and the device was ready for uploading the code. The code is shown in the Supplementary Materials.