ISpindel

Projects
Participants	Einnor, Justa, Sikkepitje
Skills	soldering, brewing, PCB Design
Status	Active
Niche	FoodHacks
Purpose	Fun

iSpindel

iSpindel DIY continuous hydrometer, for measuring the realitive gravity / density of wort. Meant as an educational project for KWBG. We created footprint for the various parts on the PCB. These can be found in the /libs dir in the repo. Furthermore we replaced the reset switch with a reed switch so you can use a magnet to reset the iSpindel without opening the container.

See also the documentation page in Dutch for easy setting up cloud data services with iSpindel here

See also TechInc iSpindel_KiCAD page on GitHub (last commit aug 2022)

See als Einnors iSpindel_kiCAD page on GitHub (last commit may 29, 2022)

Why Bat43???

It seems to me that the selection of the diode to be a schottky is a critical one here! According to the datasheet, the min. Input Low Voltage must be < 0.25×VIO while the Output Low Voltage is up to 0.1×VIO. Therefore, this leaves 500mV where the BAT43 will drop around 300mV or more. So a regular silicium diode will fail in this setup! Using a BAT43 or better is a requirement so to speak.

found here [iSpindel/issue/59]

Previous work:

• iSpindel - DIY electronic Hydrometer
• iSpindel by TheJeffrey

Alternative firmware:

• Gravitymon

Look also here: github.com/techinc/ispindel_kicad

First test results =

Woohoo data arrives in ubidots

• Did the first 90 degrees calibration
• Did the 25 degrees test in normal water (after some balancing came out at 24,8 degrees)

• during calibration i had the update frequency set to every 20 seconds, make sure you change that to something like every 5 to 15 minutes
• Ubidots only allows 4000 datapoints per day after that measurements will no longer be saved until the next day
• uploading every 20 seconds only gives you datapoints in your graph for the first 4 hours every day
• the battery will also not last very long when you do this
• all in all a good test. Don't do this if you want the ispindel to take measurements for the entire brewing process

Helpful links for calibration

• sugar wash calculator
• gravity delution calculator
• iSpindel online calibration tool

Handy Formulas

Following formulas can be used to convert Gravity values from degrees P to SG and vice versa. Plan is to use this in the firmware to decide on what value to send based on a config variable same as is possible for temperature.

• degrees P = 259-(259/SG)
• SG = 259/(259-degrees P)

TODO-List:

• Cleaned PCB repo (first version: Einnor)
• Pannelization test (Einnor)
• Reed-switch test/rework (Einnor)
• Footprint Battery Holder with sliding pads (Einnor)
• Footprint D1-Mini 8-pin version (justa) Done by Einnor
• Petling bottles order (justa) Done, 20220608. 10 pieces
• Online-service (ubidots?) uitzoeken/selecteren (sikkepitje)
• Order more parts (Einnor + Justa)
• Test whole setup on a breadboard YOLO ordered pcb and did first test on that
• Add gravity scale to firmware (einnor) not needed polynomials are for SG
• possibly fork firmware repo or create a pull request (einnor)
• add resistor types to the silk layer
• add battery + and - to the silk layer
• setup a mailing list! 😁 (Justa) Done: beernerds@lists.techinc.nl

Ordered stuff

• 30 pcb's with minor changes (ronnie)

Arrived

• 10 Petling's (justa)
• 2 GY521 Gyro's (justa)
• 1 TP4051 (justa)
• 1 Wemos D1-Mini (justa)
• 2 Battery-holders (justa)
• 5 pcb's (einnor)
• 20 BAT43's (justa)
• 2 SMD-reed-switches (justa)

In progress

• order more parts after testing

calibration data for ispindel_arnd1

[[36.5,1000.8750960475685],[39.65,1010.8838470080442],[48.85,1018.8908477764247],[57.77,1025.8969734487578],[63.8,1032.9030991210907],[68.04,1042.9118500815664],[73.52,1056.9241014262323],[75.65,1066.932852386708]]

Load @ iSpindel online calibration tool

calibration data for ispindel_bat43

corrected from 24C degrees water temperature to 20C degrees (correction is needed because SG values are related to the density of water at 20C)

• 24C [[25.2,1000],[27.17,1010],[32.71,1018],[39.82,1025],[45.85,1032],[51.5,1042],[61.1,1056],[65.25,1066]]
• 20C [[25.2,1000.8750960475685],[27.17,1010.8838470080442],[32.71,1018.8908477764247],[39.82,1025.8969734487578],[45.85,1032.9030991210907],[51.5,1042.9118500815664],[61.1,1056.9241014262323],[65.25,1066.932852386708]]

this leads to the following polynomials Corrected for 24C

• Degree 1: 966.9279707169078 + 1.4939612781443774 *tilt
• Degree 2: 973.729794397618 + 1.157456640501496 *tilt + 0.0037492943416183606 *tilt*tilt
• Degree 3: 882.113582283499 + 8.017945029109477 *tilt-0.15705832812978124 *tilt*tilt + 0.0011897660268308918 *tilt*tilt*tilt

Iterations

• Version 1, Purple PCB, Techinc Logo