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

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)

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
• Add gravity scale to firmware (einnor)
• 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

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 PCB's after testing and minor changes PCB
• 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