Dual magnetic stir controller

Overview

This is the Arduino project to build a double magnetic stirrer based on 2 fans, a 1602 LCD display, a KY-040 encoder and an Arduino Nano and a special PCB designed in the Hobbybrauer-Forum.

V2 supports dual voltage for the fans which increases the speed range.

In order to put the stirrer into operation you have to change the settings in stir.ino according to your setup (see below).

Part List

• 1x PCB "Stir V2.0"
• 1x Arduino Nano V3
• 1x Voltage regulator TE818 5-24V to 5V 3A step down buck converter
• 2x Relais Omron G5Q-1-EU 5DC printrelais 5 V/DC 5A
• 2x Diode 1N4148 Diotec
• 1x Electrolytic capacitor 1000µF/16V Yageo SE016M1000B5S-1015
• 2x Diode 1N5822 STMicroelectronics Schottky-Diode
• 4x Metal film resistor 10 KOhm 0,6 W
• 2x Fan BeQuiet SilentWings 3 120mm PWM Highspeed
• 1x Power supply 12V-20V DC / 2A
• 1x Built-in socket for plug-in power supply unit
• 1x I2C 16x2 Arduino LCD Display Module
• 1x Rotary encoder KY-040
• 2x Magnmet mount (3D printed)
• 4x Neodymium magnet 20x10 mm (N52, 1 oder 2 mm dick)

Reference

This project was created based on an idea from the german Hobbybrauer-Forum and would not be possible without the ideas from there.

The forum: https://hobbybrauer.de/

The thread: https://hobbybrauer.de/forum/viewtopic.php?f=21&t=1456

Special thanks for development and testing:

• Herbert Schmid
• Adrian Sigel
• Jens Warkentin
• Bastian Werner

Successor project of: https://github.com/micworg/stir

Overview of Functions

All functions are controlled by the KY-040 encoder:

• Short Press: change between menu, stirrer 1 and stirrer 2
• Turn when menu is selected: change between menu items (SPEED, BOOST, BTIME, CATCH, CTIME)
• Long press when menu is selected: lock all functions (unlock also by long press)
• When a stirrer is selected:
  • SPEED: turn sets speed, long press switches stirrer on or off.
  • BOOST: turn sets boost speed, long press activates/deactivates the boost function (running time is shown in the display).
  • BTIME: turn changes the boost time in minutes.
  • CATCH: turn activates/deactivates the fishing function
  • CTIME: turn changes the interval in minutes for the fish catching function
  • RTIME: turn changes speed rise time in seconds (applies to power on, stirrer on, boost on and fish catching)
  • OTIME: turn changes switch off time in hours (the timer activates immediately, 0 = switch off disabled)
  • RNVAL: random value range (a random values in this range will be added to speed)
• Other menu options:
  • BRGHT: LCD brightness

Display Indicators:

• Bottom Left: Menu
• Bottom Center/Right: displays the set values for the stirrers depending on the selected menu item.
• Top Center/Right: displays the current stirrer speed (or 'OFF' or 'CAT' (Fishing)).
• Top Left: shows the remaining time of the boost or switch off function.

Settings (in stir.ino)

Value	Description
SPEEDINC	increment of speed values when turning the encoder
FANMIN	fan minimum speed (should be a value at which the fan runs safely) (rpm)
FANMAX	maximum speed of the fan (it is important that this is the real maximum value of the fan) (rpm)
BOFF	if set boost off will also turn the normal mode off
BINC	boost time increment (min)
CINC	catch time increment (min)
RINC	rise time increment (sec)
OINC	off timer increment (hour)
CATCHSTOP	stop interval for stir fish catch function (ms)
PWM0, PWM1	PWM output pins for fan speed
PWM2	PWM output pin for LCD brightness control
I0, I1	interrupts for rpm measurement (2 and 3 for Leonardo and ProMicro / 0 and 1 for Uno)
CLK, DT, SW	pins for KY-040 encoder
R0, R0	voltage select relais pin
RTHRES	voltage switch threshold (rpm)
RINTERVAL	regulation interval (ms)
RDELAY	extra regulation delay when value changes (ms)
RTOL	regulation tolerance (rpm)
RNDINTERVL	randon value range change interval (ms)
SINTERVAL	speed measurement interval (ms)
SAVERAGE	speed measurement average
SAVETAG	parameter save identifier
SAVEDELAY	delay in seconds before parameter will be saved to EEPROM
LCDB	LCD brightness steps (10 values, 0=off, 255=max)