1.8" TFT display with ST7735B

   I buy an small 1.8" TFT display with ST7735B driver and I try to connect directly to Arduino Uno board as I see on net... but result was not good... display is almost white

and just disconnect accidentaly the GND I can see something...

   So, I search on Arduino forums and on net (article INSTRUCTABLES: Arduino TFT display and font library ) and I found a solution like Nokia 5110 monochrome display .. I put 1k resistor on each data pins to Arduino to display:

and I tested more Arduino library for this display with ST7735 driver (from Adafruit, TFT library, ucglib library, etc) and I made  move to see .. movie is named ST7735B display with Arduino board

NOTE: Original article is in roumanian language, see Afisaj TFT de 1,8" cu driver ST7735B !!!

Tachometer (RPM) on 8digit 7segment led display with MAX7219 using Arduino

Bibliography:

- https://www.gammon.com.au/forum/?id=11504

- http://www.mikrocontroller.net/attachment/189505/Drehzahlmesser.ino

- Modul de afisare cu 8 cifre LED din 7 segmente fiecare controlate de MAX7219

- my sketch: https://github.com/tehniq3/tachometer-RPM-/blob/master/RPM_intr_nick_gammon_1.ino

Under & overvoltage relay for AC main power supply (2)

original article in roumanian language

   After I test the Measuring AC Voltage with an AC to AC power adapter from OpenEnergyMonitor and put my result on article Measuring AC Main Supply Voltage with Arduino (2) and after I made Under & overvoltage relay for AC main power supply now I change schematic for made a new version for voltage protection relay using this schematic

   If I use main_supply_emonlib_under_overvoltage_ver3.ino sketch after module is powered, on display I see the voltage on main power supply:

and after I push MENU/OK button, on display is undervoltage thereshold, who cand change with + & - buttons:

    After I push MENU button, value is stored in EEPROM memory, on display is overvoltage thereshold, who can be change by + & - buttons:

after push again MENU button, value is stored in EEPROM memory, on display is delay-off tine in second for reconnect coil relay after voltage inoutside range:

   In under & overvoltage relay with Arduino (2) movie you cand see the cases and how you cand cheange value for undervoltage, overvoltage and delay-off time:

   If I use main_supply_emonlib_under_overvoltage_ver3c.ino value for main power supply is displayed with a number after comma (point), exactly as in under & overvoltage relay with Arduino (3) movie:

31.07.2020
   I added a sketch to use LCD1602 alphanumerica display on i2c connexion instead existing display (with MAX7219 and 7-segment led display). Sketch is main_supply_emonlib_under_overvoltage_ver4.ino !

02.08.2020
   I added a new sketch with best implement of delay-on to connect the relay... see main_supply_emonlib_under_overvoltage_ver4a.ino

Under & overvoltage relay for AC main power supply

   After I made a test for Measuring AC Main Supply Voltage with Arduino, now I change the sketch for made protection relay with adjustable limits for undervoltage, overvoltage and delay-off time using 3 buttons:

   After power the module, Arduino read and calculate vltage for AC main power supply and if is ok, coil relay is powered:

   If push MENU/OK button, on display is SET

after 2-3 seconds, on display is undervoltage threshold, who cand change using + & - buttons:

    After you push MENU/OK button, is displayed overvoltage thereshold, who cand change using + & - buttons:

   After you pus MENU/OK buttons on display is delay-off time for reconnect coil relay after voltage is outside good range, also you can change value form 1 tp 20 seconds using + & - buttons:

    After you push MENU/OK button, on display is main voltage:

   I write main_voltage_3.ino sketch who made exactlly in picture, but it more easy to understund cases if you see under & overvoltage relay with Arduino movie

Bibliography:

- Releu de protectie la minima si maxima tensiune retea

- Releu de protectie la minima si maxima tensiune retea (2)

- Masurare valoare tensiune retea (2)

- Measuring AC Voltage with an AC to AC power adapter