Consumption measurement for MAX7219 32x8 led display

   For measure the consumption for display made with 4 8x8 led modules drived by MAX7219. I use clock presented in article named ceas animat complex cu date de pe net, whitch use just a development board WeMos D1 Mini and display with 32x8 leds.
   Schematic for a module with 8x8 leds is:

Leds are controlated through muplexing system, so consumption is low.

    First, I removed the display for measure the resistor control for consumption:

I used also a microscope:

Value is 103, so is 10kohmi. You can ckech using an online calculator:

   My display is powered at 3.3V, but I also made measurements at 5V.

   I chose this clock because it can be controlled from a local web page and it's easy to change the intensity.
   We have selected the intensity at 0, the one commonly used at night or when it is cloudy outside and the average consumption is 16mA at 3.3V and 28mA at 5V:

   I selected the intensity at 4, the one commonly used during very bright daytime and the average consumption is 46mA at 3.3V and 66-73mA at 5V:

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