Measuring AC Main Supply Voltage with Arduino (2)

   In article named Measuring AC Voltage with an AC to AC power adapter from OpenEnergyMonitor I found a interesting solution for measure AC voltage.
   Schematic is

   I use EmonLib library like in article:

   On DSO I see on R1 resistor

and at A2 input of Arduino board (on R4 resistor):

   I use an LED display with 8 digit 7-segment drived by MAX7219 (I present on article namend Modul de afisare cu 8 cifre LED din 7 segmente fiecare controlate de MAX7219

   I use some configuration for LedControl library (dosc at The Arduino LedControl library):

   Test schematic is

   I write main_voltage_emonlib_1.ino sketch and upload in Arduino board:

  I made main supply voltage measured with Arduino (2) movie:

Measuring AC Main Supply Voltage with Arduino

   If you need to measuring AC main supply voltage with Arduino must made some calculation.

   I use a simple schematic:

   I can directly measure the DC voltage on R1 resistor. I use internal reference from Arduino Uno board (compatible board with ATmega328 microcontroller) so maximum value for U2 can be

U2 = U1*(R1+R2)/R1 = 1.1*(1+22)/1=25.3V

  AC voltage U1 so DC voltage U2 = U1*1.41-Udiode

  If we put value in equation

U1 = (U2+Udiode)/1.41

because I use trafo U0 = k * U1.

  For tests, I use a trafo imprinted 220V/2x12V 200mA but if I measeure voltage from secondary coil

I found 11V when main voltage is 220V, so k = 220/11=20. I use an 1N4007 diode and Udiode=0.65V.

  I use an LED display with 4 digit 7-segment drived by TM1637 (who I present on base blog in article named Afisaj cu 4 cifre controlate de TM1637 si Arduino and sketches are at https://github.com/tehniq3/TM1637-display):

   Schematic for display put on Arduino Uno is:

   I write main-voltage_0.ino sketch and upload in Arduino board and I made a movie named main supply voltage measured with Arduino

Home acces using keypad from outside and push button from inside

   I made a system for home acces with delay-off using keypad from outside and push button from inside. I write a sketch for use actuator or solenoid.
   In stand by mode, solenoid (or actuator) is released.
   After I indroduce good code *1234# from keypad actuator is unlocked for 0.7 seconds; about 5 seconds acces is permited, after that actuator is locked for 0.7 seconds. Same cases are when push button from inside.
   If you use solenoid instead actuator, after I introduce good code *1234# from keypad coil solenoid is powered about 5 seconds, after that coil solenoid is released.
   Base test schematic is:

but if you use actuator, schematic is

and if you use solenoid, schematic is

   If you use acces_code_keypad_1.ino sketch, system work like in deblocare usa cu cod din exterior si buton fara retinere din interior movie 

   A comrade, Tommy, made a permanent montage on PCB for actuator:

   I put an alphanumeric LCD1602 display on i2c and an RTC module with DS3231 (or DS1307) and base schematic is:

   If you upload acces_code_keypad_3.ino sketch. in standby mode, on display is hour & date:

and when acces is shared and a open padlock is displayed.

   In movie named door lock acces with code and pushbutton you cand see all I write: