ssaguiar
New Member
Hi to all.
I am working in a poject in wich a pic controls an electric oven.
In the original circuit, there is a mains sensor so, if the mains power drops below some level, the pic turn off the oven.
The circuit pictures are attached below.
I just don't understand how this circuit is suposed to work and why it uses 2 pis of the pic (pin 4 - RA3 and pin 9 - RC7/AN9).
Ra3 is an input/output only pin and pin 9 is an input/output or analog.
In the circuit, the main voltage is rectified by D1, D2, D3 and D4, wich generates V_IN1 and V_IN2.
V_IN1 is regulated by a 7.5 Volts Zener diode and pass thru he circuit made by Q3/D2/R8 to generate the pic's suply.
V_IN2 pas by the circuit composed by D6/D5/C2 to generate the -12 Volts supply for the reles and buzzer.
The ground is made by the comon conection point at C1/D4 and D5/C2.
At the mains rectifier circuit, the mains voltage pass trhu the 1M / 2200 capacitor and the 47R resistor and the 150 K resistor and feeded to the R3 and R4 resistors.
Then, one circuit go to pin 9 thru the circuit composed by R5 (1K1 / 1% resistor) and D3 (3.9 Volts Zener). This pin can be analog pin or i/o pin.
The other circuit, composed by D1 Zener, R1, Q1 and R1 make the circuit wich goes to the pin 4, wich is an i/o pin.
I just don't get how this circuit work.
Can anybody help to analyse this?
Thanks
I am working in a poject in wich a pic controls an electric oven.
In the original circuit, there is a mains sensor so, if the mains power drops below some level, the pic turn off the oven.
The circuit pictures are attached below.
I just don't understand how this circuit is suposed to work and why it uses 2 pis of the pic (pin 4 - RA3 and pin 9 - RC7/AN9).
Ra3 is an input/output only pin and pin 9 is an input/output or analog.
In the circuit, the main voltage is rectified by D1, D2, D3 and D4, wich generates V_IN1 and V_IN2.
V_IN1 is regulated by a 7.5 Volts Zener diode and pass thru he circuit made by Q3/D2/R8 to generate the pic's suply.
V_IN2 pas by the circuit composed by D6/D5/C2 to generate the -12 Volts supply for the reles and buzzer.
The ground is made by the comon conection point at C1/D4 and D5/C2.
At the mains rectifier circuit, the mains voltage pass trhu the 1M / 2200 capacitor and the 47R resistor and the 150 K resistor and feeded to the R3 and R4 resistors.
Then, one circuit go to pin 9 thru the circuit composed by R5 (1K1 / 1% resistor) and D3 (3.9 Volts Zener). This pin can be analog pin or i/o pin.
The other circuit, composed by D1 Zener, R1, Q1 and R1 make the circuit wich goes to the pin 4, wich is an i/o pin.
I just don't get how this circuit work.
Can anybody help to analyse this?
Thanks
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