I am trying to create an inverse switch. The processor in my car turns on the extra 12v supply for radio for the purpose of backlight illumination when the parking lights are on. 12v passes through the illumination knob and the radio receives 0.2 - 12 v (at Pin A ) depending on the desired illumination level (usually 9-10 volts).
Radio head unit also has LCD screen that has night/day brightness setting. When the pin A has positive voltage, radio needs 0 voltage on Pin C to switch the LCD to night mode. But the current microprocessor doesn't provide this signal so I need an inverse circuit.
I jump wired the pin A to this circuit so I can use it as a signal. Pin A current is still supplying the backlight lamps of the radio as it is going to the circuit.
In summary,
Pin A -----------------> Pin C ---> Radio LCD
------------------ ------- -------------------------
0 volts ----------------> 12v -----> day mode (circuit does this correctly)
0.2 - 11.7v (variable)-> 0v -----> night mode
Problem with the circuit is, it does not drop the pin C (output) to 0 even though there is >5 volts on the MOS gate. What it does is this; from 0.5 to 11.5 volts, as the voltage on Pin A increases, voltage on pin C decreases the same amount. Shouldn't be the drain voltage 0 when gate has more than >5v? What am I doing wrong here?
I attached the circuit diagram and the MOS spec sheet. I am a newbie so please explain what you mean. Thanks!
Radio head unit also has LCD screen that has night/day brightness setting. When the pin A has positive voltage, radio needs 0 voltage on Pin C to switch the LCD to night mode. But the current microprocessor doesn't provide this signal so I need an inverse circuit.
I jump wired the pin A to this circuit so I can use it as a signal. Pin A current is still supplying the backlight lamps of the radio as it is going to the circuit.
In summary,
Pin A -----------------> Pin C ---> Radio LCD
------------------ ------- -------------------------
0 volts ----------------> 12v -----> day mode (circuit does this correctly)
0.2 - 11.7v (variable)-> 0v -----> night mode
Problem with the circuit is, it does not drop the pin C (output) to 0 even though there is >5 volts on the MOS gate. What it does is this; from 0.5 to 11.5 volts, as the voltage on Pin A increases, voltage on pin C decreases the same amount. Shouldn't be the drain voltage 0 when gate has more than >5v? What am I doing wrong here?
I attached the circuit diagram and the MOS spec sheet. I am a newbie so please explain what you mean. Thanks!
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