Nutmegzzzz
New Member
I have a 741 comparator circuit (attached) using a 6.2V zener diode as a reference voltage at IN- (Pin 2). I supply the IN+ (Pin 3) with a LiPO battery voltage of 7.2V (varies between 6.0 - 8.4 dependant on charge) and as the voltage falls I want the output to go from high to low when battery voltage is at ~6.0V. I see the 741 output a high well enough (Vcc = 6.4V; Output = 5.49V), but my problem is when the 741 outputs a low (Vcc = 6.3V; Output = 1.65V). It should be mentioned I am using the LiPO batteries to power the 741 Vcc + (Pin 7) and ground for Vcc- (Pin 4). I've tried putting a potentiometer at the offset but that really screws things up.
Note that I require the output to be zero so that I can interupt current flow with an opto-isolator and shut the system down to prevent the LiPO batteries from futher discharging and getting damaged.
The additional diode (D1 at the + input) is used to ensure the voltage at the + input will eventually become less then the - input. The 402 ohm resistor is used to limit current through the zener diode.
Thank you for your time and any assitance is very appreciated.
Bill
Note that I require the output to be zero so that I can interupt current flow with an opto-isolator and shut the system down to prevent the LiPO batteries from futher discharging and getting damaged.
The additional diode (D1 at the + input) is used to ensure the voltage at the + input will eventually become less then the - input. The 402 ohm resistor is used to limit current through the zener diode.
Thank you for your time and any assitance is very appreciated.
Bill