From: "Kivela Marko" <makivela@NCSBSR01OU.ntc.nokia.com> To: "Eric Behr" <behr@math.niu.edu> Date: Fri, 29 Aug 1997 08:05:36 +0300[Marko had problems with the "Maxi" controller turning on momentarily at power up - EJB]
I changed opamps pin 2 to 3 anv vice versa. I realized the other controllers found on your page are controlled directly by the opamp. The Maxi version includes a buffer transistor controlling the mosfets. This transistor causes a 180 deg. phase shift, so when the opamp's output is high, the fets are off. This is the reason why the opamp's inverting and non-inverting inputs must be reversed. Of course, the transmitter's function must also be reversed.
Now the controller works fine. Motor stays off when connecting power and it shuts down when the battery's voltage falls. I estimated also that it is almost impossible to use thermal protection the way it's presented on the diagram. PTC's resistance change is so slight when temperature rises that it cannot be used this way. If it is used this way, thermal protection will not work when the battery is fully charged. It works only just before the controller shuts down the motor for low battery voltage.