Below is a schematic of a current regulator using a comparator IC2. The board is from an XP-605 ELENCO bench top adjustable power supply. Searching the WEB was unsuccessful in finding any original schematic so I resorted to reverse engineer the board and came out with this schematic. The configuration appear to be a simple negative feedback loop feeding a Darlington configuration for current amplification. IC2 is absent from the main electronic board. The PCB do not indicate which IC part number is utilized. It only shows a socket for a DIP8 chip. I found several possibilities of replacement comparators but none was using Pin7 as a power input and pin6 as the amplifier output. LM311 appear to be a potential candidate performance wise but not pin compatible with the DIP8 socket. From the schematic it would appear that pins 1,4,5 are utilized as a zero offset trimming capability. So, my speculation suggest the following: Pin1 Trim input Pin2 negative input of a OpAmp or Comparator Pin3 positive input of a OpAmp or Comparator Pin4 Negative supply Pin5 Trim input Pin6 Output (most probably open collector) Pin7 Positive supply Pin8 not used in the circuit, ?
The Question: I am searching for a replacement IC comparator ( perhaps OpAmp) to match the DIP8 pinout above described and compatible with the electronic schematic. Can anyone help ? Much appreciation :)