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Need help finding replacement for dual op amp marked as pm93BH

Other Parts Discussed in Thread: TL082, TL062, TLE2072, LM258, TLE2142

I am looking for close replacement. 

Need help finding replacement for dip-8 dual op amp pm93BH

ic from unit controls cooling and heating unit made by honeywell 

main ac supply to cooling/heating unit is 24vac split +12 and -12

only markings on IC dip-8 pm93BH with national Instruments logo

no Google entries and no datasheets

It is a DIP-8 low dual op amp 

supply VCC is 20 VDC need to handle approaching 28vdc

looks like Tl062, TC072, Tle2072, ca1458, lm353, lm258 and Tl082 pin layout (from linear ic tester BK Precision )

Looking at the component with a huntron tracker 2000

vcc to ground like a zener but at high range  to top of the zener cut off like diode

inputs to output from IC all look like diodes on all ranges

I am looking for close replacement 

op amp outputs connect each to the coils of two separate relays

relay Midtex 603-772sy 3amp 240vac

Thanks for any help

  • Hi Andrew,

    Not finding any references to that part number. It appears to be a customer designated part number to conceal the device's identity. Your measurements may be revealing the ESD cells internal to the various pins.

    Can you provide the portion of the schematic that includes the pm93BH device? That might provide some clues as to how general purpose, or specific, this dual op amp may be. 

    Regards, Thomas

    PA - Linear Applications

  • Hi

    I have no schematic.

    pin 1 connect directly to relay coil

    pin 2 resistor network voltage divider circuit 

    pin 3 resistor network voltage divider circuit 

    pin 4 direct to ground 

    pin 5 resistor network voltage divider circuit 49.9k to h/c-I(possible heat cool input)

    pin 6 resistor network voltage divider circuit 47k to three other resistors 49.9k, 95.9k, 30.1k leads to more capacitors and resistors

    pin 7  directly connected to coil

    I think my only option is to just try one and hope for luck.

  • Hello Andrew,

    It looks like the mystery op amp uses the standard dual op amp pin out. That is good. Therefore, you may be able to try a number of high-voltage op amps providing they are available in the 8-pin DIP package. I have no idea how much current the relay coil requires so that is a big unknown in all of this.

    Take a look at the TLE2142. It's a high-voltage op amp that is available in a 8-pin DIP package. If you need more output current, we will have to look for a higher output current device.

    Regards, Thomas

    PA - Linear Applications Engineering

  • Thanks this worked great. Had these in stock.