simple circuit reverse engineering

[ted]

For double op amp is almost standard - pin #4 is ground or minus and #8 is +, the easiest way to find out  where you connect the battery

[ted]

[ted]

Double check your drawing - op amp is in strange configuration

I did not notice that the op amp is upside down.

Correction
IN - to control laser beam
IN - photodiode modulation signal
Signal Out - from photodiode
Red + voltage supply
Black - voltage supply

[TomGeorge]

The reason I need to use that particular sensor is that I have 5 of them available, taken from old welding machines and doing that exact job of sensing the welding temperature.

How were they integrated into the old welding machines?
Tom..

[cloxart]

@Ted: you say black = -V, but black is going into OUT1??

@ TomGeorge: I have no way to check, they were originally mounted on some induction welding machines (CEIA LOGE 23) but the machines has gone and the manufacturer that I contacted said they do not have any documentations as it is a very old model.

[ted]

correction of correction

[ted]

[cloxart]

thanks Ted,
I guess I should start testing it... do you think I am correct in assuming that on the laser beam wire I must connect a current limited supply?

[ted]

All LEDs required current limit, the simplest is a resistor - 200 -300 ohm .
That is 3V laser diode.

LED wire (brown ) - required modulation signal,

google - chopper amplifier