simple circuit reverse engineering

dual = 2 op amp in one package

opps, sorry I meant BIPOLAR
http://www.analog.com/media/en/technical-documentation/data-sheets/AD706.pdf

Op amp can work in two modes or single mode of power supply.
google - dual supply op amp circuit and single supply

here is the schematics i was able to make

post # 1 top drawing, which wire is red and which white ?

from top to bottom:

left side:

yellow
white/red
green
red

on the right side:
black

I sent you a PM Ted :slight_smile:

From top
IN - to control laser beam
OUT - signal from photodiode

  • voltage supply
  • voltage supply
    Black
    control bias op amp
    The circuit is using only one op amp.
    Double check your drawing - op amp is in strange configuration

google - ir thermometer circuit

https://www.google.ca/search?q=ir+thermometer+circuit&rlz=1C1NCHB_en&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiPxdD5zpLbAhVJ_IMKHfJDAd8Q_AUICigB&biw=1440&bih=784

great! but red wire is going straight into pin8 (v+) of the ic?? and green into pin1 (v-)... is there something i dont get? obviously there is :frowning:

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:
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

cloxart:
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.. :slight_smile:

@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.

correction of correction

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?

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