In summary, this person is using a TL084 op amp to amplify voltage generated by two red LEDs. The problem is that the op amp is too sensitive and it reacts when circuits or wires are tough. This makes the circuit unstable. Other than that, the circuit works fine. One solution is to reduce the gain of the op amp by changing two resistors to something like 100K or 10K.
#36
aruna1
111
0
well how can i adjust sensitivity i.e where to add POT to adjust if i use these 3 pin IR modules?
If you want to reduce sensitivity, you could just do it by reducing the power to the light source.
Or, you could actually detune the light pulse frequency from 38 KHz. These devices have a tent-shaped response, so they would work fine, but at reduced sensitivity, if you tune the input off frequency.
Or, you could do as I suggested above. Get the receivers looking down black tubes, so they get light from only one direction.
Also, some of these devices operate on 32 KHz. If you had each second one on 32 Khz and the others on 38 KHz, this would give some more immunity from adjacent sensor pickup.