Vizier87
Active Member
Hi everyone.
I've built an IR circuit for "event detection" like this:
I just used one of the op-amps from an LM358.
Between L1 and L2, it needs to be sensitive enough so that even a strand of hair sets the LED D1 on.
Which I managed to do quite nicely.
My problem is, the circuit's comparator tuning at R3 is not specific for different power sources, even when they're all at 5V. If I plugged in different supply sources, I'd have to recalibrate the pot again. And also, once powered off, the calibration sometimes need to be tweaked again too, though not as much as switching to a different supply.
Is there a better way to handle this analogically? I know I could just probably use a uC to establish a baseline and capture the event based on the minor perturbations from the baseline but I prefer to keep this as analog as possible.
Thanks!
Vizier87
I've built an IR circuit for "event detection" like this:
I just used one of the op-amps from an LM358.
Between L1 and L2, it needs to be sensitive enough so that even a strand of hair sets the LED D1 on.
Which I managed to do quite nicely.
My problem is, the circuit's comparator tuning at R3 is not specific for different power sources, even when they're all at 5V. If I plugged in different supply sources, I'd have to recalibrate the pot again. And also, once powered off, the calibration sometimes need to be tweaked again too, though not as much as switching to a different supply.
Is there a better way to handle this analogically? I know I could just probably use a uC to establish a baseline and capture the event based on the minor perturbations from the baseline but I prefer to keep this as analog as possible.
Thanks!
Vizier87
