I’m looking for an IR LED/phototransistor pair with a similar package and form factor as the part used in the QTRX-HD sensors. A similar thread (here) recommended the Sharp GP2S700HCP as a possible contender, but this part has a much smaller sensing distance than what is offered by the QTRX-HD. I’ve tried this part number in my custom build, but it simply does not perform as well as the part used in the QTRX-HD. Does anyone know of any SMD reflectance sensors with a comparable sensing distance to the QTRX-HD sensors?
We treat the Sharp part as a part we could use in our QTRX modules, though we do not commit to a particular component. What kind of range are you getting, and how does that compare to figure 8 in the datasheet:
Hi Patrick - thanks for getting back to me.
I have a custom reflectance sensor pcb that is designed after the QTRX-HD-02A. For my application, I’m looking for a good sensing distance in the 10-15mm range. The QTRX-HD performs well in this range whereas the Sharp sensor does not. The Sharp sensor does have good sensing distance in the 3-6mm range, as described in Fig.8 of the datasheet, but the photocurrent that is being received at distances outside of that range appears to be much lower than that of the QTRX-HD. Can you verify whether I should be expecting roughly the same performance between the GP2S700HCP and the part currently used on the QTRX-HD?
Yes, I was saying we expect similar performance. You could try swapping sensors between boards to look for where your performance limitation is coming from. Sometimes you need to adjust various components/operating points to get good performance, especially when you’re trying to push the limits of the sensor.