Clarify role of solder jumper in operation of Optotap v2.4.1

[thclark]

In the Operation at 5V section of the OptoTap readme

The V2.4 OptoTap PCB has been tested to work fine from 5V to 24V inputs with no modifications. However, this does induce a bit of additional voltage drop from the switching regulator IC going into LDO mode. If you would like to run the V2.4 OptoTap at 5V, my first suggestion would be to just run it at 5V with no modifications. It will most likely work just fine.

However, it does have the capacity to bypass the whole buck converter circuit. Note that this also bypasses the polyfuse, so there will be no overcurrent protection.

To make this modification, you need to cut the trace between the center pad and 24V pad on the rear of the PCB, then use some solder to bridge the center pad to the 5V pad. To reverse the change, just desolder that bridge and re-connect the center pad to the 24V pad with more solder.

This suggests that initially, there should be a bridge from 24-centre. However, most v2.4.1 PCBs (I've seen 3 in person now from 3 different sources) have no "trace" (by which I think is meant bridge?), just three segregated pads.

So the statement is confusing for people running 24V, as it creates an ambiguity around whether the 24v-centre pads should be bridged or not.

Here's what I think is true:

• If running 24v, you shouldn't bridge the 24v-centre pad
• If running 24v, and you do bridge the 24v-centre pads, it will still work but you won't benefit from overcurrent protection
• If running 5v, you shouldn't bridge the 5v-centre pad initially
• If running 5v and you experience too great a voltage loss (*) for the trigger to work correctly then you should bridge the 5v-centre pad. This will remove the overcurrent protection but reduce the voltage loss in the circuitry.

If my assumptions are correct can someone please confirm, and I'll happily make a PR to tweak this README for clarification.

*I assume you can measure this between the ground and the signal output pins, but what's a sensible range that this output voltage should be, when operating correctly?