Current sensor for OSD or FrSky elemetry up to 30A.
Just another useful brick in telemetry equipment is current sensor. With right OSD or FrSky software it allows to show not only current draw but also remaining battery capacity, and this feature is VERY helpful in FPV.
I checked market for possible solutions and easiest (but not very cheap) way of doing this is to use Allego MicroSystems hall chips. I chose ACS713 chip because it is available at reasonable price, is available :-), and have current range sufficient for me (I don’t expect to go beyond this in my current models). It has also linear output proportional to passing current and moreover: it has separation between sensor and output, so one can use it to sense on high or low side.
So, chips arrived and there was time to design sensor. Agrhhh, it requires 5V of supply voltage so I had to add voltage regulator. 2 chips, let’s make schematic:
I set filtering capacitor to 100uF to average current, so few redings per second should be accurate with it. If not, larger capacitor will be needed.
PCB size is designed to fit XT-60 connectors on both sides:
So, let’s make PCB:-)
Laminate etched. It looks like it was a little too long in bath, but it will be tinned anyway, so no problem this time.
Soldering time:-) Because copper traces could be too thin to pass such high current, I added additional copper wires on its path.
Current sensor is also excellent place to branch power supply for other sensors, OSD and Video transmitter, so I added small JST connector.
With heatshrink wrap cover sensor is ready.
Tested and it (of course 🙂 ) works.