Joined: 08/07/2015 04:57:16
I've built a couple of "live GPS tracker" devices that use a 3DRobotics radio to relay the data stream from an RC-aircraft-type GPS module to a base station. They run well off a single-cell LiPo battery.
In order to improve their range, I bought a couple of Anarduinos with the RF96 LoRa radio modules to try out. My expectation is I'll get some increase just from the hardware, and (I hope) some more by preprocessing the NMEA stream in the Anarduino to reduce the volume of data so I can cut the baud rate and improve sensitivity.
But I see a possible problem. The spec sheet for the MCP1703 regulator says its typical dropout voltage is about 525mV, but can be over 700mV if I get some that came from a "less-than-best" batch.
That means I could use at most 30% of the battery's nominal capacity, and possibly as little as 15%, before the regulator drops out.
The pinout diagram for the Miniwireless module says Vin can be anywhere in the range of 3.3 to 7V. Is that really true? Or will the regulator output get unreliable if Vin gets below the 3.8-4V the datasheet specifies as the minimum?