I'm building a battery powered project that includes a PING sensor from Parallax. With the PING sensor powered, the project uses 43 mA. With the PING sensor not powered, the project uses 23 mA. A very big difference.
The vast majority of the time the PING sensor is not needed so I've decided to control its power. This seems like a good way to accomplish the task...
...with the PING substituted for the LEDs. I used a 2N3904 for the transistor (because that's what I have) and a 1K resistor for R1. It's working very well.
Is 1K a good choice? Will a different resistor reduce the PING-on power consumption, the PING-off power consumption, or the overall power consumption? Does it make any difference what resistor I use?
I've searched for answers but I honestly don't know if I'm even searching for the right thing. Some people say use 1K, some 3.3K, some 10K. The schematic shows 1K or 2.2K. There are a few transistor-resistor calculators but I don't have a clue what to enter for all the values.
Thanks for any guidance, Brian