ESP8266 Community Forum

- Tue Nov 10, 2020 6:17 pm #89400 I need to dispatch a rat that's turned up in our garden to take advantage of my wife's bird feeders but my wife tells me I need to do this without also killing the birds!
I'm thinking of making a box to contain the trap but with a small door which is closed except when it's dark when then are no brds about. I don't have an acessible power source so it needs to be battery-operated, so very lower power consumption.
I have a small geared 12v motor (which works at 9v) and some microswitches so I can construct the opening/closing mechanism. I'd like to run an esp8266 at a very lower power state, waking every 15mins to check the light, open/close the door if necessary, connect to wifi and publish the state of the trap if it's changed, then go to sleep again. I'm thinking of powering the esp nodemcu and motor with a 9v PP3 battery, which I think should last a while if it's doing nothing most of the time. My problem is finding a way to power the motor in forward/reverse that doesn't use significant power while the motor is not actually in operation. I can handle the code but my electronics knowledge is minimal and I'm struggling to find help online. Can anyone provide a little guidance please?
I'm also open to any ideas on how I could do this differently, provided they are also over-engineered, of course!

- Thu Nov 12, 2020 1:19 pm #89419 H-bridge motor controllers seem to cause a significant voltage loss so may not power the motor and I haven't yet found whether they consume much power when not energised. I wondered about mechanical relays; the ESP can trigger a relay but not the relay coil, so it would cause a constant drain. I need a solution triggered by a high ESP pin that consumes minimal energy when the pin is low. Any suggestions?

- Sat Nov 14, 2020 4:13 am #89435 nodemcu is a bad choice as the voltage regulator and usb-serial converter constantly consume several mA.
Unfortunately their developers ignore this aspect with each generation.
Powering from a 9V battery still worsenes the situation as more power is wasted than used:
3.3V*XmA =Wused vs. (9-3.3)V*XmA=Wwasted

- Sat Nov 14, 2020 7:46 am #89437 Thanks for that, so apart from my problem trying to minimise power wasted in the motor driver circuit when it's not operating, the nodemcu board would waste power even when the ESP is in a low power state?
Would it help to have additional batteries to power the noemcu at 3v or add an external buck converter for the 9v source?