ESP8266 Part3

The Proof of Concept is going well! The ESP8266 is now a working transponder, sending its ChipID when the reed switches tripped to LapTrackerTK program over Wi-Fi! Exciting stuff. Up to this point I’ve been powering the ESP with two AA 1.5 volt batteries in parallel. I know you all judged me and in retrospect I'm regretful. So, its time to fix that...

The ESP8266 is a 3.3 volt device. The usable voltage is something like 1.7-3.5 volts. There are plenty of 3.7 volt LIPO's online for pretty cheap but I wanted to avoid batteries all together. One less thing to charge or go buy packs of. The ESP is considered a low power device, however real world experience has shown that when the device sends vi Wi-Fi the power consumption increases, killing battery life.

Expectations of the ESP being powered by the RC Car somehow was initially daunting. The NiMH 6Cell battery is 7.2volts, and is variable as its drawn down by the car. The electronic speed control on the other hand connects to the Radio Receiver which has several channels available. My receiver has 3 channels, however I’m only using 2. One to the electronic speed control (which also powers the receiver) and one to my steering servo. That leaves an unused channel ripe for the picking.

I had an old steering servo that was heavily damaged. I cut the wire and used that as my power connector to the receiver. I'm sure they are plentiful and cheap online. Looks like they are 100mm connectors

Looking up the specs on the receiver, its 5Volts output at 2Amps. Plenty of power for the ESP. My initial thought was to build a "series resistor voltage splitter". I couldn't find the total resistance of the ESP online. My ohm meter didn't give an accurate reading either but a little trial and error I ended up figuring the ESP was at 60 ohms. I ended up with a 12 ohm resistor in line with the power input, but I could only manage to drop just over 1 volt on the resistor. An increase in that resistance value did something weird and would cause the resistor to drop over 4 volts and start heating up. Anyway, even with the ESP running at the high end of 3.9 volts, it did power on! Success! oh but its UGLY! This wouldn't do, so I started poking around and reading some forums. Eventually I figured I needed a Linear Voltage Regulator.

I ended up sourcing the 3.3Volt regulator from Adafruit. Pretty straight forward. 4-15volts input, a few capacitors, and stable 3.3volts output!
http://www.adafruit.com/products/2165

I cut some PCB board and played around with a layout. The PCB board I have is more breadboard than PCB. To make the connection between the components required either a solder bridge, wires, or some other conductor. I don't have the greatest wire sitting around either, so I opted to layout the components in a way that will allow connections using the leads of the components, either cut and soldered or bent over. Not super clean but will do the trick for now.

Once everything was in place, I plugged in the connector to the receiver and fired it up. Success! Reading 3.3Volts, no overheating, and no need for any additional batteries.

UPDATE!!! -- [ESP8266 Part4 - Infra-red] -- Now with IR Triggering!

Enjoy!