How to build an open WiFi finder using ESP8266 and two coin batteries

n the past few months ESP8266 has created a real revolution in the IoT space. I’m using it in a project that will hit Indiegogo in a month or so and you, of course will support me ☺ During the development process I’ve learned a lot and I want to share a part of it. Let’s build cheap open WiFi finder together! Software NodeMcu firmware https://github.com/nodemcu/nodemcu-firmware ESP8266 flasher http://www.xe ...

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Circuit provides constant-current load for testing batteries

Suppose that you need to test a 1.5V, AA-size alkaline battery. You can apply a short circuit and measure current, or you can measure open-circuit voltage, but neither method properly tests the battery. A suitable test current of approximately 250 mA gives you a more reasonable test. You can use a 6Ω resistive load at 1.5V, which produces an output voltage of 1.46V at an ambient temperature of 25°C if the b ...

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Try the most favorite type of batteries

Perhaps the most frequently used rechargeable batteries on the market nowadays - Lithium-Polymer (Li-Po) can be found also in our offer. From the beginning of electronics, the world searches for an “ideal” rechargeable battery. So far such a battery doesn´t exist (maybe supercapacitors in the future), but Li-Po (Li-Pol) cells are quite near to an ideal in some aspects. Very low self-discharge (approx. 5% / ...

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