Electronics

I wanted an ESP8266 to answer a simple question: is mains power available? The ESP8266 was willing to help, provided nobody introduced it to 230 V. An ordinary isolated 5 V wall adapter already gives us a useful signal: its DC output disappears when its mains supply disappears. We can watch that output and leave the mains side inside the adapter, where it belongs. Two resistors make the voltage suitable for the development board's ADC. The slightly less obvious requirement is keeping the observer alive when the thing being observed switches off. ...

I found this 60W Electronic Load to be quite useful for testing small power adapters and supplies. While it is possible to homebrew an adjustable electronic load we recommend getting this electronic load module or a better-but-costlier one like the UNI-T UTL8212+ electronic load. Observations You can stress-test power supplies using this electronic load quite easily and conveniently. It turns out that the Orange branded 12V 2A or 3A adapters from Robu are of really poor quality. The output voltage drops to less than 2V when the load current is increased to around 1A. This is NOT the first time that the Orange branded stuff has turned out to be of poor quality. In the end, you get what you pay for. ...