This project is about home safety and security monitoring, but the update is crack for electronics designers. [Simon Ludborzs] continues to work on his prototype as well as he’s wonderful about sharing his success as well as failure in a conversational manner.
In April we saw his initial design which combined a SIM900 GSM modem with his own board to let him monitor his home safety and security system without hiring a monthly service. above you can see a snap of his newest prototype. It’s not fully populated as he’s testing the power supply… which in this state puts out 0V. certainly that’s not up to his design specification so he started hunting around for the issue. He tells a tale of woe which is near to our hearts. He removed Q6, which is BC807 transistor, in purchase to test the FET used on the board. This brought it to life as well as had him looking into the datasheet of the part as well as its footprint in Altium. The footprint is right, the schematic symbol is wrong. There’s a lucky fix though. above you can see the original design. The fix was just to rotate the part. This is illustrated as a change in the layout, but it worked with the original pad location. They’re not square to the transistor’s legs but they do still fit the outline.
He goes on to tension test the PSU output as well as then talk about whether it’s enough for the rest of the project. all in all a fascinating read!