The other day I’ve built myself an ESP8266 WiFi dual-relay for standard DIN rails. Electronics Bottom PCB The bottom PCB is fairly simple, input goes through a polyfuse and a bridge rectifier such that I can power it both from 8VAC-12VAC or 12VDC. And then just a 7805 with protection diodes and a heatsink. At 12V the 7805 dissipates around 0.6W of power which doesn’t sound much, but it gets hot.
I have an old Leitz REDYX variable AC transformer for 6V and 8V tungsten microscopy lamps. Unfortunately it does not contain a fuse, so in other words if the transformer has an isolation failure it will start smoldering until the main circuit breaker for the room trips. So I figured to improve the safety I should add a fuse. In this case I’ve only fused the primary side, it might be a good idea however to fuse the secondary sides as well.
So I recently rescued an Apple PowerBook 170 from ca. 1991. I couldn’t find the power supply, but fortunately the power connector is just a standard DC jack requiring 7.5V - so I removed the (probably broken and internally leaking) NiCd battery. So I took a DC jack, hooked it up to my lab supply …and bingo! Started up right away! However the mouse ball didn’t worked initially, turns out it was dirty.
I decided to switch the content management to Hugo, because my old site was a mess out of custom Perl scripts that generated me the static HTML. Hugo on the other hand does this all for me and in a consistent manner.