Збирач потоків

Last year at a social get-together, I got immensely bored and heard a fire truck siren in the distance. I began brainstorming ways to model the ramping-up and ramping-down of the Q-siren and came up with this simple VCO design and a large capacitor. Like the physical sirens, the circuit has a power button (to ramp up the frequency) and a brake button (to quickly reduce the frequency.

A fun side effect of the way I designed the controls is that when both buttons are depressed, the steady state frequency falls somewhere lower than it otherwise would, which mimics what would probably happen if you tried accelerating the turbine while the brake was engaged. (I have never heard this actually happen, but it’s a fun thought.)

I’m sad that I’m not allowed to post a video on here, but if someone asks for one I’ll figure out a way to share it.

These are on aluminum boards that I reflow with a hot plate. Just setting down a raw LED on the hot plate causes the glow to begin and ramp up as it gets hotter, and stops glowing when you take it off the heat as it cools. The boards next to this one didn't glow because they had already cooled down, so I know it isn't from a glow in the dark effect from the building lights.

I did not test how long it glows for. I would expect it to fade out eventually. Maybe the heat just lets it drop to a lower energy state and it has to recharge from ambient light. Light glow in the dark but with heat required.

The temperature sensor of the heating station gave up and now it heats up indefinitely. Perfect for making your PCBs very crispy and crunchy.

I am offered a huge lot of electronic components from a former TV repair shop that was active from 1973 - 2015. Resistors, capacitors, transistors, IC's and many other components. HV transformers (TV), switches, knobs, inductors, subassemblies, ... Most of it is sorted in over 40 Raaco bins, and the rest is partially sorted/unsorted. They are asking 400 euro and I have to decide tomorrow by noon. I think I will buy it, but it will take time to move it all and sort it again.