So, over the last few evenings I’ve managed to finish the first useful board for my new extendable PSU; a 5v board that can supply around 3 amps. It has a trim control that allows the output to be adjusted from 5v to 6v, and two op-amps wired as voltage comparators that illuminate a couple of LEDs to indicate over or under voltage conditions (less than 5v or more than 6v).
Now all happy that I’d got my first board up and working I set about designing the next one that can provide a variable 0 to 30v at around 1 amp.
Happily playing with some ideas on my breadboard I suddenly noticed smoke coming from the circuit, a bang, and then a piece of the voltage regulator went flying past my head.
The problem was, besides a fault in my design, I hadn’t noticed that the regulator was starting to fry.
I did have an amp meter in series with the board but I didn’t see what it was reading.
What’s needed I thought, is something that can alert me to when things are getting hot.
So, I’ve started on a new project. It will have the ability to monitor multiple temperature sensors and report audibly if one or more of them exceeds a pre-defined temperature. All this so I can eventually measure and record the discharge curve of a battery pack. See previous blog entries to find out more about that.
That’s another breadboard with a half finished prototype put to one side, and the start of another project; multi-temperature sensor alarm project. I need to think of a more snazzy name than that. Whilst it would have just been simpler to pick up some cheap data logger off Ebay…. it wouldn’t have been so much fun.
Oh.. and a word of warning. Electronics on the whole is a safe hobby. Baring the old soldering iron burn or stabbed finger when a screw driver slips, you should be pretty safe if you are sensible and carful. However, things do go wrong and most components will complain venomously if they are stressed beyond their design parameters; or just connected the wrong way around. I’m fortunate in that I wear spectacles and they offer a limited amount of eye protection, but you do need to be carful. When things start to go thermonuclear, it usually happens fast.
If you’re ever present when a tantalum capacitor explodes, you will wish you had a gas mask and fire extinguisher handy never mind a pair of spectacles.