0000 0000 0011 0100

Joule Thief stable output development PCB

I have pushed the button on so many PCB designs in the past that I now look back at the older iterations with a degree of regret. I have come to recognise and appreciate the value of this digital evolution because I learned a lot in the process - but I still want the money and all of that development time back please!

The design I'm going to look at in this blog is the stable joule thief PCB shown in an earlier blog. To be fair to the circuit it has always worked well in each iteration, and I have always hurriedly opened up the packets from the manufacturer, soldered them up and huffed and puffed about the place quite...er...chuffed.

But...the latest incarnation is the huffiest, puffiest and chuffiest I think (well, until the next one I guess). The requirements for the PCB have changed over time (along with my understanding of PCB design). 

Originally the PCB was specifically developed for a dedicated night-time "candle" project, but the project evolved to require the following:

1. Stable voltage output for running a microcontroller
2. All pins of microcontroller broken out
3. Solar panel input to rechargeable battery if required
4. Breadboard friendly for development
5. Less SMD and more through hole components for ease of soldering

Blurry for a reason - not proud of all of these!

All versions do work as intended, but the latest is really nice as it fulfils all of the design criteria. Here are the steps along the way.

As per usual as soon as the PCB arrives and is soldered up I am already thinking of the next iteration, but in this case the result is so useful I've thrown it on my Tindie Store in case anyone might find it useful/fun as well.

Next I want to use two QX5252 ICs and (maybe) drive the output throughout the day when a solar panel is connected (at the moment using one QX5252, the output current is shut off when charging the battery). I get the feeling that I might be doing iterations of this damn thing for a few years yet! And loving it...