Bottle light update

I’ve been working on variations of the Joule-Thief -based bottle lights I’ve been making. I made a couple using strip board for the through-hole components but its clunky. Better yet would be SMD components stuck directly onto the structure…

Joule Thief circuit using tape to adhere SMD compnents

Some time back I adopted a simple technique I saw where you use sticky tape to put SMD components across copper tape “traces”. This was my first go at a slightly-less trivial circuit and not surprisingly it failed. I’ve not really diagnosed exactly where the problem was yet. It could be I got something in backwards, but more likely its one or more bad connections. I used some tape I had bought that is normally used for repairing polytubes and greenhouses. The idea is that its UV-stable and semi-permanent - regular scotch tape or sellotape becomes brittle over time and would fail. But this stuff is quite thick and and doesn’t grab so much (less sticky) so even as I was putting it together I was concerned it wouldn’t hold down those components well enough to make a reliable electrical connection.

I could just glue the components down, but with the capiliary action there’s a good chance the glue would get in between the component contacts and the tape. So better still would be a conductive adhesive. The good ones (silver particles in a silicon or expoy base) however are spendy so that’ll need to wait while I save my pennies. Backing up a little, of course the strongest and most reliable solution would be to solder the joints. I’m trying to avoid that for a couple of reasons: first because any heat-based process risks distorting and melting the substrate - which is currently PET (Polyethylene terephthalate) plastic. The second reason is a bit more fluffy - I just want to find other ways to assemble these circuits that are maybe more kid-friendly, or less intimidating or don’t require special tools. That might yet turn out to be an unreasonable and impractical requirement but I’m not done yet.