Flux residue and fairground games (Patreon)

Flux and carnival games (Loud 8-bit noises!)

Filmed on the fly while travelling, so will look and sound very different. Further to discussion on a live stream about whether it's safe to leave flux residue on PCBs, I dug out the prototype of a fairground game from almost 30 years ago and checked the condition of the tracks where the flux residue had been left on. There was no indication of any corrosion. I think the flux corrosion issue relates to the aggressive acid based fluxes used in more demanding soldering applications like pipework. The PCBs were all hand etched with a resist layer that is left on and soldered through. The display card was stripped and given a chemical tin plating. Any slight patterning on the larger tracks is where the surface was slightly pitted during etching due to the nature of the laser printed transparencies being a bit "grey" in larger black areas. This game was a classic wheel of fortune type of game that travelled with various fairgrounds in the UK. Looking at it now I'd give it more functionality, but at the time it worked well in its application. I'd also use a much more complex randomiser, as the simple one I implemented for the game start sequence has a distinct pattern. However, the game randomiser itself was based on a counter running continuously in the background, that was sampled when each game was started, so it had the ultimate randomisation of human input. These days I'd also use an RS485 driver chip for the network, but still use opto-isolators, as there are a relatively small number of nodes on the network, and the opto isolation was needed, as the power cards operated at mains voltage. The display used standard fairground cabochon light caps with four 60V lamps in series on 240V. A power driver card was mounted in an enclosure on the back of each display panel. The digital sound effects are generated in software with a simple 3-bit resistor based digital to analogue converter. On the full size operator consoles the speech was recorded onto several ISD audio chips that each had several samples cued up by the microcontroller. The small controller in this video was an emergency backup unit if the main controller got damaged in any way. It allowed the game to run without the speech, but still had a player operated start button. In use, each player would get handed a (captive) number token on a cord. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- http://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty. #ElectronicsCreators