Gas usage monitoring

[cliffwright]

Perhaps a bit late in the day ... but judging from the datasheet and the findings of the example you linked to, I think you may need to connect an NPN transistor to the photo transistor output of the OPB704 - essentially to form a darlington output. This is because it looks like under expected detection conditions the 'on' current of the phototransistor alone will likely be in the region of 100uA which will not pull the digital input low enough. I was going to suggest something like 545-2254 from RS but I see you have already ordered . I don't know how much into electronics you are but you might have an NPN transistor handy anyway or maybe back to Maplin ... I would imagine pretty much any small signal NPN should be good enough. I would suggest this transistor is wired in at the location of the detector rather than at the module.

Bugger That'll teach me for being impatient . . .

I don't know how much into electronics you are but you might have an NPN transistor handy anyway or maybe back to Maplin ... I would imagine pretty much any small signal NPN should be good enough. I would suggest this transistor is wired in at the location of the detector rather than at the module.

"Not very" is the answer . . . general wiring I'm fine with . . . but 'electronics' I have to scratch my head a fair bit and refer to the likes of Wikipedia for calculations . . .

I'll see what I can do with this once it arrives - I might email you for advice if I can't fathom it though!