OK, electrically let's talk about exactly what is going on here. Basically a phototransistor is like mounting a small solar cell to the gate of a transistor and running the transistor in a switching (rather than amplifying) mode. With the LED butted right up against the photosensitive gate it provides more than enough light energy to provide the switching effect we are seeking. Switching can be looked at as merely amplification past the limits of the transistor...the transistor merely becomes conductive, like a switch.
So you just hook up the input like you would any other LED (because it IS an LED) that part is easy, however what you do is you set up the output like in the schematic, by connecting the appropriate leg to VCC (in the case of TTL +5V) determined by which way the diode effect goes (you don't want the voltage to go against it, or it just won't switch...just logically figure it out, or breadboard it first). And then the other output leg becomes your isolated, voltage-converted output. Sorry I'm overexplaining this, but for the newbies I think it good to explain it operation thoroughly and logically. OK, now in this schematic, you'll notice its got like a zener or something and its multistage. I don't think you need this sophisticated a set up necessarily (assuming you are selecting one from mouser or somewhere). You can use just a regular phototransistor (1 stage) optoisolator. Why? Because the driving LED has more than enough juice to saturate the gate on the phototransistor single stage or not. On Tuesday, November 8, 2016 at 7:39:33 AM UTC-7, mzimmers wrote: > > Hi, all - I thought I posted something about this last week, but a search > doesn't turn it up, so here goes again. > > I'm working through Molloy's book, and trying to build the opto-coupler > circuit in chapter 6. I'm not a hardware guy, so I'm feeling my way along > here. The diagram doesn't show specifically how to wire up the four > connectors. I looked at the data sheet for the device, which was helpful, > but still doesn't get me home. > > I could trial and error, but I've already fried one component, and they're > not easy to come by in my area. Can anyone help clarify this configuration? > > This is the specific device: opto-coupler > <http://www.farnell.com/datasheets/2050347.pdf?_ga=1.151569401.1989118912.1477330330> > > Thanks... > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/c8a65086-deb8-427a-b0cd-22ec4c9e4528%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
