jaydag71
New Member
Hi folks! Today I am having some problems with sorting out some photo transistors that I've salvaged from a bunch of old mice' . They appear to be all the same- these are 3 leaded devices which has led to some confusion this morning while testing them out for a line sense array/edge detectors. Please find attached crappy jpeg with a picture of one.
Feel free to flame me, but my problem is that I have tried taking measurements in various configs and am getting the same results when I swap out what I am assuming is the base with the emitter. ie.
if 1=e & 2=c & 3=b
I tried 5V with 100ohm R in series to c, gnd the e and take some voltage readings under both ambient and with an IR led firing into the ptrans from both the b (4.96 amb -4.98IR) and the c (5.01amb -4.99IR),, but then I swap the gnd from e to b and take the measurements from e (4.96amb - 4.99IR), and again from c (5.01amb - 4.98IR).
I've noticed that most line follow bots take the output signal from the collector, but I tried the same tests this time from emitter:
This time swapped the 100ohm r over and placed it between e and gnd. Vcc into collector (5.01V) and take some voltage readings from both b (4.96amb - 4.99IR) and of course from e (0.00amb - 0.01IR),, swap the b and e connections and re-test,, e (4.96amb - 4.98IR) and b(0.00amb - 0.01IR).
I am now plainly confused. From where am I supposed to take the useable output signal? which pin is indeed the real emitter?? Does it even matter ,,if I am able to get a variable signal output from the device something is working right? Sure would like a datasheet though....any help much appreciated,, jd
Feel free to flame me, but my problem is that I have tried taking measurements in various configs and am getting the same results when I swap out what I am assuming is the base with the emitter. ie.
if 1=e & 2=c & 3=b
I tried 5V with 100ohm R in series to c, gnd the e and take some voltage readings under both ambient and with an IR led firing into the ptrans from both the b (4.96 amb -4.98IR) and the c (5.01amb -4.99IR),, but then I swap the gnd from e to b and take the measurements from e (4.96amb - 4.99IR), and again from c (5.01amb - 4.98IR).
I've noticed that most line follow bots take the output signal from the collector, but I tried the same tests this time from emitter:
This time swapped the 100ohm r over and placed it between e and gnd. Vcc into collector (5.01V) and take some voltage readings from both b (4.96amb - 4.99IR) and of course from e (0.00amb - 0.01IR),, swap the b and e connections and re-test,, e (4.96amb - 4.98IR) and b(0.00amb - 0.01IR).
I am now plainly confused. From where am I supposed to take the useable output signal? which pin is indeed the real emitter?? Does it even matter ,,if I am able to get a variable signal output from the device something is working right? Sure would like a datasheet though....any help much appreciated,, jd