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What IR source & two terminal Photo transistor can be clubbed to replace either QRD1114 or CNY70 reflective sensor pkg? Answered

I'm referring to - Building of a SPURT BOT(a simple line following robot) submitted by ignoblegnome (See https://www.instructables.com/id/Build-a-SpurtBot-Line-Follower/).

I'm building one for my cousin who's in the 7th grade & found this to be the most simplest & one that looks like its been made by a kid.           It looks so, as it has the least number of electronic components. But unfortunately i have been unable to find both QRD1114 & CNY70 reflective sensor packages.

While going through the comments section, i saw a comment by the author himself saying that the package can be replaced with an IR LED & a 2 terminal Photo transistor which happen to be the same components that make up both QRD1114 & CNY70 packages.

I would be extremely thankful to fellow users if they could mention the exact part/component number of the IR LED & a 2 terminal photo transistor that can be clubbed & used instead of QRD1114/CNY70 for the same voltage rating & circuit used in the instructable mentioned above.

I need this info ASAP, THANKS a TON & kindly forgive me for my bad grammar.


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Jack A Lopez
Jack A Lopez

9 years ago

I can't believe a circuit that simple actually works!  Well from looking at the video, I guess I have to admit it does...sorta.

What I was going to say is that probably the easiest place to find a suitable IR LED, plus phototransistor, is going to be in an old computer mouse.  That is the old style of mouse, the kind that has a big rubber-coated ball in the center of it.  These, the LED and photransistor, look at each other through a big slotted wheel.  You can't miss them.  Also worth noting, the phototransistor you will find in a the old mouse is actually two phototransistors in the same package, so from the outside it has three terminals, but it really is two two-terminal phototransistors wired together.

Regarding that IR emitter/transistor, in the same package that Ignoblenome is using  (QRD-1114), I think I have seen one of those, or something similar, in a speed control sensor, in the tape mechanism, of an old answering machine, where that sensor looked at spinning wheel, with black and reflective wedges on the back.

Regarding actually getting this thing, the line-follower bot,  working,  I think it will be worth your while to sort of get the sensor working first, and actually look at those voltages and currents with your voltmeter.  I expect there may be a certain amount of tweaking of resistor values.

I don't know if you noticed this or not, but the circuit diagram in Ignoblenome's picture,
and the one in the video (at arournd 2:14)
don't exactly match.  Too me this suggests a design that is sort of evolving, and that it might be necessary to adjust it somewhat to match the components you've got at hand.

I mean I hate to say things like this, when it kind of looks like you were seeking some kind of exact recipe to follow, one which you could expect to work if followed exactly, but I'm not sure if this is that kind of recipe.