Gadget freaks, model railroaders, roboticists or cat-hosts will love the versatility of the Sharp IS471 infrared proximity detector. It is the size of a transistor, operates over the 4-16 volt range, and can detect objects about 4-9 inches away by reflected IR pulses.
The basic implementation requires only the IS471, an IR LED and a 9 volt battery and can be built by most any tinkerer in less than 10 minutes.
Remove these adsRemove these ads by Signing Up

Step 1: Gather the parts

The parts you'll need are:
1) the Sharp IS471 (available for $2 at: or $3 from, and others)
2) a 940nm IR emitter (such as the Fairchild QED-234, available from for about 50 cents, and other sources)
3) Something to mount the above two items on. You've got a lot of options here. There are several excellent Instructables on making your own PCBs. If you want to try it out before doing the etching thing you can use a pluggable breadboard (not shown) or go with a small piece of perf-board (pads on .100" centers, shown at bottom left).
4) 9 volt batter and battery clip
5) Soldering iron & solder, diagonal cutters (if not going the breadboard route).

If you'd rather not etch, but still want something snazzy you might drop me a line about the very small custom perf-boards I had made at (shown at bottom right), priced at $2 each for the bare boards, postage included).

Step 2: Putting it together

Insert the leads of the IS471 into the perfboard close to an edge. The leads will need to be spread out just a bit, since they are spaced more narrowly than the average perfboard holes/pads. Note that the flat side of the IS471 needs to face outward, since this is the side that "sees".

Bend the IR LED to the right as shown below. With the LED positioned as shown the short lead (the cathode) is on top.
1-40 of 112Next »
s444kee1 year ago
Brilliant!!! This is just one half of a circuit i am trying to build.

I am trying to activate upto 12 LEDS consecutively with each detection from the proximity sensor.

To make the circuit more bespoke i would ideally like to have the 12 LEDs in 4 banks containing 3 LEDs each. From a four-position selector switch I would like to choose whether the LEDs 1 - 3 light, 1 - 6 light, 1 - 9 light or 1 - 12 light.

Any help greatly appreciated.
offlogic (author)  s444kee12 months ago
Sounds like you've got it pretty well figured out.
rahulkhairnar12 months ago
I'm unable to find IS471F can you tell me alternative of it..,,,n please reply as much as's urgent
offlogic (author)  rahulkhairnar12 months ago
I'm not aware of any alternate parts off the top of my head.
I know they have them in stock here:
You might be able to put something together with a tone-decoder (LM567), led and a phototransistor or something.
rahulkhairnar12 months ago
I'm unable to find IS471F can you tell me alternative of it..,,,n please reply as much as's urgent
Flanders881 year ago
Which program do you use to draw your circuits schematics?
Tobor19771 year ago
I'd like a LED to light up when the detector detects something, is there a simple way to do that?

Thanks for the help.
Tobor19771 year ago
Great thank you for the quick reply, just ordered the dectors.
can u design the circuit ? i need it to light up 10 LED's
offlogic (author)  EccentricNeko1 year ago
I can do better than that, I'll just send you a link!
Tobor19771 year ago
Nice circuit. Two questions... how long did it takefor the company to make the custom perf boards and do you know if these components are available at Radio Shack? Thanks!
offlogic (author)  Tobor19771 year ago
I used Pad2Pad to handle the fab, and pushed it out to 3 week turn to keep it super cheap (under 20 cents per board). And, no, gotta order the detectors from the Internets.
is it possible to make it activate and stay activated until you wave infront of it again ?
offlogic (author)  EccentricNeko1 year ago
It's possible to add a flip-flop to do this, but the basic circuit alone won't do this.
The venerable 4013 or a pair of NAND gates can do this nicely.
esg.8272 years ago
Im making an array of LEDs , i want them to turn on and off with something like this, would it be possible??
offlogic (author)  esg.8272 years ago
The datasheet is at
Raw output is good for sinking 50mA.
offlogic (author)  esg.8272 years ago
Subject to the raw current output of the IS471, yes.
Otherwise add a transistor buffer or a driver chip to up the current capacity.
fbujold2 years ago
ir-detector for about 10$ you suppply 5 V you get an analog output .5 to 4 volt. No hassle garantee!
offlogic (author)  fbujold2 years ago
Yeah, that's a great device if you need proportional analog output.
It's expensive, but great if you don't just want a simple OC output!
Radio shack has changed this chip (276-1323) recently (somewhere around January 2008). If you get it from radio shack make sure it's the one you want!
thank u
rthapliyal2 years ago
does it give analog output???
coz it's not clear from the instructions that i does...
and also is IS741 available in india???
offlogic (author)  rthapliyal2 years ago
Nope, it's a discrete logic level, 1 or 0.
Not sure about availability in India, check local Sharp distributors or order via Junon over the interwebs.
shaunwhite3 years ago
Is the Vcc using 9v? because base on the datasheet of the QED234 Fairchild, it says tht the forward voltage is only 1.6 volt and a forward current of 100mA. Wouldnt it spoil the IR LED at tht voltage? Please educate me as i'm just a newbie in this sort of things
offlogic (author)  shaunwhite3 years ago
If you hooked up an LED straight to the 9V batt it wouldn't work for long! :)
The Sharp part is made to handle this matter. It works just fine, trust me (as Bernie Madoff used to say).
Also if i run the 5V my PIC works on? Nice sensor by the way
offlogic (author)  sde meeter2 years ago
Yep, seems to work fine from 5VDC.
I think 4.5VDC will be at the lower limit, though, so no 3.3VDC.
reajrdn2 years ago
Stumbled onto all this info. Really exciting even for an ol' guy like me.
Far too many years from making PCBs and little widget circuitry.
At 80 yrs. old, am again starting a new company and the IR LED and Sharp IS471 may solve a problem--- better, create an opportunity.
I'm in Folsom, CA Home 916 989-3005
Office in Fair Oaks, CA
Would like to find some people who are into making PCBs and Proximity sensors. I need some help because my electronic savvy is too far lost in deep core.
And, possible opportunity for anyone looking to join an emerging company.

Carl Rea Jordan (emerging)
I have several other start-up and need some entrepreneur-type minds.
offlogic (author)  reajrdn2 years ago
I'm sending you an email, Carl. Curiosity and all. :)
Mike Nelson2 years ago
Not sure how hard it would be, but could you setup the "Alert" to go off when the IR Detector sees the IR light? So reverse basically? would it be a NOT chip or is there an easier way?

I want to setup an IR LED on one side of the cat food container and the detector on the other side, and have it light up a separate light when the food is low enough for the IR LED's path to not be blocked by cat food... so the path would be normally blocked...

offlogic (author)  Mike Nelson2 years ago
It's doable. The detector output is good to 50mA at up to 16V.
Just reverse the logic, so that your device operates on a logical 1 instead of a 0. For the step 8 example, you'd use an NPN transistor instead of the PNP shown.
Or an inverter chip, if you like.
cwienands2 years ago
Nice instructable. For the lazy amongst us, check out optoswitches such as the "Photo Reflective Sensor (SEN130A3B)" from Seeedstudio. Disclaimer: I'm not related to Seeedstudio in any way, it just happens that I ordered a couple of them the other day and had the part number available.
amruth3 years ago
Hi there author, i would like a LED get triggered when i move my hand in front of the detector. How do i make it happen, should i connect the positive side of the LED to the V-out pin and the negetive pin of the LED to the negetive side of the power source.
offlogic (author)  amruth3 years ago
Yeah, what steveastrouk said!
Sorry, I've been off for a while.
Nice little project BTW.
No, connect the LED anode to the V+ pin, connect the LED cathode (via a resistor) to the Vo pin.
Instruction #2 above indicates to connect the negative leg of the infrared LED to IS471F pin 4. Sharp IS471F data sheet indicates this pin 4 (GL) is an output voltage rating of 16. If the data sheet is correct and one connects as indicated above, will the proximity sensor still function properly?
offlogic (author)  warrendkelly23 years ago
That's the max rating of the driver.
It drives the IRLED just fine, really!
bvstang19675 years ago
Hello, I am an industrial design student and have been tasked with creating a Point of purchase display that makes use of light. I wanted to create a circuit that when an individual walks by the display would light up. Basically what I would like to know is there a way to increase the range of the detector to 3 or 4 feet? I would like to use a circuit similar to this one in conjunction with a relay circuit to activate a flashing led circuit that I found here:

My electronics skills are rusty at best, I'm willing to get my hands dirty (with soldering flux I guess) but do you think this may be to complicated for a novice?
1-40 of 112Next »