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Simple Proximity Detector Circuit Based 555 IR

Simple Proximity Detector Circuit Based 555 IRSimple Proximity Detector Circuit Based 555 IR

The NAND gate is a standard 74LS00 that you can get anywhere – even Radio Shack, same with the 555, IR detector (RS Everlight or Sharp GP1U58Y) and IR LEDs may even be gotten at Radio Shack. Parts are easy to find and simple to connect. This does not need any fancy wiring or parts placement. Make sure that you use a .1uf bypass cap next to the 555 and next to the IR demodulator. Tweak the 2K pot until you have 38KHz, in the event you have a ’scope, this is a 1/38,000 period, or about 26.3us. in the event you are using a Parallax Basic Stamp II for your robotic controller, you can feed the output of the 555 in an I/O port and measure the frequency very basically. The code to do this is below. It assumes that you are using port 7 as the 555 input port.

sometimes you need a simple solution to an issue and you don’t mind if your main controller has to do the work. This IRPD requires the main robot processor to pick which side to look at, and requires it to “debounce” the results for reliably operation. But, it still works well without any complex program code.

‘Basic Stamp II Freq Counter
O555 con 7
freq var word

count O555,100,freq
debug dec5 freq*10,cr
goto Loop

One of the nifty things that make the 555 circuit fun to use is that you can use it to do IR communications with other devices that read IR at 38KHz! If you run pin 4 of the 555 to a Stamp II port instead of just tying it high, you can use the serout Stamp II command to modulate the IR in such a fashion that other IR demodulator equiped devices can read it! I’ve done it, it works – Have fun.