Obstruction Detector With 12C508 IR

Description

This project is inspired by the DPRG IRPROX project. They have a pretty good PCB layout and idea. I would like to thank them for posting their project for all of us to see and learn from, I wouldn’t have started PIC programming without them, or at least not nearly as quickly come up to speed! The pinout on my board allows either a five-wire or a four-wire connection to be made the former uses a disable line if desired. You can also put in a resistor or use a trimpot to adjust range. The trimpot locations are very generic, most pots will fit. Be careful not to adjust pot to 0 ohms! The IR proximity detector works very well, even in a brightly lit “noisy” environment. Instead of modulating the IR LED for 600us and then looking for a detection, I now look for a detection after every on/off cycle of an IR LED and count the number of hits that I get. I also look during the ‘off’ cycle when none of the IR LEDs are on and count the number of false hits that I get there. If I get more good hits than false hits then I say its a true detection. I then increment a counter as a sort of timer, when it passes a certain threshold, I notify a hit. At this time I check to make sure that a minimum number of good hits has been attained. At the same time I keep track via another time-out counter of noise hits. When this counter passes a certain threshold it then removes any detection that has been set. I fiddled a lot with the various threshold values for minimum number of good hits, time-out values and divisors for updating the false hit counts, and finally settled on the ones that currently used. I’m calling it a success and moving on to other projects! The source code for the, uhm, DLC IR proximity detector can be downloaded below as well as the PDF documentation for this kit.

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Proximity Detector Circuit Based 555 IR

Description Sometimes you want a simple solution to a problem and you don’t mind if your main controller has to do the work. This IRPD requires the main robot processor to choose which side to look at, and requires it to “debounce” the results for reliably operation. But, it still works really well without any complex program code.
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 can also be gotten at Radio Shack. Parts are easy to find and simple to connect. This does not require 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, if you have a ‘scope, this is a 1/38,000 period, or about 26.3us. If 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 easily. The code to do this is below. It assumes that you are using port 7 as the 555 input port.

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

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Lightning Detector Circuit

This Do-it-yourself lightning detector circuit can be a especially sensitive static electricity detector which can supply an early warning of approaching storms from inter-cloud discharge properly prior to an earth-to-sky return strike takes location. An aerial (antenna) formed of the brief duration of wire detects storms inside a two mile radius. The circuit emits an audible warning tone from a piezo buzzer, or flashes an LED for each discharge detected, providing you advance warning of impendig storms so that precautions may be observed.

The primary characteristic inside the lighting detector is the circuit’s ability to be set near to self-oscillation, with its leisure optimised via the bias resistor values demonstrated within the circuit diagram. The oscillator is dc coupled and feedback is routed through the collector of TR1 towards the base of TR2, whilst the overall loop acquire is set using the multiturn(12, eighteen or 22) preset VR1.

Lightning detector circuit establishing

To create the lightning sensor, change preset VR1 for oscillation by monitoring test point TP1, which must be at roughly 7volts peak-to-peak. Test level TP2 should be at +6V dc. Now readjust VR1 back again a bit to quit oscillation; use a screwdriver to touch the aerial-side of C1 a variety of occasions; the alarm ought to sound for one or two seconds then stop. If it continues, create a extremely tiny adjustment back again and recheck. The other technique is to electrostatically cost a plastic ruler after which draw your finger shut to discharge, about two meter away through the aerial.

Driven from a nine volts battery the lightning detector circuit consumes about 600 uA in standby. Powered continously it could supply a fantastic yr of uninterrupted monitoring. When sounding the alarm, the current will rise to 4mA based on the low current sounder WD1. A minimal three volts system is required for a great output level and it is going to create a “pinging” alarm to warn in real time of any electrostatic pulse activity.

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