38kHz Detection Question

morris4019

So i have been playing around with the Stamp Stack II (solarbotics advertises a 100% compatable to Parallax BS2). Anyways, I have not found better documentation or instruction than parallax Robotics With The Boe-Bot. The stamp stack is designed to slip on to a breadboard, which is nice. I am currently using some 38kHz IR detectors hooked up to pins 0 and an IR Led hooked up to pin 1. My question is that the documentation for the BOE BOT is saying to hook the IR LED up to pin x through a 1k resistor (and i have tried many different combonations.) The problem i am having is that hooked up the way the documentation says, i have to actually run a 36000 PWM and I only get about 2-3 inches of detection. I took it upon myself to build a 5v regulator with a LM317, so I used a 2n2222 along with my output pin from the STAMP to switch 5v to the IR LED through a 1k resistor. Now I get 18 - 20 inches of solid range at 38kHz. Is this a common problem with the STAMP modules?


-Mike

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kwinn

A 1K resistor seems a bit high. What voltage is driving the led. If it is 5V then 180-220 ohms is usual. For 3.3V 100-120 ohms.

morris4019

It is 9v regulated to 5v with lm317. Thats kind of what i though about the resistor being a little high. Anyway, I tried all the way down to 100ohm and did not have very good luck, or should i say detection range, when connected straight to the stamp. But with the same 5v through a transistor, with the output pin from the stamp connected to the base, it seems to work great.

Next step is a motor driver for my gear motors.

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······ I'll try everything once [noparse]:)[/noparse]