stan2004 posted:RayL posted:... I can see that you and I are going to be conversing on these and other technical matters over time.Let the games begin!As I said, I've posted extensively on the topic of IR occupancy sensing though mostly from a DIY, roll-your-own approach. I am still very much interested in peeking inside the MTH ITAD to better answer recurring questions on how it should be hooked up to [fill-in-the-blank].If you are going the Arduino approach with discrete IR LEDs and IR phototransistors, this can dramatically drop out-of-pocket cost vs. using ITADs or modules from Azatrax and the like.As shown above, an LED-phototransistor pair is about 25 cents. Each would need a resistor to connect to a 5V Arduino input/output pin. Note in the 2nd example eBay has a board module with the resistors on it for a bit more. Additional modules shown have the transmitter-receiver pair with additional electronics with features such as a trimpot to adjust the LED current (much like the Range adjustment on an ITAD).As you have witnessed first-hand, there can be issues with ambient Infrared energy masquerading as a reflection from a passing train. More sophisticated ITAD devices (such as the Lionel 153IR) pulse the IR LED at some frequency (in the kHz or thousands of times per sec)...and then have the receiver "tuned" to look for IR reflections at this magic frequency. Since ambient light would not be pulsing at this magic frequency, ITADs using this method generally perform better. There are even eBay modules that incorporate these so-called modulated IR LEDs and matching detectors.Above is from an earlier thread so prices/availability are questionable but at least give you an idea of what's out there. If you are a hard-core programmer, you can write code to do the LED pulsing (on the transmit side) and frequency detection (on the receive side); this allows you to use the naked components shown earlier. What the above modules do is simply let you send a simple "ON" command to start the modulation, and returns a simple "ON/OFF" digital signal indicating detection of the modulated reflection.
stan2004 posted:RayL posted:...That's only part of it -- I have 2 of the 40-1028 ITADs that I can't get to activate unless I cover the window completely.
Regardless of how I adjust the range control, the relay will only 'click' when the window is completely covered.
...Could the relay "click" be from it de-activating? If you do an OGR search on "MTH ITAD" you will find threads decrying over-sensitivity to ambient light. So if you are testing this on a bench with a desk lamp nearby or near a window during the day, ambient light can activate the ITAD...and only when you block the sensor window does it de-activate. This would explain the backwards behavior. If this applies, as you can read about in more detail in the other threads, some ideas include re-positioning (not always practical with the lock-on design) or fabricating a shade/awning or similar shielding to give the sensor what amounts to tunnel-vision.
I have not seen the guts of the MTH ITAD, but for similar devices like the Lionel 153IR, the range control knob only adjusts the brightness of the transmitted IR beam. This IR beam bounces off the passing train back to the IR sensor which activates the relay. So if it is indeed ambient extraneous light activating the ITAD, messing with the range/sensitivity control is ineffective which can be confusing.
Of course you may simply have defective units. If this is the case and out-of-warranty, are you considering DIY troubleshooting/repair? I will assist if you can post photos and are handy with a meter and soldering iron. Or if you are just going to toss them, consider sending one to me as I've been curious to see the MTH ITAD design and I can post a teardown report here for future reference. Previous threads have given confusing/conflicting statements on the functioning and wiring of the MTH ITAD. Here's a teardown I did for the 153IR which another member sent me.
"Or if you are just going to toss them, consider sending one to me as I've been curious to see the MTH ITAD design and I can post a teardown report here for future reference."
Stan2004; If you want one of the MTH ITADs, I'll need an address to mail it to. I'll send you the RealTrax 40-1028. It does work! I'll look for your 'teardown' report.
Ray
