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I have quite a few of these on my layout and it always seemed to me both leds were kind of dim, particularly the red one which comes on in place of green when tripped. I asked Dennis Zander if anything could be done to improve this, such as change the load resistors for these guys. Dennis promptly responded; obligingly sending me the circuit diagram and the board layout showing where the respective resistors are located.

The red led has a 10K load resistor and after some playing I discovered that jumpering it with a 3.3K resistor (approx 2.5K effective resistance) really smartens it up. Both it and the green led are way more visible. The picture below shows the added resistor in place, and it still fits easily within the signal housing. The video clip is a comparison of the modded sensor on the left compared to a stock sensor on the right. This is from a line of sight a bit above horizontal, like you would normally see them on the layout. A straight on video comparison is not quite as dramatic, but still noticeably improved.

With Dennis kind permission I am putting this mod on the forum in case anyone else cares to make similar changes. My plan is to swap all mine over in batches of perhaps 3-4 at a time, as time permits. You can either solder a small jumper 3.3K axial resistor in where I did, between the anode of the red led and the cathode of the SPD as shown. Or you can replace the original SMD 10K resistor with a 2.4K on the board, or simply solder a 3.3K SMD resistor right on top of the OEM 10K on the pcb. Any of these options will work the same.

One of my favored Z-Stuff layout configurations is one or more 1011’s in parallel, driving a blind 1070 (to get the longer turn off delay of the 1070), which in turn drives a 1008A relay which then actuates the end device(s). In this configuration when any one of the 1011’s trips (sensing a train), all other 1011’s trip to red, as does the 1070 and the 1008. I tested the modded 1011 in one such setup on the layout paralleled with 3 other 1011’s. Works perfectly, actuates everything as it should, and trips in response to all other 1011’s. Much more visible than the others though. Yay!

I checked the comparison current draw and pre-mod is about 48ma; post mod perhaps 1ma higher.




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Video 1
Last edited by Rod Stewart
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