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This circuit was designed by Stan2004 and is documented in the Electrical Reference Materials & Manuals sticky topic above in this category. It is item #1 in the topic in the thread called "Electronic Projects on the OGR Forum Developed by OGR Members", graciously maintained by rtr12. The thread has links to the original topic, which contains the circuit and the original gerbers.

Recently I wanted to put a tester in a caboose cupola roof, but the original board size a little large. So I redesigned it to about 3/4" x 1.125" size, which fits way better. Here is a 3D board view and a few pics of the finished caboose:

3D Front-Top View R1.01

Board ready to go into the cupola. Note the leds are on the other side (top) of the board:


Mounted up inside the cupola, and re-installed on the shell:


Finished and on the track being tested:


The green led indicates the board is powered up. If a spike higher than 33 volts is detected as the car rolls along, either one or both of the red leds flickers unmistakeably.

I used 3mm leds to minimize the impact in the caboose, but it is still visible enough for track testing purposes. All parts are the same as the original; the only change is the board itself. If anyone wants to build one like this the gerbers are attached 2 posts down.



Images (4)
  • 3D Front-Top View R1.01
  • 79D7DBBD-CC31-42AD-83AA-72E0103A69B5
  • D92EB8ED-DCEE-416D-9EF4-7BF740ADCDF9
  • F430EE39-8F6B-442C-B933-6763CF7D8EAB
Last edited by Rod Stewart
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Thanks for the kind words John. It was a fun little project.

So here is the circuit once again, and the revised very simple board layout. The parts are very easy to pick off the circuit diagram, and you can use either 3mm or 5mm leds. I chose 3mm just for minimal visual impact on the roof of the caboose. The only unusual parts are the two 1N2527B zener diodes. The gerbers are attached below.

Circuit SnipR1.01 Board Layout

The boards are about $1.50 each in a lot of 3 from OSHPark; and the rest of the parts might cost about $1.00 more. The only ones that cost more than about a penny a piece are the 1N2527's. For J1 you can use a 2 pin Dupont connector, or a JST-EH, or simply hardwire the board if desired. Light 28AWG wire is way more than enough because the current draw is peanuts. J1 is marked Roller and Wheels, but polarity is not important.

I'll send a note to Tom to see about getting it added to our project list.



Last edited by Rod Stewart

Note received! It's been added to the existing PCB listing in the projects list and linked here for anyone wanting more details.

Electronics Projects Developed on the OGR Forum by OGR Forum Members  -  1. - Track Transient Spike Detector

This is a cool project Rod!  For anyone needing that last little 'nudge' to get into the electronics part of the hobby, this project could be the one! 

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