I had previously added TCS Keep Alive modules to a few of my locos and was rather impressed, not only in their ability to keep locos rolling smoothly over dirty track but also in their ability to help the locos crawl along even slower than before. Thus, I want to add these modules to all of my locos. However, even at the discounted street prices between $20 and $25, I would have to spend a small fortune to equip all my locos. Thus, I decided to try my hand at “Do-It-Yourself” Stay Alive modules.
Using the advice of the DCC columnists at both Model Railroader and Model Railroad Hobbyist magazines, I purchased enough electronic parts to assemble five (5) stay alive modules. As I already had everything else I needed for assembling these modules, the unit price worked out to $5.24 each. Assembly was pretty straight forward and if you can install a hard wired DCC decoder in an older loco, you can assemble a stay alive module. My finished modules are simlar in size to a TCS KA2. I installed the first two in a pair of Athearn Blue Box EMD F7 locos that I had previously remotored using Mabuchi FK-280SA 14200 motors. Both of these locos now smoothly and quietly crawl around the layout at about 2 scale miles an hour without a hiccup. Just to see how far these locos would travel without power, I laid a strip of blue painters tape about 14 inches long atop one rail of the main line. With the loco at speed step 10 of 128, the loco traveled the entire length of the tape and almost came to a stop before the two lead wheels rolled beyond the end of the tape and the loco resumed it’s previous speed. Not bad at all, especially for five bucks!
I also discovered that its pretty easy to test your Stay Alive before you install it in a loco. Simply charge the Stay Alive for a few seconds using a 9 volt battery. Be sure to touch the blue wire to the positive post of the battery and the black wire to the negative post. Remove the battery after a few seconds of charging. Attach a 1K ohm resistor to the negative lead of an LED, then touch the blue wire of your Stay Alive to the positive lead of the LED and the black wire to the resistor lead. If you assembled your Stay Alive correctly, the LED will light signifying it’s ready to install in your loco. That’s all it takes. Keep the 9 volt battery and the test LED handy on your workbench until you finish assembling all of the Stay Alive units you plan to make.
If I am correct, one thing that you might want to consider adding to your home made keep alives is an isolation switch. Keep alives can interfere with programming your decoders. If you install an isolation switch to cut off the keep alive power to the decoder when needed you won’t have any problems reprogramming your decoders.
Model Railroad Control Systems sells a circuit board and has a parts list as well as DIY kits (all the parts) for stay alives for those of you who want a simpler DIY alternative and still save some money.
Disclaimer: I do know Seth (the owner) and was a beta tester for this product.
Nichicon supercapacitors 2.7 volts, 1 Farad (use five per module)
MFG P/N: JUWT1105MCD
ON Semi - Zener diode, 13 volts, 5 watts (use one per module)
MFG P/N: 1N5350BG
Yageo Carbon Film Resistor - 110 ohm, 1/2 watt (use one per module)
MFG P/N: CFR-50JB-52-110R
Taiwan Semi Rectifiers - diode 1 amp, 1000 volts (use one per module)
MFG P/N: 1N4007G-K ROG
Blue and Black 30 awg wire (I had these on hand)
1/16" and 3/4" shrink tubing (I had these on hand)
There are useful step-by-step videos on YouTube including a video by Larry Puckett (DCC Guy) of Model Railroader Magazine fame. Just look up “Build your own Stay Alive” to find this and several other videos.
It is simplest to build a linear, flat module with the five supercapacitors side by side. I used Larry Puckett’s suggestion of using double sided tape to hold the capacitors in place while soldering. Start by bending the negative lead of one capacitor 90 degrees away from the center of the capacitor and flat with the top of the capacitor. Bend both leads of the second capacitor 90 degrees, flat to the top of the capacitor and away from the center of the capacitor. Place the two capacitors side-by-side on the double sided tape with