Keep alive for TCS FL4 function only decoder

[craigolio1]

I put this decoder in a Bombardier cab car for lighting. The car is very light and the decoder resets quite often. Adding weight is not an option. Has anyone ever added keep alive to this decoder?

Thanks.

Craig

Edit:  this is N scale. I probably have room for a TCS KAC2 keep alive add on piece but maybe that's over kill. The power drop outs happen regularly, but only last an instant.

[peteski]

So you are using it with couple LEDs only?  That is relatively low current draw.   If you installed a "real" keep-alive module it would keep the lights on for quite a long time. What I'm saying is that it is probably an overkill.

I suspect that just adding a regular large value cap will be quite satisfactory. Something like a 1000 micro Farads should smooth out any dropouts.  Probably even a smaller cap would work too.

I have FL4 in my stash. If you are not sure where to hook it up I can try to figure that out (next week).

[RBrodzinsky]

It is REAL easy. The FL4 has a ground wire available!  It is the black w/white stripe.  So hook the blue wire to the positive side of the cap, the black w/white stripe wire to the negative.

[peteski]

It is REAL easy. The FL4 has a ground wire available!  It is the black w/white stripe.  So hook the blue wire to the positive side of the cap, the black w/white stripe wire to the negative.

That makes things easy, doesn't it?
With 1000 micro Farads or more I recommend to add a resistor/diode circuit to the cap as shown here. It will limit the initial charging current and protect the rectifier diodes on the decoder from overload.

[craigolio1]

Guys that's amazing. Thanks so much for the instructions. It's going to be so easy I just wish I did it while I had it apart. Pretty sure I have the parts already.

Craig.

[RBrodzinsky]

The real question is how goes the truck experiment?

[craigolio1]

The real question is how goes the truck experiment?

I know I’m resurrecting and old thread but there has been some progress. This project was shelved for a long time due to a stall in the truck improvement project, but a recent development on that has brought me back.

I went ahead and installed the keep alive. It went very smoothly. I have a stick pile of 470uF tantalum capacitors that I don’t want to use In locomotives as They are only 16v. I’ve had a few explode during testing. But there is lots of room in this car body. So I wired two In series and that makes it a 32v cap but half the capacitance. Wire another series pair in parallel and that makes it a 32v 470uf.





The assembly tucks nicely into the model and isn’t very visible through the doors, which is why I chose this spot.






As far as the truck parked object goes, this one uses the version one truck that had bronze bushings. It rolled better than stock but not well enough to have a train longer than about 6 cars. It is however a great way to add power pick up, and with keep alive it’s now flicker free.

Recently I have experimented with the bearings and wheels from a Rapido LRC car. @CNR5529 was helping me with tuning those trucks and noticed that the bearings were remarkably similar in size to the bushings. He popped a set of LEC wheels and bearings into this truck and the car absolutely glides, which makes it really promising. There will be an update in the other thread soon.

Craig