How practical would it be to install a capacitor circuit in line between the power pick up and the decoder's power input? The objective being to keep the sound and engine running thru short intervals of no power from the track, such as over a dead frog on a unit that has only pick ups on one set of trucks, or somethind similar, even dirty track. How large a capacitor (both physically and electrically speaking) would this capacitor be? Any thoughts?
I once caught a train in my pajama's. How it got in my pajama's I'll never know... (sorry, Groucho)
ds137How practical would it be to install a capacitor circuit in line between the power pick up and the decoder's power input?
After I posted the Question, I thought about that. I wondered if it would act essentially as a "filter" on the DCC signal. Just a thought. How about between the Decoder and the motor..... still thinking.
ds137Just a thought. How about between the Decoder and the motor..... still thinking.
The life-saver capacitor has to go to the inside of the decoder after the rectifier where the decoder converts the power to DC, after the signal is "sensed", but before the power is manipulated for consumption by the motor. Some decoders actually have a set of holes on the circuit board for this sort of thing to be soldered. It would be better to just get the decoders that are designed for this sort of thing instead of trying to do it for yourself, that is unless you are a EE and completely understand the interworkings of the specific decoder.
Look at the LENZ gold decoders and accessories.
This issue was posted just a few days ago. Surprised you missed it. I wonder where you got the term, lifesaver? By the way, it is keep alive or stay alive term used with capacitor. Click on the link below.
[ur]http://www.members.optusnet.com.au/mainnorth/alive.htm[/url]
Don't even think of using the capacitor like you want to. The capacitor is used as a storage device in this application. Some decoders have a pair of wires for this application and come with a capacitor.
If you do this, pay attention to how you hook up the capacitor. I corresponded with a fellow in a different forum who connected the capacitor the wrong way and had magic smoke come out of the tender, read decoder smoked, and found capacitor insides spread around the inside of the tender. Some people do not want to believe that will happen. Follow the instructions and you cannot go wrong.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
A capacitor across the motor leads is a bad idea for several reasons. The main one is it shorts high frequency signals, which unless you are using a cheap decoder that doesn't use a high frequency or 'supersonic' drive, is exactly what the decoder is putting out to the motor. Keep in mind that with the older Soundtraxx decoders, you put a capacitor in series with the speaker. Why? To block low frequencies and pass high ones. You cna read up on capacitors, it's not exactly liek a switch, but basically they will act as a short to high frequencies and as an open circuit for lows, the exact point dependent on the value of the capacitor. This is why for a DC loco they work fine across the motor - the do nothing to the DC power going to the motor, but short the high frequencies generated by arcing brushes, thus blocking potential RF interference. With DCC, this will interfere with a high frquency drive and also back-emf detection, so if your loco has a capacitor across the rushes, it's best to cut it off when adding a decoder.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I don't know how I missed it either..... I think I saw the term "Lifesaver" on a Lenz ad in MRR and skimmed over most of it. I thought that it would be a great idea if it could be made to work for a few cents or dollars worth of parts to retrofit some of my more finicky engines. I am planning and building expansions to the basic layout I have and know I will have some trouble with some of my engines in areas that will have extensive switching moves over dead frog switches. I have a bucket load of Atlas under table switch machines I thought I might use but since they don't power route, looks like I'll have to bite the bullet and pay up to go the reliable Tortise machine route and power the frogs. Probably the best solution anyway but like most of us, trying to save a few bucks and use what I have. Looking at a dozen switches, so if a few dollars of electronics parts might have solved it, it was worth a shot. Always looking for innovative solutions. Thanks for all the replies, but I posted before I thought it out....