G Scale Model Train Forum banner
21 - 40 of 62 Posts

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #21 ·
Not a good choice as it draws too many amps. The Aromat has a coil resistance of 450 ohms (80 ma). The RTE is 90 ohms so draws five times as much current to operate (400 ma). This is current that could be going to the sound system and its loss will just reduce you idle time before the system kicks out.

It doesn't have to be the Aromat, but you want as low of a current (high of a coil resistance) as possible.
 

·
Premium Member
Joined
·
1,973 Posts
Received the Super Caps and couldn't wait to play.
Base Test: Sierra switch ON, no battery, no caps, system stuttered and came alive @ 12V.
First Test: Sierra switch ON, caps in place of battery, ran it for 45 sec, (I was slow to react on the video) removed track power and the sound continued for 60 sec before the caps were fully discharged just as I attempted to add track power.
Second Test: Switch ON, ran for 60 sec, removed track power. Sound system idled for 45 sec, restored track power and sound ramped up.
Third Test: Ran for 30 sec and disconnected the caps. When the caps were reconnected the system started up with no stuttering. I published the First test, have the videos of the other two and if requested will upload them also.
 

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #24 ·
I'm glad they are working out for you. I've done several and never had a problem. The president of our club said he tried it and for whatever reason, had no success. I'm thinking he did something wrong (maybe one cap in backward?)

I also got an e-mail from a local who was also asking about them, tried them with success, and is now able to use his Sierra again.
 

·
Premium Member
Joined
·
1,973 Posts
I am very happy with the results using just the 3 supercars. Today I received the last of the parts I needed to assemble the low voltage cut off. Want to do at least 1, just because.
 

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #27 · (Edited)
OK, an ALERT!!!

The other day I was running my USA 44-tonner with a Sierra and Supercaps with the relay cut-out. I was running fairly slowly and noted smoke coming from the engine. I immediately turned it off.

Today I opened it up and could see no shorts. I disconnected the Sierra and started it up and it ran fine on the stand. I connected the Sierra and it was the source of the smoke on the board. (Sheet!) Looks like possibly a voltage regulator, and now the input reads 2.5 ohms.

I had run this engine like this many times in the past without problem. After I opened it, I noted that the negative battery wire to the relay had come off the relay, but don't know if this happened en-route or on the work bench, probably the latter.

Ther are other possible culprets including the lighting voltage regulator which is not being used, but could have fallen onto the board as it was unsecured, tangled in wires, and sitting right above the Sierra board.

And, it could have been due to running too slow where the cap continually charges/discharges to near nothing making the board run hot over time. As I said, until there is some charge on the cap, the Sierra sees it as a momentary short. But the boards are fairly robust and seem to handle this on a usual basis.

This is the only one I've had fail and I've done several. If one wanted to take care of this possiblilty, you can put a 1 or 2 ohm resistor is series with the supercaps. Then the board will never see the temporary "short circuit." It will take a moment longer before the sound becomes fully active because you are now charging the caps through a resistor.
 

·
Premium Member
Joined
·
1,973 Posts
Stan, I know exactly what you mean about 'leaving memory'. to quote Al Bundy, "brain can only hold so much, when something goes in, something has to come out".
toddlin, smoke is never a good sign. Will make a note of adding the resistor, thank you for sharing. I found the exact relays you recommended. There are no contact markings. Didn't want to ASSUME anything, and tossing and turning wasn't solving it. Using what I have found on other DPDT devices confirmed the connections. Tired old eyes were strained, but I am now secure in the connections and go back to bed. Good Night All
 

Attachments

·
Premium Member
Joined
·
4,042 Posts
For DCC operations with the supercaps I use a resistor for charging the caps and a diode for the discharge. This limits the inrush current esp when you start up the command station with many engines on the track!! Should work for DC operations also.
 

·
Premium Member
Joined
·
1,973 Posts
TODDALIN, (darn spell check). I have received the relays from two different places. Exact same Aromat part number. Seems to have been at least two runs of them. The one in the upper pics has 8 connection pins, 2 for winding and the other 6 for the relay contacts. Ones I received yesterday have 10 connector pins. Data sheet shows 2 for winding and 6 for relay, the last two on the opposite end from the relay have no internal connection. Just to make life more interesting. But will still do the test as above just to be sure.
EDIT: just ordered the 1 ohm resistors for the safety factor.
 

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #31 ·
Once I've determined the "pert near" value using the pot on the relay, I replace it with a fixed resistor. Seems to be less variable.
 

·
Premium Member
Joined
·
1,973 Posts
TODDALIN, this may sound stupid, changing the resistance of the pot, what exactly am I adjusting? And how would I know I found the sweet spot? Thank You
EDIT: Found a posting of yours from 2015, Sputter-Instant Recovery , answered my questions. Thank You Again.
 

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #33 ·
Also, the capacitance (10 mfd shown) of the small cap may be a bit different (but maybe not as you are using the same relays). You want to keep the value low, but if it is too low the relay will go into "chatter."

What is happening is that when the relay begins to trigger, it lifts its contact and this stops the current from flowing to the relay so it goes back into its "relaxed" state where it again picks up power and begins to trigger and lifts its contact...

With the 10 mfd capacitor in place, the capacitor charges instantly as the relay is triggered and when the relay lifts its contact, the capacitor provides the necessary current to complete the "cycle" so that the relay armature actually reaches its other contact where it will stay.
 

·
Premium Member
Joined
·
1,973 Posts
toddalin, (it worked this time). In my attempt to make the circuit look as professional and neat as possible I am building it on a real circuit board with solder holes. First I put the super caps together to make sure I had them right, and they are. All wired up, and NOT. The sound board acted as though the caps weren't even there. I suspected the relay wasn't operating, so I trouble shot backward from there. I found I soldered the wire one hole off on the board, for the relay contact, so the circuit was always OPEN. Old eyes, bright light, many shiny spots on the board all added up. As soon as I joined the two contact areas I could hear the board clicking so I knew I was on the right track. Ran it for a few minutes to allow everything to charge up, turned it off for about an hour and it came right back as though it had a battery. SO I wanted to be slick, make a video of it after being idle with a meter across the caps. NOT, the meter took enough away from the circuit so the caps were now below the lowest amount for the board to start up again. Took the meter back off, charged the circuit again, it functions perfectly. THANK YOU VERY MUCH. Now lets see if I can make a few more.
 

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #35 ·
I just use "dead bug" architecture. Glad it is working for you.
 

·
Premium Member
Joined
·
1,973 Posts
toddalin: had to look up 'dead bug' architecture. It is exactly as the name says, components mounted like on pins, Think I have an issue with the pot, more later. Still havin' fun.
 

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #38 ·
Let's ask Greg, and anyone else who may be able to provide an answer.

If a Sierra Soundtraxx sound board is run continually with its charging circuit running into an open load (infinite resistance), can this burn out it's voltage regulator or other parts?

I've run several Sierras on the supercaps without problem. Some have a relay cutout but I typically run them above the minimal voltage so they "see" the caps.

Recently one burned out what appears to be a voltage regulator. With the engine open, I can still watch it smoke, but there is very little bit of magic smoke left in it to release.

The train was running slow, testing the track, so the Sierra was primarily seeing an open circuit. Of course a dead Sierra battery also produces an open circuit as I've confirmed on an old battery.

So, theoretically, can running the charging circuit into an open load over time harm the board?
 

·
Registered
Joined
·
3,478 Posts
Discussion Starter · #39 ·
After further thought, the Sierra never does try to charge an "open circuit" because it always sees at least 450 ohms for the relay coil, even when the caps kick out.

61933
 

·
Premium Member
Joined
·
1,973 Posts
toddalin, I seem be experiencing a problem when my track voltage is below 10. The sound system seems to revert back to stuttering or just suddenly stops. I am adjusting the pot to see if that has anything to do with it. Any suggestions?? thank you
 
21 - 40 of 62 Posts
Top