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Super Modulator
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Let me post the schematic for battery operation from Sierra, this might help avoid confusion, or at least give the starting point. Adding the diode, I agree with Todd's assessment and idea of protection.



Todd and many others who have installed these are correct about the alternate pins for the battery plug in the connection and why you would use them. Many of these connectors get broken, use it as you please, you have a backup that is more reliable and robust.

Greg
 

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Discussion Starter · #82 ·
Will be anxious to see the results. (y)

BTW, I revised the schematic. I think I had the diodes in backwards. Wouldn't have hurt anything, just wouldn't have worked.

Greg, you were supposed to catch that. :geek:

 

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toddalin: if you are reasonable sure of the above, I will order parts and join in on the fun. And looking at the schematic from Sierra my suspicions were confirmed, I was 'seeing' something, just didn't know what.
 

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Discussion Starter · #84 ·
I'm good with it. Lets see if Greg will "buy off."

At the price for the BB modules through Bangoods, it pays to get 3 or 5 for the price difference. As versatile as they are, I'm sure you could find some use for them.
 

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toddalin: I already have a use for them. The A-1-A shark I built I used diodes to drop the voltage to the motors so the fans and lights would come on before it moved. This seriously limited the top end. Would like to remove them, add the boosters for the lighting and fans, then add the limiter so not to over rev or burn the LED's. That will allow the loco to start at a lower track voltage and reach a more scale speed as it is somewhat limited at this time.
 

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toddalin: did some testing of the boosters I wrote to you about. All tests done at the setting on the unit as received. I added a lamp and voltage limiter at the end which also acted as a load for the booster.
Track Voltage-----Booster Out
4.0----- 5.8
6.0----- 9.1
10.0---- 13.0
12.0---- 13.1
15.0---- 15.2
20.0---- 20.0
At this setting the unit seems to level out at about 15V, which I don't see a problem with. I took video's of the tests showing each meter, but doubt anyone is that interested. As a last note, the limiter held at 3.0 - 3.1, but need more testing before I convert the Shark.
EDIT: adjustments: found if you adjusted for more boost at a certain threshold the unit starts fluctuating short circuits, adjusting for less boost can bring the threshold higher before it starts fluctuating, it also levels out sooner.
 

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OK, confused again... what is the goal here? I thought the issue was to try to basically get the sound system to run all the time and eliminate the battery?

Would you mind explaining what we are trying to do?

Normally the units I was talking about have a set output... the post above seems to not have the voltage limited, and makes no sense in terms of eliminating the backup battery and lowering the voltage that the sound can continue with.

Confused... please clarify...

Greg
 

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Discussion Starter · #89 ·
One wants to be able to run the engine at a much slower speed than the ~12 volts now necessary to keep the Sierra system operational and provide a reserve for the power down/idle sequence sounds after track voltage is removed.

My thought is that that buck/boost should maintain 7-8 volts running from track power with track voltage ranging from ~5.5 volts to max throttle and the cap provides a reserve when the power is cut. This is apparently what the Phoenix Big Boost does except that it allows down to ~3 volts input from the rails to operate so is more "sensitive" on the "bottom end."

If we can get the Sierra to operate and the cap to charge down to <6 volts on the rails (rather than the ~12 volts now required) which is pretty slow, I think we've achieved to goal.

But based on the data, if 6 volts input is only getting 9.1 volts output, that's not going to get us there and we are probably looking at ~9 volts to get the system running/charging falling short of the goal.

Also, as the voltage goes above this ~9 volts input, we need it to stay at 7-8 volts so it doesn't burn out the board. Perhaps there are settings on the buck/boost that Nick needs to explore to get to where we need to be.
 

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So what you are using is not a regulated output boost inverter, but some kind of boost circuit with an unregulated output?

Seems that is adding problems, not removing them... then your supercaps will have to have overvoltage protection, I would think... and that will probably eat into the margin you are working so hard to maintain.

Greg
 

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Discussion Starter · #91 ·
So what you are using is not a regulated output boost inverter, but some kind of boost circuit with an unregulated output?

Seems that is adding problems, not removing them... then your supercaps will have to have overvoltage protection, I would think... and that will probably eat into the margin you are working so hard to maintain.

Greg
Right, the voltage to the Supercaps cannot exceed 8 volts. I figured that if the BB module was set to produce 8 volts, ~0.7 volt is lost though the diode and the cap should be safe.

At 7 volts, the caps see about 6.3 volts and that should be plenty to run the Sierra reliably as the battery had a 6 volt rating.
 

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Prayers not necessary, and I gave all that info to toddalin yesterday, and you over looked #85 & #86 posts mentioning the LIMITERS. Allelectronics, call it Step Up Voltage Converter, part #UDC-2. They also offer a UDC-3, but that one started at a higher voltage.
First let me say I don't have the thoreitical knowledge to deslgn a circuit, just the practical experience and training (telecommunications) to see what happens in a simple operating circuit. 5V to track, B1 is going to cost at least 1V, train barely moving if at all, the booster is receiving 4V and putting out close to 6. I suggest removing R1 and the first diode (and possibly the second) as the limiter will act as the load and protection. The sound is starting and the caps are charging. As the track voltage increases the booster levels out (out put is equal to input) at about 14 and then stays same as the track voltage, I tested to 24V to make sure it would be strong enough to with stand full track power. To limit the voltage install a limiter after the booster, like I am doing for the LEDs and fans on the Shark. My limiter for that application is set for 3, for this battery circuit set the limit to 7 or 8. as the latest print shows. Since there are the same number of Supercaps as on the other, if the track v drops to 0 they will feed the sound board for about 60 seconds before depleting but if the track voltage is held at 4 the system will still see 6 and keep the sound board going. I tried to cover the whole process. If anyone has a different board in mind please say so.
As I said previously, have the videos showing the meter readings at the different points I described. Think I have enough left over parts from other projects to assemble something later today. Hope to post something showing forward progress, or disappointment.
EDIT: Guess I should have posted the video, show it better than I could say in words.
 

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Discussion Starter · #94 ·
So you are doing a boost/buck, but using two boards rather than a single combined board.

As long as it works and you have the space, it should really be no different and maybe better as you have a wider selection of boost boards available, some of which will use a lower voltage, as you found.
 

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toddalin: I'm not crazy about devices all rolled into one. Example: stereo system, amp, turn table, tuner, CD player all in one enclosure, one feature goes the whole item has to be replaced, not designed to be fixed. Also in this case gives me access to the power coming out of the booster for other uses. And you are right, this booster had the lowest starting voltage I could easily get. The diesel locomotives I have are from the end of the steam era so there is more than enough room inside for anything. Frankly I am diesel stupid, can't tell the newer ones apart. Yesterday was such a nice day I spent outside, today rain is predicted so hope to get some more testing done. I'll keep you posted.
 

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toddalin: some encouraging progress: Referring to your print: took my voltage readings after B1, so 1.25V less than track power. I used a diode between the limiter and + side of the supercars, possible protection for the limiter, which is now set to 7.5. Advanced the super caps directly to the actual battery input leads which are before the on/off switch and charging jack. The caps started to charge and the sound system stuttered at 4.5V (after B1), left it alone to allow the booster power to climb, which it did to over 9V. I let it run for couple of minutes. I slowly lowered the feed voltage till it got to 4, and the limiter was still reading 5.9 and the sound system was still functioning. Thinking of removing the one diode, but want to see what it is costing the circuit before doing so, if only .5 going to keep it in. The locomotive wheels started to turn at about 4V of track power, so if I wanted to I could install diodes in line with the motors to keep the loco still till the track voltage climbs, like it did with the Shark. With the booster on the sound system I would only need a couple and the loco will still reach close to scale speed. Your thoughts please??
 

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Discussion Starter · #97 ·
Sounds like you've found a viable solution. When you are sure that everything is working and no smoke is released, you should do up an article. There is no reason that you shouldn't be credited with this and there certainly are a lot of Sierra boards that could use it.

When complete, this would be great for the GR Newsletter, but you would first need to submit the article though a Club. If you don't belong to a Club, we could work it out. For example, I could put it in our newsletter under your name and it could go in that way.
 

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toddalin: have you received your boards from Bangoods and started your testing yet?? Been just too nice outside to play inside last few days. Next time at the bench intend to replace the limiter with one that doesn't have a V meter and make the installation permanent. Will also add a couple of diodes to lower the power to the trucks.
 

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Discussion Starter · #100 ·
I had not ordered the boards. I have two of the original Phoenix Big Boost Boost/Buck limiters that I will eventually try when time allows.
 
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