# LGB 2020 Stainz Locomotive: Trouble Installing Bridge Diode Rectifier/Adjustable Step-Up DC Switch Boost Converter Power Supply Module



## LGB333$$$$ (Oct 11, 2017)

Hello Electrical Experts! I used a 2A 1000V 2W10 Bridge Diode Rectifier input to an Adjustable Step-Up Switching Booter Converted Power Supply Module 2 -24v to 5v-28v 2A (picture below) to install a Massoth LED Spot Light powered at 22 volts into an LGB 2055 White Pass Alco Diesel.......worked great. Today I used another one of these devices to power a new 18v smoke unit I installed into an older LGB 2020 Stainz locomotive and set the output to 20 volts. I also used a second module to power the Stainz' 18v headlight and taillight. I soldered two sets of output wires to the Stainz motor block's track power output, one set to power the smoker, the set to power the lights. When I tested the Stainz on my DC roller wheels test track, it operates fine from 0 to 5 volts, then between 5 volts - 8 volts, the lights flicker badly and the smoker pulsates smoke. Over 8 volts, the problem stops and everything works fine.....motor, lights, smoker. Why do I get the flickering lights and smoking........what do I need to do to solve this operating issue.......add another electronic device? I tried to attach a short video of the Stainz operating with this condition but wasn't successful.


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## Greg Elmassian (Jan 3, 2008)

Hah!

Let me ask, is the power input DCC?

This might be a ah-hah for you.

Greg


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## LGB333$$$$ (Oct 11, 2017)

Greg - No, the input power is DC.


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## LGB333$$$$ (Oct 11, 2017)

I tested the Stainz again (DC Analog Power!) on my test stand and the pulsing/flickering of the lights and smoker occur between 5 - 6.2 volts.....outside of that range, it works well.......see the photo below. I'm wondering if I have the adjustable power supply module turned up too high. I set the adjustment for 20 volts at around 5 volts input so the lights and smoker would work well with the Stainz operating at low speed. I'm going to disassemble the Stainz (ugh) again to get access to the two booster modules I placed inside the boiler.


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## krs (Feb 29, 2008)

What exactly are you using as a "DC" power supply?
Do you have a scope to see if DC is actual "pure" DC or if the supply provides pulsed DC at low voltages to improve slow speed running.
Compared to your previous use of these devices you are now drawing a lot more current with the smoke unit.
What happens if you disconnect the smoke unit but leave the lights connected? Do You still get the flickering?


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## Greg Elmassian (Jan 3, 2008)

You are using a "step up" DC to DC converter, and you expect it to run from 0 volts on up?

Please realize there is an integrated circuit and other elements (oscillators) that need a minimum voltage to operate.

What is the minimum voltage specification on the converter?


I'm figuring at very low voltages, the converter just passes DC through...
Then when you raise the track voltage until there is *almost* enough voltage to TRY to run the IC, and now you have erratic operation as the circuit tries to run... 
then once you give it more voltage that puts the converter in it's operating range, it works.
I first saw something similar in the lights in an aristo, the lights flashed weirdly. Turns out the aristo had a voltage regulator driven from the motor output... not terrible, but the voltage regulator was a PIC processor, and under low voltage, the processor tried to run, then reset, then tried to run... blinky blinky...


Think about your laptop, could you vary the input voltage to make it run slower? Think why you cannot do that. Integrated circuits need a minimum voltage to operate. They are not analog. Neither is your converter.

Greg


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## LGB333$$$$ (Oct 11, 2017)

Greg - My posting #1 has a photo of the boost converter I'm using. It's specs are below. After chatting with Knut I've ordered a different boost converter with higher capacity specs and will try it. The existing boost converter causes the lights and smoker flickering with just the smoker or just the lights, or both operated together.

*Product description*
*Specifications:*
Input voltage: 2V - 24V
Output voltage: 5V - 28V
Output current: max. 2A
Efficiency: > 93%
Size: 36 mm x 17 mm x 6.5 mm
Pin Definition: Input to IN-IN + / Output to OUT-OUT +

*Warning:*
1.Do not reverse the positive and negative poles to avoid any possible damage.
2.This module is only for raising the voltage; Input voltage should not be over than 24V to avoid any possible damage
3.Please make sure output voltage is stable before using the module to avoid any possible damage
4.Do not use without load or light load (less than 10% of output power) or connect too much things on one module
5.Do not connect too much load on the output voltage
6. Please use the heat sink when working for long hours.


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## Greg Elmassian (Jan 3, 2008)

So the first concern is "this module is only for raising the voltage".

What do you have the output voltage set to, and is it ALWAYS higher than the input? 

In addition, you can deduce that the minimum difference between the input and the output is 3 to 4 volts. Is this ALWAYS true in your installation?

I think you will get my "drift" here, you should not try to use this with a variable input DC that sometimes has the input higher than the output.

I think you need a converter that is a "boost-buck" converter... not boost only.

Greg


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## LGB333$$$$ (Oct 11, 2017)

Greg - I've ordered some of the modules with the higher specs but won't be delivered until April. I'm working on an old LGB 2020 Stainz made 40 years ago that has no factory circuit board. It operates off DC track power using 18 volt screw bulb headlight and tail light and the old type 18 volts smoke unit with the metal shaft......smoker gets its track power from a copper contact on the metal shaft and the other contact on the bottom of the metal shaft. I'm wondering if the metal shaft might be causing some of this flickering issue. As you may know, without any 5 volt regulator like the newer LGB locomotives have, these old Stainz must get up to a very fast speed before enough voltage gets the lights bright and the smoker to work at all. So, my objective is to install an adjustable boost converter to the the lights and smoker to operate well at the normal slower operating speed, around 5 - 7 volts track power. So I had set the converter output to 20 volts. But when operating the Stainz at about 5 - 6 volts track power, the converter would cause the flickering effect. So, your guidance that the output voltage should always exceed the input voltage was achieved but the problem still occurs.


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## Greg Elmassian (Jan 3, 2008)

Well, seems that the converter is not living up to its specifications.

You would think that from 2 volts up it should work, and the input voltage range is above that minimum voltage.

The only other item I can think of is perhaps you have a DC supply that is putting out pulses that interfere with the converter.

Do you have a "pure" DC supply that can be varied, like a lab power supply?

Alternatively, what is your DC supply, and what specifically it the throttle if separate?

Greg


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## LGB333$$$$ (Oct 11, 2017)

Greg Elmassian said:


> Well, seems that the converter is not living up to its specifications.
> 
> You would think that from 2 volts up it should work, and the input voltage range is above that minimum voltage.
> 
> ...


Greg - I use an LGB 50111 AC 5 Amps Power Supply with an LGB 50179 5 Amps DC Throttle. 

I've removed the LGB Stainz project from my workbench until I receive the higher capacity boost converters sometime in April. I'll then see if that resolves my issue. I've got seven other customers' LGB locomotives in queue for repair or DCC sound installations, so it's time to more on from this Stainz challenge for now!

Thanks for your technical advice.


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## Greg Elmassian (Jan 3, 2008)

No problem, am interesting, so pop this back up when you get the new converter.... something is not making complete sense here yet.

The LGB throttle is PWM isn't it?

Get a lab power supply sometime, that has well filtered variable DC.

There's bunch of models, you can often find them used inexpensively.








HP HEWLETT PACKARD 6205B DUAL DC POWER SUPPLY | eBay


This item is in used condition and shows wear from use.



www.ebay.com





Greg


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## LGB333$$$$ (Oct 11, 2017)

LGB333$$$$ said:


> Greg - I use an LGB 50111 AC 5 Amps Power Supply with an LGB 50179 5 Amps DC Throttle.
> 
> I've removed the LGB Stainz project from my workbench until I receive the higher capacity boost converters sometime in April. I'll then see if that resolves my issue. I've got seven other customers' LGB locomotives in queue for repair or DCC sound installations, so it's time to more on from this Stainz challenge for now!
> 
> Thanks for your technical advice.


Okay, I just receive a boost and buck converter and the 18 volts smoker works well at low speed @5 volts track power which is converted to an output of 18 volts to the smoker ! See the photo of the boost-buck converter below. I decided to only connect the smoker to it and changed out the 18 volts lights and replaced them with LED lights connected to the motor's output. So when the Stainz moves in forward positiion, the headlight LED activates, and when the Stainz moves in reverse, the headlight goes out and the rear light activates.......did this by switching the rear light's wires to only work in reverse direction. I'm glad the boost-buck converter approach was suggested! I tried to attach a short video of the Stainz operating on my test stand but I couldn't figure out how to do it.


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## Greg Elmassian (Jan 3, 2008)

Great... thing to remember when you use these, they are not isolated... be careful of situation where you need isolation (often old sound cards)

Congrats!

Greg


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## LGB333$$$$ (Oct 11, 2017)

Question for Greg or Knut - All these modules specifications indicate they are for DC use but a hobbyist friend of mine has also used a DC Buck module to reduce his the DCC voltage for his train car lights on his DCC layout. I tried DCC on one of the DC Boost modules and it worked. Is it okay to use the DCC current on the DC boost, or DC buck, or combined DC Boost & Buck Power Supply Modules?


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## Greg Elmassian (Jan 3, 2008)

so DCC is square wave AC... so if it worked, clearly the module had a full wave bridge on the input... surprise... maybe be designed to keep it from being blown up by reversed connections.

So, you lucked out, it is clearly NOT a standard in a boost/buck regulator...

Greg


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## xmas111 (Feb 6, 2021)

Hi Everyone,

I've been using the same DC-DC Buck converters as Tom mentioned above. I did install a Full Wave Bridge rectifier on each of the converters and they work fine with DCC power.

As Greg said, DCC is a AC square wave and the full wave rectifier converts it to DC. If you look at the schematic of a DCC decoder you'll find most of them have a Full wave bridge in them too.

Here's a quick video of the cars I added LED's and incandescence lamps in using the DC-DC Buck converters with DCC track power.

John


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