Large Scale Central

Smoke Units 18 - 24 Volts - How to Increase Voltage

Electronics
#1

Very old LGB locomotives use 18 volt lights and smokers 18 - 24 volts…they lack the circuitry and voltage stabilization for using 5 volts lights and the smokers. What device could I install into these older LGB locomotives to allow use of 5 volts devices? I thought perhaps installing the Massoth Power Caps to provide continuous 18 volts input to these 18 volts lights or smokers but I don’t think they would work without being connected to a DCC decoder. I feel it’s a waste of money for me to replace defective 18 volt smokers in these older LGB locomotives since they don’t produce any meaningful smoke unless the locomotive is going “90 miles an hour” around the track!

Any suggestions from the electronics engineers on this forum would be appreciated.

Thanks

#2

EDIT: I just re-read your post. Even though you say Increase Voltage I think what you really want is to run 5V devices from track voltage up to 24 volts. If I got that right, then…

Search Amazon, or your favorite electronics seller for DC-DC Buck Converters. They are dirt cheap, so you will find them in multiple unit packs under $20. They will step down DC voltages voltage above 3.2V. They work good with a constant input voltage, not sure how they would perform with a variable input voltage like track power.

This snipped from a description

  • Input voltage range: DC 3.2V to 35V (input voltage must be higher than the voltage output to 1.5V or more can not be boosted.)
  • Output: 1.25V to 30V DC voltage is continuously adjustable,

Also found this in the Questions & Answers that makes me think if you set it with a constant voltage, say 15 volts in, the output will stay stay stable at 5V so long as the input is above 6.5V.

Will v-out stay stable w/ a changing v-in? for instance 14v in and set for 3 v out but over time input (battery) drops to 11v.

Yes. The output voltage is almost completely independent of supply voltage as long as input remains at least 1.5V above the output.

#3

Tom - Look up LM315 voltage control circuits. They will take any input voltage and limit them to what ever output you want to stop at. I use one in my K27 to control track voltage after converting to use an AirWire ESC.

#4

In accordance with your original premiss, YES you can increase the voltage to your lights and smokers far cheaper than changing everyting out to 5 volts and putting in a 5 volt regulator. All you need is a DC-DC step-up power booster.

The link takes you to one that can handle 2 amps (should be sufficient), but Banggoods has other amperages available.

https://usa.banggood.com/1pcs-MT3608-2A-DC-DC-Adjustable-Step-Up-Power-Module-Booster-Power-Module-p-1213134.html?cur_warehouse=CN&rmmds=search

#5

Bob - That’s what the DC-DC buck is based on. You can buy the complete circuit for less than the LM315 alone, or so I’m told.

#6

The suggestion of the LM315 allows the same components (mostly) to cover almost any output voltage with only small value changes to a couple components. Bucks are, as you stated usually fixed in/fixed out. The LM will tolerate a wide variety of input voltages and still clip the output to what you need. Here is a link to the schematic I developed for the K27. The LM circuit is in the lower left of the drawing. One LM, one fixed resistor and one variable resistor. Set the output voltage with a digital meter and you are fixed to go. http://www.gscalejunkie.com/GeneralPics/K27Mods/K27_Wiring_Diagram_R2.pdf

Here is a link to the build thread for your reading pleasure: https://www.largescalecentral.com/forums/topic/22079/major-k27-overhaul

#7

Most of the Buck converters I’ve seen, and all the ones I have purchased are variable input with a wire wound pot to set the output. So, fixed values - No.

If you have access to IC’s at a reasonable price without minimums and don’t mind building up the circuit, then by all means go for it. Personally I’d rather just solder 4 wires and be done.

#8

My question is what do they do before they reach the minimum operating voltage? Do you get some lessor voltage, or are they essentually dead up to that point like a typical voltage regulator?

#9

I’ve been buying tiny adjustable regulator boards off eBay for $11 a pair and getting my suethe smoke units for $17 each wholesale. I buy 4+5volt units and run them at 5.5-6.8 volts and my engines are smoking wonderfully. A huge difference with my bachmann climaxs and shay. I run analog DC so this has been a perfect fix.

#10

Couldn’t you use an LM780x to regulate the voltage to whatever voltage that you want? It is a lot smaller than a boost buck.

I am using an LM7809 to run my 5v LGB smoke unit hot for DCC controlled effects but it is connected to constant DCC voltage. Not sure what would happen if connected to a variable voltage. I would guess it would be fine in that the voltages lower than the Regulator’s max voltage would be variable right up until it reached max regulated voltage. So in the case of an LM7809, voltages 0-9 would work like normal but anything higher than 9v would be seen as 9v. Hopefully someone smarter on this stuff can answer this question.

Will need to screw it into the lead weight for a heatsink if using it for smoke.

#11

Folks - I just tried a test on a MT-3608-2A Step Up Power Booster on a 19 v. light bulb and worked great. When I applied about 5 v. the light bulb was bright getting 19 - 20 volts. The problem is when I applied reverse polarity input to the device, it started to smoke. So, what’s needed to handle the reverse polarity condition when a DC locomotive operates in the reverse direction?

I’ve also found some cheap adjustable regulators on eBay I’ve tired in the past also operate only with one direction polarity. The Massoth 6 v. regulators, much more expensive, operate with both polarity inputs.