Although we have plans to come out with custom boards for supporting higher motor currents and other features/functions relevant for larger scales in the future, for those wishing to use LocoFi™ today to run their trains requiring higher motor currents, we are providing schematics for modifications required for LocoFi™ 1st Gen (DDLLHA) and LocoFi™ 3 (DULLHB) that can be used to interface with any external H-bridge (widely available from several third party manufacturers) that takes 3.3V compatible inputs of PWM (pulse width modulation) and DIR (direction). We are using MD13S (shoutout to our customer Sam Walkup for doing the research) as an example in the wiring diagrams below.
Note: Please do not confuse the grey and yellow wire colors shown above being used to interface the external H-bridge with the motor out- grey and rear light yellow.
Update: 08/31/24
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There are 3 options available:
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DIY. If you’re comfortable, the above modifications can be performed DIY. It is recommended to use a microscope and a soldering iron with a fine tip and good temperature control to perform these modifications. NOTE: Doing itDIY will void the warranty!
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Large Scale Modification Package 1 for LocoFi™ 3. We expose the PWM and DIR for you that can be interfaced to an external H-bridge of your choice. You will purchase your own H-bridge and bridge rectifier (if needed) and solder up the connections as per the schematic. “FULL” warranty included. Order it directly here: Large Scale Modification Package 1 for LocoFi™ 3. Note: This is not being offered for DDLLHA anymore.
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Large Scale Modification Plug’n’Play Package for LocoFi™ 3. We not only expose the PWM and DIR outputs but rather solder up connections to a MD13S (included), 15A bridge rectifier and 4700uF 50V electrolytic capacitor filter circuit (included for track powered) and replace the stock speaker with a bigger 40mm round speaker (with baffle) for bigger sound. Now, it’s just plug and play. “FULL” warranty included. Order it directly here: Large Scale Modification Plug’n’Play Package for LocoFi™ 3. Note: This is not being offered for DDLLHA anymore.
For those requiring modifications to their current modules, please contact us.
Other notes: For modifications performed by us for Large Scale Modification Package 1, the PWM is yellow and DIR is white. They will be grouped together with blue for GND. Please check the “Notes” section of the invoice. Again, please do not confuse this separate group of white, yellow and blue with the lights. You will notice that this group of wires can be traced back coming from the onboard metallic ESP82xx WiFi chip. With DIY or Large Scale Modification Package 1, we do not provide external components like the H-bridge module, bridge rectifiers, resistors, capacitors, voltage regulator, etc. and are not included as part of the modifications. The bridge rectifier current rating should be equal to or higher than the H-bridge current rating. The H-bridge current rating in turn should be equal to or higher than the motor stall current rating. H-bridges supporting high currents may require heat sinks. Also note that if you’re going to use MD13S, it comes with a harness that is colored white for DIR and yellow for PWM which is opposite to our color coding convention.
For the Large Scale Modification Plug’n’Play Package, the addition of bridge rectifier will bump up the minimum operating voltage by about 1-2V.
Below, we also provide a schematic for locomotives requiring not only high motor currents but operating on AC power. The wiring diagram is for DULLHB but a similar modification for DDLLHA as seen in the wiring diagram using DC power above can be performed.
Questions? Drop us a note.
This post was inspired by the following thread: Interfacing LocoFi™ to H-bridge
Picture of a COMPLETED Large Scale Modification Plug’n’Play Package.
Optionally (for track power):
Large scale modification may require brighter lights. For many cases, using a 5mm bright LED should work just fine. However, for super bright lights, you can use something like 1W (8mm) LEDs. Since LocoFi™ modules “out of the box” cannot supply this higher current requirement, you can use the following schematic as an example to amplify and light up the higher wattage LEDs.
If ordering the Large Scale Plug’n’Play Package, you can add on the brighter front and rear lights for an additional $25. Each light will have one 1W 8mm LED by default and will come with all required additional components (like buck converter, resistors, transistors, etc.) wired up so that you don’t have to do anything but install the LEDs in their sockets. Additional LEDs at $5 per LED.
As demoed at the Great Train Show Pleasanton 2023. The bridge rectifier and the electrolytic capacitor at the beginning is to support even AC. Note the louder, deeper sound from the speaker. Not to mention support for 13A for the motor(s). Demo of diesel sounds.
Here’s a demo of steam sounds in large scale.
