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Yard Master & Research
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Reverse units are cheep enough and repairable. Whoever has done it to date has failed on producing a good circuit diagram. I have not searched recently so who knows? They are less expensive than mechanical ones.
 

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Discussion Starter #6
I need one of those for my mth proto sound units. They leak and die.
No schematic bit there are alot of electrical wizards here. I could buy one but i have time on my hands.
 

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You can buy one for a few bucks. Here's a sample. Approximately $2.25 shipped via the "slow boat from China. About the same size as a C-cell. And with the trim pot you can adjust the voltage up or down to manage the horn volume (Beware: high over voltage could burn out the horn).

GRJ has other, smaller units that use different technology (buck regulator instead of linear regulator). I'm finding the linear regulator behaves better under varying voltage conditions especially with it's large capacitor. And the trim pot is more robust, reliable.

542093
 

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I have been thinking I have a 2023 that needs reverse,. maybe I should try electronic and replace it down the road.
I took some time to investigate this. I could not duplicate the mechanical E-unit with some simple circuits and/or off-the shelf modules. You need some type of logic that remembers the last direction state after power down. And that becomes unwieldy unless you have a PCB manufactured. That's the beauty of the mechanical e-units, They mechanically remember the last direction state.

Another idea is to use the existing e-unit to drive a relay for the motors windings/brushes. That would offload the full amp draw of the motor from the e-unit fingers thus greatly extending their life. But that requires a rectifier/regulator module for the relay coil and multiple relays if you want neutral.

I also investigated a wireless remote control relay module. But it wouldn't be idiot proof. You could push the remote fobs's reverse button while the train was running at a hefty speed.- like throwing a car into reverse doing 50 mph. And you'd need to power down where the train is not moving but some voltage is still on the track to power the receiver's associated rectifier/regulator module. Not an ideal solution.
 

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And that becomes unwieldy unless you have a PCB manufactured.
Actually, if you're building them yourself, getting a few PCB's made is the easy part. I've lost count of all the unique boards I've had made, and they're quite cheap and easy to do.

That's the beauty of the mechanical e-units, They mechanically remember the last direction state.
The electronic reverse boards, at least the vast majority of them, only remember the last state for a few seconds, easy to do with cheap parts. Truthfully, one of the problems with mechanical E-Units is they remember the last direction state! :D

It would be very cheap to actually use a fifty cent PIC processor and do a reverse unit with frills, directional lighting, MARS light, and automatic ditch lights. No rocket science here, but there's really no significant demand for such a product. If I thought a few hundred of them would sell, I'd cook one up.
 

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Discussion Starter #11
John, not rocket science, computer science, right? You have to program the PIC. Publish the schematic and we will buy the PIC from you, $10 or so. A few hundred might sell if the total cost was low and the physical size was small. Do it for America John.
 

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Actually, if you're building them yourself, getting a few PCB's made is the easy part. I've lost count of all the unique boards I've had made, and they're quite cheap and easy to do.

The electronic reverse boards, at least the vast majority of them, only remember the last state for a few seconds, easy to do with cheap parts. Truthfully, one of the problems with mechanical E-Units is they remember the last direction state! :D

It would be very cheap to actually use a fifty cent PIC processor and do a reverse unit with frills, directional lighting, MARS light, and automatic ditch lights. No rocket science here, but there's really no significant demand for such a product. If I thought a few hundred of them would sell, I'd cook one up.
I think the focus here is a replacement for pre/postwar e-units. The amount of replication of the original functionality is open (e.g., neutral, last state). Do you mimic the antique functionality or update to a modern operating scenario. A "Pleasing all the people all the time" conundrum.

What S/W are you using for designing PCBs? I had a S/W package but got turned off as it only had SMT devices defined and I had to define all the "older" parts I wanted to use - too much like work to be fun.
 

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I remember that one, I actually saved it when Paul posted it. He did a very professional job of reverse engineering the unit. It's the basic DC motor reverse board, so for PW AC motors, it would have to be different. However, it does illustrate many of the techniques you'd use for any discrete component reverse board.

I think the focus here is a replacement for pre/postwar e-units. The amount of replication of the original functionality is open (e.g., neutral, last state). Do you mimic the antique functionality or update to a modern operating scenario. A "Pleasing all the people all the time" conundrum
Very true. My approach for something like this would likely be two DPST relays and a PIC processor. That way I could easily mimic either functionality in software, so there's be a common hardware platform. I'd also probably use a thru-hole part like I did on the Super-Chuffer. That was done so I could simply replace the processor to upgrade the software, important in a board that someone has already soldered a bunch of wires to in their locomotive. ;)

What S/W are you using for designing PCBs? I had a S/W package but got turned off as it only had SMT devices defined and I had to define all the "older" parts I wanted to use - too much like work to be fun.
I'm using DIPTRACE, it has lots of models of thru-hole and SMT parts, but you do end up frequently making some parts. There is also a very active user community that is making libraries of parts. I end up making about 5-10% of the parts I need for most projects. One bonus of DipTrace is the parts creation process is easier than many packages. I tried Eagle PCB, and their parts generation process was a PITA, so I moved on.
 

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Discussion Starter #15
So john, remember the Peugeot and net being able to get parts, well it relates to your DPST. Most 70's diesel cars had a device to shut off the fuel. It was a motor with a worm gear and a dual pole switch with cross over wiring. Function would be forward and reverse no neutral but it was super simple. DC of course.
 

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There are plenty of AC compatible reverse boards as well, my comment was just on the one that was nicely reverse-engineered, that was a DC reverse board.

So john, remember the Peugeot and net being able to get parts, well it relates to your DPST.
I don't get the reference at all! You're equating a DPST relay to a Peugeot? I won't be buying French relays, I'll buy the ones made right here in the good ol' USA! :p:p

If you're saying I suddenly can't get a relay if one fails on this board design, think about the ten's of thousands of products that we use every day with custom electronic circuits. The comment applies to all of them! If you prefer to go back to the stone age and use flint knives and stone axes, that's fine. However, I live in today's real world. ;)
 
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