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I have been working on a few electronic projects in my new found spare time and have designed a nifty little circuit to "kick" the E unit with DC instead of AC.  Since it is the AC on the e unit's coil that causes some Lionel operators to gnash their teeth(and some don't mind the nostalgic noise) the solution is to kick the e unit with DC.  Ahhh, but you say the DC will overheat the coil and magnetize it.  My solution solves both of these quirks. The motor still runs on the track AC voltage.  

 

First, I built a 1 second 555 timer circuit and the pin#3 output is used to energize a little DPDT 5 volt DC relay.  The common and normally open contacts of this relay are used to send a 5 volt DC pulse(1 second long) to the E unit.  Therefore, the E unit only see 5 volts DC for one second each time it is asked to rotate the drum.  Yes, you do need to modify the E unit but I can make that explanation easy if you want to try it.

 

If anyone would like to see the circuit, I will post it if I can figure out how to put a CAD drawing on this thread.

 

Before you say yes please post, understand that this is an electronic circuit based on a 555 time which needs 5 volts DC to work....full wave bridge and a 5 volt regulator is part of the design.

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Originally Posted by Kenai:

 Ahhh, but you say the DC will overheat the coil and magnetize it.

An ingenious adaptation of Magic-Electrol, however, I have not experienced this at all in ~ 30 years of running Lionel engines like this.

 

If you want to degauss a "magnetized" E-unit solenoid, for whatever reason, run it on AC.

Last edited by ADCX Rob

I did use the ac initially but decided that if I don't like to hear the buzz all the time, I don't like to hear it for 1 second!!!   The DC was available anyway and it was pretty easy to isolate the E Unit coil from chassis ground.  I now have a really cool working model of a way too involved set of circuit boards fit inside my Boston and Maine GP-9 that does the E unit trick and also has diesel engine rumble sounds that  vary with engine speed, a nifty diesel horn that is triggered by the Lionel horn/whistle relay, a mini audio amplifier and even a circuit that maintains the dc power to all the required electronics with a 9 volt battery.  That battery is only required to give current when the track voltage is turned off.  This keeps the diesel sound running or the horn honking when the diesel E unit is activated.  10 seconds after no track voltage is sensed, the battery is disconnected from the circuit and remains dormant until the track voltage returns.

 

I am working on a final set of schematics and maybe even a board layout for this concoction!!  I really tried to get it all inside the GP-9 even with a small speaker but it was just too much and the tiny speaker sounded fake.  I now have a dummy Boston and Maine GP-9 that carries a pair of oval speakers.  Two grayish wires leave the powered engine and drape over the shared couplers to feed sound to the speakers inside the dummy. Kinda looks like air line if you squint.  

If you can open a DWG file, I have attached the final(and quite complicated) circuit I have created.  I uses a modified existing diesel sound circuit in conjunction with an E Unit timer circuit and even a 9 volt rechargeable battery supplementary circuit for when the track voltage is interrupted.  This keeps the diesel rumble and the horn features working when the track voltage is missing during E Unit transitions.  There is a 555 timer circuit that disconnects this battery after 10 seconds on no track voltage.

 

The trick is making it compact enough to fit inside the diesel engine body!!

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Lots of electronic in a small package

It's a clever idea but it seems like a lot of complication for an anachronistic old E-unit. If I have E-unit problems I find it's more expedient to simply put a manual reversing switch on the loco, which also simplifies double-heading arrangements. I don't want sequential reversing for most of my O-gauge train operations; I usually lock out the E-unit.

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