The Electronic E-Unit (EEU) will replace the mechanical E-Unit in
Lionel and other AC-powered engines.  It sequences through the four
states like the mechanical unit, and will resume at the next state when power
is restored, regardless of how long power has been off.
It uses 10 amp mechanical relays rather than semiconductors to control motor
current, so there is no power loss or dissipation issue running higher power
2-motor engines.  A customer provided lock-out switch will retain the
prior state – forward, neutral, or reverse – just like the mechanical
unit.  DC motors can also be controlled, but an external bridge rectifier
must be added to rectify the track AC waveform.
The EEU now includes a power-up default option. When enabled
it will power-up either in forward or the last state it had been after power is
shut off longer than 2 seconds.
This
can be handy to maintain synchronization of multiple engines pulling a long
train.
Directional headlights can be controlled along with the motor.  Just
connect the headlight lead to the “hot” armature terminal for the
respective direction. The other headlight terminal normally connects directly
to the chassis.
The Electronic E-Unit is  2″ x 1.7″ by .8″ high, and should
fit where the mechanical e-unit had been.  It was described as a kit in
the April/May 2019 issue of O-Gauge Railroading (#305).  This fully
assembled and tested version uses surface-mount components.
The
Electronic E-Unit may be mounted with double-backed foam tape or a mounting
flange to the chassis.  A double-sided adhesive mounting pad is included
along with a mounting flange.
Complete
instructions are available here:
http://jvde.us/rr/eeu_instructions.pdf