Quiet E unit fix causes whistle, horn to go off.

[trains4fun]

I tried the diode/capacitor fix listed in this old noisy E unit discussion. 

It does quiet the E unit perfectly, but the problem is it fires off the horn or whistle continuosly.  

CW80 transformer.

Any Ideas on what could be wrong?   Capacitor neg to ground, diode cathode toward E unite, capacitor positive connected to E unit after the diode.  Or does this just not work  with horns and whistles in the mix. 

Or does it really need a full wave bridge isolating the e unit coil completely isolating it from the rest of th system? 

Any success stories?

I have a 2065 with an original E unit that makes 0 noise, but all my others make noise of some kind and I would like to quiet them if possible.  

[ADCX Rob]

By blocking half of the AC sine wave to the E-Unit with one diode, & referenced to chassis ground, you have introduced a half wave DC bias in the opposite direction to the chassis... so yes, it really needs a full wave bridge isolating the e unit coil completely from the rest of the system.

[lionelsoni]

The rest of your locomotive is powered directly from the pickup, and not from the e-unit coil's terminal, right?

[trains4fun]

Thanks for the information about the full wave bridge, it makes sense.  In fact I bought some just in case when I bought the other supplies.

For the other question, the configuration only ran the coil.  

I think I just re-discovered the stand alone horn relay.   Resistor of the right value, capacitor and a diode or 2 in the right configuration and you induce DC current on the track..  

I am not trying to make all my E-units noisless.  A little buzzing is OK.  The worst offender is in the F unit.   The shell acts as an echo chamber and it is almost as loud as the horn.  

[BigAl 956]

Or does it really need a full wave bridge isolating the e unit coil completely isolating it from the rest of th system? 

Yep, that'll silence the buzz. This also works with any buzzing accessory where buzzing is not needed.

[Firelock76]

Gee, I always loved the sound of the E-unit, struck me in the same way as a double drum roll before a military band starts a selection, a little taste of something really good that was coming.

To each his own, I suppose.

[lionelsoni]

I would try the bridge rectifier without the capacitor first.  That might be quiet enough for you and will avoid the extra coil heat that will come from adding the capacitor.

[trains4fun]

Put in the full wave bridge, silent.   rated at 400V 1.5 amp, $2.99.  There is a barely audible buzz at full voltage.  Can only be heard when everything is silent. Fixed the problem for me.  

[lionelsoni]

Did you need to use the capacitor?

[GeoPeg]

trains4fun

Put in the full wave bridge, silent.   rated at 400V 1.5 amp, $2.99.  There is a barely audible buzz at full voltage.  Can only be heard when everything is silent. Fixed the problem for me.  

I assume you did as ADCX Rob mentioned, and that is fully isolated your e-unit coil from the system, or more specifically from using the frame ground. That implies you no longer have a working e-unit switch, correct? Did you just leave the e-unit coil permanently wired into the circuit, or did you add another switch somewhere?

[GeoPeg]

Rephrase: Did you just leave your e-unit coil permanently wired into your NEW circuit.....?

[lionelsoni]

If the bridge rectifier is wired immediately upstream of the coil, with the two ends of the coil connected to its + and - terminals, and its ~ terminals connected to the places where the coil wires were, there is no need to isolate the e-unit frame, and the switch continues to work.