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I have a fairly simple setup; basically two loops powered by separate CW-80 Transformers. I have several engines with sound cards installed. The issue I have is the bells activate on all the engines whether they are running or idling. The whistles, on the other hand, only activate with the engines at idle; not when in motion. Exception: my cheap Pennsylvania Freight works almost all the time.

 

 

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If you measure the DC voltage on the track (red meter wire to the center-rail, blk meter wire to the outer-rail), it should be very small DC voltage (less than 1 V).  When you press the Horn/Whistle button, it should jump to several Volts positive as long as button is pressed.  When you press the Bell button, it should jump to several Volts negative as long as button is pressed.

This is how sound cards are controlled.  

I don't have a CW-80 but I made this short video which shows what to expect.  This is an MTH Z-750 controller which uses a similar transformer "technology" as the CW-80.

The voltmeter is a low-cost, hobby-grade meter that you can get FREE (with coupon from Sunday newspaper) from Harbor Freight Tools.   The point is to show that you don't need a fancy-dancy, professional-grade meter to make this measurement!

In this case there is negligible (less than 0.1V) DC voltage when no button is pressed.  With Horn/Whistle you get several Volts of positive DC (albeit no "+" sign shown on meter); with Bell you get several Volts of negative DC ("-" sign shown on meter).  This DC voltage does not materially change with variations in AC track voltage...note the brightness of the lock-on lamp changing as voltage control is rotated up and down.

The video has sound; in this case it's an MTH PS2 engine you're hearing.  But the mechanism of detecting the DC voltage on the track to activate Horn/Whistle and/or Bell is the same as your Sound Cards.

Last edited by stan2004

You "modified them with a sound card' of what type? Considering that, it almost doesn't matter what its in. I.d. sound issues by sound board and whatever is triggering it in the loco, another board, tach wheel, Reed switch, etc.

Do the bells shut off at speed? No to low speed bells is prototypical in ways. This may be happening by design. Not a perfect design without an on/off, but I could easily see this being a feature in a low cost setup.

Also try activating and holding the bell control on for various times 2 to ten seconds each try. You may have it "locked on" like tmcc.

Check can the transformer simply by switching rail input. If the whistle/horn is now stuck, your transformer has a DC bleed.

It could also be a sensitive trigger circuit and a bi polar cap on the motor and or input power to sound might be needing a filter(cap) too. The "magic light bulb" trick might even work to smooth things.(12v, 14v, 18v bulb powered by track. Experiment some.)

The bells work just fine, both at idle and in motion. The problem is with the whistles. They activate just fine with engines at idle. But only occasionally, activate while in motion. I checked both track ovals with a multimeter and had proper readings. Next time, I'll try the light bulb trick. Thanks everyone for your input.

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