Reversing polarity of the whistle diode for KW transformer

CKOGR Forum Member DIGITAL SUBSCRIBER

Happy Easter!

Have any of you added a DPDT switch to reverse the polarity of the whistle diode in a Type KW transformer? I did it this way: http://jwtrains.com/Tech%20Tip_7.htm (note that I think he means DPDT, because the only DPSTs I found have 4 terminals).

I played around with this yesterday, and just hooked everything up with test leads, and it works, but I'm trying to figure out where I can fit the switch in the case. Seems like the easiest place would be in the back by the binding posts, but it there isn't enough room, at least with the switch I have, without shorting out the binding posts. I'm looking for ideas. I do have an external bell & whistle button, but I like the way the transformer whistle controller works, especially after the stud diode upgrade. Thanks, Chris.

4/20/148:53 AM

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gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

Probably the easiest way is to either find a slimmer switch, perhaps a slide switch.

You could also make a small "doghouse" on the top or front to mount the switch.

4/20/149:22 AM

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Boxcar BillOGR Forum Member MEMORIALIZED MEMBER

Take a look, not my idea but it works great. The switches are mounted on the rear of the ZW.

https://www.google.com/search?...52772327%3B150%3B150

This has been around a long time.

Bill

4/20/149:51 AM

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gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

That's a big doghouse on the bottom with the switches in front. Good idea, looks like it was part of the transformer. I wonder if this was a product someone made for these upgrades or a one-off?

4/20/1410:11 AM

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CKOGR Forum Member DIGITAL SUBSCRIBER

After some thought, I think I'll "doghouse" it. I don't want to have to reach in back of the transformer and blind feel between binding posts to toggle between bell & whistle. I had some time yesterday afternoon, and was able to drill a hole in the back plate just above the power cord. I ran lamp cord to the rectifier points, and temp'd the toggle switch & stud diode outside of the case. I just need to find the right project box and mount it to the case. I'm thinking of mounting it high, on the back (12 o'clock when looking down on the KW). Thanks for the suggestions.

4/27/147:43 AM

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CKOGR Forum Member DIGITAL SUBSCRIBER

I think it turned out well. Found a small project box at the same surplus outfit I got the DPDT switch from. I used Scotch brand reclosable fastener tape to attach the box to the case. This will allow easy removal so the case can be removed to service the rollers, circuit breaker, etc. I tried velcro, but there was too much slop.