Intermittant Whistle/Horn

2) Most likely the old selenium type rectifier in the ZW is not up to specs. These deteriorate with age. This assumes the locomotive is functioning properly. You could replace the rectifier in the transformer (this does not give you a bell) or

 

1) Build an external one. These work best with pure sine wave transformers. Shown here

 

http://www.jcstudiosinc.com/BlogShowThread?id=412

 

It can be automated with relays,shown here,there are also some pictures of the diodes used

 

http://www.jcstudiosinc.com/OG...AndWhistleController

 

3)

 

Easier just to try another loco and see if it works right. If it does it could be the other loco. If not it could be the transformer. If the horn relay is bad,most likely it is just dirty contacts. 

 

Dale H

 

 

 

 

The horn circuit in the ZW was designed to operate the whistle relay

in old trains with a motor in the whistle. Modern engines with DC can

motors do not draw enough current to operate the horn/whistle

circuit with any reliabillty.

 

Testing the switch contacts or disc with a meter does not indicate if the

circuit will operate the horn/whistle. A test of the circuit is to use an old

analog meter with a pointer. With the meter connected across the

transformer terminals and set to DC, and with the train running,

operate the horn button. The meter should read about 3V DC for the

horn to operate. If the meter does not read around 3VDC, then add

more load to the transformer like cars with lights.

As a quick test you could also use one of the Lionel 6-5906 sound activation button to verify it is the ZW's horn circuit. Dale H's external horn/whistle circuit is two buttons combined into one.

 

-John

I think I might like to try making an external horn or whistle/bell button. For a ZW I understand I need 12, 6amp diodes. Radio Shack has 6A, 50V Rectifier Diodes, Part# 276-1661. Is that right? Does anyone happen to have a Digikey part#? They have a bunch of different kinds listed.

 

 

Any general purpose diode,6 amp,50 volt or more. Allelectronics.com has them ,there are numerous ones that will work. 

 

The Radioshack ones will work but they are more expensive than other suppliers. They usually have them in their parts drawer.

 

http://www.radioshack.com/prod...sp?productId=2062591

 

Dale H

Sorry to be do dense...just want to make sure I order the right one. Will this work?

http://www.allelectronics.com/...6-AMP/600-PIV/1.html

 

 

Thanks very much! Actually, I printed out your pictures and diagrams some time ago as I knew I would be doing this eventually. I already have some push button switches and euro-style barrier strips in my parts bin (although not 7 position). I'll let you know how it all turns out.

You can cut the terminal strips as needed. Make sure you use switches which can carry 10 amps minimum. Can be automated to blow automatically with relays.

 

Dale H

 

 

10 amps?! Wow, I'm glad you said that. The one's I have in my bin box are .5 Amp. I guess those would have heated up quite nicely. I better do some more shopping.

 

In looking at the circuit, the pushbutton is normally open, so to me it looks like during normal operation, all the current on the hot side is running through all the diodes to the track but then when you push the horn button, half the current skips 5 of the diodes but goes through the 6th and half the current goes through all the diodes. (And the same thing for the whistle button.) Is that right? In Gunnrunner John's circuit, he only has 5 diodes on each side of the chain and I guess with his button he's shunting 4 diodes instead of 5. Does that make a difference?

6 pair will work in all cases

 

5 pair will work in most cases

 

If you use relays,you can use the light pushbuttons

 

Dale H

Just curious (only because I happen to have one in my spare parts bin), but is there any reason I couldn't use a single  125 VAC , 10 Amp DPDT (center off) toggle for both the horn & bell circuits?

Here's a simple whistle/bell box I built some time back, I use it for testing conventional stuff.  All I really needed was two SPST push-button switches, but those were what I had in my parts box. 

 

 

That's good to know because I have 2 steamers, 2 diesels and a GG-1 both circa 1955-1958.

I've used this on a bunch of them, never found one that it didn't work on.  OTOH, including the extra diode is not a major problem.

 

It works!! Thank you Gunrunnerjohn & Dale H. Attached is a quick pic of my test rig.

 

This is a combination of suggestions from both. I didn’t want to wait for a mail order so I bought the diodes locally from Wayne Electric, a small electronic supply shop here in northern NJ, for 99¢ each but the only size jumbo euro-style terminal block they had was 12 positions which meant I could only use 5 pairs of diodes after cutting it in half. (Radio Shack no longer carries the jumbo size euro blocks.) The DPDT toggle is a left over from a long gone N Scale layout. I tested all my engines and whistle tenders and they all work like a charm. Maybe it’s my imagination but even the old post-war tenders seem to have a lot more oomph to their whistles!

 

Thanks again guys.

 

Instant gratification is a wonderful thing!

 

Glad it worked out,

 

A question on the switch current rating.  Are 10A switches recommended in case a diode blows?  I built one of these using 3A switches, powered by a KW.  Thx, Chris.

Chris-

 

Yes, I would use a 10A switch. Since the KW is capable of kicking out at least 10amps fully loaded, higher rated switches will last longer. If you use a switch rated too low, the high current will cause the switch contacts to pit and prematurely fail.

 

-John

I guess it makes sense to beef up the switches.  I have some 15A coming from digikey.  There sure isn't as broad of a selection once you go above 3A.  Thx.

Remember, you're only running one locomotive at a time on this track and using the whistle/bell switches, right?  My little box used 6A switches, which I figured was plenty for a single consist.  IMO, 15A switches are overkill for a whistle/bell box.