For those who have not been following my post on the layout planning forum I was having big problems with DZ-1008 relays blowing up on me and could not figure out what was happening. I first thought I wa snot wiring them correctly but that was not the case. I had the turnouts and relays powered by the accessory tap on a Lionel CW-80 which was programmed for 16 volts. I blew up 6 relays before I called it quits. A friend took a look at the circuit board inside the 1008 and said it appeared the transistor had blown from over voltage. Once I switch from the accessory tap to the throttle lever the problem went away. Dan came over today and tested two CW-80's I have with an oscilloscope and sure enough on start up the voltage spike on one was 28 volts and on the CW-80 I was using a whopping 32 volts. No wonder I was blowing relays like crazy.....................Is this just the luck of the draw with me and CW-80's or does Lionel have a big problem???
Just a note BEWARE if you are using the accessory tap on the CW-80.

Joe

Joe Fauty

Original Post

I tested it with a one shot trigger and obtained the voltage spikes. I found one peaked at 27.2 volts and the other at 37.4 volts both would simmer down around 13.volts  the spike is contributed to the trans former power up voltage and you mus be aware of the spike to keep from blowing the circuits. It has to do with the magnetic flux on power up you need to be aware of it when using the accessory voltage ports. All transforms will sipke on start up and need to be watched. using the variable output there is now problem. You would need to put a pulse limiter on the output. 

 

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I’ve used cw80s for switches and accessories and never suffered damage. The spike must be pretty quick.

What transistor is used in the DZ1008s? Usually 50 v is a minimum for transistor voltage rating. If this is a typical hazard, some rethinking on ratings or circuit protection would be good.

Chuck TCA LCCA ARRL BMWMOA

Sounds to me like the control circuitry for the accessory output is not operating quickly enough to keep the voltage from spiking.  You might be able to try a snubber capacitor across the accessory output to limit the spike.  I would start with 0.1 uf non polarized.  You will need the o-scope to determine if this helps.  I am also curious to know if a spike is seen on the variable output.  My guess is that there will be no spike if the throttle is set to zero on turn-on.  I don't have  a CW80 on hand so I can't make any measurements here.

Regards,  Phranzdan 

Phranzdan: I am using the throttle now and have no issues.

CJack: I don't know what transistor is used in the DZ-1008. The voltage spike does not affect the DZ-1000 motors nor Atlas O motors or snap relays for obvious reasons. It seemed to be only the 1008 relay. I alerted D Zander but have not heard back as yet.

Rod: I don't know how long the spikes lasts (probably only msecs) but I would think an on/off switch after the transformer would work just fine.

Joe

 

Joe Fauty

I'd use a TVS across the output of the transformer.  A popular one in use here is the Littlefuse 1.5KE36CA. FWIW, a 34V peak spike shouldn't be a major factor, that happens frequently in our environments.

The TVS is a Transient Voltage Suppression device that whacks voltage spikes that exceed it's clamping rating.  It's connected across the output of the transformer to suppress any excessively high voltage spike.

Model Structures posted:

CJACK - do you have any issues with light bulbs on your accessories?

Joe

No. But if I powered them with the A output,  they oscillated in intensity a bit. The accessory side was more stable.

Chuck TCA LCCA ARRL BMWMOA

I added the TVS diodes mentioned above to my CW-80, Type S, and my VW last January.  My little railroad is happy now.  They are cheap insurance.  Don't forget properly sized circuit breakers.  

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Stan, I have no idea how that got in there, but I fixed my link.  I'd suggest you remove that link from your quote as well.  I don't recall ever linking to Allied previously, I normally refer to parts like this on Digikey or Mouser.

I just deleted my post so I think we're good.  For anyone ordering this part, if you do a web search to shop around, use the following search term:

1.5KE36CA

make sure you have the letters CA at the end.  Pricing is all over the map - from 10 cents to well over $1 each.  I see someone on eBay even invoking "Lionel" in the title!    This is a generic part.

 

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