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@Lou N posted:

Norm,

I have one of these in the queue for upgrade.  What did you use for the antenna?

Regards,

Lou N

Whatever TAS used to supply with their EOB upgrades. My set had EOB for many years before I swapped it over to ERR. I was fighting what turned out to be a grounding issue and found the Cruise Commander was less picky about the Centipede set having poor grounding. I added some ground jumpers to the trucks at some point even after converting over. I have long insulated block triggers for my signals and some diesels hate it. The bad grounding clue is if they run better when the train they are pulling enters the block and bridges the ground.

For what it’s worth I could never pull a load hard enough to annoy the standard rectifier and mosfet/heat sink setup with EOB or ERR. YMMV though.

For what it’s worth I could never pull a load hard enough to annoy the standard rectifier and mosfet/heat sink setup with EOB or ERR. YMMV though.

According to Jon Z. it's not that you truly overload it, but just get it hot enough to increase the leakage current, that's what does the FET's in.  You're not actually overloading the FET's max current.

I think the old Lionel DCDRs used the same FETs as the ERR stuff?  I’d have to go look though. I have a few in the stash. Anyone remember how those DCDRs used to slam motors to a reversed voltage stop at high speed/direction change? I have a project on the bench right now with one. Brought back memories!

Have you guys ever tried getting those small extruded aluminum heat sinks for the rectifiers?

I have a few heat sinks I have pulled off old computer CPUs and video driver chips. I didn't use one on the Cruise M rectifier but have used them on an E unit used in a conventional Lionel GG1 that was prone to overheating.

Lot of useful parts in old desktop computers. Good idea to strip them out before recycling.

Pete

@Norton posted:

Just a reminder, My K-Line ABA had six motors driven by a single non cruise DCDR.

I would think that board is just as suseptable to overheating and failure as the ERR Cruise boards if that was an issue. Then again maybe not. Maybe Jon Z knows the difference or how K-Line got away with it.

The DCDR uses triacs, a totally different animal.  The FET's used on the Cruise boards would be a lot more susceptible to the reverse leakage current and voltage from the rectifier.  I'm sure that Jon does indeed know the difference.

I’m also of the mindset that having more than 10amps available at the track is in arc welding territory.

A tale told to me many years ago by a Youngstown Model Railroad member (2 rail DC powered by car batteries)...One night someone dropped a nail and it went across the tracks and it did weld.  Available instantaneous current will get you every time.

I designed my own O scale DCC decoder and used 40A MOSFETS.  Purely a matter of convenience with no expectations of needing that amount of current.

Lou N

@Lou N posted:

Yes.  Bergquist makes paste type heat sink grease but also makes film type.  Some sheets are adhesive on both sides allowing the attachment of small heat sinks.  Copper is a better choice of sink material.

Lou N

Lou, that is what I thought for years.   About  3-4  years ago I bought some finned copper stock and similar aluminum finned stock and made some sinks for the triacs and bridge on a pair of DCDRs  for which I was planning on driving four 545 motors with one DCDR in a pair of Lionel 18952 Alco PA-1s. I wanted to rob one of the DCDRs for use in a Williams Trainmaster with twin Pittman motors. The copper sinks are still working well however I am not sure there is a clear advantage, as copper will absorb heat faster aluminum will dissipate it faster. I cut the finned copper and aluminum into roughly equal shapes and installed them on two identical DCDRs and A-B running the four motored AA pair 15 minutes at as close to the same speed as I could on a circle of O-72. Running in conventional with the track voltage set on 14v.  After the fifteen minute run I stopped and as fast as I could point my digital IR thermometer at the case of the triacs  I read the temps first with the copper finned DCDR then with the aluminum version they were less than one degree apart.  I figured that was the limits of my test setup. Then I ran across an article on the web where the writer was discussing this very topic and his conclusion was what I had decided from my experiment.  I was trying to find that article tonight but before I did I ran across a related discussion about automobile radiators Aluminum vs Copper.   https://www.researchgate.net/p..._aluminium_or_copper  Read about  1/3 down the page and look for the name Ammar Eqbal, Indian Institute of Technology Patna where he says the best heatsinks are a composite with a copper base and aluminum fins.  I am glad I did the test but to my way of thinking it was a draw.          j

Last edited by JohnActon

Keeping it cool to minimize the leakage current is far more important than the actual rating of the bridge.  8A is plenty with the heatsink, why make it larger for no apparent gain?

A 10 amp bridge will generate less heat than a 8 amp, won't it?  At a given current.  If these things are getting that hot that they are breaking down. even heat sinked to the chassis, you'd figure I higher current rated bridge would be less likely to breakdown.

Last edited by superwarp1

Ever try wiring the motors in series in each unit? I've always wanted to try that with an ERR CC but never have for some reason.

All that will do is greatly reduce the pulling power as each motor will not be able to generate maximum torque at the lower voltages available.  I have actually tried it, but that was the only effect I saw.  I think the right way it to manage the cooling of the rectifier in addition to the FET's.

@superwarp1 posted:

A 10 amp bridge will generate less heat than a 8 amp, won't it?  At a given current.  If these things are getting that hot that they are breaking down. even heat sinked to the chassis, you'd figure I higher current rated bridge would be less likely to breakdown.

Actually, given similar voltage drop specifications across the diodes, it'll generate exactly the same amount of heat, think about it.

Most modern dual-canned engines seem a bit overpowered anyway. Combined with relatively steep gear ratios, the real idea behind wiring motors in series (in each unit) would be for smoother control with some level of acceptable loss of speed pulling power. I never tried this with CEMF control but it might be worth experimenting with next time I open up my Centipedes.

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