Power/DCC Bus Taps - Does Anybody Make One Like This?

[C855B]

What will you need 5VDC for all over the layout? Instead of running it all over the layout why not provide 5VDC only where needed from 12VDC by using a simple 3-terminal voltage regulator (like 7805)?

The other thing I'm puzzled about is what hi-amperage boosters will feed your monster DCC bus?  I'm worried about the ability to trip the short circuit protection when the short occurs on the track fed by thin feeder wires.  Also high-amperage and N scale seems like a bad combination. I see melted models in the future. 

5V will be tapped for detection logic and signals, and there will be plenty of it spread around to warrant a separate power bus for it. Besides, 7805s are not "simple". They're a power-sucking, heat-generating pile o' crap.   (I've been using 7805-pin-compatible switching regulators for over a decade. Your point is taken, however, there may be savings in localizing the lower voltage versus running duplicate copper. I'll review the upstream/downstream considerations, one of which is putting more load on the 12V bus rather than spreading the wealth.)

Where in this did I say I'm using high-amperage boosters? 5A, max. The 12V and 5V buses will be probably 10-15A, but those will get both branch and local distribution protection. I have LOTS of experience with power supply distribution fusing from my 2-way radio days, so I'm bringing that knowledge over.

[peteski]

5V will be tapped for detection logic and signals, and there will be plenty of it spread around to warrant a separate power bus for it. Besides, 7805s are not "simple". They're a power-sucking, heat-generating pile o' crap.   (I've been using 7805-pin-compatible switching regulators for over a decade. Your point is taken, however, there may be savings in localizing the lower voltage versus running duplicate copper. I'll review the upstream/downstream considerations, one of which is putting more load on the 12V bus rather than spreading the wealth.)

Where in this did I say I'm using high-amperage boosters? 5A, max. The 12V and 5V buses will be probably 10-15A, but those will get both branch and local distribution protection. I have LOTS of experience with power supply distribution fusing from my 2-way radio days, so I'm bringing that knowledge over.

LOL, 7805 is a simple and well-proven analog (not switching) regulator.  Power sucking pile of crap?  Not any more than any ol' analog regulator.  They are sill widely used and I don;t see anything wrong with them. As far as generating heat, it depends on the input-output voltage differential and on the current supplied to the output. But you know all that.  Many of my applications of 7805 don't require a heat-sink.

I'm also really surprised that nowadays there are still 5V designs around. I would have thought that CMOS logic took over the half-century-old old TTL circuitry. CMOS allows 3-15V supply so it is much more flexible. Someone out there is stuck in the past.    But now that you explained, it does seem to make sense to have a dedicated 5V bus.

You didn't say that you use high-power boosters - I also don't follow your layout thread very closely, but with 12 AWG bus I assumed high-amps.  I'm curious as to what will be your longest main bus run with one of your not-so-high-amperage boosters?

[C855B]

I have to design for bus runs of 60-75', so therein lies the big copper. Besides, I have beaucoup 12AWG in multiple colors left over from building construction, so may as well make use of a resource already paid for. The boosters will be somewhat centralized (two exceptions) and will live on shelves at the extreme end of the power buses, hence the long runs. I could move them to the center of their supported buses, I guess, cutting the bus runs in half, but with the big wire it won't make a measurable difference.

Last time I used a classic 7805 was a 78L05 on a serial com port level converter, one lousy 8-pin chip. Even with only about 20-30mA drawn by the converter, the regulator bucking down from 13.8V would get fingertip-burning hot.

5V is still sort of a standard for mixed-device integration. TTL is an antique format, but 5V lives on, I guess.

[peteski]

Last time I used a classic 7805 was a 78L05 on a serial com port level converter, one lousy 8-pin chip. Even with only about 20-30mA drawn by the converter, the regulator bucking down from 13.8V would get fingertip-burning hot.

Ah, the low-power version in the TO-92 case?  So, with 13.8V on the input and 30mA the regulator dissipated around 0.27W. I agree - that will make that small case quite warm. 

[Chinapig]

Hi
I use these Wago blocks to distribute my bus power.  I just hot glue them to the bottom of my baseboard.  No screws required.  It's a 5-way lever operated connector for solid, stranded or flexible conductors.  At less than £0.50 they're a bargain.

http://www.screwfix.com/p/5-way-lever-connector-222-series-pack-of-40/38224?kpid=38224&cm_mmc=Google-_-Product%20Listing%20Ads-_-Sales%20Tracking-_-sales%20tracking%20url&gclid=CPKfgd67qtACFQ5mGwodz-0GKQ

Cheers, Ted

[C855B]

Thanks, Ted, for reminding me about the Wago taps. They're stocked at the local D-I-Y store. I'll get a handful to try on the next errand there.

[C855B]

Looking for the Wago taps online discovered they have a new design, their "221" series:



Like the original, they are rated for 12 thru 24AWG, solid or stranded. These are about half the size of the original Lever-Nuts and look very promising. I have a batch of 2-, 3- and 5-pin versions on their way.

Thanks again, Ted!

[Chinapig]

Yes, I should have remembered that we only buy the newer sort now as they are easier to handle.  We use these on our club's oNeTrak modules and as well as being fast you can easily change the wiring if needed.  As far as wire size goes, they can take our stranded 50/0.25 main bus which is about 13AWG.  They may just take 12AWG but I don't know.

Cheers, Ted

[John]

I get wanting bulletproof wiring ... and I hope you guys find what you need  .. I'm just not sold that MILSPEC  is needed for a layout wiring scheme

[C855B]

Go ahead, John. You laugh.

Nah... my career has been steeped in hardware integrations, and it was learned long ago that quick'n'easy, cobbled or homebrew solutions are a b!tch to diagnose and fix. This layout will be way too big to be sloppy, careless or inconsistent. A little bit of analness now will be rewarded by fewer issues down the road, and in those rare instances it will be much easier to deal with.

[C855B]

Looking for the Wago taps online discovered they have a new design, their "221" series:

The sample pack arrived today, and I couldn't get over to the layout fast enough to try them out. These are really nifty! 2-, 3- or 5-wire versions all seem to be available from several eBay vendors @ about 50¢ each. At $1 per tap (that is, both wires), a damn sight less costly than what I was looking to do, and for connecting more than a single branch at a tap, cheaper than "suitcase" taps. When I clean up some of the wire runs tomorrow I should take an "in use" picture or two.

[John]

Go ahead, John. You laugh.

Nah... my career has been steeped in hardware integrations, and it was learned long ago that quick'n'easy, cobbled or homebrew solutions are a b!tch to diagnose and fix. This layout will be way too big to be sloppy, careless or inconsistent. A little bit of analness now will be rewarded by fewer issues down the road, and in those rare instances it will be much easier to deal with.

Naw .. I admire you for your commitment to excellence .. and i do understand .. my wiring is a challenge sometime to troubleshoot .. and sometimes I wish I had put in sub panels . but the evolution of my layout has been one of continued redesign and changing things around .. so I live with it ..  I will do it differently on the next layout

[Chinapig]

That is the beauty of the Wago connectors.  They allow you to do continual redesigns and upgrades quickly and easily.  Pull the clip up on the connectors and the wires come out.  The blocks are re-usable.  No soldering required.

Along with these Wire Insulation Displacement Contact Connectors, which are available in two or three port styles, I solder very little under the baseboard nowadays.

http://www.ebay.co.uk/itm/Securely-UR2-3-Wire-Insulation-Displacement-Contact-Connectors-50X-100X-Durable-/301545578764?var=&hash=item463584610c

Cheers, Ted

[peteski]

Naw .. I admire you for your commitment to excellence .. and i do understand .. my wiring is a challenge sometime to troubleshoot .. and sometimes I wish I had put in sub panels . but the evolution of my layout has been one of continued redesign and changing things around .. so I live with it ..  I will do it differently on the next layout

Is this your type of wiring John? 

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BTW, this is for real - it is under an NTRAK module of one of our club members. 

[dckuk]

Tried this as a temporary expedient:

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Strip household power cable conductors, one pair for each buss, and wire the toggle into each side, and the track to the center.

Much easier to rip out and throw away when I build a "proper" control panel!