Club layout short driving me nuts

[Maletrain]

Regarding the effect of DC on Frog Juicers, this is all I could find  (on the Tam Valley website):

"Common Contact Questions:

"Q: I sometimes operate my DCC layout as DC.  I know they will not work with DC but will this hurt my frog juicers?
"A: A lot of model railroaders have done this and it has not caused any damage.  However, I can't warranty your frog juicers in this case."

[Ed Kapuscinski]

Now that it's solved...

A pirate walks into a bar with a steering wheel down his pants. the bartender says, “hey dude, what’s with the steering wheel?” the pirate responds, “ARRGH, it’s driving me nuts!”

[Point353]

Now that it's solved...

A pirate walks into a bar with a steering wheel down his pants. the bartender says, “hey dude, what’s with the steering wheel?” the pirate responds, “ARRGH, it’s driving me nuts!”

[peteski]

A monkey with a pirate hat - how very appropriate! 

[Sumner]

Regarding the effect of DC on Frog Juicers, this is all I could find  (on the Tam Valley website):

"Common Contact Questions:

"Q: I sometimes operate my DCC layout as DC.  I know they will not work with DC but will this hurt my frog juicers?
"A: A lot of model railroaders have done this and it has not caused any damage.  However, I can't warranty your frog juicers in this case."

I'm finishing up all the bus wiring on the layout and changing them into new and different districts.  I was testing to see if all the different sections of the new district were connect to each other with a Tech 2 power pack by connecting to the end of the buss and checking along at different points for voltage.  I forgot that this part of the bus was originally connected to a Tam Valley Hex frog juicer and it was still connected.  I had the power pack turned up to about 9 volts.  Then I saw the LEDs on it were lit up.  I checked on the internet like you did and found that I probably didn't hurt it.  I'll know more when I connect that track up to the right track outputs on the command station soon.  I'm hoping that it is still fine.

Sumner

[peteski]

I would imagine that any device using DCC signal as its power will be fine if accidentally connected to DC.  After all DCC is basically a DC voltage which reverses polarity multiple times a second. So with DC it is like the DCC signal "froze" for extended period of time.  I wouldn't  expect the devices like frog juicer to actually function as designed, but no damage should occur.

[jagged ben]

As.long as the voltage isn't too high. 

[peteski]

As.long as the voltage isn't too high.

True, but most DC throttles are not designed to go over 12-15V and DCC is also designed to handle those and a bit higher voltages, so theoretically it is safe. Buy yes, if you throw 30VDC into the circuit, things might get nasty.

[Maletrain]

I'm no electrical engineer, so this is just supposition on my part. But, wouldn't most DCC boards use computer logic type components that run on DC, so that the first thing in the power pickup circuit is a rectifier?  If so, the it doesn't matter if it's AC or DC in, because it is DC out, either way.

Maybe somebody with more knowledge about such things can explain what parts of a DCC circuit could be at risk from DC.  But, let's not go into the issue of voltages above the component ratings.  That will kill anything, even if it all goes into a rectifier.

[peteski]

Yes, the electronics (microcontrollers or miniature fully-functional computers) which run the decoders and other "intelligent" DCC accessories like the juicer absolutely require filtered and regulated DC voltage to run from.  Yes, I'm sure there is a rectifier in the juicer, and as I mentioned, feeding DC voltage should not harm them. Items such as DCC  decoders even recognize DC voltage and go into DC-running mode (if so enabled). As far as the juicer goes, it might  not properly detect the track polarity mismatch and not switch its output appropriately. But since the frog is isolated from the other tracks this should not be a problem.  I don't own any juicers so this is all theory on my part.

[$2 Bill]

While the DCC Decoders etc get power from the Track & each have Rectified Filtered Power Parts in/on them... DCC doesn't use "AC."

Base & Booster(s) output to the Tracks is combine Balance Serial data stream with Fixed 13-14 DCV to run whatever.
So a signal on 1 Rail, the Exact Opposite Mirrored signal will be on the other rail. To see in real time, need 2 trace O-scope, probe tips to rails, Ground to Neg of Fix DC out.

In PC world DCC Data acts similar to SATA or USB (USB3 & up) ports but only One-way data from controller to everything else. Look up RS-485 too but ignore the ground to get close to what DCC developers emulated. (RS-232 RS-485 & related could use "AC" seeing Negative Volts but later versions allow "DC" signalling. Example: 0-Xv as 0, Y-5v as 1 & any volts between X & Y is invalid & ignored.)

Yes, Decoders etc also regulate to 5V 3.3V or lower for the logic. This could use 7800 family like 7805 & related parts to a "Buck" Regulator depending on power used by the logic  etc. 78xx05 is "same" as just 7805 but extra letters may mean package type, low cutoff, & other specs. Same happens to nearly all parts.

Decoders etc can Die/Fry when gets too high volts or too low volts.
7800 series & related regulates by dumping heat for the extra volts. Many Small format packages like TO-92 & surface mount parts are already limited to the max volts, max amps or Both.  Example: Full Version 7805 is rated input 35V, output 5V 1A with proper heatsink but a surface mount part maybe only rated input 15-20V, output 5V 0.1A (100mA).
Motors/Coils see Low Volts then tries to pull more Amps for a given load. In turn the H-bridges etc controlling them Heats Up way more.

So in Short... (too late) There's many ways they can make Decoders, "frog juicers" & other DCC parts. Most or even All could claim DC compatible but "blow up" when connected to some DC power packs sim to the "war" Rapido vs MRC Railpower 1300 in https://www.therailwire.net/forum/index.php?topic=59608.0 & many other places. And the Warranty will be Void.

[peteski]

You seem to have incorrect understanding or  DC decoder circuitry.
Decoders do not use the vintage analog voltage regulators (like the 78XX ICs). I have reverse engineered many, and I don't recall ever seeing those regulators on board.  The microcontrollers usually run on 3V and since they use very little power, a typical voltage regulator to convert the rectified DCC voltage to 3V use a simple resistor/Zener circuit. 

More advanced sound decoders (like ESU) actually use DC/DC buck converters to derive a regulated voltages lower than the rectified raw.

The H-bridge motor driver and all the function outputs also produce variable voltage output using PWM, so there is minimal power dissipated as heat at the transistors (since they are used in a switching mode, not analog).

Also the audio amplifiers are usually class-D (so there is  again minimal power dissipation by the audio chip itself), although I have seen MRC sound decoders using LM358 analog amplifier.

So why exactly can lower voltage permanently damage a decoder (other than it not functioning properly for the time the voltage is too low)?

Also, the DCC track  power is not "Base & Booster(s) output to the Tracks is combine Balance Serial data stream with Fixed 13-14 DCV to run whatever.". The voltage itself  *IS* the data stream. It does not ride on top of a DC voltage.  The high current DC voltage itself flips polarity, representing the serial bits of data in the data stream.