DCC booster - no output, questions

[mmagliaro]

So, as most of you know, I'm not a DCC guy.  But I devised an overload detection circuit (it was posted to the forum here a month or more ago), and as it works for DC, pulsed DC, AC, and PWM, I wanted to try it out on a DCC track supply.   So I bought an old, supposedly "never used"  "Easy DCC" booster board on the cheap off eBay.  It's one they haven't made in years.

I figured I'd just power it up, slap a load across it, and see if my detector would sense the correct current.

Well, I hooked up 18VAC input to it( as the instructions indicate).  But I don't see bupkis coming out of the track terminals.   Not DC, not AC, and an oscilloscope shows nothing either.   I expected to see a basic square alternating wave of about 12v amplitude.

What I DO see, if I hook the oscilloscope between ground and either output terminal, is a ratty rounded half-wave that is about 20v in amplitude and about 60 Hz in frequency.  And it's the exact same thing on both output terminals.

So, can I not get away with this?  Do I have to plug something into the actual command bus to make this thing output its square waves?

[jagged ben]

You might have to send it a command to turn track power on.  I don't know anything about EasyDCC though.

[peteski]

DCC boosters are basically like audio power amps.  The command station feeds a low-level DCC waveform to their input, then they present the amplified version to the track.  Well that is greatly simplified explanation (because unlike audio amps, boosters are not linear amps). Without the DCC signal at the input, they won't work.  They are unable to generate the DCC packets themselves  (thus no DCC type voltage pulses to the track).

And also like Jagged Ben mentioned, there might also be signal needed to enable or disable the output.  If you can find some documentation for it, you might be able to figure out what connections to the command station it uses. But without a DCC signal coming from command station, this is a no-go setup. 

My friend uses older CVP EasyDCC system on his layout. I will see him on Monday - I can check his setup.  This is it. The boosters are mounted on the side walls. Command station is in the center.

[John]

Max ... not sure if this will help, but CVP has some of the old manuals on their website .. this might be the one you have

https://www.cvpusa.com/doc_center/B5_Book_Updated_April_2012.pdf

https://www.cvpusa.com/doc_center/v1_3_T9000E.pdf

[mmagliaro]

DCC boosters are basically like audio power amps.  The command station feeds a low-level DCC waveform to their input, then they present the amplified version to the track.  Well that is greatly simplified explanation (because unlike audio amps, boosters are not linear amps). Without the DCC signal at the input, they won't work.  They are unable to generate the DCC packets themselves  (thus no DCC type voltage pulses to the track).

And also like Jagged Ben mentioned, there might also be signal needed to enable or disable the output.  If you can find some documentation for it, you might be able to figure out what connections to the command station it uses. But without a DCC signal coming from command station, this is a no-go setup. 

My friend uses older CVP EasyDCC system on his layout. I will see him on Monday - I can check his setup.  This is it. The boosters are mounted on the side walls. Command station is in the center.

Well, that explains why I can't get away with this just to test current capacity.  I was assuming the booster put a +- alternating square wave on the rails, and it got MODULATED by the DCC commands.  i.e. That the pulse width and frequency was altered by the command to encode the command as bits.   I was hoping I could get a basic waveform out without spending a couple hundred bucks on a command station.  Oh well.  At least it only cost me 7 bucks.  Ha.

[drgw0579]

If you put it on the Trading Post, I'm sure somebody will snatch it up.   Working EasyDCC components are still in demand, even though the vendor doesn't support the older stuff.

Bill Kepner

[Sumner]

...........t without spending a couple hundred bucks on a command station.............

You can put together a great one for well under $50...

https://dcc-ex.com/#gsc.tab=0

... maybe way less if you have an Arduino or I think now maybe an ESP32 laying around and you can even connect to it with a phone throttle.

Sumner

[peteski]

Well, that explains why I can't get away with this just to test current capacity.  I was assuming the booster put a +- alternating square wave on the rails, and it got MODULATED by the DCC commands.  i.e. That the pulse width and frequency was altered by the command to encode the command as bits.   I was hoping I could get a basic waveform out without spending a couple hundred bucks on a command station.

Sounds like you imagined DCC signal to be sort of like a modem signal.  A modulated carrier frequency waveform where the carrier is always present.   It is not like that. It is more like a serial interface (like RS-232).  There is no carrier, just digital data in the form of ones and zeros being represented by the flipping voltage.  There is no background carrier frequency which would be always present

[rodsup9000]

 A little late to the party, but I have been using Easy DCC since they came out in 1998.
 You need to take a 6 pin modular cord and place one end into the jack marked "input". Strip the other end.
The two outside (#1 and #6) will be your DCC signal inputs from the command station.