The "too much booster" Legacy booster

Just turn it up to 11 I always say!

Holy Cow Adrian!  Are you trying to run trains on MARS? I'll be looking for a glow on the horizon toward the west...

FWIW, I have to say, most of the credit for the booster goes to the late Dale Manquen, he did the original design and proved the concept by traveling around to layouts and testing it.

Adrian - Definitely interested in what you find out and how you weeded out the parasitics. Does your device help you located where the TMCC signal is leaking to earth ground?

Thanks,

Bob D

NJ HI-Railers

The words “too much booster“ have never crossed the Gun Runners lips. Couldn’t have! Never happened!

How many Gigawatts is that?

@lpb007 posted:

The words “too much booster“ have never crossed the Gun Runners lips. Couldn’t have! Never happened!

No, but I never got that carried away!

Well it's working. The layout is drawing about an amp. I mean an amp of 455 KHz signal... not power. It feels wrong but works well

I hope you guys don't try to run DCS on that layout with that feeding the rails!

You'll have TMCC/Legacy signal all the way out to the Aircraft Carrier docked.

Jim

@Adrian! posted:

Well it's working. The layout is drawing about an amp. I mean an amp of 455 KHz signal... not power. It feels wrong but works well

Can you please elaborate.  I am working with a 30'x 200' multi level layout with probably numerous parasitic connections.  The GRJ/DM buffer is working fine, but always looking for ways of improving the TMCC signal.

Thanks,

Bob D

@rad400 posted:

Can you please elaborate.  I am working with a 30'x 200' multi level layout with probably numerous parasitic connections.  The GRJ/DM buffer is working fine, but always looking for ways of improving the TMCC signal.

Thanks,

Bob D

Remember Bob, if you boost the strength of the TMCC signal, you risk killing the DCS signal.  The whole reason the tuning pot was added to the TMCC buffer was to balance the boost to get reliable TMCC/Legacy signals but not stomp on the DCS signals.

@gunrunnerjohn posted:

Remember Bob, if you boost the strength of the TMCC signal, you risk killing the DCS signal.  The whole reason the tuning pot was added to the TMCC buffer was to balance the boost to get reliable TMCC/Legacy signals but not stomp on the DCS signals.

Understood, the current buffer is staying in place and not implementing anything that will affect the DCS signal.  Just want to see if there are any takeaways from Adrains experiment that can be used for diagnostic purposes.

@rad400 posted:

Understood, the current buffer is staying in place and not implementing anything that will affect the DCS signal.  Just want to see if there are any takeaways from Adrains experiment that can be used for diagnostic purposes.

Well, given enough current, maybe you can track down the parasitic connections by looking for the smoke!

If you add a longwire antenna to that 150 watt transmitter, you should be able to take over control of all Lionel command engines throughout the continental USA.

Hopefully, no one from the FCC--who is familiar with Federal Regulation Title 47, CFR Part 15--is an OGR forum fan.

@Bruce Brown posted:

If you add a longwire antenna to that 150 watt transmitter, you should be able to take over control of all Lionel command engines throughout the continental USA.

Hopefully, no one from the FCC--who is familiar with Federal Regulation Title 47, CFR Part 15--is an OGR forum fan.

I mean its funny ... but also not correct in terms of FCC things.

So no one gets the wrong idea:

1. We're not even close to a quarter-wave or resonant (600m / 1800 ft). If you look at an offset fed lambda / 18 structure (about where we are your dipole radiation efficiency is around 0.25%, like not even competing with a hertzian-dipole.

2. it's inside a building full of return wires so the E-field is going to be confined since the near field is shunted out by the near field ground.

3. It's only like 0.001 lambda over the ground so all we can do is induce an image current, not actually radiate (antennas over planes don't radiate). It's a capacitor not a radiator.

You're cool to develop whatever power you want, as long as it stays conducted and not in a radiating mode of propagation. The deflection amplifiers in an old 36" CRT are basically the same level of power and frequency as this thing. That's where I drew the inspiration for a class AB from.

Understood, the current buffer is staying in place and not implementing anything that will affect the DCS signal.  Just want to see if there are any takeaways from Adrains experiment that can be used for diagnostic purposes.

Its  interesting actually. There were some unexpected benefits... before we hooked up this mega-driver... the common mode (potential from the layout ground to building ground) had a lot of components from 60 Hz stuff all the way up to several MHz (we have a lot of radars and stuff here in the harbor). So when you would look at the time domain on the scope you'd have a broadband fuzz of 2-3V, then a general wiggle to it that was the original booster of maybe another 0.5V superimposed, then the occasional ~12V pkpk DCS packets.

With the mega-booster in place the voltage is really really well defined and crisp now... a sharp sine wave on the scope. That makes sense since the Thevnin impedance looking back into the thing is basically zip so a lot of that fuzz can't couple in. So now I see a very clean 3V at 450 KHz that transitions into a very crisp and well defined DCS packet.

It feels like what we lose in mode conversion desensitization (Lionel going from the intended common mode to differential mode potential and coupling into the DCS packet) we more than make up for by having a cleaner and crisper waveform with less of the fuzz layer on top.... It's always hard to quantify broadband fuzz, but DCS actually felt more responsive with this thing in than out. I'm not thrilled by the fact we're circulating an amp of signal current, and the SPS modules that power the driver are making a noise that tells me they aren't thrilled either.

The amp of current is what get my attention.