Chopped versus full sine wave- a missed issue with the Z-4000

That presentation has a number of errors. The critical error is running the Legacy engine on reduced voltage, not on the standard 18vrms as recommended. The sawtooth waveform and the smooth waveform would reach the same peaks (actually 25.5 volts, not the error of the mentioned 18 volts) and look essentially the same if the sawtooth waveform and smooth waveform transformers were set to the full voltage of 18vrms making most of the argument moot.

The useful advice one can get out of the presentation is if using a smooth waveform transformer, it must be capable of 18 vrms when running Legacy. And when running in conventional mode, a sawtooth waveform transformer is recommended. 

Do you really think those cheap controls are better than a ZW or a a Z-4000? You must be joking. I only run Z4000s or 180 PH Bricks and my trains run beautifully 

 That dated video, electronics have changed. I would not recommend a chopped waveform transformer for LionChief plus locomotives. The peak spike voltage kill the tiny power transistors in the circuit. Recommended DC transformer or smooth waveform transformer.

I only wish I were around for the "pitching" of the Z4000, even though it's heavy, I would have done my best to catch it!

There is no contest for command operation, I run the Lionel PH180 bricks, pure sine waves and my command stuff runs just fine, thank you.

In case my irony escapes you, IMO that's a total crock.  Under very limited circumstances in conventional operation, the sawtooth waveform helps with smoke production, otherwise it's a determent.

John, Using DCS, Legacy/TMCC only (no conventional) is there really a preference to the PH180 Bricks to the Z4000 ?

Thanks Dean

Chuck Sartor posted:

 That dated video, electronics have changed. I would not recommend a chopped waveform transformer for LionChief plus locomotives. The peak spike voltage kill the tiny power transistors in the circuit. Recommended DC transformer or smooth waveform transformer.

So...it’s the fast rise time of the peak voltage that is the issue? Because the peak voltage is the same...except for the dc option of course.

gunrunnerjohn posted:

 

... Under very limited circumstances in conventional operation, the sawtooth waveform helps with smoke production, otherwise it's a determent.

Another circumstance is with passenger cars with LED strip lighting using electronics such as:

The constant-brightness and flicker rejection performance at low track voltages will be better. 

Additionally, there is anecdotal evidence that for DC can motors, the slow speed performance (less than 10 sMPH) can be better with a chopped/sawtooth voltage.  This is because the pulsating nature of the rectified DC voltage can be more effective at overcoming mechanical impediments/variations. 

OK, I need to more specifically define my point, or I will be boiled in oil:

1) I do run conventional with a mix of Legacy and MTh locos.  I like smoke and the Legacy locos did not do well with the z4000.  Hence I am more happy with the Z-1000s.  "....limited circumstances" was my point like Stan and GRJ mention.  

2) I did have tears in my eyes when I sold the Z-4000.  it was sweet but ..... Next time I will pitch it to GRJ for sure!

3) If I remember the scope traces John and others captured of the saw tooth and sine wave, the peak voltage is not the same.  The peak of the pure sine wave varies where the chopped peak is constant.  I do have several lion chief + that have been fine so far so I would love to hear more details on Chuck's point.  

If the max of the sawtooth is the same voltage as the smooth, then the peaks are the same. 25.5 volts when the rms is 18.

i posted above that the sawtooth was reversed in the video, but it was not. Just forgot how it was drawn.

RWDeano posted:

John, Using DCS, Legacy/TMCC only (no conventional) is there really a preference to the PH180 Bricks to the Z4000 ?

Thanks Dean

Not really, it's just that the Z4000 is much larger and more expensive for the same power.  If you're strictly running command, the bricks are considerably cheaper for the same power.

Z-1000 half throttle.

Z-4000 half throttle.  Note voltage at lower right is wrong, it should be 10V, probe setting wrong when I shot the screen.

As you can see the sawtooth waveform is about the same peak voltage as the somewhat distorted waveform of the Z-4000 at similar throttle settings.  Also notice all the "hash" on the baseline of the Z-1000, this is likely what drives some engines nuts.

CW-80 at half throttle.

As you can see, the excessive ringing on the CW-80 is likely where it got it's bad reputation, that's almost surely what causes issues with specific engines.

gunrunnerjohn posted:

RWDeano posted:

John, Using DCS, Legacy/TMCC only (no conventional) is there really a preference to the PH180 Bricks to the Z4000 ?

Thanks Dean

Not really, it's just that the Z4000 is much larger and more expensive for the same power.  If you're strictly running command, the bricks are considerably cheaper for the same power.

One of the issues I've found with the Z-4K when running Legacy command is with the watch dog signal in that if I bring the throttle up slowly the Legacy engine thinks it should be starting in conventional mode and won't respond to Legacy commands. The easy solution, of course, is to raise the throttle quickly to vertical (which is about 18v). You would think that you could just leave the throttle at the vertical position and just turn the Z-4K on and off and problem solved, but it doesn't work that way. The Z-4K has some sort of failsafe operation where it won't start if a throttle is left up - you have to bring it back down to zero first. The Brick doesn't have that kind of issue because you just turn it on and you have 18v, so slight advantage to the Brick.

Street price of two bricks is about $220.00 and the Z-4K is about $360.00 so there is a significant but not huge price differential, so advantage Brick.

With the Z-4K you can run conventional engines using the throttles if you want, but you can't do that with just the Bricks, so advantage Z-4K.

The Z-4K also has two independent outputs (14v and 10v) at the rear to run accessories, which the Brick does not have, so advantage Z-4K.

The Z-4K has killer looks and displays nicely, while the Brick looks like a sticky mouse trap - advantage Z-4K.

Your mileage may vary.

I have a Z4000 on my work bench and one for my test tracks I use 5 PH180 bricks on the layout with one on the shelf for backup. I run strictly command so the bricks are what I want, power in full voltage and 10 amps. I need more options on the work bench and I absolutely need the voltage and amperage meters. I have plans to put meters in the layout but haven’t yet and it looks like I’m losing access to the layout so they bay never get there 

cjack posted:

That presentation has a number of errors...

Yes, I've had problems with that clip since it went live.

Regaurds to Z4K handle voltage rise slowly, I use the Z4K receivers, with the DCS remote program start voltage, this allows you to set start voltage from zero to (x) ie. I use 0 volts  straight to 17 volts then range limit, I use 22volts top setting. This is a feature I enjoy with (3) Z4K's and 6 tracks. (more than 6 tracks requires combining some tracks with additional Z4K's) I never touch the Z4K. Trade off is the loss of the Volt and Amp Meters on the Z4K. Read out is PG I believe,( I have the Z4K's under the table so I really can't see the meters anyway). So I just ordered Digital Volt Amp Meters from Tony"s Train Exchange, RRAmp Meter Version 4, AC volts 0 to 27.6 amps 0 to 18/20 ( with 3 digit readout less value of 10.0 gives hundreiths above 10.0 tenths) This way I will mount these in a visible location. 

Dean

I wonder if there might be a slight possibility that big L might have slanted the video in their direction and against the Z4K? Naw, what am I thinking? 

Rod