DigiTrax Simplex v Duplex

[Edervarg]

Hi, I am a newbie to this forum and relatively new to Model Railways.  I am building out a mid sized Christmas Diorama in HO scale to go under our Christmas Tree.  I have a Z21, 3 x Digikeijis DR 4018 - 2 for turnouts and 1 for various LEDs.  I also have a DR4088RB.  I understand track voltage from Z21 is 16v AC (I think), I also have a couple of 12v 4Amp DC adapters I am using for lights.  The local supplier who provided some of the kit advised and sold me a Roco power supply 16v 50VA which he said I should be using for multiple lights and as the power to the Digikeijis devices.  So my questions are why use DC vs AC and what are the pros and cons?  Also I read somewhere that best to be driving LEDs at 12v (when rated for same, most purchased 12-18v) rather than higher as they burn out faster.  I have searched the internet but find the discussions confusing and often not relevant.  Any advice please??   

Edited September 7, 2020 by Edervarg

[Newbie2020]

I'm setting up my first layout and thinking of going down the DigiTrax route with either Digitrax EVOXD Evolution Express Advanced 5A/8A Duplex Starter Set or Digitrax EVOX Evolution Express Advanced 5A/8A Starter Set. 

 

Am I correct in thinking that the latter is the simplex version? If so, what benefits does Duplex offer for the extra 100 pounds(ish) in cost?

 

Clive

 

Think this ison the wrong bit so Ive re done it in the questions section!!!

Edited September 7, 2020 by Newbie2020

[Oldddudders]

The cheaper version is tethered only, as it arrives. No radio, no infra-red. Add a UR90 and you get infra-red, as the throttle comes with that capability. It does not have duplex or any other sort of radio capability, even if you add a UR93. For that you need the DT602D throttle.

[brossard]

The choice of DCC system usually comes down to look and feel I think.  All the "proper" systems do what they say on the tin.  I had a Digitrax system but never really liked the feel of it (and neither did any of the club members).  The club settled on NCE as a standard.  That was more than 10 years ago and it has worked great in all that time.  I like that I can hold the NCE throttle and access all the controls with one hand.

 

You probably should take a look at other systems before deciding.

 

John

 

 

[Nigelcliffe]

41 minutes ago, Newbie2020 said:

I'm setting up my first layout and thinking of going down the DigiTrax route with either Digitrax EVOXD Evolution Express Advanced 5A/8A Duplex Starter Set or Digitrax EVOX Evolution Express Advanced 5A/8A Starter Set. 

 

Am I correct in thinking that the latter is the simplex version? If so, what benefits does Duplex offer for the extra 100 pounds(ish) in cost?

 

 

The systems under discussion use Digitrax' new DT600-series throttle (looks like an Owl).  This is a substantially better throttle to use than the old DT300/DT400/DT500 designs.

 

Simplex = Digitrax' old Radio throttle system.  Now obsolete, and not relevant to the context of a new system.   Allowed one-way from throttle to command station (so cannot get any data from command station back to throttle).   Not legal for use in UK/Europe (wrong radio frequencies).   I think Digitrax can't repair some of it now due to lack of components.  Anything on sale for Simplex will be old stock. 

 

Duplex = Digitrax' newer Radio throttle system.   Legal in Europe/UK (technically only if its the "CE" badged versions, but radio spec is the same between those with certificate and those without).   The newer UR93 transmitter reported to be significantly better than the old UR92.  

 

Also available from Digitrax are the "non-radio" versions, which are typically £100 cheaper than radio (ie. the cheaper of the systems discussed).   So, throttle is wired to base station.  Can unplug and move to new position whilst train is running.    Those would support Infrared wireless (one direction) with an appropriate IR receiver (I think the DT600 series still do IR).  But, IR is unreliable, requires line of sight, etc..  OK for limited use at homes, but not a patch on Radio.  

 

Final option for wireless is WiFi.  Can be either via a computer (eg. running JMRI), or the Digitrax LNWI device.  The Digitrax device is NOT certified for UK/Europe, so technically not legal,   but wireless frequences will be close to those which are legal.   Requires a WiFi capable throttle, which is either a smartphone running a suitable App (EngineDriver or WiThrottle being the two main choices), or a WiFi hardware throttle (TCS have one on-sale in the US market, or DIY options). 

 

 

- Nigel

[Oldddudders]

Also worth noting that the DCS210+ (it is sold with a USB connection, which I think is the plus) command station/booster is not sold separately by Digitrax, other than in these Evo sets. I have no idea why. 

 

I can suggest that if you are interested in Nigel's suggestion of DIY Wifi, you look carefully at the costs of the Evo systems against buying individual items. Little point in having e.g. the tethered system and then adding DIY Wifi if you find the DT602 doesn't get much use. It may, though, be that Digitrax has priced the sets as a bargain, although I doubt that. If you buy individual components then the command station/booster will have to be the DCS240, which is very highly specified (400 locos and 400 throttles at a time may be more than you anticipate using), and not cheap.

 

I have happily used Digitrax for more than 20 years, but that is not to say it is the best, or best value, system for you. 

[Nigelcliffe]

I sort of agree with Ian's comment on separate vs. complete set, and sort of disagree.   Even if the DT602 isn't going to get much use, I'd still get at least one full-feature Digitrax throttle.  So, if stuff isn't working, there is a fall back to test things.   Which means buying at least the cheaper Evo set (or going for the DC52 Zephyr instead as a system).  

 

I don't think any of the WiFi throttles can do programming (suspect not, because I don't think programming is part of the WiThrottle Server protocol).   So, absence of a Digitrax throttle would mean only programming option (for even the most basic such as setting loco address) is via computer and software such as JMRI/DecoderPro.  

 

Much as I like JMRI (I designed the roster view in DecoderPro), I'd still like to have a "only using the maker's option" for fallback in the event of something not appearing to work.  

 

 

 

- Nigel

Edited September 7, 2020 by Nigelcliffe
typo in second para

[Michael Hodgson]

The whole principle of DCC controllers such as Z21 only works by supplying AC to the track.  

The locos have DC motors and have to be fitted with a decoder "chip" which converts the power to DC as well as acting on instructions sent as data to them from the DCC command station.

 

LEDs run at only about 10% of your 12v supply.  They will burn out if too much current is passed through them.  To prevent this from happening, you have to include a resistor in series with each one to limit the current they draw.  You could run them at say 16v, but then you would need a higher value resistance. 

 

LEDs (and standard diodes) only conduct electricity in one direction, and AC conducts in that direction only half the time.  As they break down if power is applied the wrong way across them you would also block this reversed voltage by adding a diode connected the other way round if you want to run them off AC.  This converts the AC to "half-wave" DC. 

 

Lamps would be supplied with a resistor suited to the voltage specified, 12v being the most usual as it is a commonly available DC voltage.  If it was specified that they can run at up to 18v, they should therefore be supplied with such higher resistance, but you would be safer running them at this lower voltage, and they would not be quite as bright.  

[Il Grifone]

The LED series resistor is calculated from the supply voltage less the LED voltage (This varies with colour from about 1.5V for red to about 3V for white). It's not very critical, as LED brightness does not vary a great deal with current, once they are near full output. I aim for 10mA which gives 1kΩ for 12 V and 1k5Ω for 16/18V.

As regards AC versus DC, LEDs should be fed from DC (incandescent lamps don't care), so a bridge rectifier is necessary. Smoothing the supply (a 1000μF capacitor should be sufficient) will eliminate any flicker.

 

Power supplies are usually nominal, quoting voltage at full load. The output can be several volts higher under light loading. Keep the lighting circuits separate from anything with intermittent loading to avoid brightness changes.

[Edervarg]

Thank you all for your input.