Which decoder for which loco

QUOTE (digger1962 @ 8 Jan 2009, 15:44) <{POST_SNAPBACK}>I'm sure this is going to sound like a pretty daft question to those of you who use DCC, but at the moment I don't and am unsure. I am considering converting my current DC OO layout to DCC.

There seems to be a number of different types of decoder on the market from a number of manufacturers. Add to this the fact that you can get single sided, double sided and some without any wiring harness at all I'm confused as to which will fit my locos.

Are there any sites around that give advice on which ones fit specific locomotive? I don't particularly want to purchase one only to find that I can't fit it due to space constraints.

The option of no wiring harness looks the better option to my uninitiated eye, but I guess there are reasons why it might not be the obvious choice.

Any help would be most gratefully received as always.

Many thanks.

Mark.

Mark

For non equipped locos (with no 8 pin board ' known as DCC ready) the all in one with no harness is not for you (the ZTC 4007 as an example) get one with a harness, remove the 8 pin male plug on the end and follow the steps on many sites that show how to hard wire a decoder in; try at all times to use heat shrink over your soldered joins and keep the final wired unit nice and tidy to avoid any moving parts coming into contact with the harness of wires.

I have done many non DCC ready loco's and have not (yet) experienced any difficulties; plus the fact its quite nice to potter away in this manner, pop the body back on etc etc; you can also if you feel brave add lighting and such things as smoke fans on diesels or smoke in steam, all controlled by the chip; it'll default as CV1 to number 3, so for short addressing change to say the last couple of numbers as the cab. If you own an ECoS controller then numbering is really a thing of teh past although each unit will still require a dedicated number.

All the best

CFT

I too like the TCS decoders, DP2X-UK for the direct plug in, M1 and M1P for those with a little more room. I can't say I have tried the MC2 but if they are as good as the M1 (or better) then they are certainly worth considering. Price-wise, the TCS decoders generally represent very good value for money.

For Heljan diesels I have standardised on ESU decoders (LokPilot and LokSound) and these work very well with the Heljan mechs, which consume a little more power than Hornby or Bachmann types. Finally, for those locos I only occasionally use, such as the NRM Deltic, Falcon and 57 601, I use the cheapie Bachmann decoder (which is really a stripped down ESU anyway), which has fewer fine-tuning capabilities bu still works very well in the diesel outline models with can motors and heavy flywheels. ESU prices have recently gone up so I'm not sure how they'll stack up in the value stakes.

Lenz are good but expensive.

I do have a few Digitrax decoders but I don't find the fine motor control all that good. However, they have issued a new, updated range recently with BEMF which may well work better. For hard wiring Bachmann SR N class 2-6-0 locos the DZ123 (now DZ125) is one of the few that will fit in place of the circuit board within the firebox (the circuit board gets discarded during the hard wiring work).

Most decoders do have a power rating. Older locos can take more power to run but, strangely, this power curve is not linear. Start up can consume power as can the load on the back. Full speed running also makes the chip hot. In between these two extremes is a happy medium.

Most of us enjoy running locos at more prototypical speeds for the sorts of layouts that space considerations force on us. This is particularly true of steam and even Britannias which had poorish brakes for their weight and relied on not entering situations at speeds that required heavy braking anyway.

Most decoders are adjustable for speed. There are two ranges of CV's 2, 6 and 5 which control start voltage, mid and top speed. The max value for top speed in CV 5 is 255. If a speed table is enabled then this value will be in CV94.

Most express steam engines such as the Brits would only reach speed on a long gently graded and curved track with no junctions or turns within miles. I think one would need about 70 ft by about 50 ft layouts to enable such speeds realistically.

Dcc is a revelation in terms of slow speed power and prototypical acceleration rather than the sudden flying starts and unprototypical speeds that DC has traditionally offered.

Hi Sennapod

Top speed is not governed by the power rating of the decoder - the 1 Amp rating is the maximum permissible power it can handle.

The speed of the locomotive is governed by the DCC track voltage and the the decoder settings for motor control. If the decoder is still at the factory default settings the top speed will be the maximum available . If the track voltage is 14v then the motor will receive about 13v. The Old DC controllers can sometimes put out around 17v giving a greater top speed.

The Motor receives pulses of power from the decoder , so the power is not on 100% of the time , at top speed it may have power on for 90% of the time . decoders with Back EMF detect voltage when the motor power has been switched off.The motor acts as a generator when no power is applied , then the decoder can measure this for motor control
This is an over simplification to what actually happens though

Some motors do run better than others under DCC control , Some of my older Fleischmann loco's are the same -only running at about 60% of the top speed that they would on DC (my DCC track voltage is about 14.5v) they did run the same as the old DC controller when the DCC track voltage was 20v with my bad old Roco power Supply - but that caused other problems - internal lighting in coaches very bright etc.

But even at 60% of the old top speed they are running faster than the scale speed of the real locomotive

Regards

Zmil

***To correct Davids post.

The maximum in a CV is not always 255. It can also be 64.

The option for every speed related CV is zero, which by default in every brand is a direct equivalent to maximum - therefore, if you are not sure your decoder is set to max possibility in every way you have two options.

(1) do a factory reset which will set Mid and top volts to zero

(2) check CV5 and 6 and change them manually to zero.

*** Sennapod: In either case the loco which is running slower will be doing so because of track voltage as Zmil said. If you have one of several unregulated brands of DCC you could increase track voltage a little by using a slightly higher voltage transformer. If you have a better brand you MAY be able to increase it via command centre settings... you will need to read the manual or tell us the brand so we can advise you. Bear in mind that there are negative results from increased track voltage - including premature decoder death and coach and loco lighting that, if incandescent not LED, may either burn out or melt the item its installed in.

In either case, manufacturers now make loco's more for realistic speed than top possible speed... so its a "patch" for you, not a general market need

Richard

***Hello Mark
The capacitors are there for when the loco runs under DC, to stop interference.
* When a decoder is installed, it contains far more effective suppression parts and the caps on the loco are just not needed.
* While their effect may be greater or smaller depending on the loco, what they ALWAYS do is come between the motor and the decders back EMF, filtering and masking it so that the decoder is not able to make the loco work as smoothly as it would with them removed.
* It is always OK to remove them and doing so will have no negative effects at all on loco or loco performance - ever!
* Many locos will run far, far better on DCC with them removed but a loco will never run better under DCC with them in!

It takes only two snips with the cutters - just remove them. (yes, there can be more than one) by snipping very close to the capitor disc and make sure the bare ends don't contact metal. they are always across the motor leads so removing them changes no part of the motor drive circuit.

regards

Richard

You have to be careful with some of the new Hornby locos as the leads on the cap are are quite short and snipping the lead could lead to an inadvertant cutting of the motor lead. Best to remove the shrink wrap, unsolder the cap from the wiring and do this one leg of the cap at a time so you don't mix the wires up, cut a new piece of shrink wrap and slip over one wire, solder the wires back together and slip the shrink wrap over the join. Repeat for the other leg.

Charles Emerson
Queensland
Australia

QUOTE (dwhite4dcc @ 12 Jan 2009, 01:13) <{POST_SNAPBACK}>Mark,

The strict answer to your post is no, it is not absolutely necessary.

Richard is also right. Quite a few locos seem to run on chips better without any of the manufacturers electrics at all.

I have left them in on some and taken them out on others and I really believe that the quality of the chip dictates more than the removal of any capacitors.

I had to leave the capacitor in on a Hornby Q1 as when I snipped it, post install, the loco died. Had to solder it back in!!