TTS decoder in different Loco

[Kev C]

 

Hi - I am new to DCC and Hornby TTS Decoders . If I put say a Class 66 decoder into a Class 59 . Apart from the sounds not being true to the Loco Class will it still work ok and is this the same for steam locos ?

[96RAF]

Welcome.

Yes it will and yes it is.

[Kev C]

 Many Thanks RAF96

[96RAF]

Run what you like unless you are a rivet counter. I have a TTS Class 67 diesel in my Class 90 electric and no-one has noticed yet And a Tornado in my GWR pannier tank.

[2e0dtoeric]

It will sound a bit odd if you put a diesel decoder into a steam loco, though!  😛

I suppose you could tell anyone who comments that it's oil-fired, not a coal burner!

[96RAF]

It will sound a bit odd if you put a diesel decoder into a steam loco, though!  😛

I suppose you could tell anyone who comments that it's oil-fired, not a coal burner!

 

To be fair a lot of mine are just mounted in a representative platform for testing. I could get away with any appropriate class chassis with a cardboard box on top.

[Fishmanoz]

Will still sound odd if you haven’t matched the box class to the decoder!!

[blackfive41]

I would not recommend fitting a Hornby TTS decoder into Bachmann, Heljan or Vitrains locos.  In simple language the TTS range of decoders does not provide enough power (amps) for many of the motors used in other manufacturers products.  The decoder will 'burn out'.  You tube has videos of peoples bad experiences in using the TTS decoder in Bachmann, Heljan and Vitrains locos. Not seen anything about Dapol.  But that does not mean there is not a problem.  It gets technical in deciding which other manufactures products you can safely use the TTS decoders in.  Perhaps the moderator can elaborate further.   

[96RAF]

If in doubt about a particular model then carry out a simple DC stall current check of the motor and compare with the TTS or your particular spec. Same principle if you change the speaker or install lights - stay within spec. Never stall check a model with a decoder installed, always unplug it.

 

As an analogy you would not carry more people in your car than it was designed for nor would you tow a trailer heavier than the manufacturers posted limit, so why do folk complain when they overload a decoder and it fails.

 

Oh - and don’t believe all you see on blather tube. The duff posters are usually easy to spot but you have no way of checking if they know what they are talking about other than your own prior knowledge, in which case you probably don’t need their input anyhow.

[2e0dtoeric]

Almost totally irrelevant, but I agree with not believing the babble-channel.

I was looking for set-up guidance on a new bit of kit - nothing at all to do with railways - was watching one that looked promising, but then noted that he couldn't even get the product name correct, either in the text or his speech, and it is only two letters, a central digit and a mathematical symbol!! (X9D+, if you wanted to know!). He managed several variations of the possible combinations.  😮

Bin!

[Chrissaf]

I usually end up screaming at the screen in frustrated anger with some of these 'so called' YouTube experts. When it comes to electrical matters, they are nearly always talking complete and utter drivel. Most of the so called reported problems are 'self inflicted' issues borne out of their ignorance on the subject.

[SteveM6]

“YouTube says, so it must be gospel” I despair sometimes.

Yes it’s always best to do a stall test and TTS may not cope with older locos of any manufacturer but with the current crop of locos there isn’t going to be an issue.

I have fitted TTS to a number of Bachmann and Dapol locos and the only issue is the height of the DCC socket when combined with an 8:21 adapter which is fairly easy to solve.

[Phil_Spiegel.]

For those possessing a multimeter ( as everyone should. ... Especially if fitting decoders to locos ) .... A 'less stressful ( to the user ) method of assessing the 'stall test' is to use the multimeter to measure the impedance of the motor directly ... ..and do some very simple arithmetic....   V=IR is ohm's law.  The risk is having too much current ...resistance stops this.

V =track voltage ... For 'safety'' assume 20 Volts ( round figure close to maximum possible)

R= motor resistance ..... If it is 40 ohms or HIGHER then the maximum current possible will be 0.5 Amps which is the continuous rating for the TTS decoder motor.

Hand turn the motor, if possible: you may notice momentary dips in the resistance, as the coils switch, and 2 are momentarily in parallel..... This is the worst case value, and will be half of the higher measurement.

A Dapol 0 gauge class 08 shunter motor resistance measured 80 ohms. .... So okay.

Heljan diesels are well known as taking a high current .... And I have found that a 10 ohm (and high, 10 watt rating) resistor, in series with the motor, will prevent the current rising above 0.5A, therefore allowing a TTS decoder to be used safely ( no risk to the decoder )....

( the decoder is rated for a momentary 0.8A ...which may occur as the coils switch under slow rotation... Or if stalled at that precise position)

But obviously this reduces the power available to the loco motor ...... And if you have inclines on your layout, a helix, or perhaps tight curves, or run long, heavy trains, you !may observe the power loss .... But you can safely turn the 'speed' (throttle) up to compensate 8-).

If you are modelling a traction depot .... One of the greatest opportunities to use mass diesel sound and deafen people... Then you should find that the TTS range provides an affordable way of providing that synchronised sound. And an aubibly idling diesel justifies the time taken to change direction etc, and adds gravitas.

I'm looking forward to the next batch of releases being announced: Hopefully 'classic' and 'modern' DMUs ....as these spend much time idling away in platforms prior to running their next service !  

Then we need a 'small package' which will allow sound to be included in all those small steam locos from a Terrior upwards.

(Note that I have opted for safe values in the examples above .....if you accept that your track voltage is lower, such as 15 V on track  giving a max of 12-13V across the motor, then motors with lower resistance can be okay.  V=IR. 12= 0.5 x 24 .... 24 ohms lowest value ..

Or perhaps 12 = 0.8 x  15 as the coils switch .....30 ohms when only 1 coil in circuit.

The other, safe and non-depowering method for a diesel, is to use a separate silent motor decoder .... Especially one which allows functions to be user-set. Then the TTS is just adding sound ..no problem,  apparently this is not effective for steam because the TTS decoder would be unable to monitor the motor commutating ...from which it assesses speed ???

Note that at a talk to MERG many years ago, Bernd Lenz advocated that the current when wheels slipped under a heavy load, was a better guide for measuring  maximum. current demand ( continuous) than the actual stall current ( no motion, noback emf ) .... Their decoder rating includes both a continuous current and a reference to that (stall) for up to 3 seconds.

But the meter measured value should be the most pessimistic assessment... And if that says its okay then it shouldbe

 

 

 

[96RAF]

Be aware that TTS is self protecting on the motor circuit but not on the functions output, hence switching on lights and sound (even if within limits) can invoke the overall protection if the motor is already taking the current towards the top limit.

[ColinB]

I have used TTS decoders in my Bachman A4 loco and it appeared to work OK. I had to change the speaker as the Hornby one didn't fit. I don't know how the circuitry of the TTS is designed, because most modern electronic chips have port overload protection as standard ( I am sure the PIC has ), so how Hornby manages to supply a chip that has no overload protection on its ports (DCC calls them functions) defeats me. I bought a Bachmann really cheap DCC chip, off Hattons, and the data sheet goes to great lengths to say all its functions are overload protected.