The Doc Posted October 6, 2019 Share Posted October 6, 2019 This question may have been asked many times before, but the search facility hasn't been any help, so here goes: I've got a TTS Gadwall A4 where the "chuff-chuff" rate matches the loco speed really well, but when I fitted an A1/A3 TTS decoder to a B17 (Barnsley) it's "chuffing" much too slowly. It sounds like it is crawling along when the model is moving at a reasonably high scale speed. A similar thing occurs with my Railroad Class 31 and 40. The diesels sound (to my ear) like they are chugging along slowly and not working very hard even if they are flying around at a scale 80mph. Is there any way, by changing some CVs, I can either make the sound chip produce "faster" sounds without altering loco speed, or reduce the power to the motor but maintain the same engine sounds? Or am I expecting too much of a (relatively) cheap sound fitted loco? Link to comment Share on other sites More sharing options...
Chrissaf Posted October 6, 2019 Share Posted October 6, 2019 Or am I expecting too much of a (relatively) cheap sound fitted loco?.YesThe TTS decoders have very little customisability..Changing the motor algorithm CV might possibly affect the sounds, but more than likely just the motor response and could make motor control worse than it currently is. Link to comment Share on other sites More sharing options...
96RAF Posted October 6, 2019 Share Posted October 6, 2019 There is nothing you can do to alter the TTS chuff rate to better match the wheels apart from use a different decoder, one say that has 2, 3 or 4 cylinder sound files that will synchronise more closely with your wheel speed. The chuff is gleaned from up to 18 separate recordings that are played in sequence at a point determined by the throttle applied, loco road speed and motor BEMF. You can adjust the BEMF cutoff point after which it is ignored but you cannot effectively change the chuff change over points. As to the diesels you can change the notching window using the TTW CVs - see the manual. This is akin to using sport , normal or ice/snow mode in your fancy automatic car, whereby the change points are moved within a specified window range. However driving a diesel is not like driving a car, as the engine is not directly connected to tje wheels, rather by an electric motor. The driver calls for power to the wheels and the engine surges to provide this power then once it is moving it drops back a pace. This occurs within the TTW range and according to how much throttle you apply determines what the engine does - rev and drop back, rev and sustain, notch up or down, etc. Link to comment Share on other sites More sharing options...
The Doc Posted October 6, 2019 Author Share Posted October 6, 2019 Thank you for your replies. It looks like I'll have to put up with the sounds as they are, or just turn them off! All the locos run very smoothly so I don't want to do anything to make speed control worse. Link to comment Share on other sites More sharing options...
Ruffnut Thorston Posted October 6, 2019 Share Posted October 6, 2019 At least the whistle still works when the 'chuff' (F1) is turned off....as do all the spot sounds on F keys.... It's just one of those things.... 😉 Link to comment Share on other sites More sharing options...
LMSFan72 Posted October 10, 2019 Share Posted October 10, 2019 Here is an idea. The TTS decoder will operate sounds without being attached to a motor. Therefore it might be possible to use a different decoder to drive the motor and configure the speed setting CVs of that decoder to match the sounds coming from the TTS. This would need both decoders to have the same address and both wired to the pickups but only the non-TTS wired to the motor... Link to comment Share on other sites More sharing options...
96RAF Posted October 10, 2019 Share Posted October 10, 2019 Here is an idea. The TTS decoder will operate sounds without being attached to a motor. Therefore it might be possible to use a different decoder to drive the motor and configure the speed setting CVs of that decoder to match the sounds coming from the TTS. This would need both decoders to have the same address and both wired to the pickups but only the non-TTS wired to the motor... Ain’t going to work...here is for why. TTS steam requires the motor bemf to regulate when chuff is on or if it should coast. The chuff rates are recorded at set speeds, not as a dynamic and progressive recording. There are usually around 18 sets of chuffs which come into play as the throttle is increased and when decreased the chuffs drop out in favour of coasting noises. You can clearly hear these chuff sets change as you increase the throttle speed step by speed step. Diesels on the other hand have only four or five bands of engine revs (notches) which respond purely to throttle amount or not in accordance with the TTW algorithms set in the decoder. This means a diesel decoder can operate in a dummy car as if it was powered, whereas a steam decoder cannot. Link to comment Share on other sites More sharing options...
LMSFan72 Posted October 11, 2019 Share Posted October 11, 2019 Oh well, just an idea! Although, given the space in the A4 how about wiring a cheap thin cd motor to the TTS and having it installed in the tender doing nothing other than spinning and a regular decoder chip in the loco.... i know you're probably getting on towards £20 above a TTS but the experimenter in me feels like giving it a try! Link to comment Share on other sites More sharing options...
LMSFan72 Posted October 11, 2019 Share Posted October 11, 2019 ...might mock that up on my test rig Link to comment Share on other sites More sharing options...
96RAF Posted October 11, 2019 Share Posted October 11, 2019 BEMF is a measure of load, so a free spinning motor will not show a load. You could try ‘braking’ the motor to induce a BEMF with dummy car throttle changes.e.g have the pinion rub against a rubber block. I’m not saying it would work but it might as an ESU decoder test rig has a free spinning motor albeit with a flywheel so some inertia to overcome at throttle change. Link to comment Share on other sites More sharing options...
Howbi Posted October 11, 2019 Share Posted October 11, 2019 I even tried various value resistors between the decoder and motor thinking that would reduce the motor voltage compared to the decoder at each throttle setting but made no difference, just got a very hot resistor.......HB Link to comment Share on other sites More sharing options...
LMSFan72 Posted October 11, 2019 Share Posted October 11, 2019 maybe diodes to do the voltage drop that way. Something else to try Link to comment Share on other sites More sharing options...
96RAF Posted October 11, 2019 Share Posted October 11, 2019 I have some low resistance, high wattage resistors (around 10 ohm, 5 W) for testing DCC controller short circuit response and they are quote large (2cm long by 1cm square) and they get too hot to touch under load, so their use as slot-car loco tamers may be a non-starter due to possibility of body damage from the heat generated. Link to comment Share on other sites More sharing options...
2e0dtoeric Posted October 12, 2019 Share Posted October 12, 2019 LMS fan - diodes wouldn't work, as they only allow current to flow in one direction, so you have immediately 'killed' the ability to reverse!A 'flowing' diode only drops about half a volt anyway, and to pass the current of half an amp, would need a pretty big case, so you run out of space again!If you have a 'proper' transformer/rectifier power supply - not a modern switch-mode - have a look how physically big the rectifier diodes are, to give you a clue. Link to comment Share on other sites More sharing options...
Chrissaf Posted October 12, 2019 Share Posted October 12, 2019 This reply is just to clarify some points raised in previous member replies. I would not recommend trying this on a DCC decoder controlled model. DC Analogue only, so not actually relevant to the OP's original question..Diodes could work theoretically, if you put additional diodes in parallel but the other way round......example below../media/tinymce_upload/28f47888d600a695d30962c6d63d3b3a.jpg.The advantage of using diodes over using a resistor, is that the diodes drop the voltage but with very little heat..The down side, is that they would also require the controller to be turned up further from the 'stop position' before the loco starts to move as the voltage drop across the diodes is a near constant. Thus the controller output (in the example) would have to exceed 1.8 volts before the diodes start to conduct current through them..If you need a higher voltage drop, then you just increase the number of diodes in series in 0.6 volt steps..You can also tweak the forward and reverse motor response by having more or less diodes in each row. So let's say that the top row controls forward direction and the bottom row controls the reverse direction. If the top row had two diodes and the bottom row had three, then reverse would have a higher voltage drop than when going forward..Diodes from the 1N4000 series would be suitable as they are all rated at 1 AMP and are physically small..This is a theoretical reply as I have never tried this in practice. I would say try this on DC Analogue locos only. May not work well with more sophisticated DC Analogue controllers that rely on measuring loco motor BEMF voltages (not an issue with Hornby's basic controller).. Link to comment Share on other sites More sharing options...
Plumloco2 Posted October 12, 2019 Share Posted October 12, 2019 Hi I used the diodes as in Chrissaf's reply in all my locos before DCC . I had a 1.5V bulbs across the first 2 diodes in both directions. It then gave me contant brightness & directional headlights. It did reduce top speed. Some locos were just too slow so was glad when DCC came along. Link to comment Share on other sites More sharing options...
LMSFan72 Posted October 12, 2019 Share Posted October 12, 2019 I have also used them previously as per Chris. I have also used SMD components, so very small size Link to comment Share on other sites More sharing options...
Wobblinwheel Posted October 13, 2019 Share Posted October 13, 2019 So, is the consensus that the chuff synchronization for the A4 TTS decoder is accurate? I've been considering putting TTS sound in one of my A4's, but after watching some videos, I got the impression that the chuff WASN'T accurate! Seemed good at very slow speeds, but didn't increase proportionally as speed increases. Was I hearing things? Link to comment Share on other sites More sharing options...
96RAF Posted October 13, 2019 Share Posted October 13, 2019 So, is the consensus that the chuff synchronization for the A4 TTS decoder is accurate? I've been considering putting TTS sound in one of my A4's, but after watching some videos, I got the impression that the chuff WASN'T accurate! Seemed good at very slow speeds, but didn't increase proportionally as speed increases. Was I hearing things? Short answer Mike is NO it is not accurate across the speed range. I find TTS steam acceptable because I listen with my ears not my eyes and once the wheels are turning at any speed no one can count chuffs anyhow. Link to comment Share on other sites More sharing options...
SteveM6 Posted October 13, 2019 Share Posted October 13, 2019 I agree with the last comment, but being pedantic, if you are watching the real thing at any distance then the chuffs don’t match - light travels faster than sound so there is a mismatch in the real world as well. Link to comment Share on other sites More sharing options...
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