NIK

Hi, A ESU Lokpilot 5 DCC decoder arrived and I replaced the Zimo MX634D with the ESU decoder to try and improve the running. I put the revision 2 Hornby 4 VEP power coach on my rolling road and ran the ESU Lokpilot 5 "Autotune" feature. I didn't get the same motor control (Back EMF etc) CV values as a friend who autotuned his 4 VEPs on the flat bits of his layout. I only have a 4 foot test plank to hand at the moment and the autotune runs the powered vehicle at high speed for 1.5 to 2 seconds. As the values on the rolling road were noticeably different I used CV values similar to his: CV51 = 11 CV52 = 4 CV53 = 94 CV54 = 29 CV55 = 16 Slow speed running was then pretty good on the flat but when I made quite a down gradient the VEPs speed was a bit erratic. I lowered CV 55 value to 8 and that made the down speed smoother. Next to try it on Beggarwood Lane with all the VEP coaches, first the EMU on the flat and then down the gradient. Regards Nik

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Hi, Did you mean LMR in both instances?. Regards Nik

Hi, Just for a bit more detail, without a suitable current limiting resistor between bridge rectifier a typical DCC decoder bridge rectifier will be damaged by the initial current as the capacitor charges. A diode is needed between the capacitor positive back to the +ve on the bridge rectifier so the charge from the capacitor can be supplied to the appropriate bits of the decoder when contact is lost with the track. Regards Nik

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Its near the end of the financial year so pick any road - it will have roadworks on it.

Hi, I had it a number of times recently while creating or editing an RMWeb topic reply. Regards Nik

Hi, I've just had a funny one while evaluating a new (revision 2) Hornby OO 4 VEP in SWT livery. I noticed while trying the DCC slow running of the power car on a test plank that it was jerky in one direction (to the left) but smooth in the other. Turning the power car end for end and it was smooth to the right and jerky to the left. I cleaned the track, added a stay alive and tried adjusting the Zimo MX decoder K and I parameters to no effect. I then noticed the test plank has a slight slope to the left. Levelling the plank and the power car was smooth in both directions. Making the plank lower at the right hand end makes the power car jerky running slowly to the right but not the left. I will check the flatness of the club layout I intend to run the VEP on (at least the bits where the VEP may be running slowly and are also seen by the public). I've got some ESU Lokpilot 5 decoders on order so they may help with slow running on gradients. Regards Nik

Hi, I've just noticed on my SWT new 4 VEP power car the slow running going forward is a lot better when the power bogie is at the 'front' than when it is at the back. Does the great weight over the motor bogie crush dirt on the top of the rails so the pick up on the trailing bogie is better?. Regards Nik

Hi, Re surface mounted point motors I would avoid the micro linear servo type as they tend to have not enough power to reliably operate points. Regarding DCC decoders for locos I try and use Zimo decoders when they are available. Of course selecting a decoder that is small enough and powerful enough is a higher priority than manufacturer. I don't have much experience about consistent stopping and braking especially if you intend using ABC control with distance control. Regards Nik

Hi, According to the Hattons DCC decoder manual and JMRI Decoder Pro definition the Hattons decoders do not have a brake on a function feature. Did you mean a MERG CANCMD2?. Regards Nik

Or the original Hornby 4 VEPs - the mystery being how the two designs got approval. Regards Nik

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Hi, Its section 11.1.4 of the Lokpilot 5 manual that deals with 'autotune'. I don't know if this also works on rolling roads as in that case most of the loco has no momentum. Regards Nik

Hi, I've yet to fit a servo in a model railway vehicle but servos typically need a power supply of 5 volts and they draw hundreds of milliamps (more than a 5V logic level output from a small decoder). As far as I know small DCC decoders that can control servos don't come with 5 volt power out. One way is to make a circuit with a fast bridge rectifier to convert the DCC to DC and then a DC to DC converter to drop the rectified voltage of about 12 volts down to 5 volts. I don't know if anyone makes such a circuit, German or USA suppliers would be the most likely to. Regards Nik

Hi, I spoke to a club member who has just bought two SWT 4 VEPs about the slow running problems I had with mine. His VEPs ran badly with ESU Lokpilot 5's until he did the autotune. So I will try a Lokpilot 5 and see if it improves the running on mine. He also said the wheels look rough and sound rough at speed. I've now done a few runs of the VEP on a club DCC layout and it runs smoother with the three trailer coaches. I help with a gradient and curve predictor which predicted the VEP should just go up a 1 in 40 gradient with 36 radius curve given a run up rather than a standing start. The 4 VEP would go up the gradient with curve without signs of spinning. However I haven't measured the static friction of the trailer wheels yet and they have an effect on the prediction. The VEP would not haul any extra coaches up that bit of track although the club coaches to hand were not free running. There was one two inch long stretch on the gradient with curve where the 4 VEP would not start without spinning its wheels but apart from that it was fine (the gradient/curve predictor does not presently deal with starting on an up gradient/curve). Until the whole layout is up I wont try any speed tests - will it exceed the 130 scale mph my original 4 VEP does?. Regards Nik

To add to what Andi said, there are commercial DCC decoders that offer control of servos. Regards Nik

Hi, At last the nearest to an exhibition friendly box for a multiple unit. My SWT VEP runs poorly (stuttering but not cogging) when slow in one direction but smooth in the other (Zimo MX634D decoder). Tried adjusting the motor CVs to no avail. Lights not flickering but will try adding stay alive. I think the wheel flanges are finer. The trailer coaches have 12mm dia wheels and the motor coach ~13.3mm dia. I will have to start saving in the hope Hornby do the Blue Grey unrefurbished VEPs to the same standard. Regards Nik

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Hi, The motor coach turned out to weigh 427 grammes, so just 11 grammes more than the Bachmann 4 CEP equivalent and one gramme more pull (47 grammes) than the 4 CEP. I haven't measured the static friction of the trailer coaches but the gradient and curve predictor I've been helping with predicts this 4 VEP should be able to start on a 1 in 40 gradient with a 36 inch radius curve. Once I've DCC the VEP I can try it on the 1 in 40/36" radius gradient on the club layout Beggarwood Lane (although the incline is scenic and has no third rail so VEPs and the like wouldn't in reality go up it without diesel assistance). Regards Nik

Hi, Just received my 4 VEP in SWT. The power car may be the heaviest RTR OO EMU power car at 427 grammes. I haven't got a way of measuring OO speeds at the moment but here is a plot of current vs. DC voltage for the power car (with interior lights): I'm going to dig my vernier callipers out to measure the wheel flanges and other wheel dimensions. Regards Nik

Hi, Excuse my ignorance but how do you get 20% off?. Hi All, Note when I bought a SWT 4 VEP from Kernow and selected Royal Mail I was charged £15 for postage. Regards Nik

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Hi, Beggarwood is largely down for an extended period while another club layout has its wiring completed in time for our exhibition on the 9th and 10th March. The SR C-C booster loco was tried out on a few tracks and the jury is out on whether the large wheel slop causes problems on the layout. I noticed one coupling was drooping and that may have caused a tendency to derail. Once derailed it had a tendency not to re-rail itself on trailing points but that may be due to our third rail which is in the process of being lowered. The loco has not been timed yet to see if its fast enough for passenger trains. One of the revised Hornby 4 VEPs in SWT livery has been ordered for evaluation of the cab ends, roof ventilators and the chassis. Our open days are a free for all stock wise so hopefully the new VEP once DCC'd will get a run out at out next open day on the 7th April. I might try and sneak the Jaffa Cake 4 CEP into a carriage siding. If we get enough funds and a following wind the layouts may be in our new club hut. More scenery is being added neat the tracks and could encroach on signal sight lines and signal locations so we need to get signal positions finalised. We have a signalling engineer in our club so we need to run the finalised plan past him. We now have a Just Giving link on our BNHMRS website for fitting out our new hut, so any donations would be gratefully received. Nik (on behalf of Basingstoke and North Hants Model Railway Society - still looking for members)