Suzie

I think that this is the problem item. I don't know what it is, but you need to replace it with something that gives out at least 24V DC or at least 16V AC. 16V DC is not enough input to a CDU.

It can be a serious problem - I saw one very large chap lean all his weight up to his elbow on to a large 0-gauge layout supported on slightly fewer trestles than it should have had which dipped about six inches under his weight. I think it survived but there could have been a very nasty mess.

Tune in app works, but stops working when you are out of cellular telephone range.

It would be nice if that radio app was there...

That is a controller setting and not a decoder setting.

I just got a secondhand Tesla X and it seems like quite a nice car, but it is looking like a radio is an optional extra on modern cars as I cannot find the radio. Satnav appears to use Google which I guess is O.K. although I would rather have Waze. It has taken a fortnight to get access to the glovebox which was protected by a PIN number - which could only be cleared by sending a photo of the V5 to Tesla, and DVLA do not send the V5 out as quickly as they might. It has been quite a learning experience. I am especially not getting used the doors and everything being motorized - even the charging socket cover has a motor to open it. I was quite impressed that the granny charger it comes with is 3-phase - so it will charge at full 11KW AC rate if I find a suitable red commando socket to plug in to! Looks like lots of room to cart bits of layout around which is the important thing of course.

You need to look at the original post - it asks a general question. To which you can only give a general answer. I gave up with sub £25 decoders for general use some time ago because they all had shortcomings that made the cost saving not worthwhile most of the time (along with a lot of the more expensive decoders). If £25 is too expensive, then people will need to say what compromises they are prepared to make (poor motor control, unreliable packet decoding, noisy motor drive, complicated motor setup, insufficient function outputs, wrong size, inadequate power output, etc.) I am sure that there are some cheap decoders that work well in some locos, but there is no general cheap decoder that is universally good. I have tried a lot of decoders, and there is only one brand that makes decoders that can just be dropped in to any loco which will work without any configuration, and they do that for around £25.

The cheapest is most unlikely to be good enough. Plan to spend £24 for a direct plug-in decoder, or £25 for one with wires and get a Zimo MX600 (wires/wired plug), MX637(PluX22) MX638(21MTC) or MX618 (Next-18).

Also how fat is the wire in the 25-way cable? You can solder 16/02 wire quite easily in to a 25-way 'D' connector and a couple of these should suffice to carry the DCC a short distance, but 25-way cable is only likely to have 7/02 wires in it at best (and most are thinner than this) so you will really need four per bus wire if the 25-way cables are any length.

The DS64 will operate four signals but you will have to set it up to operate 'slow motion machines'. Manual for the DS64 is here:- https://www.digitrax.com/media/apps/products/stationary-decoders/ds64/documents/DS64_flattened.pdf

Yup! That is the problem. Electrofrogs are so much easier with DCC, it is no surprise that the only trouble you are having is with the Insulfrogs.

I think you will find the problem is with the Insulfrog point and not the Electrofrog one. Try putting insulated joiners on the Insulfrog point frog rails and see if the problem goes away. Insulfrog points specifically are not suitable for use with DCC because the frog rails are too close together and can be bridged by the tyre of the wheel - other dead frog points don't have this problem.

What is the resistance of the coils on the failed relay? they should be between 864 Ohms and 1056 Ohms and if they are you probably have not damaged the coils. If the coil is damaged it is probably down to not using an inverse parallel diode to divert the back EMF from the SEEP motor (1N4148 diodes are ideal for this and very cheap).

I suspect that you may have a faulty relay here. Those you have are good for up to 27V so you cannot cook them from the 24V output of your CDU. The most likely thing that has happened is too much current through the contacts welding them together due to a shorted load when testing. Sometimes a good beating with the wrong end of a big screwdriver can free the contacts but it might be permanently dead. Carefully check that you have wired the contacts correctly, they are not always connected intuitively. I would not give up yet - plenty of people have achieved excellent reliability so stick with it.

There is a lot of wire and choc-blocks in line with the DCC feed from the ECoS to the track. I think that simplifying it might help a bit - much as it goes against the grain for making fault-finding easy.