Bachmann uses the 8 pin decoder. I noted looking for an 8 pin decoder that most of them on Ebay were either hard wire or nine pin. Is the nine pin the thing of the future?
the 9 pin is a jst plug. the ones I've seen are on digitrax and tcs decoders where the 9 pin plug is where the wiring harness plugs directly into the decoder. you can buy 8 pin to 9 pin adapters, those are included with digitrax or tcs decoders with the 8 pin nmra wiring harness,
on a similar note, I recently acquired several bowser locomotives which have a 21 pin plug in place of the normal 8 pin plug. I've never seen one of those before. is there any way to add dcc to these at reasonable cost short of pulling the circuit board and hardwiring the decoder?
I think you can buy decoders with 21 pin plugs.
The 21 Pin MTC decoders are mainly used in European locos. They actually use a 22-pin connector, with one pin blanked out to force proper orientation during installation. The NMRA recognizes it as a 'defacto' standard, but stopped recommending it's use in 2010.
21 Pin MTC is slowly being phased out in favor of the PluX (PluX8/12/16/22) standard, which is being adopted by both the NMRA and NEM.
Len