My Deltang Tx have a single indent, usually 0% throttle and maximum throttle. I was thinking of speed matching a pair of locos with each loco controlled by a different Tx. If two or 3 intermediate detents were available I could speed match the locos to one of them. This could give more flexible consisting?
Could you fit such an item to a Tx?
I'm not 100% sure I understand what you are after here, but for what its worth, the speed control on a Deltang transmitter is just a 10k potentiometer, with a single centre detent as you say. This just feeds a DC voltage to the transmitter pin.
You can replace this with another 10k pot with whatever you want by way of detents and it will still work OK.
However I have found the centre detent one very hard to find as a separate component, I'm not sure you would find anything more elaborate.
An alternative approach would be to fit some sort of preset or trimmer to adjust the centre point of the existing pot. The trimmer would adjust the voltage corresponding to te centre position. Connecting a trimmer across the existing pot, say a 10k trimmer with a 47k resistor in series at either side, might be a place to start.
Other suggestions, there is a "calibrate" function in the TX software that is intended to align the software "centre" value with the actual voltage at the centre of the pot. You could try calibrating the TX with the pot set slightly off centre.
There is also a facility in the Rx software to adjust the full speed setting of the loco, I have not tried it myself but it might give you what you want.
I have checked online and multi indent pots are available including the single indent one used in Deltang Rx. 11 positions seems common, a centre indent and 5 each side.
There are 2 forms of consist available with the Deltang Rx-22. A simple one where 2 speed matched locos are bound to the same Selecta position. This is OK for permanent consists but you can't run each loco independently at the same time. Then there is the true consist which has to use Selecta position 6 for controlling 2 or more locomotives and different positions for each locomotive. For me that means 2 locos per Tx-22. I could speed match all the locos but can't control more than one or two. To complicate matters to speed match you change the maximum voltage output of the RX and using max speed is not always desirable.
With a multi indent pot you could speed match at any pot position between locos on different Tx-22 and have a form of multiple consisting!. Say you have 3 locos on each Tx speed matched you will have available 9 different consists. with 4 locos it would be 16 locos.
I am not saying this is a good idea but if it is practical it would make the Deltang system potentially more like DCC for consisting. Using two Tx side by side is practical and would be easier if there were speed notches just like real locos.
That's a useful link Bob. Eleven indents looks the most useful as indent 6 would be the same as the single indent on the Deltang pot. Each indent would theoretically give 20% throttle increments for centre off and 10% increments for low off.