Thursday, September 17, 2015

How I installed a Deltang Rx65b receiver/controller in my IP Engineering 'Jessie'


My IP Engineering 'Jessie' locomotive has had a somewhat chequered history (see How I constructed an IP Engineering Jessie loco). She got through three mechanisms before I finally fitted her with a USA Trains motor block (see How I improved the mechanism for my IP Engineering 'Jessie'). She has now also been through three radio control systems. The first was quite successful - using a transmitter from one of those small r/c helicopters, a receiver and a Brian Jones Mac5 ESC (see Progress Report 43). However, after some further experimentation, I decided to standardise on Deltang radio control equipment on all my battery r/c locos and so, for a while, she had an early Deltang Rx60 receiver/controller fitted. However, this provided unreliable as her third mechanism drew more current than this receiver/controller could handle. So I replaced the Rx60 with an Rx102 receiver connected to the Brian Jones Mac5 ESC.

Since that installation (about two years ago), David T at Deltang has developed and released the Rx65, which can handle up to 3 amps - more than sufficient for 'Jessie'. I have been meaning to replace the Rx102/Mac5 combination for some time (in a bid for standardisation of kit), but it has only been recently that funds have become available to make the change.

Ordering the receiver

One of the most daunting aspects of starting out with Deltang equipment is the range of receivers which are available on the Deltang website. Even when you are familiar with the receivers which are more appropriate for garden railway locos, there are several variations on the basic receiver which need to be specified when ordering.

I knew I wanted the Rx65b to operated with my Tx22, I also decided that I did not want any wiring attached (N) and that I wanted the version with the extended aerial (U) as the metal body of the loco shields the aerial which cuts down the range of the receiver, so I ordered an:


For more information about the variations of receivers and ordering see Getting started with Deltang radio control in the garden

UPDATE (December 2015) Please note: Since writing this blog post, the default functions of the output pads on the Rx65b have changed and there is now no need to re-program the pads (see below)

Soldering leads to the pads

After ordering directly from David T via email (see Getting started with Deltang radio control in the garden), the receiver arrived the following morning by first class mail, My first task was to solder on the leads.

I use an Antex XS 25w soldering iron (Maplin Code FR12N) with a 0.5mm No. 55 replacement bit (Maplin Coce N85DS). I always makes sure the bit is well tinned. I've discovered the secret to tinning is to apply the solder while the iron is heating up - once the bit has reached its full operating temperature the solder tends to oxidise rather than coat the bit.

As I was using a Peter Spoerer / MTroniks DigiSounds sound card and also required a front light on the Jessie, I tinned the following pads on the receiver:
  • The power input pads (+ and -)
  • The motor output pads (between the input pads)
  • Output pad 2 (for LED directional lighting) - I wire my receivers in reverse (I mistake I made with my first couple of receivers and so now wire them all in reverse for consistency with the Tx22 transmitter). Normally, the front directional light is pad 1 (or Pad A)
  • One of the negative (-) pads (for the other lead from the LED)
  • The C output pad (for the horn input on the soundcard - pad C is programmed to respond to channel 5 from the transmitter (ie the bind button)
  • Pad 3 (for the start/stop function on the soundcard - pad 3 needed to be re-programmed to respond to the direction switch on Tx22 (see below))

To ensure I could apply the solder quickly and cleanly, I fixed the receiver board to the bench with a small blob of BluTak (saves having to hold it down with a finger), tinned the iron with a small blob of solder, touched the end of the solder to the pad and then touched the pad and the solder with the tip of the iron. Almost immediately the solder flowed on to the pad and the iron was removed. So far I've not cooked any of the 15 or so receivers that I've soldered in this way including the much smaller Rx60s and Rx61s (famous last words??).

I then stripped, tinned and snipped the ends of the wires and soldered them to the pads using the same approach - lightly tinned the iron, touched the wire to the pad, touched the wire and pad with the end of the solder and then touched the wire and pad with the tip of the iron until the solder flowed.

First I soldered the power and motor leads, and the LED lead to pad C (this would be the basic requirement for an rx connected to a simple sound card needing just a horn or whistle trigger).

I then soldered the leads to one f the negative pads (beside the negative input lead) and to pads 2 and 3

Finally, I soldered the power input and motor input leads to the soundcard to the power and motor leads on the rx. I could have soldered these directly to the motor contacts and to the power contacts on the switch and battery or patched them into the leads, but the rx was the most easily accessible point of contact and, while I had the iron handy ......

 Once the wiring had been connected, I bound the receiver to the Tx22 (see An overview of Deltang radio control) and checked all was working as it should - ie the motor working properly, the direction light functioning as expected and the whistle sounding when the bind button was pressed.

At this point, the soundcard was not responding to the direction switch on the Tx22 as it had not been re-programmed to send the right signal to the Rx65. So the next step was to re-program the receiver.

Here's a diagram showing the wiring for the loco in total.
Click to enlarge

Re-programming the Rx65 receiver/controller

As indicated above, the output from Pad 3 needed to be re-programmed to go 'low' (ie 0v) when the direction switch was operated on the Tx22. Consulting the programming information for the Rx65b on the Deltang website.

This indicated that the program coding which I needed to send to the receiver was:

 ie Menu 3, Pad 3, 1=on/off LED (momentary), Channel 3 (ie direction switch output), Idle High, Ch low (=4)

In effect, when the direction switch on Tx22 is in the off position, then 3v is being sent from pad 3 on the receiver (ie 'Idle High'), but as soon as the direction switch is turned on, the output from the pad drops to 0v. In other words, the output from pad 3 goes 'low'. (I hope that makes sense - not sure how else I can explain it).

I now use the Deltang Prog4 to re-program all my receivers, as it is by far the easiest way of programming them (once it has been set up - see How I reprogrammed a Deltang Rx65 with a Deltang Prog4.)

 The text file which I sent from the Prog4 to the Rx65 was, in this case,
The programming took me no more than ten minutes including plugging the Prog4 into the computer, binding it with the rx, writing and saving the text file, sending the file to the rx and then testing with the Tx22 to make sure it had worked.

I was then  ready to re-assemble the loco and give her a test run.

UPDATE (December 2015)

After some discussions with David at Deltang, the default outputs from the pads on the Rx65b have been changed. There is now no longer a need to re-program pad 3. Pad9 or Pad10 now provide 0v output when the direction switch is moved on the transmitter. Simply wire the soundcard trigger to either P9 or P10 and the card will start and stop when the direction switch is flicked momentarily one way or the other (dependent on which pad is used).

NOTE: To protect the Rx65b from excess voltage being transferred back along the trigger wire (because the soundcard uses 5v and the Rx65b uses 3.1v), it is advisable to wire a 1k resistor in series with the sound trigger lead.

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