Deltang Rx102 Receiver

extended aerial
wire aerial

The Rx102 receiver is well suited for use in large scale live-steam or battery powered locos. It operates on 2.4GHz using the Spektrum DSM2 protocol; thus it operates just like any other DSM2 receiver but includes some useful features for model railway control. The Rx102 is small and space for it is easily found in most locos. As shown in the image, the Rx102 is supplied with large black and small red jumper plugs; these are used for output configuration and programming.

The Rx102 free-air range, when used with a DT transmitter, is approximately 50m-60m. This will be reduced indoors due to absorption by furniture / fittings and reflections from metal surfaces. Range is also reduced if the receiver aerial is in a metal enclosure. Ideally, the aerial should be placed outside the loco body and clear of any metal. Two versions of Rx102 are available: with a short wire aerial and with an extended aerial for use on locos that have a completely enclosed metal body. The active tip of the extended aerial is placed through a hole in the loco body. Neither aerial should be cut shorted or made longer as this will affect operation of the receiver. It is important to perform a range check after installation to ensure you have full control of your loco at all positions around the layout.

Rx102 has 7 sets of output pins for 5 servos and 2 on/off switched circuits for lighting (2 more servos may be connected, but require an additional lead). It can be powered from a battery of 3.2V up to 10V, although use of a 4 cell NiMH rechargeable battery or the 5V regulated output from a speed controller is normal.

The pin sets, numbered from the top of the diagram below, are 0.1" pitch to take standard R/C plugs. Rx102-1 is the default configuration, Rx102-2 and Rx102-3 are intended for use with Tx23 and are available on request. Pins 8 and 9 are pads on the receiver circuit board and require an optional lead for use.

Pin 1chan 1 servo chan 2 servochan 3 servo throttle (adjustable throw)
Pin 2chan 4 servo chan 3 servochan 5 servo
Pin 3chan 3 servo chan 5 servochan 7 servo direction (adjustable throw)
Pin 4chan 2 servo chan 1 on/offchan 3 on/off
Pin 5chan 5 servo chan 7 on/offchan 6 on/off
Pin 6front LED light front LED light front LED light auto directional light
Pin 7rear LED light rear LED light rear LED light auto directional light
Pin 8chan 6 servo chan 4 on/offchan 5 on/off requires optional lead
Pin 9chan 7 servo n/an/a requires optional lead

Live Steam (top)

For live-steam use, the Rx102 outputs can be connected to standard R/C servos to operate the regulator, reverser, blower, gas valve and whistle. Rx102 will work with any servo that uses a standard (1ms - 2ms) pulse width control signal and operates off the selected battery voltage - e.g. Blue Arrow 3gm.

When used with a DT Tx20 transmitter, throttle is on pin1/chan1 controlled using the large speed knob and direction is on pin3/chan3 controlled using the toggle switch. Servos, plugged into pin1 and pin3, are linked to the regulator and reverser. The battery can be connected, via an on/off switch, into any of the unused pins.

Battery Powered Loco (top)

An Electronic Speed Controller (ESC) such as the Mtroniks Viper should be connected to pin1/chan1 as shown in the diagram. The Rx102 is powered from the ESC 5V output.

Any of the DT transmitters can be used or a Spektrum compatible stick type transmitter. DT Tx21 and Tx22 transmitters have an inertia control which gives a more realistic acceleration and deceleration by slowing down the rate at which the throttle channel is changed.

Tx22 also provides the Selecta function allowing up to 12 locos to be controlled. All locos may be powered-on simultaneously and are activated using the Tx22 12-way switch. Rx102 is supplied with Selecta disabled; this is easily enabled (see below).

Receiver Binding (top)

The Rx102 must be bound to a transmitter before use. Once bound, Rx102 remembers the transmitter identity and searches for this when it is switched on. When binding, we recommend that servo rods are disconnected in case they are incorrectly set. Battery powered locos should have the motor unplugged in case the throttle is not set correctly or the ESC not cailbrated for the throttle off position.

To bind a receiver, it is switched on with no transmitter active (for normal operation, the transmitter must be switched on before the receiver). Rx102 is available with manual bind or auto bind:

manual bind
manual: The black jumper plug supplied with the receiver is connected across the signal pins (top row) for #5 and #7 and then the receiver is switched on. If fitted, chan5 servo and both LEDs must be removed when manual binding.
auto: The receiver enters bind mode approximately 20 seconds after power-on if it has either never been bound or it fails to find its bound transmitter. It is not necessary to remove the plugs for chan5 servo or LEDs when using auto-bind. An auto-bind receiver may also be forced into bind mode using the manual method.

Bind mode is indicated by a rapid flashing of the receiver LED and the following steps should be followed:

  1. transmitter switched off
  2. switch on the receiver in bind mode (manual or auto)
  3. on DT Tx22 and Tx24, move the Selecta switch to the required position
  4. only when receiver LED is flashing rapidly, hold down the transmitter bind button and switch on
  5. wait for the transmitter to indicate that it is in bind mode and then release its bind button (the power LED on DT transmitter will flash rapidly when binding)
  6. after a short delay, the receiver LED should flash slowly and then stay on
  7. the receiver is now bound to the transmitter
If the receiver LED does not come on solid (no flash) within 10-15 seconds, the bind process has failed. This can happen for several reasons and does not normally indicate a fault. During binding, the receiver searches for the transmitter's signal and this can be distorted by holding the transmitter and receiver to close. So, if you get a bind fail, try again after moving them slightly further apart or changing the relative orientation of the aerials. Binding is most reliable when no other 2.4GHz transmitters are turned on.

Cruise Control (top)

If the receiver loses the signal from the transmitter, for example when going through a tunnel or behind a garden building or some dense bushes, the Rx102 outputs hold their current setting until the transmitter signal is reaquired. Outputs also hold when a Selecta-enabled receiver (see below) is de-selected.

'Output hold' means that the loco will continue doing whatever it was doing before the loss of signal (or de-selection). This allows a form of 'cruise control' which allows you to switch off the transmitter if, for example, you are running the loco round a continuous circuit.

Selecta (top)

DT transmitters Tx22 and Tx24 have a 12 way Selecta switch to control up to 12 locos. Using the Selecta switch, locos are brought under control one at a time. When not selected, the Rx102 outputs hold their current setting - e.g. a loco which is moving when deselected keeps moving.

Rx102 is normally supplied with Selecta disabled. To toggle whether Selecta is enabled or disabled:

  1. turn off the receiver and transmitter
  2. put the black jumper plug on signal pins (top row) for #4 and #6
  3. switch the receiver ON and remove the plug

Directional Lighting (top)

Pins #6 and #7 can be used to drive front and rear LED lights; pin #6 powers a forward LED and pin #7 a backward facing LED.

Rx102 has an on-board 3.1V regulator and 180 ohm resistors in series with the signal pins so limits the LED current to approximately 12mA. The LED should be connected between the signal and negative pins (top and bottom rows).

The default setting is for the LEDs to follow the throttle channel with 'centre-off' and is appropriate for a battery loco with ESC. For live-steam use, the LED behaviour can be reprogrammed for 'low-off' and this uses full-range throttle on chan1 and directional control on chan3.

To toggle whether the directional LEDs operate as 'centre-off' or 'low-off':

  1. turn off the receiver and transmitter
  2. put the black jumper plug across signal pins (top row) #3 and #5
  3. switch the receiver ON and remove the plug

Emergency Stop (top)

Transmitter chan7 can be used as an 'Emergency Stop' function - e.g by connecting this to a push button or toggle switch. If chan7 is set low (1ms pulse width), the throttle (chan1) is reduced progressively to a close. Once the 'Emergency Stop' (chan7 not low) is released, the transmitter throttle control has to be closed to allow the receiver output to work again. The close position is determined by the setting of the Directional Lighting function:

  • when Directional Lighting is set to 'center-off', chan1 is taken to the mid/neutral position
  • when Directional Lighting is set to 'low-off', chan1 is made 'low'

To toggle whether Emergency Stop is enabled or disabled:

  1. turn off the receiver and transmitter
  2. put the black jumper plug across signal pins (top row) #2 and #4
  3. switch the receiver ON and remove the black jumper plug

DT transmitters are available to special order with an Emergency Stop button, contact Micron R/C for details.

Servo Settings (top)

Servo outputs on pins #1, #2 and #3 (chan 1, 4 and 3) can have the throw, centre and direction modified. The output pin to be set must first be selected using the small red jumper:

pin #3

pin #2

pin #1
  1. turn off the receiver and transmitter
  2. put the small red jumper plug across signal pins
    • #4 and #5 for output pin 1
    • #5 and #6 for output pin 2
    • #6 and #7 for output pin 3
  3. switch the receiver ON, wait for the LED to flash every 1/2 second then remove the red jumper plug
  4. switch the transmitter on, the receiver LED will flash once per second until it acquires the signal and then the LED will go off
  5. plug a servo into the selected output
  6. verify that the servo responds to the transmitter

Only one output pin can be changed at a time. Go through the above steps to select a different output pin to change.

Pins #4, #5, #6 and #7 are now used to make changes to the selected output by using the large black or small red jumper plug to connect a signal pin to either of the negative pin or positive pin. When inserting the red jumper plug take care: DO NOT place the red jumper so that it connects a negative pin (bottom row) to a positive pin (middle row); doing this will short your battery.

Only the output being changed works while making changes to it. Low and high side throws can be changed by up to 16 steps each way. The middle neutral position can be changed by up to 32 steps each way. The receiver LED will flash and throws will change one step per second while a plug is installed. The LED stays on for 3s when throws are returned to their 'mid' position. The LED stays on solid when you reach the end of the adjustment range.

Throw, centre and direction of all other pins can be set by temporarily programming the channel to pin #1, #2 or #3, making the servo setting change and then re-programming the channel back to the required pin (#4 through #9) - see Advanced Servo Settings for details.

High side throws
  • increase: use the large black plug to connect pin #7 signal pin to negative
  • decrease: use the small red plug to connect pin #7 signal pin to positive
Neutral position
  • up: use the large black plug to connect pin #6 signal pin to negative
  • down: use the small red plug to connect pin #6 signal pin to positive
Low side throws
  • increase: use the large black plug to connect pin #5 signal pin to negative
  • decrease: use the small red plug to connect pin #5 signal pin to positive
  • reverse: use the large black plug to connect pin #4 signal pin to negative
  • normal: use the small red plug to connect pin #4 signal pin to positive

Programming (top)

The type of output for each Rx102 pin can be changed using Prog3 or Prog4. The choices are:

  • servo - to drive a standard 1ms - 2ms servo (or ESC)
  • on/off - to power a LED or other device with 3.1V when on, 0V when off
  • directional LED - automatic on/off controlled by chan 1 (and chan 3 if low-off selected)
One output is changed at a time.

When setting up a program on Prog3, the LED flash value for each pin should be as shown in the table below - pin 1 on Prog3 corresponds to Level 1 setting (always 1-flash), pin 2 uses Level 2, pin 3 uses Level 3, and so on.

Prog3 Pin 1 - always 1-flash.
Prog3 Pin 2 - selects the receiver's output number (eg: 3-flash = pin3hi ).
Prog3 Pin 3 - selects the type of output (eg: 1-flash = servo).
Prog3 Pin 4 - selects the controlling channel number (eg: 4-flash = ch4).
Prog3 Pin 5 - changes other characteristics (any value if not used).

The number of LED flashes for a Level are show in bold:
Level 1 Level 2
Output number
Level 3
Output type
Level 4
Channel number
Level 5
Other choices
1 1-8 = P1-8 1 = Servo 1-7 = Channel 1-7 (eg: 1,2,1,4 = P2, Servo, Ch4)

1 1-8 = P1-8 2 = On/Off LED 1-7 = Channel 1-7 1 = ON when Ch is low
2 = ON when Ch is mid
3 = ON when Ch is high

4 = OFF when Ch is low
5 = OFF when Ch is mid
6 = OFF when Ch is high
Off in other positions
(eg: 1,3,2,5,1 = P3, On/Off, Ch5 Low ON)

On in other positions

1 1-8 = P1-8 3 = Front Light
Center off
1-7 = Throttle Ch1-7 (eg: 1,6,3,1 = P6, Front Center off, Ch1)
1 1-8 = P1-8 4 = Rear Light
Center off
1-7 = Throttle Ch1-7 (eg: 1,7,4,1 = P7, Rear Center off, Ch1)

1 1-8 = P1-8 5 = Front Light
Low off
1-7 = Throttle Ch1-7 1-7 = Direction Ch1-7 (eg: 1,6,5,1,3 = P6, Front Low off, Ch1 Thr, Ch3 Dir)
1 1-8 = P1-8 6 = Rear Light
Low off
1-7 = Throttle Ch1-7 1-7 = Direction Ch1-7 (eg: 1,7,6,1,3 = P7, Rear Low off, Ch1 Thr, Ch3 Dir)

Advanced Servo Settings

Servo throw, centre and direction of pin #1, #2 and #3 outputs can be changed as described in the Servo Settings section above. Servo settings for other output pins and channels may also be changed by using pin #1, #2 or #3 to set the throw, centre and/or direction, then reprogramming to move the channel to the required pin.

For example, to set the throws on pin #5, chan 5:

  1. program pin #1 to be chan 5 (1,1,1,5)
  2. set the throw using the black and red jumper plug method
  3. program pin #5 to be chan 5 (1,5,1,5)
  4. re-program pin #1 to be chan 1 (1,1,1,1)
Changes to throws, centre and direction will be 'remembered' when that channel is no longer associated with pin #1, #2 or #3.

© Micron Radio Control