DSM2ir for Coax Heli's

These receivers allow you to control popular miniature IR or FM based helicopters with a DSM2 transmitter. The DSM2 receiver may be connected directly to the existing IR receiver to replace the IR signal. This allows greatest control and most features. Alternatively, the DSM2 Rx may be used to create a stronger 'IR Bridge'.


DSM2ir receiver options (Rx31 is also available without socket).


Rx31 on S107 (Rx31 held on with velcro/dual-lock).
Hood over IR sensor if to be flown with other IR (made from heat-shrink tube just pushed on and open end blocked with foam)
Installing Rx31 on S107/R5 receiver (top).
Positive to switch, negative and signal to IR sensor pads.
Installing Rx31 on S107/R5 receiver (bottom).


Cut trace between pin 7 of LM393 (red arrow) and pin 7 of SN8P2501 (green arrow).
Connect DSM2ir Rx where the brown/red/orange wires connect


Rx100 + 1S Lipo + 3 IR leds between signal and positive pins 2, 4 and 6 (180ohm resistors already on Rx board).
Simple but IR power is weak (only 10mA per led)
Rx100 + 2S lipo + 5 IR leds (in series) + 10ohm resistor (for led current) + Fet + 1k resistor (for Fet pull down).
Good IR power (each led 'sees' 100mA); about half power when lipo falls to 7v.
2S lipo powers Rx100 through servo lead connected to Pin 5.


1. Better quality transmitter.
2. Control yaw with the left, right or both sticks to better match or ease transition to more sophisticated helis.
3. Full yaw even with opposite trim.
4. Full yaw and pitch at the same time (square vs round stick openings).
5. Trims on all channels and saved on a model memory basis.
6. High speed band for more accurate control.
7. Reduced mid-stick deadband for more accurate control.
8. Single stick configuration (presets) to change settings quickly (eg: to try different sticks for yaw).
9. Longer range.

With direct connection:
10. Any number of helis fly together with no interferance from other Tx's, sunlight, appliances, etc.
11. Remote control of two switched outputs (eg: for led 'searchlight').

With optional IR Bridge:
12. Higher power and ability to position better to improve IR link quality.


-The Led flashes once every ~2s while scanning and comes on solid when the Rx locks onto the frequencies in use. Scanning is quickest when the Tx is switched on before the Rx.
-It is normal for the led to then flicker occasionally. This is because the IR cycle is different to the 2.4 cycle. This does not affect control.
-The Rx has 'quick reconnect'. So if the Rx is switched off and back on after connecting, the Led will normally come on very quickly.
-Immediately after scanning and before the Led comes on solid, the Led flashes the Preset currently selected. It flashes this twice. These flashes are easiest to see after 'reconnecting'. So if you are unsure of which Preset is active, switch the Rx off and on while leaving the Tx on. The Preset flashes will be more obvious.
-The Rx can be bound to two Tx's. The first half of the scan process is used to search for the first Tx and the second half for the second. The 'first' Tx is the one that the Rx last connected to. Binding will replace the 'second'.

-22s after switching on, if the Rx does not lock onto a signal, it will go into Bind mode. The Led will flash rapidly.
-Switch Tx on in bind mode. The Tx bind button can normally be released once the led stops flashing rapidly.
-The Rx replies for several seconds during which time the led will flash twice per second.
-The Rx then scans for the normal signal. As soon as the led comes on and stays on the Rx is bound.
-If the led does not come on within 12s or continues flashing every 2s, the bind has failed. Allow several flashes then start again. Try moving the Tx closer to or farther from the Rx (between 1cm and 2m). Try changing this distance during the 3s and 7s periods in steps 2 and 3. Try changing the orientation of the Tx relative to the Rx (eg: move through 90 degrees). Try holding the Tx bind switch on longer. Bind with another Rx and then try this one again. Check that batteries are charged. Binding is more reliable with no other Tx's on.

-IR helis can be controlled by direct connection (hard wired) or over IR. IR limits the number of IR-based helis that can fly together as their signals get mixed up.
-If the Rx is wired direct to the heli's IR Rx and its IR sensor is removed or masked, you will achieve much more robust control in busy environments, the heli can be flown outdoors in direct sunlight if there's no wind, have more range and almost no limit to the number of helis that can fly together. Quicker updates can also give more accurate control (see Band section).

The Rx is intended to be used with many IR helicopters. The way in which the IR Tx communicates with the heli is called a Protocol. The following protocols are available:
-Protocol 1: S107/R5 (default)
-Protocol 2: S107/R3
-Protocol 3: SH6020/6020-1/6025
-Protocol 4: S026/S108
-Protocol 5: S022 (direct connection only)
-Protocol 6: Udi
-Protocol 7: J-Kart

Most IR Tx's have 2 or 3 Bands. These try to allow more than one heli to fly at the same time by changing the idle time between IR transmissions. These DSM2ir Rx's have four bands. Bands are protocol-specific and the table below is indicative of the time between each transmission. The 'shorter' bands give better response but are more susceptable to interferance with more heli's using IR. Band 4 is mainly intended for direct connection.
-Protocol 1 Bands 1-4: 120,180,64,64ms
-Protocol 2 Bands 1-4: 120,180,64,64ms
-Protocol 3 Bands 1-4: 120,154,176,64ms
-Protocol 4 Bands 1-4: 162,195,125,64ms
-Protocol 5 Bands 1-4: 55,55,55,55ms
-Protocol 6 Bands 1-4: 160,193,135,64ms
-Protocol 7 Bands 1-4: 137,137,137,137ms

3-channel IR Tx's have one stick for yaw. DSM2 Tx's have two sticks that can be used for this purpose. You can select one or both sticks to control yaw:
-Stick 1: Right stick on DSM2 Tx controls yaw (Aileron/Roll stick). Left stick used for S026 back pitch trim and switched outputs on other helis
-Stick 2: Left stick on DSM2 Tx controls yaw (Rudder/Yaw stick). Right stick used for S026 forward pitch trim and switched outputs on other helis
-Stick 3: Both sticks controls yaw (mixed in Rx). Gear switch used for switch 1 ouput; switch 2 and S026 pitch trims not available

-Throws (Travel Adjust, Dual Rates, etc) are intended to be used at 100% on DSM2 Txs that can adjust these.
-Channels 1-4 (TAER) should be set to 'normal' direction (ie: not reversed).
-Some IR Tx's have yaw and pitch trims. DSM2 Tx's have trims on every stick. Where possible, these are used to achieve the same purpose. This is not possible on the S026 Chinook. So the stick that is not being used for yaw operates in a similar way to the pitch trim buttons. Left stick is Back trim and Right stick is Forward.
-Throttle trim can prevent the system from arming on startup. So may sure it is not set high.

-The Rx has two outputs to switch something on/off in flight. On Udi helis, this feature controls the existing nose light through the IR receiver. To achieve the same thing with other helis, remove the wires to the led from the IR Rx and connect them between Pin1 and negative on Rx100/101 (or between Pin2 and negative). Rx31 uses different pin numbers and needs a resistor as well. Rx100 outputs can drive an LED (<10mA) direct or be used to switch a Fet/Transistor for heavier loads. Rx31 has provision for an on-board Fet.
-The left/right stick that is not being used for yaw (eg: left stick if the right is being used for yaw) is used to toggle the led on/off (Yaw Stick mixes 1 and 2). If both sticks are configured to control yaw, only the Gear switch can operate this function. The Gear switch has to be toggled in both directions each time the led needs to be toggled on/off.

In order to make it easy to switch between the various settings, six combinations of Protocol/Band/Stick can be saved as 'Presets'. Any combinations are possible. The Rx is supplied with Preset 1 enabled. The others are invoked by holding one stick at full throw until the Rx locks onto a signal. The Rx remembers the last choice. The Rx will flash the chosen Preset number twice after locking onto the signal. The Rx is supplied with the following pre-configured:
-Preset 1: Left Aileron/Roll stick: Protocol 1 (S107/R5), Band 4 and both sticks enabled.
-Preset 2: Right Aileron/Roll stick: Protocol 2 (S107/R3), Band 4 and both sticks enabled.
-Preset 3: Forward Elevator/Picth stick: Protocol 3 (SH6020), Band 4 and both sticks enabled.
-Preset 4: Backward Elevator/Picth stick: Protocol 4 (S108/S026), Band 4 and both sticks enabled
-Preset 5: Left Rudder/Yaw stick: Protocol 5 (S022), Band 4 and both sticks enabled.
-Preset 6: Right Rudder/Yaw stick: Protocol 6 (Udi), Band 4 and both sticks enabled.

-Programming is the process of associating a Protocol, Band and Stick to a Preset. Programming is done over radio link so the Rx must have been bound to the Tx (described elsewhere). Programming can only be performed as the Rx starts up. Only one Preset can be configured per startup.
-Four attributes have to be selected. These are the Preset, Protocol, Band and Stick in that order. These four have at least three options each (eg: Stick 1, 2 or 3). The Led flashes these options. The led flashes always start with the currently active Preset and the existing settings associated with that Preset.
-Settings are saved automatically after setting the last attribute.

-Switch the Tx on with 100% throws or greater, trims roughly centered and no channels reversed. 'Pinch' Rudder/Yaw and Aileron/Roll sticks together (both left/right sticks in towards middle of Tx).
-Switch Rx on. The Led flashes once every 2s while scanning and then comes on flickering very fast. Programming mode has been invoked. Release all sticks and the first series of flashes represent the Preset.
-To accept an option, push the Elevator/Pitch stick forward (to top of Tx). The Led will come on flickering very fast again until the stick is released. The next attribute (eg: Protocol) can then be set.
-To reject an option, pull the Elevator/Pitch stick back (to bottom of Tx). The Led will flash the next option (eg: a 1-flash for Preset 1 becomes a 2-flash representing Preset 2). Note that the previous flash sequence has to finish before showing the next sequence so be patient; there is no need to rush. The number of flashes always increases by one and then 'wraps' to the single-flash again.
-An option has to be accepted for Preset, Protocol, Band and Stick. Switch off at any time to abort/cancel. Choices are saved as soon as the last choice is made. The Led should come on solid and Rx then operate normally.

-As a safety feature, Throttle has to be closed before you will be able to control the heli. The closed position is only detected once the Led has come on solid. Please note that if your throttle trim is set too high, the throttle may not come down low enough to arm the system.
-In normal use, as is common with the IR Tx's, control ceases 2-4s after throttle is closed.
-The throttle stick is not used for Programming or for selecting Presets. It can be in any position during those processes.

-Pin1,3 switched outputs (on heli), idle low, active high
-Pin2,4,6 drive IR leds direct with 1S lipo (IR bridge), idle high, active low, 38k pwm (connect between signal and positive with 1S lipo)
-Pin5 drive IR leds via Fet (IR bridge), idle low, active high, 38k pwm (connect signal to Gate of N-Fet)
-Pin7,8 direct connection to IR Rx, idle high, active low, no pwm

-Pin8 direct connection to IR Rx, idle high, active low, no pwm
-Rx101 is a cut down Rx100 with identical features. However, Pins1-7 have been cut off so their features are only accessible via tiny pads on the boards

-Pin3 direct connection to IR Rx, idle high, active low, no pwm
-Pin4 drive nose led direct (on heli), idle low, switched output (<5mA so series resistor required with led)
-PinB second switched output and can drive on on-board Fet (2A max if fet is fitted, <5mA if not)

Home Videos About Buy Email