Six-Channel Reeds using the ‘Tiny-6’ emulation encoder
Its been some time since the original 12 channel Reeds emulation encoder was developed. Although it was and still is a very successful project, I was never able to produce PCBs for it in quantity so only a relative few were made compared to the hundreds of single-channel emulation encoders in use.
Besides my own Remcon-12 and Orbit-10, to my knowledge a further 31 reeds sets have been built, a few by pals I frequently fly with. Quite a few have taken the PCB foil-mask and made their own PC boards, which is great.
In answer to this availability problem I've recently done a new six-channel encoder for Reeds, I call this one 'Tiny-6' as its only an inch square. Its heavily based on the existing full-house Reeds encoder software, written entirely in assembler, but this one uses a readily-available, commercial SMT PCB instead of the original home-brew boards.
Features - the new 6 channel 'Tiny' is a true six-channel Reeds Emulation Encoder with a few ‘conveniences’. It has trims on all functions, servo reversing on all functions, servo slow on all functions with two transit speed options, and a single-handed range check mode. All the trim, reversing and transit speed configuration settings are saved to flash and therefore retained during power off. It runs happily of a small 2S lipo and will drive any of the Frsky, OrangeRx, etc RF modules –in the prototype I used a Frsky DFT.
Rudder/elevator/throttle suits a lot of vintage and 'period' reed models such as the Junior 60, Tauri, Falcon 56 and the Veron Robot amongst many others. Having trim on all functions is a bonus - back in the day trim was only available on elevator, needed an additional 'progressive' servo and used up two of the six channels! ‘Period’ sets suitable for conversion include the RCS Inter 6, the Ariel 6, Orbit and F&M 6, Raven 6, etc, as well as full-house sets with two dummy keys!
Heres a demonstration of the new Tiny-6 reeds set:
In flight tests using the Tiny-6 transmitter in the video, I found the 'higher' transit speed was great for my Veron Impala slope glider which responds quite slowly, but a bit 'lively' for my overpowered Cub, the slower speed was much smoother to fly and is more typical of period reed servos which were characteristically slow. The slower of the two settings is the same transit speed as I use on my old Junior 60 and Kazmirski Tauri with the Orbit-10 set - if you remember there was a video taken at the time, which you've probably seen:
I've uploaded an initial, very draft document to , its right at the bottom of the Archive page under the QR code.
Costs:
Since the commercially produced boards involve far less effort on my part, I can do them at a much reduced cost.
They're just £12 programmed, tested & delivered anywhere, thats the board, pre-wired buzzer and a few other necessary components as shown in the document.
Wiring sequence:
Theres a bit more wiring to do on the reeds encoder than a single-channel setup, but its very simple if these steps are followed:
1) preparing the switches
First of all, the supplied resistors are soldered between each of the outer contacts and the centre of each toggle switch. They can be one each side of the switch as shown, or both on one side. I think its easier to do this before mounting the switches into the case. The resistor values aren’t critical but they must be the same – with the kit I will supply either all 10k or all 3.9k resistors.
2) running the toggle positive
Identify the orientation of the encoder. Most of the connections are made to the 9 pads down one side.
Positive 5v is daisy-chained from the encoder around all the toggles, and the buzzer pos. Note that the corner positive (near D1) is full battery voltage. The toggle positive (near C2) comes from the on-board 5v regulator.
3) running the toggle negative
The negative is daisy-chained from the encoder around all the toggles, the buzzer neg and the button. Its also the negative to the module (see later)
4) adding the RF module connections:
The RF module connections are made, with PPM from A5 via the supplied diode if the module is a Frsky V8. The D series modules don’t need the diode as its built-in to the module. In practise the diode does no harm whether its needed or not and can be added as a precaution even if the module already has one.
5) wiring the channel inputs to the toggle centres, and connecting the battery:
The toggle centre connections are wired to the encoder channels:
A0 to the rudder toggle
A1 to the elevator toggle
A2 to the throttle toggle
A3 to the trim button
A4 to the buzzer base
The 2S Lipo battery is wired via the on-off switch to the power in pads on the opposite edge of the encoder.
The buzzer is normally a two-wire device but in this case a transistor has been added to buffer the buzzer drive. The whole thing as a unit is supplied pre-wired as follows and can be considered a 3-wire device as per the previous diagrams:
The buzzer assembly (buzzer and transistor buffer) is supplied ready made & tested, but here’s how I assemble them, you may come up with something better:
First, with the buzzer positive at the bottom, the leads are kept parallel whilst being bent to the left along the surface of the buzzer:
Next the 2N3904 transistor is laid flatside-down with its emitter touching the buzzer positive, then soldered:
The leads are cropped to the edge of the buzzer and sleeved servo cable soldered as follows: black to the buzzer neg, red to the collector, white to the base. Theres no wire to the buzzer negative.
Add a similar length of sleeving over the emitter/buzzer negative:
Next heat-shrink the sleeving, making sure it remains pushed up against the transistor body. Then add an overall sleeve covering all the connections:
When connecting the assembled buzzer module, red is positive 5v (from the toggle switches positive feed) black is negative (again from the toggle feeds) and white goes to A4 on the encoder.
On power-up, the buzzer should emit 3 quick pips, then silence until the trim function is used. It also ticks during the range-test mode.
Range test is invoked by switching on whilst the trim button is briefly pressed and is stopped by either a power cycle or by blipping the throttle toggle.
Servo reversing is by holding the required function briefly during power-up, so for example to reverse the elevator, switch off, hold the elevator toggle (either way) and switch on. Trim settings and reversing are saved in flash and so are remembered whilst the power is off.
If anything is unclear from these notes just ask.
Heres a summary of the connections:
Operation:
Trims are set during operation by first holding the trim button, then holding the required toggle in the appropriate direction. For example if the model has a tendency to keep turning left, and you want to apply right trim, press the trim button then hold ‘right’. There are 10 trim steps in either direction, each step ‘pips’ so from full trim to full opposite trim is 20 pips. The trim settings are saved to flash so they are maintained with power off. Trim is available on rudder, elevator and throttle channels. On an IC model, throttle trim can be used as an engine cut if the carb is set up to fully close on low throttle plus full ‘closed’ trim.
Servo reversing is achieved by holding the relevant toggle over in either direction, whilst switching on the transmitter.
Say for example on a new installation the rudder operates in the reversed sense.
Switch off the transmitter, hold either left or right rudder, and switch on.
The rudder will be reversed. Similarly with the elevator channel.
The reverse settings are saved to flash so they are maintained with power off.
Throttle is also reversible but please take extreme care when using throttle reverse – some ESCs (electronic speed controllers) will spin up the propeller if the throttle is reversed. Others go into programming mode – either way, always remove the prop from an electric model when setting up and use throttle reverse with care, especially if the transmitter is used for two models having ‘opposite sense’ throttles.
Range Check mode is entered by switching on the transmitter whilst the trim button is pressed. The servos will begin to sweep to & fro, at which point the button can be released. The transmitter can then be left cycling away whilst the model and its waggling surfaces is carried away. The transmitter pips whilst in range check mode. To exit, either flick the throttle toggle in either direction, or switch off the transmitter. Setting low-RF-power is a function of the module, the encoder has no influence over that, so range check mode can be used at full or low power. If the trim button is held continuously at power-up, after about 6 seconds the encoder will ID then return to range-check waggling.
Servo transit speed can be set to one of two options. Both options are slower than the natural speed of the servo, but the servo-slow function can be ‘slow’ or ‘fast’. The transit speed setting is saved to flash so it is maintained with power off.
To set ‘fast’ transit, hold the trim button AND up elevator, and switch on the transmitter. There will be a single pip to acknowledge the change.
To set ‘slow’ transit, hold the trim button AND down elevator, and switch on the transmitter. There will be a single pip to acknowledge the change.
A mnemonic which might help you remember this is ‘speed up’ and ‘slow down’.
Old reed sets had quite slow servos, which enabled partial control surface movement by ‘blipping’ the toggles, giving a crude form of proportional control.
I suggest using ‘slow’ initially, maybe experimenting with the faster speed as confidence and experience is gained.
Addendum:
I was just doing a plug-in mount for John, and thought it worth appending to the Tiny-6 document.
Electrically its exactly the same but just a different way of connecting it up. Its just a couple of 9-way header sockets on a 9-hole by 10-hole piece of veroboard. There are 6 cuts, a row of 5 and an odd one under the diode (between its 2 wires).
The toggles are connected with standard 3-wire servo cable, and the toggles are pos & neg to the outer contacts and signal to the centre.
Before connecting the cable, the two resistors are mounted on each switch as before, from each side to centre. Their value isnt critical, 3k to 10k is fine as long as they're all the same value.
The module and the buzzer are also connected with 3-wire servo cable, while the switched-battery and trim button only need 2 wires each.
The encoder has two rows of header pins soldered from the component side, so the pins stick out on the non-component side:
Here are a few pics of Johns board which I took as I made it up:
1) We cut a 10 hole by 9-hole piece of vero and polish it up. MMmmmmm... shiney.
2) there are 6 cuts to make, 5 in a row and one opposite:
3) The encoder has header pins soldered in (pins sticking out of the non-component side) and the header sockets are mounted on the vero:
4) We add the PPM diode (not strictly necessary now, but harmless)
It bridges the cut we made and goes banded end nearest the header:
5) When temporarily plugged together it looks like this, with the diode banded end to A5:
6) separate them again and add the servo-cable connections for the toggles, the button, the RF module, the battery and the buzzer:
7) and when its all done it looks like this:
The A0, A1 and A3 3-wires servo cables are connected to the switch toggles, which also have the resistors as before. The A5 three wire connects the RF module with PPM via the diode, and the A4 three-wire to the buzzer can be seen in the photo. The A3 two-wire connects the button (red & white pair), and the battery pos connection comes from the switch (red & black pair).
Its just a different way of achieving the same thing. I used a variation of this idea on the prototype but I managed to get the buzzer and its driver transistor on the veroboard, so as you can imagine its a bit cramped.
But it does mean I can swap the encoder in & out easily, which is nice
The switches are wired pos & neg to the outer contacts, white to the centre common. The resistors aren't critical in value, but must be the same, I use from 3k9 to 10k:
So heres Johns encoder on its finished plug-in mount, all connected up to a PP3 and some temporary toggles & button, PPM out to the HK tester showing the rudder channel pulsing away merrily:
That HK/GWS MT-1 tester by the way is superb, more facilities than my old Pulstar design and cheaper to buy than the Pulstar cost to build!
Under the encoder, the wiring is quite 'busy' and theres no reason why you shouldnt make it a bit longer on either side of the header sockets, this would give plenty of room to use every alternate hole which will make it much easier (but obviously bigger!):
Cheers
Phil