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Member postings for Mike Blandford

Here is a list of all the postings Mike Blandford has made in our forums. Click on a thread name to jump to the thread.

Thread: How to make a Taranis volume control more linear?
28/10/2016 23:03:20

I'm not certain openTx uses the inputs settings for the volume control, just uses the S1 value directly.

The volume control is a 128 step linear, digital pot. The following table is used to create 24 actual steps:
const uint8_t volumeScale[VOLUME_LEVEL_MAX+1] = {
0, 1, 2, 3, 5, 9, 13, 17, 22, 27, 33, 40,
64, 82, 96, 105, 112, 117, 120, 122, 124, 125, 126, 127

At the mid position of S1, it should be set to 40, which is about a third of full volume. The table is non-linear to provide a sort of Log function. The bottom end is set close together as when using earphones you need a very low level.


Thread: S6R receivers
28/10/2016 22:55:24

You may run the self check, if needed, by setting up channel 12, so you don't need access to the Rx.

When you run the self check, do the servos move just before the blue LED goes off?


28/10/2016 22:02:02

Have you done the self check procdure (blue LED) then moved the sticks?


28/10/2016 18:55:55

I'm not certain, but I think if you modify two lines of the lua file like this:
{"AIL2 direction:", COMBO, 0x9A, nil, { "Normal", "Invers", "Off" }, { 255, 0, 128 } },
{"ELE2 direction:", COMBO, 0x9B, nil, { "Normal", "Invers", "Off" }, { 255, 0, 128 } },

You would get the option to try turning the AIL2 and ELE2 servos off from stabilising response.

I haven't tried this, but if anyone has openTx 2.2 running on a Taranis and wants to try it I would be interested to know if it works for them.


28/10/2016 18:40:38

I think the S6R is more sensitive than other 'X' receivers. I get a higher RSSI reading, but this may well mean the close range "swamping" effect is more noticeable.

With everything powered on, press the 'bind' button on the S6R to enter "self-check" mode. The blue LED on the S6R will come on. Make sure you have the Tx far enough away to avoid the swamping. When the blue LED goes off (after the servos have moved a couple of times), move the sticks on the Tx to set the servo limits in the S6R. You should then have control of the servos.

The S6R needs to know the limits so it doesn't overdrive servos when it is driving them for stability reasons. This isn't perfect but avoids stalling a servo. I'm using differential on ailerons, so in one direction the servo limit is reduced. The S6R however drives the servo without differential, but does stop the servo before it goes too far. I'll be suggesting to FrSky they change this.

There is a "lua" script available to run under openTx on the Taranis that provides the setup functions without needing the PC, although I believe you may need to update openTx to "2.2", but this is not yet released so is only available as a "nightly" build.

Also, if you run ersky9x, I have just added the S6R setup functionality, and this is working on the SKY, AR9X and 9Xtreme upgrade boards for the 9X, the 9XR-PRO and the Taranis and Taranis Plus (and should work on the X9E but I haven't tested that yet). You could backup your openTx flash and EEPROM from a Taranis, flash ersky9x to be able to setup the S6R, then revert to openTx.

My work with the S6R is here: **LINK**, and the first post has the ersky9x builds that include the S6R setup.


Edit: Took me too long to type! One thing I have discovered. A 'problem' has been reported with channels 5 and 6, where these are driven by the S6R when applying stabilising operations that prevents them being used as 'ordinary' channels for things like flaps and retracts when not needed for a second aileron or elevator. I've found a setup value (0x80) that may be written to the direction parameter for these channels that stops the S6R driving them itself, thus making them available for 'ordinary' use. I've included this as an option in ersky9x.


Edited By Mike Blandford on 28/10/2016 18:47:58

Thread: Uh-Oh! Hijacking drones?
28/10/2016 16:17:48

So you fly using a similar device. When someone 'hijacks' your model, you just 'hijack' it back!


Thread: Dopey question from a leccy beginner
26/10/2016 19:23:31

I frequently use a hacksaw to cut a slot into the front of the threaded part of the prop adapter. This allows me to use a screwdriver in the slot to prevent the prop adapter rotating while I tighten the prop nut.


Thread: OpenTx - Questions and Problems
24/10/2016 19:13:14

I did offer it to RCM&E first, but it was declined!


24/10/2016 12:27:42

My solution to having slow retracts involves using a standard, Hi-torque servo. I used a Towerpro SG5010. This has the same torque rating as a Hitec HS-75BB Retract Servo. I then use a "Servo Pulse Stretcher" I made using a small processor. This extends the range of the servo pulse so I get this servo to rotate 180 degrees end to end. As it happens, I also have the slow operation built in to this, but it would work just as well using a slow setting in an openTx or er9x/ersky9x mix.

If there is interest I can make the details of the "Servo Pulse Stretcher" available. I re-used the same hardware I designed some years ago for a glow plug driver that was published in (another) magazine.


Thread: Open TX Companion voice
23/10/2016 10:09:40

I have had problems with quite a few programs in the past when installing them in the "Program Files" directory as Windows has protection on this.

Now, I always use a directory called "Progs", and do all my installs in there, no more problems!

There is a directory called "Program Data". I think programs are supposed to use this for data, and not part of their installation directory, but if you are writing for multiple platforms (Windows, Linux, Mac), it is more difficult to use.


Thread: OpenTx - what is the fuss really about?
20/10/2016 00:55:55

When calibrating the sticks I would also recommend just moving each stick in one direction at a time, e.g. either up/down or left/right. Sometimes, if you move a stick to a corner, one direction moves a bit further than you get just moving it up/down or left/right.


18/10/2016 00:53:32

Suppose you want some rudder coupled with the ailerons, but don't know how much. You set the rudder channel up like:

+20% AIL
*50% LS offset 50% (the MULTIPLY multiplex)
+100% RUD

With the left slider (LS) at one end you get 0% of aileron mixed to the rudder channel and with the LS at the other end you get 20% mixed. Now, while flying, you may adjust LS to get the required amount you need.

The LS mix line provides a value from 0% to 100%. You don't want this going negative or you will get opposite rudder applied !


Thread: A question of physics.....
16/10/2016 22:58:49

Ted: I thought from your earlier posts you didn't think the 747 would take off, hence my question.


16/10/2016 22:40:52

Ted: What do you understand by "the speed of the wheels"? (You might look up the term "cycloid" before you answer).


16/10/2016 22:10:28
Posted by ted hughes on 16/10/2016 20:08:55:

No matter how fast the man on the treadmill runs he will always stand still (because the treadmill always matches his speed).

But if he will "always stand still" then his speed is zero, so the treadmill is also stationary if it matches his speed!


16/10/2016 21:40:42

Back to the physics!

What is the "speed of the wheels"? It seems to me there is a misconception by many to this question.

The only meaningful answer to this is "the speed of the axle" (equals the average speed of all parts of the wheel and tyre). Many seem to be assuming the conveyor belt is moving at the speed of the tyre where they contact each other.

It is a fact that, for a wheel rolling along a stationary surface without slipping, the point of contact of the wheel to that surface is also stationary. So, for those that are assuming the "speed of the wheels" is "the speed of the tyre where it contacts the belt", then the conveyor belt will be stationary whatever the speed of the 747!


13/10/2016 17:01:24

The 747 can take off.

If there is no friction (wheels/conveyor belt), then there is no force to oppose the thrust from the engines, so the the 747 MUST accelerate (Newtons first law).

If there is friction, then the top surface of the conveyor belt will drag the air above it along (opposite of wind sheer!). The resulting airflow over the 747 will then provide drag on the 747 to provide the force to oppose the engine thrust keeping the 747 in the same place (Newtons third law). This airflow will then also provide the lift to get the 747 airborne.


Thread: OpenTx - what is the fuss really about?
12/10/2016 16:06:35

BEB: The SBUS decoder using an Arduino I referenced outputs servo pulses at 18mS intervals, so is fine for analog servos.

Tom: If you have a wing with many servos, then, as Bob says, it is much easier if you only have a single connection to make.

Martin: You might try doing a 4 servo wing setup yourself, you will learn quite quickly doing that. Probably the main thing to 'get your head round' is to look at each channel, choose what you need to control it, then add a mix or mixes on the channel to provide that control.


11/10/2016 18:46:44
Posted by trebor on 11/10/2016 16:25:05:

If you purchased one of these transmitters and didn't get on with open tx could you re - install the original fry sky program ?

You also have the option of installing ersky9x on the Taranis. Ersky9x is another open source firmware that runs on a variety transmitters, and also has a PC program that makes programming the radio easier.


11/10/2016 12:29:40
Posted by Biggles' Elder Brother - Moderator on 10/10/2016 23:21:52:

The decoders cost £10.79 each, and the channel changer costs £13.49. So the all up cost of all the kit used in this post was just £35.07 and bear in mind only the decoders will go in the model, the channel changer is a one-off cost as it can be reused again on subsequent models. This FrSky kit is not expensive for the power it gives us I am sure you will agree.

If you are in to SBUS, and don't mind a bit of DIY, you might be interested in using an Arduino Pro Mini as a SBUS to PPM decoder. I've done one and the firmware is here: **LINK**.

This provides all 16 channels in one go, but you will need to aqdd the wires and connectors.


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