DX7 auto power off upgrade?

[smh20502]

Trying to see if anyone has done this mod. If you have a dx7 you know that there is no auto power off feature. Should be an easy mod but I really don't want to go through the troubleshooting if I don't have too.

[Almaz]

I don't have DX7 but any microchip and optocoupler should do the work. I believe power on/off switch is digital so you might not even need optocoupler at all. The basic idea when microchip doesn't see any stick movement for x period of time then it just switches DX7 off. If I had DX7 then I'd love to make this project.

[smh20502]

yea, I know it's an easy mod, but I've forgotten much of my basic electronics. But, what you are saying is what I'd thought. read a signal if no sig. for x time then power off. Just don't know exactly what legs to read off of.

[Almaz]

A guy made DX7 Timer for throttle stick (ch3) using microchip. Just search for this thread and you'll get pinout for 5v, ground and ch3.

[smh20502]

Just looked as a search criteria of DX7 Timer and haven't found it yet. If you find a link, can you please post it.

I knew I saw it about 6 months ago but didn't bookmark the page. Crap!

This has got to be so simple. I've probably spent more time looking for an already done instead of just doing! :censored:

[David T]

deleted link

[tungym]

Why need auto power off

[Ron W3FJW]

Some people can't remember to turn their radios off when finished flying.

[smh20502]

it's not at the flying field for me. It's at the work bench....work a while, wife comes in asks you to do something...you go do it. Sometimes it's quick, sometimes it's a couple hours...by then too late.

yea, it's easy to say just remember to turn it off. But it sure is a nice feature when you have it.

for example, how many of you have left your lights on, on the car? Now, most cars have an auto shutoff feature so the battery doesn't drain. Why did the auto companies put that feature on the car? Because leaving the lights on happens more often than many people think.


Getting a lot of comments here with no one that has the knowledge to really help. Pleas no more unless you have a solution.

[deswong]

You could use a really nasty timer solution - I remember making something similar quite a few years ago for the iron - so basically to turn it on you need to press a button - then the iron would be on for 5 minutes - at 4:30 it will beep to remind you to press the button - and if you don't it will shut off.

Also you could use a PICAXE and a transistor to control the on-off of the DX7. You could use the AD pin to read the throttle level - and if it is at 0 for more than x minutes to cut power to the DX7 - and after that make sure you put the PICAXE to nap/sleep otherwise it will sit there eating power.

Another quick and simple idea - a pressure switch of sorts embedded into one of the sides - let go of this and after 60 seconds it will turn off your transmitter - but I wouldn't trust this... in case something fails and it turns off your transmitter mid flight!

[smh20502]

You're ideas are essentially what I was thinking, except for one...pressure switch.

I really like this idea. Then I only have to work with a power switch and not worry about reading a signal.

Thanks. This is probably one of the most useful ideas I've seen. I was thinking piezo strips but they generally require pressing and depressing, some type of flexing, etc. on a continual basis...but charged switches. Now that will work.

[pmackenzie]

If you have a dx7 you know that there is no auto power off feature.


I have never seen a transmitter that had an auto off feature. If the goal is to save your Lipo tx pack it might not work. Whatever circuit you are using could still draw enough current to kill the battery. In any case I would never use a transmitter that could turn itself off :eek:

A better and safer solution IMO would be a beeper to remind you to power it off.

Pat MacKenzie

[smh20502]

You mean that you would rather kill a battery? Why?

I just can't understand why someone would rather inadvertently drain a battery.

Please explain exactly why you feel it better to drain the battery. Please don't say that's not what you mean. The beeper idea indicates that one is present to turn off the battery. Or that someone has great hearing. What of those that have trouble hearing?

[Almaz]

I have never seen a transmitter that had an auto off feature. If the goal is to save your Lipo tx pack it might not work. Whatever circuit you are using could still draw enough current to kill the battery. In any case I would never use a transmitter that could turn itself off :eek:

A better and safer solution IMO would be a beeper to remind you to power it off.

Pat MacKenzie


Any microchip in sleep mode takes almost no power at all. I'm just lazy right now to do the calculation but I'm sure the battery should last around 10 years in sleep mode if not even more. On the other hand the battery would go dead before any microchip in sleep mode would kill the battery

[pmackenzie]

I guess I would be worried that it might malfunction and turn it self off in flight.

If you run NiMh or NiCd there is no danger from running the battery down.
None of the manufacturers supply or recommend Lipos as transmitter packs.


Pat MacKenzie

[Capt. Crunch]

I put a red blinking LED on mine, works fine.

Yes, forgeting to turn it off in the shop is what started the idea.

[pmackenzie]

Any microchip in sleep mode takes almost no power at all. I'm just lazy right now to do the calculation but I'm sure the battery should last around 10 years in sleep mode if not even more. On the other hand the battery would go dead before any microchip in sleep mode would kill the battery

Microcontrollers run at lower voltages than the Lipo pack, so you would need a step down regulator.
The voltage regulator might draw enough power to drain a battery if you left the tx for a week or longer.


Pat MacKenzie

[Almaz]

Microcontrollers run at lower voltages than the Lipo pack, so you would need a step down regulator.
The voltage regulator might draw enough power to drain a battery if you left the tx for a week or longer.


Pat MacKenzie


Depends on what regulator you are about to use and some of them in sleep mode draw almost nothing I just don't remember the exact model off my head but I can provide the datasheet once I check my computer.

[pmackenzie]

Depends on what regulator you are about to use and some of them in sleep mode draw almost nothing I just don't remember the exact model off my head but I can provide the datasheet once I check my computer.

If you do find the datasheet, please let me know. I have a different application where this could be handy.

Pat MacKenzie

[Almaz]

Here you go a very low current consumption LDO. I had another LDO with higher input voltage range but I just can't find the datasheet.

[pmackenzie]

Thanks.
A bit low on input voltage range for the DX7, but there might be others out there that would do.

But I still would not want an auto-off feature on a tx :D

Pat MacKenzie

[Almaz]

As you can see only 1ua -10us consumption which is nothing. If you look around I'm sure you can find with higher input voltage and I'm sure it'll be in low UA range. Think about wall clock battery which usually last for a year working 24/7 and switching on and off.

[deswong]

I have a very bright backlight on my DX7 - which makes it really obvious if I have left it on. The beeper on mine seems quite loud actually - but I always check out of habit after each flight to see how much battery power is left...

I wouldn't want an auto-off on the TX in case it failed mid-flight. I had in the past set up an ignition kill switch on the car (real car) and that had failed me while driving on the highway at 100k/hr) which almost ended up in a catastrophic event!

That is my rationale anyhow. An easier and cheaper mod would be to add a lipo alarm and mount the beeper somewhere else that would be louder to remind you that you've left it on...

[deswong]

Oh, and on the DX7 you can change where the low voltage alarm sounds - so I have that set as well to let me know earlier.

[smh20502]

Ok, fear of technology? A good reason. I tend to want more current technology to rectify the errors within my cranial cavity. There is also the issue of that same cranial cavity making a direct connection with my rectal cavity....so any technology that can rectify that is welcome.

Yea, I wouldn't recommend using lipo's for most people either due to their inherit dangers. But, I've yet to have one puff, or malfunction of any kind. Most if not all the problems that I've seen are due to user error.

[deswong]

There's some interesting stuff over at: http://www.diy-electronic-projects.com/p183-High-And-Low-Voltage-Cut-Off-With-Time-Delay - you can use the low voltage cutoff section and the relay section to do what you are looking to do.

As I've mentioned before you can do this also with a picaxe, but will probably need the same setup for the relay section if you are intending to do a full power cut to the TX.

The main reason for me not hooking up something similar is that I may one day fly inverted - which means the throttle will be in the down position - and the cutout may trigger at that point. I would maybe consider the throttle down and the throttle hold switch active for 5 minutes before cutting power to the TX.

I'm not sure if you are flying a heli or plane, so that may or may not apply to you. I have noticed on the DX7 there is no throttle hold on a Acro model.

I would look at using a solid state or optical isolated relay for this purpose, to minimise interference to the transmitter.

Now, all of that has got me thinking, because I wanted to make my own picaxe auto timer for the DX7 - maybe I should just incorporate all of this into it as well!

[Almaz]

Deswong:

I think you got it wrong. The link you posted for low voltage cut off will not work for transmitter. The circuit must read sticks and when sticks do not move for X time then shut off transmitter. We are not talking about saving the battery but we are talking to shut down transmitter due to inactivity for X time of period. Like I already mentioned before the easiest way to do it with PicAxe/Microchip/Tiny chip just by reading sticks and after 5-10 of inactivity shut down power to the transmitter. Easy and simple.

[smh20502]

Almez/deswong

This is exactly why I wanted to start this discussion. As Almez mentions...it's the stick inactivity that I want to look at. Each time there is any stick movement the timer would be reset. Simply by going off of the throttle just simplifies the project.

Yep, I'd have to agree a PIC would probably be the easiest way to do this. Since A PIC would be the most reasonable...The I might as well read off both sticks.

A read off both sticks should satisfy all issues regarding cutting off too early. I don't know of anyone that can fly anything without any stick movement for more than a few seconds let alone 5 minutes.

This all boils down to saving battery life. Many of us get distracted either at the field talking with buddies or at home by family. This distraction doesn't happen often but when it does it can ruin a flying day....less you have several sets of tx batteries. If so, this entire process is moot for that person.

Almaz...any PIC's you'd recommend? Also, happen to know if the sticks output a digital signal or analog on a dx7

[Almaz]

Any pic with internal clock should work fine. What compiler are you going to use to program pic?

[deswong]

The sticks are an analog signal.

[smh20502]

Compiler? Don't know. Though I'm reasonably electronics competant....much in regards to programming has been left op to others in the groups I've worked with.

Most of my experience is analog. But I don't let that stop me. Anything I need to learn...I do.


Interesting that you ask. I was just looking up data that I'll need to know...

my brain hurts...LoL

[Almaz]

The sticks are an analog signal.


Microchip shouldn't have any problems to read sticks. Also sticks can be analog and digital. Stick potentionalmeter is analog and output from trainer port should be digital.

[deswong]

http://microcontrollershop.com/product_info.php?cPath=148&products_id=527

This looks easy and useful :) I didn't know such powerful and easy tools were available!

[Almaz]

http://microcontrollershop.com/product_info.php?cPath=148&products_id=527

This looks easy and useful :) I didn't know such powerful and easy tools were available!

Yep I have a full version installed on my computer but for some reason never used it. FlowCode should be very easy and you can even add your own code in C.

[smh20502]

time for me to get back to the books. C? been 10 years since I've looked at that.

[Almaz]

time for me to get back to the books. C? been 10 years since I've looked at that.


If I were you I would suggest to start with basic language instead of C. Proton PicBasic free or Microebasic is free or for Pic18 swordfish is free. If you PM me I can get you full Proton version for $20.

[Richard Cox]

I would use the aileron stick. Sailplane guys don't use much throttle. I would also
add an alarm maybe one minute before the TX goes down.
The Multiplex transmitter has this feature built in.

[Comatose]

On many Spektrum transmitters there's an unencrypted serial signal running to the rf deck. You can read all the stick positions at once with one pin that way.

[deswong]

Really? That would be good if there was - it would mean you could use a small picaxe which only has one ADC to detect... Do you have any more information?

==
Edit:

http://www.rcgroups.com/forums/attachment.php?attachmentid=1260979

There is the info - if I get some time over the long weekend I might write some code and see if I can get this to work.

This seems quite safe therefore to make a power off upgrade, as it can poll the TX module to detect stick and any data transmission - so if no data has passed in say 5 minutes it would be safe to do a soft-power-off via the TX module and sound the buzzer.

[smh20502]

Sweet....

Tax season is over...all I have is a small honey do list and I'll be able to do something with the info provided.

[deswong]

On many Spektrum transmitters there's an unencrypted serial signal running to the rf deck. You can read all the stick positions at once with one pin that way.

This signal is different - where it is still "live" with no throttle input.

With how this works, DSM2 means that all the signals are mixed into one serial data stream and burst over the air - this results in faster reception of signal data.

I have had a bit of a play and can't get my small picaxe to extract the data.