Landtastic: Landing Gear Retract Controller (and more!)

[Mr.RC-CAM]

I am proud to announce LANDTASTIC, the latest RC-CAM project. This is a continuation of my other thread: I am ready to try a Park Flyer with retract gear (http://www.rcgroups.com/forums/showthread.php?s=&postid=1641512).

Landtastic is perhaps the ultimate parkflyer landing gear retract controller. This tiny microcontroller based gadget offers servo-slow capabilities, remotely activated navigational lighting, and a lost model finder alert.

Feature summary:
World's first full featured, user programmable, R/C parkflyer landing gear controller.
Slows down any standard proportional servo, allowing up to ten seconds of retract time. Servo torque is not affected.
End-of-travel inertia brake gently parks the retract system.
Sophisticated navigation lighting; Remote activated Landing Lights and anti-collision Tail Strobe.
Lost Model Finder alarm for those unexpected landings in the brush. {Note: The alarm is not available on Rx's that have failsafe features.}
Works with any R/C system (AM/FM/PCM) that has a switched servo channel (i.e., Aux or Gear toggle switch).
Works with stock proportional servos, analog or digital.
No modification required to the R/C system. Plug-in installation.

You will need to be able to read simple schematics and have experience with soldering electronic components. The PIC microcontroller will require flash-programming (low cost tools to do this can be found by searching the net).

The full details to the project are found on the rc-cam.com (http://www.rc-cam.com/) site or by Clicking Here (http://www.rc-cam.com/ldtastic.htm).

I will provide pre-programmed PIC IC's to those eZoner's that do not want to invest in a PIC chip programming system. Cost is $6.50 (USD) each. Shipping is $3 PER ORDER (not per chip) to USA destinations, and $4 outside the USA. PayPal Only (no other payment method is accepted).

I will include the required C1 cap (.1uF mono ceramic) with every Landtastic PIC ordered.

If you are interested, please PM me (http://www.rcgroups.com/forums/private.php?s=&action=newmessage&userid=5920) to obtain my PayPal account info. Do not use email -- the only way I can verify you are a eZone or RC-CAM forum member is if you use the PM feature. Non-members will have to join to take part. It is strictly a hobby effort on my side, so please respect my simple requests.

Please do not contact me with questions concerning price, availabilty, and project details. All that is found in the above, as well as the status update area shown below. It will help out if you just trust what is read here (I will keep it updated).

If you have any technical questions or comments please do not email me. Instead post them in this thread or in the rc-cam.com forum, so that others can learn (and help solve problems) too.


**************************************************

Landtastic Project Status area. Updates will be posted here.

Dec-22-2004: Original eZone thread discussion concerning GWS Formosa and servo slow is found by clicking here (http://www.rcgroups.com/forums/showthread.php?s=&postid=1641512).

Jan-20-2004: Landtastic Project Web Page online. Click here (http://www.rc-cam.com/ldtastic.htm).

Jan-20-2004: Pre-programmed PIC offer valid until further notice.

Feb-27-2004: 4-for-the-price-of-3 offer ends today.

[downeym]

I dont suppose you can provide some gerber data for a board can you?

[Mr.RC-CAM]

I do not have a PCB design at this time. I was thinking about laying one out and ordering commercial fab house parts. But, it is just not cost effective for small orders.

If you need artwork for kitchen sink etches then it is best to design your own. That way you can ensure you use the trace widths that work best for your methods. For sure, you would probably hate my skinny little traces. ;)

RC-CAM

[downeym]

I have a nice PCB routing machine at work.. I know usually you include gerber with your projects and thought you might already have a design done. No big deal. I can lay it out myself when I get a chance.

Thanks for the effort! I can always count on you for intersting projects. My camera interface is still working great! :)

[Marion]

This is just what I was trying to develop, but for use on flaps instead of the landing gear. Super!!

I just sent you a PM...

[Mr.RC-CAM]

...just what I was trying to develop, but for use on flaps instead of the landing gear. Please let us know how that app works out for you.

The device can be used in any R/C app where the servo speed needs to slow down. For example: it will nicely tame the movements of a camera panning servo (wireless video app).

RC-CAM

[IceDancer]

RC-CAM:
The Pic kits arrived in todays mail. Talk about FAST service.
Thanks Much ! !
Sam.

[Mr.RC-CAM]

Wow, the US Postal workers must have realized how vital that delivery was!

Hopefully we will soon hear some project feedback from eZoners. If any errors are seen (even silly typos) then please let me know. Comments of any kind are welcome. But I really hope there is some good news to report.

BTW, I noticed that some text was missing in the downloadable instruction sheet. It has been corrected. I did not change the version date on it, so if you have printed it out please assume your copy is bad and just download it again.

RC-CAM

[KLH]

Also got mine in the mail today! Great service!
Thanks!

Kern

[Modellhobby]

RC-CAM
I have PM'ed you. Looking forward to heat up my solderpen.:-)

/Stefan

[Marion]

Got my chips in today's mail. Plugged them into my circut board -- and all works great !!
This is really a super PIC, done by a super programmer too :-)

No flight reports yet -- bad weather here. They will be used to help slow down flaps for better flight characteristics on my Ultra Stick .60.

Thanks for your efforts....

MarionDK

[Darren Hintze]

I have one of these as well and will be soldering it together and testing it this weekend. Hopefully I can post some pictures Monday.

Darren

[Marion]

I for one, think this is a really great gadget. I plan on building and using a number of them. Anybody else building one of these?

[Norman Adlam]

Mr RC-Cam,

I must compliment you on providing interesting DIY projects for us combined RC and Electronics tinkerers, and for providing it for free! :p

Keep up the good work!

Cheers,

[downeym]

here here!

[Mr.RC-CAM]

You are all welcome. It's good to hear that the project is getting some use by other modelers.

RC-CAM

[Marion]

Oops -- Problems :-( I just tried unsuccessfully to program two 12F629 chips. I used PICALL (version 1.3) and new PICs from Microchip. I used the HEX files from RC-CAM site. PICALL says it programmed and verified everything OK.

I get no response from either chip -- no servo action, no indicator actions -- zip, dead, so to speak.

Anybody have any ideas here ?? I have two chips left, and am reluctant to try those -- for obvious reasons.

Ideas? Comments? Suggestions??

[Mr.RC-CAM]

I have two chips left, and am reluctant to try those -- for obvious reasons.If your programmer is working correctly then you can reprogram the 12F6xx chips many times. They are FLASH technology.

Anybody have any ideas here ??Check the config fuse settings used during programming. I'll bet they are wrong or have not been programmed.

RC-CAM

[Marion]

You were right about the Configuration settings. They did not read back correct. I changed them manually, and reprogrammed the Config. However, I still can't get the blasted things to work.

There are two additional config setting not mentioned. One is called BG0 and the other BG1. Any idea what these do and how they should be set?? I have them both set off.

I am beginning to think my chips are bad. I'll have a new bach is a few days. I'll post an update thereafter. &^&%$@!! electronci gadgets -- I love 'em -- Really

[Mr.RC-CAM]

There are two additional config setting not mentioned. One is called BG0 and the other BG1. Any idea what these do and how they should be set?? I have them both set off.These are the factory calibration bits for the Brownout detector. They are factory set and the end-user must NOT change them. Normally the programmer system would not reprogram these as a default setting. You do not want to enable that feature!

Are you sure your chips are bad? Unless they have been subjected to adverse harm they are unlikely to be defective. If they are defective then I would first suspect one of two things: (1) Programmer system hardware is defective (2) The Factory OSC Calibration byte has been accidently re-written during programming (do NOT change it!).

RC-CAM

[Marion]

To All.....

I got my chips programmed and working great this afternoon. If you want a real challange, try doing this with a tiny SOIC size 12F629 chip !! Yeah, I got that one working too :-)

[Marion]

Mr. RC-CAM, and others interested.....

I suspect my programmer did overwrite the OSC caliberation bits, but can't prove that.

Another possibility for damaged chips here is a high static electricity environment. Especially bad duing the low humidity winter months.

However, all's well that ends well. As posted above, I did manage to get things working OK.

I'd appreciate comments from others going down this same path. Anybody else working with this project ??

Marion

[Mr.RC-CAM]

MarionDK, thanks for the update. I too would be interested in hearing how other Landtastic project builders are coming along.

RC-CAM

[Marion]

For those interested in the strobe and / or navigation lights. www.batteryspace.com has high intensity white LEDs at 50 for $19.95. They also have them in blue at the same price.

I bought one each from Radio Shack yesterday -- at $5 and $4 respectively :-( Man, I shoulda shopped online first !!

[Marion]

I wanted to make a very small version of this project, so used SOIC size 12F629 chips. To do that I needed an adapter to go from the SIOC size to the DIP size my programmer uses. Commercial adapters cost about $200 -- way outta my price range for hobby things.

The photo below shows what I made. Yes, it is out of focus, and it doesn't look very professional. But it sure beats $200 !!

Looks like my photos are a bit to big for a single posting, so I'll post the other view in the next message.

Anbody else do this sort of "fun" thing??

Crazy Marion

[Marion]

The SIC chip is held in place by the part with the opening in it. Two 2x56 nuts hold everything in place

[Mr.RC-CAM]

There have been two reports of folks having poor success flashing the PIC Chip. Fortunately, one of the fellows took the time to figure it all out.

It seems that some hobby grade programmers are disturbing the chip's factory configured OSC calibration value. The workaround is discussed here: http://www.rc-cam.com/forum/index.php?act=ST&f=7&t=202&st=0#entry1168

For those of you that are thinking about programming extra Landtastic chips by copying one you got from me: Don't do this! The PIC's factory entered OSC cal value can be corrupted by being over-written from the chip dependant data found in the host PIC. This will probably lead to improper R/C signal decoding at the stick's end points. Instead, use the hex files on the project web page.

RC-CAM

[DrBill]

I have finished mine and works perfectly. The slowed-down servos look great. I dont have lights, just the landing gear. Worked correctly the first time, no difficulty in anything and a great little rpoject once again by Rc-Cam Man!

DrBill

[Marion]

Thanks for the link with more information about programming problems. I use PICALL here. I strongly suspect it DID reprogram the OSC value when I programmed the chip. That could have been my problem in programming from your HEX download flies. As mentioned in the other thread, I can change the OSC value in PICALL. And memory says I can also edit the program HEX files as well, but it has been along time since I looked into that - I could be wrong.

In my next attempt (today to tomorrow) I plan to first read the OSC value, save it, and put that value back into PICALL at 03FF for the programming session. I will also verify if I can edit the HEX files directily from within PICALL. I'll post my results here afterwards.

You are correct in that PICALL does use certain default values for the Config files, but once those have been modified on screen, they stay as the default for the next programming session.

[Marion]

OK Here's my report on PICALL. First I read the OSC values from the chip and saved them. You can edit all the program data bytes, and you can edit the OSC CAL value. You can also edit the programming start and end locations. (You can edit just about anything, it seems)

I tried several variations on this. Here is what I ended up using sucessfully - there are other ways too, this is just what I did with PICALL.

1. Read the chip, and the OSCCAL value will show up in the OSCCAL box on screen.
2. Write down that value.
3. Load the Landtastic program HEX file.
4. Check and change if necessary, the Config setting.
5 Type the recorded OSCCAL value in the PICALL box on screen.
6. Program and Verify the chip.
7. Read the chip and verify the OSCCAL value is correct.

An important tip to all chip programmers!!
The programmed chip WILL NOT operate until it is set up with a servo. Put the jumper on and fire up the chip, and set the desired speed per Mr. RC-CAM's instructions. Now the chip has data so it can run the serov. Until do this, there is no data for the servo to use and it will appear to be dead.

At least that is the way it worked for me. Oh, how many hours wasted because I did not think of that earlier !! :-(

Check me here Mr. RC - CAM. This is correct, is it not??

Crazy Marion

[Mr.RC-CAM]

The programmed chip WILL NOT operate until it is set up with a servo. ... Until do this, there is no data for the servo to use and it will appear to be dead.
Hmm, that is not what should happen. There is no reason to configure the LandTastic system to get it to work. Until the user decides to do so, the chip will use default settings. They are:
Servo speed: Approx 5 secs (can vary between 4-8 secs).
Stick Reverse: Off.
Servo Reverse: Off.

I am not sure why you did not see this. If your experience involved a PIC with a disturbed OSC value then that could explain the trouble. The PIC's factory OSC value must remain in place or R/C decoding will probably be goofy.

RC-CAM

[Marion]

Thanks for the reply. The chips referenced in my last post did NOT have the OSC value changed from the factory setting. I double checked that since the point has come up several times.

It appears I may still not have everything set ideally here. However, the chips are workling and that's what counts :-)

Sure hope we get some decent flying weather soon so I can post a flight report here.

[Marion]

Here are photos of my latest obsession. The smaller ones are not easy for me to make !!

Any other people have reports ??

[Marion]

Another Photo

[Mr.RC-CAM]

I can fully appreciate the small size of your SMT board. Geez, those photos make things look MUCH larger. I would guess it is nearly the size of a servo connector.

Is the LED a visual replacement for the piezo buzzer? If it is, then you can omit the transistor shown on the schematic and just rely on a current limit resistor (keep it under 15mA). Maybe that is what you have done already.

RC-CAM

[Marion]

Yes, Little Brother is close to the size of a servo connector. I went "all out" for something for a small, light park flyer on that one !!

You are right about my use of fhe LED as a repacement for the buzzer. Seemed to me that some sort of indicator might be useful for setting up the units. Thus the LED. That black rectangle on the lower right side of Little Brother is a current limiting resistor - SMD style.

Big Brother also has an LED and resistor instead of the buzzer. It also has the MOSFET for driving a strobe light. I have tried both a white LED and a blue LED for the strobe light. The blue one is impressive !! And man oh man, it is bright !!

No flights yet due to the weather and muddy field here in Northern Virginia.

A question for you.... How hard would it be to program this so that the strobe would start at power up, instead of going thru the gear up / gear down cycle to get it started ?? I am thinking of a strobe only operation, working off an unused channel.

Crazy Marion

[Marion]

Am I the only one interested in this project? I've not see posts by others lately :-( Where are the rest of you guys ???

[Mr.RC-CAM]

How hard would it be to program this so that the strobe would start at power up, instead of going thru the gear up / gear down cycle to get it started ?? I am thinking of a strobe only operation, working off an unused channel.I try to avoid multiple variants of a project (version control gets very messy). How about just putting it in parallel with the throttle channel? That way the strobe will be enabled when your ESC is armed. Low throttle controlled landing lights might just work out for you too. Don't forget I also have a nifty Nav-Lights project on the RC-CAM web site.

Where are the rest of you guys ???
My projects are very specialized and require electronic experience to assemble. So, the target audience is quite small.

RC-CAM

[Marion]

Gee, I thought this was a great project, and didn't understand how small the target audience might be !! :-( That being the case, guess I will stop my series of posts on this subject :-( :-(

[Mr.RC-CAM]

... guess I will stop my series of posts on this subject I would certainly encourage you to continue to share your project efforts.

None of my projects would be made public if I was concerned with how many folks would build them. I think some of them would be missed if I did that. And as more hobbyists see the potential of owning a PIC programmer, the odd little projects on the RC-CAM site get more attention every day.

Whether it be a nifty electronic R/C circuit, a new way to glue balsa, or a cool photo of a model airplane, sharing the fun is what it is all about. That is what drives me to spend endless hours documenting and sharing my little gadgets (I doubt many folks recognize the effort that goes into designing and publishing these "simple" PIC projects).

Thank goodness other eZoners do the same with their R/C adventures. ;)

RC-CAM

[Marion]

I agree 100% with your views of sharing projects for the benifit of others. And I do know of the unending hours it requires ( for me at least) to make something presentable.

My comment about stopping this series of postings was intended to apply only to this specific thread.

So what is your next project ?? :-)

Marion

[max z]

FWIIW I am following this thread. I intend to build this thing as well, but right now I have nothing to tell/show. Mine will probably be a DIL chip without the PC board, everything just soldered to the legs of the chip.( I will not use the strobe part). Buzzer will be replaced by a LED as Marion has done, preferrably one with built-in resistor. I appreciate your work, Mr. RC-Cam! (remember me from the aerial photography project?)

Max

[Marion]

It is good to know I am not the only one interested in building this project :-)

Crazy Marion

[KLH]

I really appreciate it when Mr. RC-CAM, MarionDK and some of the other talented folks on this site take the time share their creations with the rest of us. I love to build stuff and tinker, but when it comes to electronic type stuff like this controller I'm just a user. I can follow a simple schematic (simple is the key word here) and do an OK job of soldering, but thats about it.
I'm sure there are others on here like myself that grabbed some of the landtastic controllers when they were first offered, but haven't had a chance to sit down and install them in any planes yet. I like to have several projects going at the same time and several more waiting just to keep the old brain in gear.

Kern

[IceDancer]

Kern,

I am like you. I bought this chip to use when I put my Salamander together. It will be a while yet and then it will come in very useful indeed.

Sam.

[Marion]

Made the first flight today using Landtastic on flaps. It worked even better than I had hoped !! Previously my Ultra Stick wanted to go straight up when I dropped the flaps. It was really a violent maneuover. Using Landtastic, there is not any noticeable change in the model attitude -- it simply slowed gently. I had guessed at the "right servo speed" (about 6 or 7 seconds) and that was right on the money for this airplane.

Landastic is fantastic. It solved a serious problem on my Ultra Stick.

Thank you Thomas !!

[divya]

RC-CAM
Would it be possible to program the PIC to sequence two servos
so as to run gear doors, like the down/up P-51 sequence?

Thanks
Dorian

[Mr.RC-CAM]

I am not familiar with how the P-51 wheels are sequenced. What should happen during gear-up and gear-down?

RC-CAM

[divya]

the clamshell (inside) doors go down
the gear retracts
then the clamshell doors go back up (so they are not waving
in the wind and causing drag)

when the gear cycles back up
the doors go down, the gear comes up, the doors go up

this would be easiest with with two servos of course.
Dorian

[Mr.RC-CAM]

I can't help on that one. The Landtastic was not designed for that sort of sequence.

It could be done with a microcontroller though, including a PIC. Maybe one of the other PIC programmers on eZone will post something like that.

RC-CAM

[divya]

So this is a yes, a single properly programmed PIC could operate two servos in sequence with the just the gear up/down signal
from the receiver. Cool. This may give me the inspiration to try
some programming.

Thank you
Dorian

[max z]

Some Tx's can do it too, see http://www.rcgroups.com/forums/showthread.php?s=&threadid=217479

[divya]

Thanks for the Multiplex link.
I was not aware of that.
Dorian

[Hovertime]

RC-Cam I have noticed that this is the only one (?) of your projects that uses 12F629/75 all others use Pic12C508 family.

Is there a technical reason for it, such as more PIC features needed, or just a move toward flash (reprogrammable-reusable) pics?

[Mr.RC-CAM]

It needed the F629's flash EEPROM for storing user settings.

RC-CAM

[max z]

Mr.RC-CAM, here's a question. I did design my own purpose built retract, and I now find out I need a larger servo travel than my Tx has to offer. I cannot resolve it easily by changing the mechanics, a longer servo arm will get the angles wrong and negate the increased travel. Is there any way that Landtastic can do this, or are the endpoints set by the Tx?

http://home.hccnet.nl/max.zuijdendorp/images/gearup.gif

Max.

[Mr.RC-CAM]

The endpoints are determined by your Tx. Landtastic controls the retract speed.

If you need more travel than your Tx can provide, you might consider hacking your servo. Open it up. There are three terminals on the feedback pot. Locate the two outside terminals and then insert a series resistor in each leg. Try a couple of 1K ohm 1/8 watt. Decrease the R value if it is too much travel or if you see the servo stall.

RC-CAM

[orionRider]

Hi everybody,

I have been trying to use Landtastic (light version) on flaps, but got into some problems...
The 12F629 programs OK with the provided HEX, OSC cal set manually to factory settings.

Basically, the circuit works on its own. The servo travel is not linear, there are about 20 visible 'steps' between endpoints, but I can live with that. The main problem is that for any movement on another channel, the servo connected to Landtastic 'hiccups' severely.
Tried to add a ferrite ring, twisted cable and metallic shielding: no improvement.

Does anybody know the cause of this behaviour?

[Mr.RC-CAM]

The servo travel is not linear, there are about 20 visible 'steps' between endpoints, but I can live with that.There are actually 110 steps for full (1mS-2mS) travel and they should be linear. There is dynamic braking at the start/stop end points, which may appear as a "step" too. During programming, there are ten servo speeds available (1 Sec to 10 Sec).

The main problem is that for any movement on another channel, the servo connected to Landtastic 'hiccups' severely.I have not experienced that and I don't recall any reports about it. I doubt it is EMI/RFI (otherwise your remedies would have had an impact). If I had to guess, I would suspect there is some severe servo motor noise/ripple on the power buss. Have you tried a different BEC?

[orionRider]

Thanks for replying Mr RC-Cam, and thanks for sharing your project :)

I can see the dynamic braking, but the movement on mine doesn't look smooth at all. I didn't program anything, it is the standard 'light' setup.

The power comes from a separate rx battery, 5 NiMh cells through a Multiplex 35MHz receiver.
I don't think a faulty OSC could cause that and the chip was replaced by another one, just in case: same problem, maybe even worse... :confused:

I could try a separate power source for the flaps, but it is not practical.

[Mr.RC-CAM]

Movement: The movement may appear grainy at low speeds, but it shouldn't look unpleasant.

Glitches: It's probably the 5-cell NiMH. Landtastic works best on a 5V BEC or suitable 4-cell pack. Some relief might be found if you add a 1K ohm in series with the PIC's servo input and servo output pins. Beyond that, I would suspect it is dirty power. Perhaps an LM2940-5.0 LDO Vreg for PIC power would clean it up. As a test before doing that, run the R/C setup from a 5V BEC and see if the problem goes away.

[orionRider]

Bingo! Mr. RC-CAM, you are Landtastic! err, I mean "Fantastic!" :D

All is solved now, it was indeed the 7v delivered by the 5-cell battery that caused the circuit to glitch. With 4-cell, all is OK and the 'grain' is reduced as well. Now I can fully enjoy this little gem you gave us :)

Laurent

[Mr.RC-CAM]

That is very good news.

Keep in mind that the chip's OSCAL feature is factory calibrated at 5VDC. Plus, the PIC may suffer harm when Vcc is greater than 6.5V. So, that is why I recommend a 5V BEC or 4-cell pack.

[CarreraGTSCS]

I just found out about this device over in the FOAMY EDF forum. Looks to be just about the perfect solution for a lightweight and inexpensive way to get lights and servo slowing into an EDF jet.

My disclaimer for the following questions is that I know very, very little about electronics and have never built anything at all like this. I've been into electric flight since the early Astro Cobalt days so I can solder and + from -. :D

Is it difficult to add lights to the system? I want to have the tail and wingtip strobes blinking, the red and green wingtip lights and add red and green lights to the side of each intake by the cockpit as well as landing lights as well as tail lights on the Gripen. Will this system support all of these extra LED's?

Can the PIC be programmed on a seperate device to slave to the throttle and simulate afterburner only when going to full throttle? The best effect would be the afterburner flickering briefly when coming on and going off.

Thanks,
Mike

[Mr.RC-CAM]

Is it difficult to add lights to the system? The strobe and landing light outputs each use a 2N7000 transistor, which can support up to 200mA of LED current. For general information on LED's and how to use them, please see see my LED Calculator web page (http://www.rc-cam.com/led_info.htm).

Can the PIC be programmed on a separate device to slave to the throttle and simulate afterburner only when going to full throttle?Landtastic is configured to use a dedicated R/C channel to control the retract feature and arm the strobe light.

[Rogero]

Hello, first i want to thank you for this great project that made my scale airwolf looks pretty nice with slow retracts and custom lights.

I just want to get some help on my problem encountered lately with the Landastic circuit, i have installed JR DS-559 digital full sized servo for retracts, 2 landing lights actually installed on the wings as Blue Leds, and 5 stobe lights ( 2 on the tail, 3 in the rocket launcher ) the external BEC is set to 6V and i have used this setup for many flights without any problem.
Till last week when i wanted to land and the retracts servo refused to go down, i managed to land with the help of a friend without retracts, then i checked the wiring, servo, etc... all seems fine, after i disconnect/reconnect the main battery all works good again, but i had the same problem after my second flight too...
I took it home and checked the circuit and tried to change the servo speed with the jumper, but the PIC didn't save the new servo speed i set, or any changes made...
please any suggestions of what's the problem may be will be appreciated..
cheers...

Roger

[Mr.RC-CAM]

the external BEC is set to 6V and i have used this setup for many flights without any problem.The PIC microcontroller will be damaged if it is operated higher than 6.0V and there is a chance the 6V BEC went past this. The mfg's max recommended voltage is 5.5V.

Check the BEC with the voltmeter and replace the PIC with a new one for good measure. If it continues to act poorly then try it with a 5V BEC and see if it works correctly on that preferred voltage.