Author Topic: Mahogany DNA20 (Read 17807 times)

jbs · « **on:** July 06, 2014, 08:23:40 PM »

Ohh boy it's been a while.....

Some time ago i made dna20 stealth mamu's version. Great mod, compact and handy however i found out that having no option of swapping battery is not my cup of tea at all.
Since the battery started to play on me and i always wanted to have wooden mod i decided to make one.

The body is made of mahogany and consist 4 parts. C shape 'frame', two side covers and battery lid.
I tried to shave off as much material as possible. Side covers are aprox 2mm thick, battery lid is 3-4mm and 'frame' 2-3mm and 4mm.
From inside wood has been sealed with ca glue and from outside it's just pure and simple boiled linseed oil finish.
I was planning to go for ca glue glass finish however the plastic feel of glue would ruin natural feel and texture of wood that can be easily achieved with linseed oil.

510 connector is modified fatdaddy's 'repair kit' and now is spring loaded.
The rest is well known i suppose. Dna 20, buttons, some wire, solder, cut and burnt fingers....

The pictures are taken with rather old phone and to be honest with you they ruin my hard work.
Those of you that are familiar with the look of oiled mahogany know what i mean

Enjoy

Visus · « **Reply #1 on:** July 06, 2014, 09:18:29 PM »

That is awesome

niice mod

Like the stealth too, it was; for nostalgia sake, actually breaks stealth mod he was beta base uno with the dna20 9v, Mamu credits him in her build post about it.. awesome..

Breaktru · « **Reply #2 on:** July 06, 2014, 10:03:45 PM »

Well done. Excellent work and wiring

BTW: photos are pretty good for a camera phone

jbs · « **Reply #3 on:** July 07, 2014, 05:09:23 AM »

Thanks guys.

@Visus if you are referring to Breaktru's first dna20 in 9v battery box than yeah i know he was the first one. I chose mamu's version because of layout and less hassle of squeezing all the parts inside.

Btw. Its morning again i will update photos with the one that i will take in daylight.

Bigwhiterabbitt · « **Reply #4 on:** July 07, 2014, 09:59:32 PM »

That's a lovely bitta wood work and the way you've mounted the board is fantastic.. What are the measurements?

jbs · « **Reply #5 on:** July 08, 2014, 05:56:41 AM »

Thanks

.

Box itself without 510 connector: 76mm x 41mm 22mm.

Connector is 2mm.

The 18650 flat top battery barely fits inside.

As for 18650 mod plus dna board inside i consider it fairly small.

Bigwhiterabbitt · « **Reply #6 on:** July 08, 2014, 11:29:43 AM »

The size of a battery box Fantastic..

c1truz · « **Reply #7 on:** July 08, 2014, 02:21:16 PM »

I wish I could take the time to learn to make wooden boxes. I love the way they look. Good Job!

jbs · « **Reply #8 on:** July 08, 2014, 04:08:14 PM »

I am not a wood worker at all. Its my first wood project in my life.
Woodworking seems to be some sort of a magic but its not. Its not an easy trade, it takes knowledge and experience however its actually quite fun and interesting to learn few things about wood as a material and how to work with it. On top of that its rewarding once you get to see what you made. I spent a good few hours watching youtube videos about working with wood. All sort of stuff. Cutting, sanding, turning, finishing, plus few hours here and there about tools used in the workshop.
C1truz, its a bit of a pain to work only with basic tools but it can be done. With a proper tools such a little box is really an easy project.

c1truz · « **Reply #9 on:** July 08, 2014, 04:25:29 PM »

I'll have to look into it myself. Always wanted to. Youtube is a powerful tool now.

Bigwhiterabbitt · « **Reply #10 on:** July 10, 2014, 03:22:32 AM »

Where did you get your fuses jbs? I've havn't been having much luck finding any in the UK..

jbs · « **Reply #11 on:** July 10, 2014, 12:53:27 PM »

Fuses here:

http://uk.rs-online.com/web/p/resettable-surface-mount-fuses/6478257/

The problem is i couldn't find 3A fuses in a reasonable size so i chose to use 2x 2.6A. Technically speaking i should have used 2x 3.5A fuses for dna20 but you know... oh well.

There is a RS branch where i live. And i think they do have reasonable delivery cost compared to farnell, mouser, digikey.

You could try your luck on ebay. There are littlefuse fuses available but ofc not even one 3A rated.

Bigwhiterabbitt · « **Reply #12 on:** July 10, 2014, 03:41:47 PM »

Saw those ones.. I've been looking for these for a DNA30 http://www.digikey.com/product-detail/en/1210L450SLWR/F5790CT-ND/3661932 can't find them in the UK and huge postage cost from the US..

CraigHB · « **Reply #13 on:** July 10, 2014, 05:00:30 PM »

Littelfuse has filled sample orders for me when I've requested them. Don't know if the'll send samples international, might be worth a try.

Did you try UK Mouser (http://uk.mouser.com)? They have the 3.5A hold ones in stock. With two in parallel you're good for a trip current up to 14A, should work fine;

http://uk.mouser.com/ProductDetail/Littelfuse/1210L350SLWR/?qs=sGAEpiMZZMsxR%252bBXi4wRUIMo%2fvs2cxsbfepWN187KuM%3d

jbs · « **Reply #14 on:** July 10, 2014, 06:34:20 PM »

Thanks for help Craig.

I don't think that the availability is the issue.

You see... i suppose that for you or others involved in electronics the delivery cost is not the main issue as i would expect for instance You or Breaktru to have a fair amount of components at hand and if you do order anything you make sure that the price of your order is higher than delivery charge. In order to do so you must be in need of so many parts.

For those of us making one or two fairly simple mods that requires a minimum number of parts stocking up on components makes no sense.

The very moment you go to checkout you look in the basket and you see 5 tiny (in this case) fuses for which the delivery cost is twice the price of the fuses... well... the reaction is obvious

WTF???

It does not compute

I think its more of a matter of principle to not to pay more for a delivery than a product itself.

On the other hand i found out the hard way that quite often diy projects are more expensive to make than actually buying finished products.

kortt · « **Reply #15 on:** July 11, 2014, 12:21:46 AM »

That is one beautiful mod! Nicely done!

Bigwhiterabbitt · « **Reply #16 on:** July 11, 2014, 04:04:56 AM »

Quote from: CraigHB on July 10, 2014, 05:00:30 PM

Littelfuse has filled sample orders for me when I've requested them. Don't know if the'll send samples international, might be worth a try.

Did you try UK Mouser (http://uk.mouser.com)? They have the 3.5A hold ones in stock. With two in parallel you're good for a trip current up to 14A, should work fine;

http://uk.mouser.com/ProductDetail/Littelfuse/1210L350SLWR/?qs=sGAEpiMZZMsxR%252bBXi4wRUIMo%2fvs2cxsbfepWN187KuM%3d

Looking at what's available and working backwards from 4.5A would these be any better for the DNA30? Slightly higher trip and hold values than the 3.5A (not by much)

http://uk.mouser.com/Search/ProductDetail.aspx?R=1210L380SLYRvirtualkey57610000virtualkey576-1210L380SLYR

jbs · « **Reply #17 on:** July 11, 2014, 05:43:04 AM »

DNA20
max input current 7A - one 7A fuse or two 3.5A fuses in parallel.

DNA30
max input current 12A - one 12A fuse or two 6A fuses in parallel.

Let me quote Mamu:

'You can choose a hold current slightly under or slightly over the max input current of the converter if you can't find a fuse that is equal to the max current and still have good protection as there is a current cushion between hold current and trip current. What is important is that you don't want to choose a hold current that is too low else you'll get annoying inadvertent tripping when running the converter at or near max output or from normal operating internal heat (plus each time a fuse trips, the resistance takes days to return to the initial state). For the most part, we are using fuses to protect us and the circuit from a batt fault or reverse polarity. Either of those situations will cause a huge current dump from the batt, so no matter if the hold current is a bit high the fuse will trip rather fast.'

You can always use wire ended fuse however you can expect higher fuse resistance.

For example:
http://uk.rs-online.com/web/p/resettable-surface-mount-fuses/6478257/
min resistance 0.015 Ohm
max resistance 0.08 Ohm

http://uk.rs-online.com/web/p/resettable-wire-ended-fuses/7127528/
min resistance 0.035 Ohm
max resistance 0.11 Ohm

Is it a significant difference and how does it affect the performance of the mod? I don't know.

We need Craig's expertise in this matter.

Hope it helps.

Bigwhiterabbitt · « **Reply #18 on:** July 11, 2014, 06:30:22 AM »

I read on another post here about the 4.5A being a good compromise between min and max requirements thats why I was asking about the 4.5A. My box is the same size as yours although made of aluminium so not a lot of space. I'm going to use a single lipo for this so could probably squeeze the larger 6A fuses in if I have to but I'd rather keep it small and neat if I can..

CraigHB · « **Reply #19 on:** July 11, 2014, 02:10:22 PM »

Quote from: jbs on July 11, 2014, 05:43:04 AM

Is it a significant difference and how does it affect the performance of the mod? I don't know.

It's up to the designer really to make that determination. You can look at the losses for yourself and decide. Simply use current squared times resistance to find the loss and compare that to input. For example, using a fuse with 20 mOhms results in a loss of 2 Watts with 10 Amps draw. Total power is going to be 10 Amps times a mean 3.7V for a single cell. Input power is 37 Watts, 2 of which are going to the fuse. That's a 5% loss. You can roughly equate that to 5% of the hits being lost. For a run time on a charge of say 1000 hits, that's 50 hits being lost to the fuse.

Ideally you want loses minimized as much as possible. Getting 1000 hits off a charge is better than getting 950 hits off a charge. 1 or 2% is probably inconsequential, but 5% becomes considerable.

Also, what comes with power loass is voltage drop. It's generally not a problem, but it can be if using a regulator that is sensitive to input voltage level. Some regulators can be sensitive to source impedance which is increased by fuse resistance.

You can actually run these fuses all the way up to the trip current, but the closer you run to the trip current the higher the likelihood of a false trip. Because PTC fuses are heat driven, once they've tripped, they trip at a much lower current until they've cooled down completely. If running too close to the trip current, you can get into a situation where the fuse repeatedly trips even after the load has been reduced.

bamani71 · « **Reply #20 on:** September 02, 2014, 02:37:30 PM »

I was wondering, did you press fit the buttons or were they glued in? If glued, what type did you use?

jbs · « **Reply #21 on:** September 04, 2014, 05:54:30 PM »

Both.

Inside of the box is covered with a layer of super glue to seal the wood.

It took tiny tiny bit of super glue to secure buttons in place even though they would stay in place as press fit.

bamani71 · « **Reply #22 on:** September 05, 2014, 02:18:55 AM »

Awesome, thank you!

MFarley · « **Reply #23 on:** September 13, 2014, 05:37:45 PM »

Nice work. You did well with the mahogany.
Photos looked good to me, but I understand what you mean with trying to capture the luster of the wood in your photos.