AC/DC Adapter plug or dummy battery for k10d?

shutterdrone · 08-22-2008, 06:20 PM

It seems that Pentax used a very proprietary format plug for the AC adapter on the K10D. And, you know, they want umpteen dollars for the AC adapter.

My problem:

I've got a 12V power system running lots of other things, and I'm going to have the camera running for a long time (think time-lapse), and I can easily regulate down to 8.3V (the 'DC IN' rating) or 7.4V (the battery rating). I absolutely want to avoid a DC->AC->DC conversion, and don't want to destroy an adapter worth about $50 for the $2 connector on it.

Does anyone know anything about the connector? Some info I could use to find one from another device, or even just order one directly?

Alternatively, does anyone know of a 'dummy' battery (like the kind canon uses) out there? I could certainly gut one of the cheap minolta's, but the idea of getting the acid all over me doesn't seem too pleasing. =)

Any advice would be greatly appreciated!

!c

shutterdrone · 09-25-2008, 10:44 PM

Ok, so after some searching and some helpful pointers from others, I wrote up a DIY guide to making an adapter kit of your own (using the exact same plug pentax uses) that lets you hook up to:

12V Cigarette lighter plug
12V AC->DC Adapter
Or, any old 12V battery (or two 6V lantern batteries in series, etc.)

All using fairly inexpensive parts (total cost < Pentax K10D power adapter)

The write-up is here: DIY AC Adapter for The Pentax K10D The Roaming Drone

Hope it helps anyone else in the same boat, looking to power their camera in the field!

!c

Steinback · 09-25-2008, 11:15 PM

Thanks for the writeup. I just finished building a 6 volt lead acid battery back for my Vivitar 285 (works well, but charges the flash a little slower than I had hoped for) so I'll keep this in mind if I ever decide to build another pack for my K10.

JCSullivan · 09-26-2008, 03:52 AM

Thanks for the tut - will have to give it a closer look although I don't understand the schematic.

I was going to suggest Ian (Steinback) would probably be the right guy for this but I see he beat me to it.

Lowell Goudge · 09-26-2008, 06:27 AM

the circuit diagram is right oout of any IC manufacturer's application guide for Linear devices.

the thing that is critical is being able to purchase the plug to fit the camera.

With respect to propritary design, I suspect this is more oriented to preventing people from making a mistake between all the different power plugs they may have, and destroying the camera in the process.

while I may sound a little skeptical, why, with so much money invested in the camera, would anyone risk it over $50 on a power supply?

The application shutterdrone made is a little different, he purchased the adaptor, then modified the plug and cable by adding a commercially available plug to allow disconnecting the plug from the adaptor and using some different power sources, for different applications.

I have done a similar adaptation to the wired shutter release for my PZ-1 to not only make it useable on the *istD and K10D but also to allow cable extensions.

shutterdrone · 09-26-2008, 08:31 AM

Originally Posted by Lowell Goudge

the circuit diagram is right oout of any IC manufacturer's application guide for Linear devices.

This is very correct, that image literally came from the LM317 application guide, I just modified the image and changed the values to the parts of the circuit and the components I used.

Originally Posted by Lowell Goudge

the thing that is critical is being able to purchase the plug to fit the camera.

With respect to propritary design, I suspect this is more oriented to preventing people from making a mistake between all the different power plugs they may have, and destroying the camera in the process.

while I may sound a little skeptical, why, with so much money invested in the camera, would anyone risk it over $50 on a power supply?

The application shutterdrone made is a little different, he purchased the adaptor, then modified the plug and cable by adding a commercially available plug to allow disconnecting the plug from the adaptor and using some different power sources, for different applications.

I have done a similar adaptation to the wired shutter release for my PZ-1 to not only make it useable on the *istD and K10D but also to allow cable extensions.

I agree the proprietary design does work to prevent confusion and the mistakes related, and I sincerely doubt they added a diode to prevent current inversion from someone's DIY setup. The Pentax adapter is also highly regulated. Most 12V wall-warts are very poorly regulated, the one pictured for example, will throw very high voltages with minimal load. The circuit works to add the same level of safety as the pentax design by enforcing regulation, and a clean output.

Although, I didn't buy a cable and cut it, I purchased the connector brand new from digikey (the link is in the post).

If you look elsewhere in my blog, you'll see that I've also created a very, erm, "expansive and expensive" cable remote for the K10D - not because the existing intervalometers out there weren't good enough, but that they didn't integrate with my motion control design.

!c

Lowell Goudge · 09-26-2008, 01:52 PM

Originally Posted by shutterdrone

If you look elsewhere in my blog, you'll see that I've also created a very, erm, "expansive and expensive" cable remote for the K10D - not because the existing intervalometers out there weren't good enough, but that they didn't integrate with my motion control design.

!c

where is the DIY forum when you need it.

I have a lightinig trigger I am waiting to test out, built by modifying an optical flash trigger to drive the remote shutter release.

Am also working on remote trigger via FRS radio.

shutterdrone · 09-26-2008, 04:08 PM

Originally Posted by Lowell Goudge

where is the DIY forum when you need it.

I have a lightinig trigger I am waiting to test out, built by modifying an optical flash trigger to drive the remote shutter release.

Am also working on remote trigger via FRS radio.

Hehe, yeah, a DIY forum would be nice -- unfortunately, I've been spending more time building things for the camera than actually using it!

That will be quickly rectified though, looking forward to a week in the desert next week -- lots of time to just shoot. hehe.

I've seen some people doing the lightning trigger thing before, there's been some question as to how well one would work, but I imagine if it works 30% of the time, it's better than using bulb mode!

Trigger via FRS? That sounds fun! Why FRS instead of, say, bluetooth?

Fortunately, triggering the camera is really easy, it's all the other things that can be hard. One of my next up-and-coming projects is to build an off-camera light meter that integrates with my motion/shutter control system to make appropriate ramps in exposure during sunset/sunrise timelapses. Though, I may have to take some time off from camera stuff, I promised the lady I'd make us a new bed, and I really want to make some interactive art for the living room. *sigh* If only I didn't have to work!

!c

JCSullivan · 09-27-2008, 06:57 AM

Damn...am I the only one born with moosh for brains!

shutterdrone · 09-27-2008, 01:13 PM

All, on further testing I have found the K10D to exceed 1.5A draw on numerous occasions, and have adjusted the tutorial to reflect using an LM338 instead of the LM317 and replacing 1N4007 diodes with 1N5400 diodes. A heat-sink is also now required.

I will update the page with a new diagram and images when I return from vacation, as I don't have any LM338's on-hand, and am currently "winging" it by using two 317's in parallel.

!c

Lowell Goudge · 09-29-2008, 07:25 PM

Originally Posted by shutterdrone

All, on further testing I have found the K10D to exceed 1.5A draw on numerous occasions, and have adjusted the tutorial to reflect using an LM338 instead of the LM317 and replacing 1N4007 diodes with 1N5400 diodes. A heat-sink is also now required.

I will update the page with a new diagram and images when I return from vacation, as I don't have any LM338's on-hand, and am currently "winging" it by using two 317's in parallel.

!c

I was going to suggest that yoiu might need a heatsink to get the rating out of the regulator.

Also, this will not only depend upon load of the camera but input voltage.

Note the linear regulator will dissipate power not used by the camera. if the camera draws 1.5 amps at 8.3 volts, the reguilator will dissipate (Vin-8.3) x 1.5 watts. it will get hot if you are not careful, especially on a car, with the engine running, because the 12V car system sits at 14.5 volts when running, to keep the battery charged.