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08-08-2021, 08:37 AM   #1
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Use of K-AC132 external power adapter for K-1 or K-3

This forum thread (Looking for tips on intervalometer settings - PentaxForums.com) raises the interesting question of whether shooting with an intermediate aperture value requires power from the battery during the exposure.

I suspect it does. Conceptually, it would be trivial to determine this: measure the current draw during a modest length exposure. In practice, perhaps easier said than done. In looking at the battery chambers in my K-1 and K-3, it would be a very tight fit to insert some kind of ammeter probe (requires some kind of layering/insulating conductors between a battery terminal and the spring-loaded contact of the camera). Even tighter would be getting the leads out of the camera without compromising the weather sealing gasket of the battery chamber cover.

So, what else could one do? Run the camera from some external power source, either the AC adapter or a battery grip. I have neither of these, but somebody out there must.

My first question is "does the regular battery have to be inserted in the camera when using either of these options"? If not, then the camera is being powered completely externally, and it should be easy to measure the current draw.

The easist way for me to try this would be to get a plug which fits into the external power socket. Does anybody know what the plug is (it looks a bit exotic), or even what voltages the various pins therein expect? I can readily supply almost any voltage and can probably make some kind of contacts.

Conversely, what about the battery grip contacts. Does anybody know the pin assignments for that? They would be harder to connect to, but not impossible.

And, the EASIEST way to know would be if somebody from Pentax/Ricoh could just chime in with the answer! (I participate in a forum for HP calculators, and several of the HP engineers directly involved in the design of the calculators participate in the forum as well. They have to be somewhat cautious about revealing trade secrets, but they do often reveal intersting tidbits about the calculators and design processes.) Do we have any idea if anybody from Pentax/Ricoh monitors our ramblings here?!

08-08-2021, 09:49 AM - 1 Like   #2
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If you can find an old battery which fits the camera, you can disassemble (carefully because it's a lithium battery) the battery and remove the internal power cells. Then you can route a 2-conductor cable to the battery connectors and out through a hole in the bottom of the battery. This allows you to power the camera with the battery flap open and the wires attached to the appropriate power supply (note the word appropriate!) making sure the polarity is correct (compare your dummy battery connected to your power supply to a real battery). Just another option if you have an old battery lying around (alternately, it should be pretty simple to 3D print a dummy battery and install the power pins in slots to facilitate internal wiring and a trailing cable.)

I think if I were doing this, I would buy the $99 power adapter for the camera (K-AC132) and hack the output to the camera to allow current measurement (plus, now you have a power adapter). It is a rather special connector which goes to the camera and I'm not sure that type of connector is available otherwise. The adapter provides the same voltage as a typical battery to the camera (fully charged voltage is shown in D-Li90 diagram; typical voltage is 7.4V).
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Last edited by Bob 256; 08-08-2021 at 10:44 AM.
08-08-2021, 10:22 AM - 1 Like   #3
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QuoteOriginally posted by AstroDave Quote
My first question is "does the regular battery have to be inserted in the camera when using either of these options"?
On the K-3 when used with an external power supply (HQRP AC adapter) and battery removed, the camera powers on the moment the adapter is plugged in to the external power fitting.


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08-08-2021, 11:09 AM   #4
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Bob 256: yes, I contemplated that (the old dead battery with guts removed) some time back (for a similar reason: just to measure how much current the camera draws), and even thought I had a line on one that somebody was going to give me, but that didn't pan out. I can probably carve something useful out of a piece of wood with some contacts glued on (although I should learn 3D printing someday!).

I'm trying to avoid a $99 experiment (!), but I think the HQRP adapter Steve mentions is substantially cheaper.

Anybody got an old dead D-LI90 that I can have/get?!


Steve: thanks for the info - so, if I can figure out how to get power in there, I should be able to measure things. Do you have any means to determine the polarity of the adapter output?

08-08-2021, 02:49 PM - 1 Like   #5
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As I recall the power connector is made by Hirose and both the male and female connectors can be found on digikey.com. Use your favorite search engine and search for "DIY AC adapter K10D" to find a blog that has the pin-outs. Or search Pentax forums for "hirose" and the same info may be posted here somewhere.

With the connectors you could make a cable with connection to an ammeter without having to cut open the adapter cable.
08-08-2021, 03:07 PM   #6
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QuoteOriginally posted by Not a Number Quote
As I recall the power connector is made by Hirose and both the male and female connectors can be found on digikey.com. Use your favorite search engine and search for "DIY AC adapter K10D" to find a blog that has the pin-outs. Or search Pentax forums for "hirose" and the same info may be posted here somewhere.

With the connectors you could make a cable with connection to an ammeter without having to cut open the adapter cable.
Yep - some diligent research (aided valuably by postings here on the Forum) comes up with the Hirose part number MQ172-3SA-CV(30), available at Digi-key. I even have an account number there, but haven't checked on shipping yet. I also found a really cheap power supply version on Ebay: ~$13 - with free shipping! I'm not sure I would actually trust my camera to that, but I could cannibalize the plug.
08-08-2021, 04:02 PM   #7
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QuoteOriginally posted by AstroDave Quote
Do you have any means to determine the polarity of the adapter output?
Not at present.


Steve

08-08-2021, 04:06 PM - 1 Like   #8
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QuoteOriginally posted by Not a Number Quote
Use your favorite search engine and search for "DIY AC adapter K10D" to find a blog that has the pin-outs.
You mean this one?

DIY AC Adapter for The Pentax K10D and K20D | The Roaming Drone

Sadly, all the diagrams are 404.


Steve
08-08-2021, 06:39 PM   #9
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QuoteOriginally posted by stevebrot Quote
You mean this one?

DIY AC Adapter for The Pentax K10D and K20D | The Roaming Drone

Sadly, all the diagrams are 404.
Thanks - I'd seen that one referred to, but even those came up with a 404, so this is marginally better - but, I know enough to kludge my own wiring, and circuit if necessary.
08-08-2021, 06:51 PM - 1 Like   #10
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Yup, that's the connector - also here on Mouser.

https://www.mouser.com/ProductDetail/Hirose-Connector/MQ172-3SA-CV30?qs=%2Fh...8XNien25o7lui3

and also the data sheet on it:

https://www.mouser.com/datasheet/2/185/doc_1806181802182-2298276.pdf

Thanks for all those references everyone.

Think you're in business AstroDave.

Another choice for a dummy battery is one of those on eBay for cheap-cheap. We know they aren't worth anything, but maybe in this case???
https://www.ebay.com/itm/254101704072?_trkparms=ispr%3D1&hash=item3b29a44d88...Cclp%3A2334524
Well probably not being that the connector is little over a $.

Last edited by Bob 256; 08-08-2021 at 07:07 PM.
08-08-2021, 07:15 PM - 1 Like   #11
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QuoteOriginally posted by AstroDave Quote
I also found a really cheap power supply version on Ebay: ~$13 - with free shipping!
If that one is a dud, the HQRP is the classic fallback and falls into the same price bracket.

amazon.com : HQRP AC Adapter Compatible with Pentax K-AC132 38780 K-1, K-3, K-3II, K-5II, K-5IIs Digital SLR Camera Power Supply Cord + Euro Plug Adapter : Camera & Photo?tag=pentaxforums-20&

There are multiple happy users here at PF.

Oh...and I found the pin-outs for the Hirose connector on the blog post:
QuoteQuote:
Step 6: Wire Hirose connector. Note that the GND is the top-most pin when the plug is inserted into the camera, the +8.3V is the bottom most pin when plugged in. Center pin is unused.

Steve

Last edited by stevebrot; 08-08-2021 at 07:32 PM.
08-08-2021, 07:44 PM   #12
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QuoteOriginally posted by AstroDave Quote
raises the interesting question of whether shooting with an intermediate aperture value requires power from the battery during the exposure.
FWIW...Going back to the earliest days of electronic shutters, the assumption has been that if the shutter is open, it is power that keeps it so.


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08-09-2021, 05:51 AM   #13
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QuoteOriginally posted by stevebrot Quote
FWIW...Going back to the earliest days of electronic shutters, the assumption has been that if the shutter is open, it is power that keeps it so.
So, no need to experiment.

However, I would still like to measure the current consumption during various stages/types of operation, so I guess I will order one of the Hirose plugs and have some fun.

Thanks, again, Steve & Bob, for valuable legwork.
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