12 VDC power adapter for K-1

wings · 10-02-2019, 01:35 PM

I can find AC power adapters for the K-1, but it would be nice to have an adapter for the K-1 for a 12 vdc battery, especially when out in the field. I sent a suggestion to Pentax, however they only acknowledged the message.

Not a Number · 10-02-2019, 01:45 PM - **1 Like**

This DIY adapter would be compatible with the K-1. The LM338 power supply control chip will operate on DC as well as AC. You can buy pre-built power suppy modules based in the LM338 chip on eBay and are adjustable for the power output needed for the K-1. Check the specs one the OEM AC Adapters for the proper output. All you need to do is hook up power in, power out and adjust the output with the trimmer. And put it in a case.

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

The most difficult part is finding the power connector to the camera. The above blog lists a part number and suppliers.

**alfa75ts** · 10-02-2019, 02:22 PM

Originally posted by Not a Number

The most difficult part is finding the power connector to the camera.

The connector appears to be the mq172-3sa-cv(30) which can be found on eBay.

There are plenty of step-up or step-down DC-DC modules on eBay for a dollar or so, some have a usb input to make it easier. I'm not sure of the power requirements of the K1 (8.3volts but how many Amps?).

**kiwi_jono** · 10-02-2019, 02:24 PM

I have an electronics background and I have thought of doing my own DC power adapter also but be aware if something goes wrong it is all too easy to fatally damage a camera if something goes wrong (like full 12+ VDC gets passed through to the camera) - also voiding any warranty.
So far I have not been brave enough to do this with my K-1 and agree it would certainly be great if Pentax provided a DC adapter as an accessory.

**Bob 256** · 10-02-2019, 04:25 PM - **1 Like**

Originally posted by kiwi_jono

I have an electronics background and I have thought of doing my own DC power adapter also but be aware if something goes wrong it is all too easy to fatally damage a camera if something goes wrong (like full 12+ VDC gets passed through to the camera) - also voiding any warranty.
So far I have not been brave enough to do this with my K-1 and agree it would certainly be great if Pentax provided a DC adapter as an accessory.

Kiwi_jono is quite correct. Series regulator chips have been known to fail, putting the full unregulated voltage on the load. Toasting a K-1 would really, really hurt. Any power supply should include what's known as a crowbar circuit (Google for examples) which basically puts a short across the supply output if it goes over the specified voltage, thus preventing damage downstream. An experimenter can start with a three pin regulator like that mentioned, and add a crowbar circuit pretty easily. Even two back-to-back Zeners (with appropriate power ratings) with breakdowns just above the desired voltage and a line fuse preceding them would be effective in preventing overvoltage getting to the camera load. The latter is desirable even with a crowbar since it provides transient protection should something happen to introduce a power transient in the line.

A fake battery can be 3D printed with provisions for camera contacts and a power lead which goes to an external regulator circuit. Of course, the battery compartment door needs to remain open for this arrangement which is inconvenient and risky (to the door). Some cameras have a power connector (plug-in jack) which gets around the issue of going in through the battery compartment.

**Ex Finn.** · 10-02-2019, 04:43 PM

Originally posted by alfa75ts

The connector appears to be the mq172-3sa-cv(30) which can be found on eBay.

There are plenty of step-up or step-down DC-DC modules on eBay for a dollar or so, some have a usb input to make it easier. I'm not sure of the power requirements of the K1 (8.3volts but how many Amps?).

The Pentax AC power supply is rated to supply 2 Amps so a 3 to 5 amp regulator will be sufficient.

Not a Number · 10-02-2019, 04:50 PM

It is easy enough to add a failsafe limiter circuit. Pentax cameras have some sort of regulator on the AC adapter port to begin with since the 8.3v output of the AC adapter exceeds the 7.2v output of the LI90P and other batteries.

Even if Ricoh were to make a 12 VDC adapter the circuitry could fail as well. Warranty would cover only the accessory, not damage caused by use of the accessory. You pays your money yous takes your chances.

Last edited by Not a Number; 10-02-2019 at 05:57 PM.

angerdan · 10-03-2019, 05:32 AM

There're already threads about external power supply for the K-1:
K-1 power supply for UK - PentaxForums.com
External power - PentaxForums.com

And getting 12V is easy, since USB QC 3.0 allow to put out 12V DC.
Quick Charge - Wikipedia

You can put in a QC trigger between a QC USB port and an calble with adapter for the K-1:
Test of QC2-QC3 trigger

Not a Number · 10-05-2019, 10:32 PM

Hmmm, look at this thread:
DIY K-5 Power Supply from 12V battery - PentaxForums.com

Even though the original blog page mentioned is no longer active the datasheet for SWADJ13 regulator will show you how to hook it up and adjust the device. All you need is a "hobby box", wire, a cigarette plug adapter and the Hirose connector

wings · 10-06-2019, 09:20 AM

Originally posted by kiwi_jono

I have an electronics background and I have thought of doing my own DC power adapter also but be aware if something goes wrong it is all too easy to fatally damage a camera if something goes wrong (like full 12+ VDC gets passed through to the camera) - also voiding any warranty.
So far I have not been brave enough to do this with my K-1 and agree it would certainly be great if Pentax provided a DC adapter as an accessory.

I am like you on this, as I have a high tech background and it is not a matter of putting the components together for DIY for me that is very easy, but making sure that my K-1 is not damaged from a failed component etc. is my concern.

angerdan · 10-06-2019, 02:49 PM

Originally posted by wings

I am like you on this, as I have a high tech background and it is not a matter of putting the components together for DIY for me that is very easy,

but making sure that my K-1 is not damaged from a failed component etc. is my concern.

You can use the battery grip and modify the AA battery tray for use with external DC power like USB QC.

10-02-2019, 01:35 PM	#1
wings Senior Member Join Date: May 2017 Posts: 209	12 VDC power adapter for K-1 I can find AC power adapters for the K-1, but it would be nice to have an adapter for the K-1 for a 12 vdc battery, especially when out in the field. I sent a suggestion to Pentax, however they only acknowledged the message.

10-02-2019, 04:25 PM - 1 Like	#5
Bob 256 Site Supporter Join Date: Jun 2008 Location: Idaho Photos: Gallery Posts: 2,378	Originally posted by kiwi_jono I have an electronics background and I have thought of doing my own DC power adapter also but be aware if something goes wrong it is all too easy to fatally damage a camera if something goes wrong (like full 12+ VDC gets passed through to the camera) - also voiding any warranty. So far I have not been brave enough to do this with my K-1 and agree it would certainly be great if Pentax provided a DC adapter as an accessory. Kiwi_jono is quite correct. Series regulator chips have been known to fail, putting the full unregulated voltage on the load. Toasting a K-1 would really, really hurt. Any power supply should include what's known as a crowbar circuit (Google for examples) which basically puts a short across the supply output if it goes over the specified voltage, thus preventing damage downstream. An experimenter can start with a three pin regulator like that mentioned, and add a crowbar circuit pretty easily. Even two back-to-back Zeners (with appropriate power ratings) with breakdowns just above the desired voltage and a line fuse preceding them would be effective in preventing overvoltage getting to the camera load. The latter is desirable even with a crowbar since it provides transient protection should something happen to introduce a power transient in the line. A fake battery can be 3D printed with provisions for camera contacts and a power lead which goes to an external regulator circuit. Of course, the battery compartment door needs to remain open for this arrangement which is inconvenient and risky (to the door). Some cameras have a power connector (plug-in jack) which gets around the issue of going in through the battery compartment. Last edited by Bob 256; 10-02-2019 at 04:38 PM.

10-03-2019, 05:32 AM	#8
angerdan Pentaxian Join Date: Feb 2015 Photos: Gallery \| Albums Posts: 2,642	There're already threads about external power supply for the K-1: K-1 power supply for UK - PentaxForums.com External power - PentaxForums.com And getting 12V is easy, since USB QC 3.0 allow to put out 12V DC. Quick Charge - Wikipedia You can put in a QC trigger between a QC USB port and an calble with adapter for the K-1: Test of QC2-QC3 trigger Last edited by angerdan; 10-03-2019 at 06:58 AM.

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10-02-2019, 01:45 PM - 1 Like	#2
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	This DIY adapter would be compatible with the K-1. The LM338 power supply control chip will operate on DC as well as AC. You can buy pre-built power suppy modules based in the LM338 chip on eBay and are adjustable for the power output needed for the K-1. Check the specs one the OEM AC Adapters for the proper output. All you need to do is hook up power in, power out and adjust the output with the trimmer. And put it in a case. DIY AC Adapter for The Pentax K10D and K20D \| The Roaming Drone The most difficult part is finding the power connector to the camera. The above blog lists a part number and suppliers.

10-02-2019, 02:22 PM	#3
alfa75ts Loyal Site Supporter Join Date: Jun 2009 Location: Melbourne Australia Photos: Albums Posts: 1,356	Originally posted by Not a Number The most difficult part is finding the power connector to the camera. The connector appears to be the mq172-3sa-cv(30) which can be found on eBay. There are plenty of step-up or step-down DC-DC modules on eBay for a dollar or so, some have a usb input to make it easier. I'm not sure of the power requirements of the K1 (8.3volts but how many Amps?).

10-02-2019, 02:24 PM	#4
kiwi_jono Loyal Site Supporter Join Date: Dec 2009 Location: Christchurch, New Zealand Photos: Gallery \| Albums Posts: 2,437	I have an electronics background and I have thought of doing my own DC power adapter also but be aware if something goes wrong it is all too easy to fatally damage a camera if something goes wrong (like full 12+ VDC gets passed through to the camera) - also voiding any warranty. So far I have not been brave enough to do this with my K-1 and agree it would certainly be great if Pentax provided a DC adapter as an accessory.

10-02-2019, 04:43 PM	#6
Ex Finn. Site Supporter Join Date: Nov 2007 Location: Southern Maryland. Espoo. Kouvola. Photos: Gallery \| Albums Posts: 7,975	Originally posted by alfa75ts The connector appears to be the mq172-3sa-cv(30) which can be found on eBay. There are plenty of step-up or step-down DC-DC modules on eBay for a dollar or so, some have a usb input to make it easier. I'm not sure of the power requirements of the K1 (8.3volts but how many Amps?). The Pentax AC power supply is rated to supply 2 Amps so a 3 to 5 amp regulator will be sufficient.

10-02-2019, 04:50 PM	#7
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	It is easy enough to add a failsafe limiter circuit. Pentax cameras have some sort of regulator on the AC adapter port to begin with since the 8.3v output of the AC adapter exceeds the 7.2v output of the LI90P and other batteries. Even if Ricoh were to make a 12 VDC adapter the circuitry could fail as well. Warranty would cover only the accessory, not damage caused by use of the accessory. You pays your money yous takes your chances. Last edited by Not a Number; 10-02-2019 at 05:57 PM.

10-05-2019, 10:32 PM	#9
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Hmmm, look at this thread: DIY K-5 Power Supply from 12V battery - PentaxForums.com Even though the original blog page mentioned is no longer active the datasheet for SWADJ13 regulator will show you how to hook it up and adjust the device. All you need is a "hobby box", wire, a cigarette plug adapter and the Hirose connector

10-06-2019, 09:20 AM	#10
wings Senior Member Join Date: May 2017 Posts: 209 Original Poster	Originally posted by kiwi_jono I have an electronics background and I have thought of doing my own DC power adapter also but be aware if something goes wrong it is all too easy to fatally damage a camera if something goes wrong (like full 12+ VDC gets passed through to the camera) - also voiding any warranty. So far I have not been brave enough to do this with my K-1 and agree it would certainly be great if Pentax provided a DC adapter as an accessory. I am like you on this, as I have a high tech background and it is not a matter of putting the components together for DIY for me that is very easy, but making sure that my K-1 is not damaged from a failed component etc. is my concern.

10-06-2019, 02:49 PM	#11
angerdan Pentaxian Join Date: Feb 2015 Photos: Gallery \| Albums Posts: 2,642	Originally posted by wings I am like you on this, as I have a high tech background and it is not a matter of putting the components together for DIY for me that is very easy, but making sure that my K-1 is not damaged from a failed component etc. is my concern. You can use the battery grip and modify the AA battery tray for use with external DC power like USB QC.