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Battery third (temp) terminal as multipurpose analogue input

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Offline ahull

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Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #50 on: 17 / January / 2014, 11:32:36 »
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What do you mean by "a single series 10K"? For me a "series" consists of at least two thus can't be single.  ???
"Series" refers to how the components are connected. http://en.wikipedia.org/wiki/Series_connection

In this case the "series" grouping would be the switch and resistor..

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Btw.: What is the final opinion about the ominous interior parts of the dummy? If I could omit them I would probably make the dummies from wood.

In can't find the original Canon dummy, but if you want me to measure something on the board, I have a voltmeter.

If you had a multimeter, which could measure ohms, and perhaps has a continuity mode or buzzer, we might be able to identify the other components in the dummy batteries. My gut feeling is that they could be omitted.

Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #51 on: 17 / January / 2014, 14:26:47 »
Hmmm. I am not sure whether my Multimeter has such "buzzer" mode, at least a search in the manual does not find "buzzer".

Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #52 on: 17 / January / 2014, 14:35:15 »
It will be on the resistance range, lowest value, and may have a loudspeaker icon.

Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #53 on: 17 / January / 2014, 14:54:08 »
Hmmm. I am not sure whether my Multimeter has such "buzzer" mode, at least a search in the manual does not find "buzzer".
If you can take a resistance measurement,  the "continuity" information does not have any additional value.
Ported :   A1200    SD940   G10    Powershot N    G16


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Offline ahull

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Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #54 on: 17 / January / 2014, 15:49:55 »
Using the meter in resistance mode (Ohms), measure the resistance of the two devices. We need to know the resistance in both directions so to speak.

Place the black lead probe on T1 at the end nearest the power connector, the red lead probe on the other end of T1 and measure the resistance. Now swap the probes round, red nearest the power connector, black furthest away. measure the resistance again.

No repeat the process for T2.

Give us those four values, and we will try to make an educated guess as to the function of the two Tn devices.

My money is on them both being similar, and having a very low resistance (of the order of 1 ohm or less) in both directions.
(I may of course be completely wrong  :D )

My reasoning is that the board is marked T1 and T2, so they are probably meant to be ferrite beads to help keep the incoming power supply "clean", assisted by the two missing capacitors (or as I previously suggested some sort of over current device to protect against reverse polarity, but that makes less sense with hindsight as they both have a name prefix of "T", suggesting a transformer or wire wound component ).

In the cheap rip off version, the board has been cloned, and the filtering components either omitted in the case of C1 and C2, or in the case of T1 and T2 replaced with "Zero Ohm" resistors (wire links in effect), which are obviously much cheaper, but will fit the same board footprint.

In other words, the caps were omitted completely and the function of the ferrite beads was lost as they were replaced with wires.

This board will work perfectly well, and be perfectly safe, but will not be as good a solution as the original, in terms of protecting the camera from unwanted power supply unit (PSU) noise and transients caused by plugging and unplugging the power connector. As always you get what you pay for. In this case, I wouldn't loose any sleep over the cheaper solution. 
« Last Edit: 17 / January / 2014, 16:09:38 by ahull »

Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #55 on: 17 / January / 2014, 16:29:11 »
Hello waterwingz!  :)

Your guess is right, no matter which direction I measure, the value is always "00.2" when having the multimeter set to 0-200 Ohm range.

This is also true for "T2" the part that seems to have three (or even four?) connections, but... Hmmmm, I better attach pictures to show the values I get.

Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #56 on: 17 / January / 2014, 16:29:46 »
Now between these is no connection, also not when switching polarity.

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Offline reyalp

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Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #57 on: 17 / January / 2014, 16:32:58 »
Both.   But it's a two step hack.  You mask the door switch in kbd.c  and you add a bit of code in boot.c.   The boot.c part is something reyalp discovered,  I'll see if I can find that post.


Update : http://chdk.setepontos.com/index.php?topic=5744.msg56367#msg56367
Just a note that this is only required on some cameras. Cameras where the factory power adapter requires the fake battery (rather than a standalone DC in jack) either operate with the door open already, or have a hole for the plug.
Don't forget what the H stands for.


Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #58 on: 17 / January / 2014, 16:45:12 »
In this case, I wouldn't loose any sleep over the cheaper solution.

Okay, so it seems true that I could omit the whole board, right?

One question then: At the moment I have those 50 power supplies. Would it be of advantage to replace them with a single stabilized one? I was always thinking about that, because it would make the whole rig somewhat less heavy and a little smaller too. And also it seems that the 50 power supplies produce something that I know as "potential", don't know if this is the right word for that in english too.

This "potential" however, so I was told, is produced by little building differences between the 50 power supplies, and it resulted in the fact that I had to ground the complete rig when once shooting on a wet meadow, because I could not touch it otherwise, I got some unpleasant electric shocks, not really threatening, but enough I did not want to work with it. As soon as the whole thing was grounded into the meadow the phenomenon was gone.

Now if the 50 supplies really are the reason for these electric shocks, then I could omit the duty to have a ground after having them replaced, right?

On the other hand the fact that having 50 different supplies  could be somewhat safer. If one supply fails, I have four spare. If the "one for all"-supply fails, I am done. What would you suggest? Would you replace the 50 supplies or should I keep them?

@reyalp: the SX200IS don't work with the door open.
« Last Edit: 17 / January / 2014, 16:47:02 by Karmaschinken »

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Offline ahull

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Re: Battery third (temp) terminal as multipurpose analogue input
« Reply #59 on: 17 / January / 2014, 17:47:51 »
In this case, I wouldn't loose any sleep over the cheaper solution.

Okay, so it seems true that I could omit the whole board, right?

Yes.

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One question then: At the moment I have those 50 power supplies. Would it be of advantage to replace them with a single stabilized one? I was always thinking about that, because it would make the whole rig somewhat less heavy and a little smaller too. And also it seems that the 50 power supplies produce something that I know as "potential", don't know if this is the right word for that in english too.

Sounds like poor isolation in the  cheap clone power supplies.

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This "potential" however, so I was told, is produced by little building differences between the 50 power supplies, and it resulted in the fact that I had to ground the complete rig when once shooting on a wet meadow, because I could not touch it otherwise, I got some unpleasant electric shocks, not really threatening, but enough I did not want to work with it. As soon as the whole thing was grounded into the meadow the phenomenon was gone.

Always a good idea to ground any metal structure in case one of the power supplies fails and puts mains voltage in to the mix.

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Now if the 50 supplies really are the reason for these electric shocks, then I could omit the duty to have a ground after having them replaced, right?

Yes, in theory, but how safe is the replacement. I would ground the structure anyway.

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On the other hand the fact that having 50 different supplies  could be somewhat safer. If one supply fails, I have four spare. If the "one for all"-supply fails, I am done. What would you suggest? Would you replace the 50 supplies or should I keep them?

You pays yer money you takes your chance, however where are you going to find a 3.7 Volt 100 Amp power supply easily?
 

 

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