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The DIY stuff

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Re: The DIY stuff
« Reply #10 on: 10 / November / 2009, 05:40:41 »
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New to the forums and relatively new and inexperienced with CHDK and also electronics.
Sorry about the long post and hope it is in order and in the right place.

I went looking for a instructions on building cheap wireless remote for a Canon point & shoot camera using the exciting CHDK remote shutter facility.

OK, I have searched the web and found many references to remotes for either
   (a)    More advanced Canon cameras that have a mini jack socket and or IR receiver built in to allow remote picture taking.
   (b)    Wired remotes utilizing the CHDK hack and the Mini USB socket.

But very few meeting my requirements for a wireless version.

Now on reading these and also the CHDK forums it seems that the voltage sensed from the USB connection  can be as little as 3 volts for some cameras, or as high a 4.5 volts for others. I have a Powershot 720 IS and it appears that it is unlikely to  function reliably operating at only 3 volts However any voltage above 5.5 volts might be dangerous to the camera.

Now checking relevant postings I found some references to using Chinese made wireless doorbells and RC model controllers.  As the doorbells were listed as operating on 3 volts and the RC models controllers were more expensive,  I seized on one article that mentioned the possibility of using a cheap [admin: avoid swearing please] or burp machine.

I found one on sale at  +machine&form=KEYWORD]http://www.jaycar.co.nz/productView.asp?ID=GH1088&keywords=[admin: avoid swearing please]+machine&form=KEYWORD

This one was powered by 4 AAA cells so the 6 volts looked a bit risky.  Because of this risk I put the burper away in a cupboard and forgot about it. However we are planning a trip and when travelling a remote could be very usefull so out came the burp machine and I set about modifing it.

Reviewing some articles I I checked http://www.hackersbench.com/Projects/ding-dong/main.html
which  commented on the likely waveform and then I found Philip Schutz description using and opto coupled triac (MOC 3020)
http://digital-photography-school.com/how-to-make-a-remote-shutter-release-from-a-doorbell-diy-special

Using the MOC 3020 looked like it would solve the excess voltage problem, so  out came the soldering iron.
First I removed the speaker and connected the speaker wires to a LED. Pushing the remote button resulted in the LED glowing, but not that brightly, for about 2 seconds .

I decided to give it a try anyway and drilled holes and installed the opto coupler.  Luckily the battery holder had solder lugs at the end of each cell so tapping the coupled power supply at the 3rd cell (4.5 V) was easy.
Shaking in fear and trepidation I connected it all up and switched on the camera and receiver. Pushing  the remote button was followed a couple of seconds later by the camera's focusing beam coming to life and YES !.Success!  It took a picture. 
But, after 10 seconds or so it took another and then  another and so on ad infinitum?

After several more tries it took a picture and then semed to freeze with the recorded  picture showing on screen but I was getting no reaction to any camera controls until I switched the camera off or I removed  the USB plug.

My guess is that perhaps there is s some bounce in the switching from the MOC although connecting up a multimeter showed just a roughly 2 second pulse of 4+ volts but my meter has a very slow,  or nil, reponse  to transient spikes.

I have Canon 720 IS.... CHDK a720-100c-0.9.8-827-. Script Remote.bas   I have used the script with a wired remote switch 4.5 V  and it works as expected.
Help! Please, has any one got any ideas to solve my problem?


Setup:http://www.flickr.com/photos/38437603@N04/4092468356/sizes/o/

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Re: The DIY stuff
« Reply #11 on: 10 / November / 2009, 10:53:32 »
Help! Please, has any one got any ideas to solve my problem?
You tap the audio signal from the bell, right?

So, you're sending a ding-dong pulse train to the camera. Its brain hurts...

The simplest you could try is a capacitor as in the hackersbench link, and a ~1k resistor in series with the LED.

Re: The DIY stuff
« Reply #12 on: 10 / November / 2009, 11:14:01 »
any voltage above 5.5 volts might be dangerous to the camera.
No, it is not powering the camera or even any USB circuitry.
It is just a logic signal that tells the camera a USB cable is connected.
The signal is routed to some transistors via resistors of many kohm.
I regularly use a modified 6V mini torch.

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This one was powered by 4 AAA cells so the 6 volts looked a bit risky.

No.  
Quote
Using the MOC 3020 looked like it would solve the excess voltage problem

There is no problem.

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Success!  It took a picture.

Was the blue led lit and the screen blanked for the ten seconds ?



First of all, you do not need to use a script.

Download the DISKBOOT.BIN for your camera from this page http://stereo.jpn.org/eng/sdm/index.htm

Replace or rename the existing version.

Enter ALT mode, connect your receiver and press the switch.

Is the legend 'USB; displayed briefly at top left ?

You may need to try a few times.

Let us know what that does first.

You can also read this thread http://chdk.setepontos.com/index.php/topic,1590.0.html and check the links.


David
« Last Edit: 10 / November / 2009, 12:44:53 by Microfunguy »

Re: The DIY stuff
« Reply #13 on: 11 / November / 2009, 03:41:24 »


Re: The DIY stuff
« Reply #14 on: 11 / November / 2009, 04:45:56 »
I saw  no message about USB appeared.

That suggests the pulse is very brief.

Quote
The  blue LED lights for the 10 seconds and the pictures are focused and look fine.

Normally, that means the software is waiting for switch release, especially if the viewfinder led shows the camera has autofocused.

That is SDM's  DIRECT shooting mode.
(the word DIRECT is for historical reasons, the switch operates the camera 'directly' without needing a script).

In the Bracketing/Override menu, set focus-mode to digiscope.
Exit ALT mode, the word FAST should be at top of screen.

In this mode the camera should trigger as soon as it detects the voltage.

Let us know how you get on.







« Last Edit: 11 / November / 2009, 19:56:39 by Microfunguy »

Re: The DIY stuff
« Reply #15 on: 11 / November / 2009, 17:16:27 »
A quick update ...
I have a Chinese wireless doorbell and have just found that pin 6 of the logic IC goes high when a signal is received.
Music starts and there is a four-LED light show  for a second or so.
The output signal then goes low.

I connected the 3V signal directly to my A620 and it takes three pictures in FAST mode.

In ordinary DIRECT mode, it also takes three pictures so the output on pin 6 must pulse slightly.

I will add a diode and capacitor to integrate the pulses.

It should then take a single photo when music finishes.


EDIT
------

Why use components when we can do it with software ?
Try this version with your A720 100c :  http://www.zshare.net/download/68335211e530994f/

In menu Bracketing/Overrides you can set focus-mode to manual or digiscope to enter FAST mode.

The camera triggers immediately it detects the USB signal.

It will not trigger again until a pulse is received after two seconds.
I will make the pulse lockout time a menu option.
That now works with my A620 without any additional components.


On my camera, 'USB' was displayed for most of the music duration.
« Last Edit: 12 / November / 2009, 05:40:34 by Microfunguy »

Re: The DIY stuff
« Reply #16 on: 12 / November / 2009, 05:07:21 »
Quote
In the Bracketing/Override menu, set focus-mode to digiscope.
Exit ALT mode, the word FAST should be at top of screen.

In this mode the camera should trigger as soon as it detects the voltage.

Let us know how you get on.

Did that thanks.
Initially a button press on the remote resulted in two quick pictures but subsequent tests have been as expected.
i.e. a single shot for each press.

I had left the receiver on all night so I hope the lowered voltage (4.3V) has not caused the Double shot problem to go away. :-[
 
Thanks again forthe help. 8)
 

Re: The DIY stuff
« Reply #17 on: 12 / November / 2009, 05:11:48 »
I hope the lowered voltage (4.3V) has not caused the Double shot problem to go away. :-[


Use the new software version that I posted the link for above.


Re: The DIY stuff
« Reply #18 on: 14 / November / 2009, 22:39:59 »
Hi microfunguy
Sorry not to reply sooner but I have been trying to get my head around a bit more of the detail re the various flavours of CHDK and lessen my level of ignorance of the features covered in the menus..

When I tried the latest DISKBOOT.BIN (192,772kB 11/11/09) that you suggested, it worked as expected with the WIRED switch, but the wireless (burp machine) remote  would take only one picture  but then  no further action.
Before the button push  DIG is displayed on the left and when the remote button push happens USB is displayed and focussing happens and a picture is taken  but then no response to a further push (I waited several seconds) other than the USB text flashed once in response, but  that is all.
The camera does not freeze in that the display view moves in real time but I have to switch off.

The earlier DISKBOOT.BIN version ((185,340 kB 29/07/09)   where the blue LED holds for 10 seconds is quite workable for me so I am not too distressed, but I though I should report results.

Edit: I also note that when rumnning the DISKBOOT.BIN version ((185,340 kB 29/07/09) if the flash fires the picture is recorded the ten second blue Led completes and the flash fires again but no photo is taken ???
« Last Edit: 15 / November / 2009, 02:39:51 by Seagull »

Re: The DIY stuff
« Reply #19 on: 15 / November / 2009, 06:50:09 »

Before the button push  DIG is displayed on the left

Correct.

 
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when the remote button push happens USB is displayed and focussing happens and a picture is taken

Correct.

 
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then no response to a further push

You are locked-out for two seconds after the first pulse ends.
Try again and press the switch after three or four seconds (depending on how long your switch pulse is).
In latest version you can set the lock-out time from a menu item.
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the flash fires

probably the preflash to determine white balance, exposure or whatever.

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the flash fires again but no photo is taken

In Stereo menu set camera position to 'R' (for 'right' camera).
If synch is enable and a letter 'F' is displayed at the top you should be able to take a flash photo.

Is 'F' displayed ?

If not, tell me your Canon shooting-mode settings.



 

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