Switch closing

Professorwiz

Good Day,
I have a newbie electronics question,· I'm working with the BS2 on a BOE.· For my project I'm going to click a shutter on my camera.· I planned on doing this by using the port on the camera that goes to a remote triggering device.· The device normally has 2 buttons, one for focus and one for "take the picture".· I figure I could just hook a relay cicuit to one of the pins and have the pin close a relay to make the closed circuit on the switch.· Am I thinking correctly?· Is there something I should watch for like voltage somehow going back though the relay and into the camera?· Similar to the reason we have to put a diode so that when releasing the relay we don't get a flyback voltage?
Thanks for any help.·
Russ

Professorwiz

Not enough info?· Has someone already done a project like this?

QuattroRS4

Professorwiz,
If this interface is a simple switch closure thats fine - I think you have to be sure that this remote - is as you say it is - 'a simple switch closure' - if this can be confirmed then I am sure

Professorwiz said...
Not enough info?

will not apply and you will get all the answers you need.

Regards,
Quattro

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Professorwiz

The reason I gave a simple switch closure, was I saw a web site showing how people have made their own extended shutter release. The diagagram showed a switch that would you'd press that would make the tip and the 1st ring of a 1/8 headphone type jack make connection to focus and connection between the tip and 2nd ring to take the picture. I'll find the site and diagram. It all looked pretty simple and that's the reason I thought it'd be cool to have the stamp control this process for different uses, example put a time lapse system, or motion senser trigger it, ect..
Thanks for the help!
Russ

QuattroRS4

That Ok - I just wanted to ensure that thats all it was - before you damaged any thing ...

So what are you looking for exactly - a simple circuit to switch a relay ?

I posted this on a different thread -

http://forums.parallax.com/attachment.php?attachmentid=45487

Optionally you could use a transistor to drive the relay (or a transistor on its own - if you knew
the associated voltages and orientation of the camera interface)· but since you requested a relay circuit ·the above example shows a pvdz172n·- which is an optically coupled photovoltaic with integrated reverse biased diode on output stage ..

Regards,
·········· Quattro




▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Post Edited (QuattroRS4) : 4/4/2007 11:55:10 AM GMT

Professorwiz

I've got a circuit from the class I was taking to switch a relay, but as they say a little knowledge is dangerous.. Some one had mentioned that I might be able to get away with a transistor instead of a relay and getting rid of the danger of the flyback voltage (I believe that's the proper terminology), or should I be safe enough just putting the diode on the relay and running it like it was drawn and used before.
The damaging thing was my main concern of course. I appriciate the help.
Russ

QuattroRS4

Well 'Safety is the best Policy' as they say so - the attached example above would probably be the safest

Will that do the trick for you - If you are not confident with your electronics - get someone who knows about it to give your circuit a 'once over' before you connect anything...

Regards,
Quattro

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Professorwiz

Quattro,
Thanks for your help, the optical isolation was the direction I was thinking.· I have a couple HSR312's laying around I got on a sample order.·
I've attached the data sheet here, the internal schematic looks similar if you get a minute and can look at page 6, of the pdf, which is the schematic of the chip it looks like I could adapt this chip to your schematic using the parallel connection.· Does this seem logical to you.· If you don't have time to look, no worries, I know I'm pushing it asking all these questions.· I'm trying to learn as I go, and I will have someone that's more familiar with this look it all over before I make the connection to the camera.
Thank again.

QuattroRS4

Professorwiz,
Yeah - that looks fine as long as the current requirements to switch your relay do not exceed Imax - 320mA (if used in Parallel mode) and 190mA (in series mode). The example device in the circuit I posted has a current capability of 1.5 amps @ 60VDC.

Incidently what type (spec) of relay are you planning to use ?

Regards,
Quattro

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Post Edited (QuattroRS4) : 4/4/2007 2:12:52 PM GMT

Professorwiz

Quattro,
To be completely honest, I haven't looked that far yet.· They were using microswitches in the remote switch I got part of the idea from.· I was thinking small reed relay, but am unsure.· Do you have an idea?
Russ

QuattroRS4

Small relays like these are also fine -

http://relays.tycoelectronics.com/datasheets/w11.pdf

you will have to choose·a vlotage which·matches the supply you will be using..







▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Professorwiz

I was going to run it off the Board of education board for now.· So the output of that would be 5V correct?·
So I would need part #2-1393779-7 which has a nominal voltage of 5fdc.· I'm a little confused by the coil power, I would multiply the volts * watts to get the amps to check to see if I'm within range correct?· So 5 volts X .2 watts ?· I'm unsure of the conversion or is 200mW - .2 Watts.. sigh.. I apologize once again for my ignorance..
Rus

QuattroRS4

The supply you would use for the relay should ideally not be the 5v that supplies the stamp (i.e. not after the reg)... loads of possible issues there ...

What is the supply going to the board - before the reg ? Battery or PSU if psu what are the specs.


Quattro

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
'Necessity is the mother of invention'

Professorwiz

I can use either, but the battery is easier to use in the class, the power supply I have is a 7.5volt unit that came with the BOE kit, the school I'm going to makes a bundle with the LCD display and power supply.. I believe it's the 1 amp unit that Parallax sells.


Russ