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Thread: Keyswitch recommendation

  1. #1
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    Default Keyswitch recommendation

    Hi

    I need to fit a mains keyswitch to my projector. I have found this but I'm not sure if it's suitable due to key position removal

    Any advice appreciated (UK 240VAC)

    Ta

    tendril

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  3. #3
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    Default

    Hi Tendril

    none of the keys shown in Andys Maplin link comply with the ILDA safety standards ( or my standards either )

    the key must only be able to be withdrawn in the OFF position only ....

    this prevents any operator switching the safety circuit ON then taking out the key and leaving the desk with everything live ....

    Did i mention that it is also wise to attach the key via a chain to your body .... so you dont leave .... with it still in the switch lock


    i also have an Emegency stop button ( Estop ) in series with the key switch
    Although my switches are rated for 240V i only use them with 12V DC .... this is fed via a 100M cable along with the ILDA cable as seperate safety circuit, this is then connected to failsafe safety Beam shutter that prevent the beam emmision from the projector, this allows quick recovery in case of accidental shut off ... rather than knocking the mains supply off ...


    all the best .... Karl
    Last edited by Banthai; 02-29-2008 at 16:56.

  4. #4
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    Default

    I've got a few available I bought a lot of 10 that you can remove the key only in the off position. I am using two on my projector but I plan on using a few of the others in the future. I looked for a LONG time for them, and once I saw them on eBay I bought all that this guy had.

    I also dont use them on mains voltage. I've got a 5v interlock for my projector which in turn controls a relay that kills all the power to my projector - and also trips a shutter. Very redundant - I know - but I want the redundancy for safety.

    While I am on the topic - does anyone know a good way that I can use a standard 555 IC to make it so that if the interlock gets tripped it would take at least like 5 seconds to be able to start up again?

  5. #5
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    Karl

    Where did you get the locks? they're like hens teeth to find in the UK.

    I could use a couple.

    Cheers

    Jem

    Quote Originally Posted by Banthai View Post
    Hi Tendril

    none of the keys shown in Andys Maplin link comply with the ILDA safety standards ( or my standards either )

    the key must only be able to be withdrawn in the OFF position only ....

    this prevents any operator switching the safety circuit ON then taking out the key and leaving the desk with everything live ....

    Did i mention that it is also wise to attach the key via a chain to your body .... so you dont leave .... with it still in the switch lock


    i also have an Emegency stop button ( Estop ) in series with the key switch
    Although my switches are rated for 240V i only use them with 12V DC .... this is fed via a 100M cable along with the ILDA cable as seperate safety circuit, this is then connected to failsafe safety Beam shutter that prevent the beam emmision from the projector, this allows quick recovery in case of accidental shut off ... rather than knocking the mains supply off ...


    all the best .... Karl
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.”... Douglas Adams 1952 - 2001

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    Quote Originally Posted by Banthai View Post
    Hi Tendril

    none of the keys shown in Andys Maplin link comply with the ILDA safety standards ( or my standards either )
    yep... tried maplin myself first. The link I provided goes to a radioshack site. If you look at the pdf document it has details of key trapping for the whole range of switches, but as a noob, I'm not sure how to read the document accurately.

    The key is only required for a small portable projector, so no 100m cable runs . The projector goes up on a lighting rig out of reach of prying fingers.

  7. #7
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    Default

    Quote Originally Posted by mliptack View Post
    While I am on the topic - does anyone know a good way that I can use a standard 555 IC to make it so that if the interlock gets tripped it would take at least like 5 seconds to be able to start up again?
    depending on your budget, you may want to look into time delay relays. these can be set to delay before tripping, or to delay before resetting, or on a continuous repeat(which you'd most likely not need), but you could set one up with your interlock to kick off for n seconds before restoring power.
    you can look at the beasties here:http://search.digikey.com/scripts/Dk...?name=PB555-ND


    Please note that's for a 120VAC relay. you can get them in all kinds of flavors.
    also, on a side note, if anybody wants a 24vdc switching supply, I can get a couple spares off the tour I'm on. only a couple amps and you'd have to wait till april when I'm stateside to get them, but if you want one, pm me and i'll throw it in my suitcase.

    to get back on topic, what are you looking for? just a 555 based timer citcuit? something that can switch a scr?
    this site ain't bad to look at: http://www.circuits-lab.com/?p=432
    (I hotlinked an example for ya). there are a ton more resources lying around. my guess is that you can find the exact schematic you want without too much trouble. While it doesn't use a 555, the fourth entry on this page may do what you want. there are a bunch of cool circuits on there, it's a good bookmark for anybody.

    anyway, it's shower/beer/bed time, but have fun.
    "TO DO IS TO BE" - Nietzsche
    "TO BE IS TO DO" - Kant
    "DO BE DO BE DO" - Sinatra

  8. #8
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    Hi Jem

    they are available most places .... a lot of the confusion is in the termology and descriptions suppliers use

    for instance in this CPC link this switch does not really describe if the key is removeable or not, but if you click on the further information link it will take you to the Lorlin specs for all the models in this range and it shows
    this model is a single pole, double throw ( change over contact ) switch and says that the key is removable in only one position

    so that means .... you can pull the key in either the on or off position, depending on which side of the change over contact you wire the safety circuit

    http://cpc.farnell.com/SW02264/compo...IN-SRL-5-E-D-2

    sorry if that sounds a bit muddled but ive just got out of bed


    all the best .... Karl

  9. #9
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    Quote Originally Posted by Banthai View Post
    Hi Jem

    they are available most places .... a lot of the confusion is in the termology and descriptions suppliers use

    for instance in this CPC link this switch does not really describe if the key is removeable or not, but if you click on the further information link it will take you to the Lorlin specs for all the models in this range and it shows
    this model is a single pole, double throw ( change over contact ) switch and says that the key is removable in only one position

    so that means .... you can pull the key in either the on or off position, depending on which side of the change over contact you wire the safety circuit

    http://cpc.farnell.com/SW02264/compo...IN-SRL-5-E-D-2

    sorry if that sounds a bit muddled but ive just got out of bed


    all the best .... Karl
    Thanks Karl

    I understand what you're saying regarding the confusion over terminology. Thanks for the link.

    Hope you had a good sleep and didn't do too much dreaming about egg boxes

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.”... Douglas Adams 1952 - 2001

  10. #10
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    Tendril

    as you are mounting the laser up in the lighting rig its even more advisable to have a remote box keyswitch.

    the reason being once its up in the rig and the key is in the on position the unit is live and allows un autorised people to activate the laser whilst you are away from the controls

    if you are using the laser in public then its important to show that you have an easy way to disable the laser

    the box is very simple ( bit like me ) i have attached some photos of my box

    the main box has a short cable ( 5 metre ) this is so i can use it at localy at the projector, it connects to the projector via a 3 pin plug and socket

    if i use it over the 100m run i just use and extension cable that extends both the safety interlock and the ilda signals

    also the circuit is very simple


    hope this helps ....

    all the best ... Karl
    Attached Thumbnails Attached Thumbnails DSCF0397.jpg  

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    Last edited by Banthai; 06-19-2008 at 00:52.

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