Ghettofabulous Mark 6 aka DIY Series (big pics)

[taggalucci]

I think I said that wrong; I mean an audible or visual alert that shows the case intrusion interlock sensors have been defeated. There is something in the CDRH requirement docs that say if your interlock is defeatable there has to be an indicator to tell the person working on the projector that the interlock has been defeated. The way around that is not to have a defeatable interlock, but any interlock is defeatable... The key is to not provide a way to defeat it. Like on mine, I just need to keep my alligator clips tucked away while the projector in out in public. I am just curious how to make an additional circuit to add the defeated interlock indicator... In theory.

I believe this is if you implement a specific defeat switch, say if only internally accessible or via a dedicated key switch, then you would need some form of indicator to show when the defeat is in force. A DPDT switch would provide you 1 circuit to switch the defeat on/off and 1 other circuit the alert on/off (wired inversely).

[allthatwhichis]

I think I am going to stick with "the interlock is NOT defeatable" even though there is always a work around. I just got finished with my Kvant's interlock and I don't see a way to defeat it unless a couple of wires are disconnected and a jumper is put in place of the case sensors. With the way I have the product report I should be OK; it is apain in the ass to defeat the Kvant and my DIY projector I can make sure the gator clips are not left in the case.

[dsli_jon]

Hey Brotherman...

I don't see a way to defeat it unless a couple of wires are disconnected and a jumper is put in place of the case sensors.

IMHO / Exp, here's what you want to use for *any* door interlock:



...reason-being, a) the CDRH is very-familiar with it... (well, at least they *used* to be.... ) and can be found on countless certified laser and laser-integrated systems, and b), allows you to very-easily 'defeat' it via pulling the stem-out (I am sure you can see how the mechanism works, 'push-pull'...)

...But they like it, because it is a positive, *conscious-decision-action* - you can't 'accidentally' trip it, it takes a good-deal of force to close (or open to-defeat, via the 'pull-action'...) ...a 'micro-switch', alone, is really not-enough... using 'tape' or other such, as an interlock-defeat is, well, lame, and using a 'jumper' is inconvenient (what if you lose the jumper? now you're hunting for paper-clips: also lame... ...and also, a micro-sw can get 'bumped' - this takes far more than a 'casual bump' to close... And they're good for thousands upon thousands of duty-cycles...

You can get them here: http://search.digikey.com/scripts/Dk...ame=CKN1402-ND If you wanna get 'real-fancy', there are 'redundant' ones: http://search.digikey.com/scripts/Dk...ame=CKN1404-ND ...but you can usually find them surplus or wholesale, somewhere, for 'cheaper'...

Really, this should-be all the 'intrusion-sensing' you'd ever need - they snap right open, and kill your i-lock circuit, real-well... And since your system should *always-be* under the 'continuous-control of an operator' / not-have 'flat-head' case-screws, etc (something easily openable...) this type of 'defeatable-interlock' has classically been just-fine for the FDA, etc... (with appropriate warning-labels, blee, blah-blah...

Here's a 'typical-mounting layout':



..hope this helps... at least for 'Mark VII'...
cya
j