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Thread: Gas usage monitoring

  1. #11
    Automated Home Sr Member cliffwright's Avatar
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    Quote Originally Posted by Karam View Post
    Perhaps a bit late in the day ... but judging from the datasheet and the findings of the example you linked to, I think you may need to connect an NPN transistor to the photo transistor output of the OPB704 - essentially to form a darlington output. This is because it looks like under expected detection conditions the 'on' current of the phototransistor alone will likely be in the region of 100uA which will not pull the digital input low enough. I was going to suggest something like 545-2254 from RS but I see you have already ordered . I don't know how much into electronics you are but you might have an NPN transistor handy anyway or maybe back to Maplin ... I would imagine pretty much any small signal NPN should be good enough. I would suggest this transistor is wired in at the location of the detector rather than at the module.
    Bugger That'll teach me for being impatient . . .


    Quote Originally Posted by Karam View Post
    I don't know how much into electronics you are but you might have an NPN transistor handy anyway or maybe back to Maplin ... I would imagine pretty much any small signal NPN should be good enough. I would suggest this transistor is wired in at the location of the detector rather than at the module.
    "Not very" is the answer . . . general wiring I'm fine with . . . but 'electronics' I have to scratch my head a fair bit and refer to the likes of Wikipedia for calculations . . .

    I'll see what I can do with this once it arrives - I might email you for advice if I can't fathom it though!

  2. #12
    Automated Home Jr Member jcmiguel's Avatar
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    Hi Karam,
    This is an old post but relevant to what I am doing right now. Could I use a BC547C (RS 464-019 or Farnell 2126392) for that? I have loads of those and I am trying to set up a pulse counter with the OPB 705. Also, what type of current/voltage you can safely have on the digital inputs? I will also try the OPB720A-06Z which will need the 12V input but returns a digital on off signal of 10V and will work better on my electricity meter. However, I am not sure how to connect to the digital input without damaging the idratek module. You find the datasheet for the OPB720 here(http://www.optekinc.com/datasheets/opb720a-12z.pdf).

    And Happy New Year

    Quote Originally Posted by Karam View Post
    Perhaps a bit late in the day ... but judging from the datasheet and the findings of the example you linked to, I think you may need to connect an NPN transistor to the photo transistor output of the OPB704 - essentially to form a darlington output. This is because it looks like under expected detection conditions the 'on' current of the phototransistor alone will likely be in the region of 100uA which will not pull the digital input low enough. I was going to suggest something like 545-2254 from RS but I see you have already ordered . I don't know how much into electronics you are but you might have an NPN transistor handy anyway or maybe back to Maplin ... I would imagine pretty much any small signal NPN should be good enough. I would suggest this transistor is wired in at the location of the detector rather than at the module.

  3. #13
    Automated Home Legend Karam's Avatar
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    Yes I should imagine a BC547C would do the job (form a darlington pair with the IR phototransistor). I'm not sure if the OPB720A-06Z would distinguish between the variation in reflectivity at close range but I guess its one of those suck and see if you've got one. The Voltage you are refering to I believe is not present on the device output i.e it appears to be open collector - which is what you want. Simply connect collector end to the digital input and obviously the 0V must be shared with the digital input module 0V. But as a general reply the digital inputs should just connect to mechanical switch type devices or open collector type outputs from electronics, i.e volt free. If you really must connect a voltage signal then it shouldn't exceed 3.3V.

  4. #14
    Automated Home Sr Member cliffwright's Avatar
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    Mainly through being busy with other 'suff', I've still not managed to make progress on this subject, but would still love to integrate monitoring of my Gas usage within Cortex.

    I could do with more of a point and shoot 'idiots guide' to hooking something up to an Idratek module - does anyone know of such a blog post or such that I can refer to?

  5. #15
    Automated Home Sr Member cliffwright's Avatar
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    Am I the only one needing an 'Idiots guide'? Nobody got any advice?

  6. #16
    Automated Home Legend Karam's Avatar
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    Do you mean specifically relating to the suggested gas monitoring idea or more generally?

  7. #17
    Automated Home Legend chris_j_hunter's Avatar
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    how about :

    http://phk.freebsd.dk/Gasdims/

    http://docs-europe.electrocomponents...6b80065728.pdf

    connected to a pulse-counting digital input ...
    Last edited by chris_j_hunter; 24th January 2013 at 05:56 PM.

  8. #18
    Automated Home Sr Member cliffwright's Avatar
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    Quote Originally Posted by Karam View Post
    Do you mean specifically relating to the suggested gas monitoring idea or more generally?
    Gas at first - but I want to achieve the same thing with the electric meter (via the blinking red LED).

    Quote Originally Posted by chris_j_hunter View Post
    how about :

    http://phk.freebsd.dk/Gasdims/

    http://docs-europe.electrocomponents...6b80065728.pdf

    connected to a pulse-counting digital input ...
    Yes - I've seen this. I totally understand the principals - but don't get the electronics. This is the bit I need an "Idiots" guide for.

    I "Get" that a sensor can detect either reflected 'light' from a silvered numeric on a gas meter, or detect the pulses from a blinking LED on a 'leccy meter - I just don't "Get" the electronics to hook this up to an Idratek module . .

  9. #19
    Automated Home Guru JonS's Avatar
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    I would also appreciate a dummies guide for connecting things other relays / switch contacts to Idratek inputs.I have a IR beam break sensor crying out to be connected but the idea of monitoring gas and elec (both meters with rotatings dials) is very attractive.
    Thanks
    JonS

  10. #20
    Automated Home Ninja Viv's Avatar
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    Quote Originally Posted by JonS View Post
    I would also appreciate a dummies guide for connecting things other relays / switch contacts to Idratek inputs.I have a IR beam break sensor crying out to be connected but the idea of monitoring gas and elec (both meters with rotatings dials) is very attractive.
    Thanks
    IR Beam, do you know the model or a link for its spec?

    Viv

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