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RE: [smartsockets] Re: B7971 6 digit clocks

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  • jack
    Must be 30-75 quid I guess? Dependant on the module used. New modules costs loads, I bought a serial output all sealed Garmin on Ebay for £15. New probably a
    Message 1 of 17 , Feb 11 7:21 AM
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      Must be 30-75 quid I guess? Dependant on the module used. New modules costs loads, I bought a serial output all sealed Garmin on Ebay for £15. New probably a lot more. But we don’t need the latest and greatest as the clock is being used in a static environment.

       

      From: smartsockets@yahoogroups.com [mailto:smartsockets@yahoogroups.com] On Behalf Of fixitsan2
      Sent: 11 February 2010 01:01
      To: smartsockets@yahoogroups.com
      Subject: [smartsockets] Re: B7971 6 digit clocks

       

       



      --- In smartsockets@yahoogroups.com, jack <jack@...> wrote:
      >
      > I am interested in a 6 digit 7971 clock using these type of features, with GPS stability.

      Jack, I know you are keen to see GPS used as a time source. I am currently investigating sources of low power modules, and at te end of the day the deciding factor will always be price.
      How much extra would you be willing to pay to have GPS accuracy and stability ?

      I could put something together which measured 60mm X 50mm X 30mm, contained a GPS, battery and a Zigbee mesh radio and a solar panel which would never need external power. It could wake up from sleep, update the clock via wireless zigbee connection, within a range of 30m, twice each day, and go back onto solar charge.

      The cost is always going to be the deciding factor.

      Chris

    • fixitsan2
      ... I do have long term plans to cater for dot matrix displays too. Imagine all the possible transitions you could get with digits falling apart , and so on.
      Message 2 of 17 , Feb 11 7:24 AM
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        --- In smartsockets@yahoogroups.com, jack <jack@...> wrote:

        > London underground use LED's for the destination boards at stations. I looked at them and they are a matrix of rows and columns - they don't draw scrolling pictures but I guess they could......they do scroll 'the next train is delayed by 10 minutes' etc etc...but this clock is a different beasty.....
        >


        I do have long term plans to cater for dot matrix displays too.

        Imagine all the possible transitions you could get with digits 'falling apart', and so on.

        "What the world needs now, is bling, sweet bling"
      • fixitsan2
        ... Exactly, so the question is would you happily pay that ? www.rfsolutions.co.uk list a very small surface mount GPS unit at about £14, 45mA current draw.
        Message 3 of 17 , Feb 11 7:28 AM
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          --- In smartsockets@yahoogroups.com, jack <jack@...> wrote:
          >
          > Must be 30-75 quid I guess? Dependant on the module used. New modules costs loads, I bought a serial output all sealed Garmin on Ebay for £15. New probably a lot more. But we don't need the latest and greatest as the clock is being used in a static environment.
          >

          Exactly, so the question is would you happily pay that ?

          www.rfsolutions.co.uk list a very small surface mount GPS unit at about £14, 45mA current draw.

          The only problem I have as a user of GPS is that I don't like the extra coax cable required usually for the antenna, in order to locate it near a window. This is why I installed a GPS in my loft and used 433MHz radios to receive the retransmitted time signal. Using Zigbee is just the modern twist on that, Zigbee transceivers are available at £10 each.

          Chris
        • jack
          Well I guess a remote GPS module is really fancy - but how do you power it. Now you have to ask - is there a power source near the GPS which needs to be near a
          Message 4 of 17 , Feb 11 7:57 AM
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            Well I guess a remote GPS module is really fancy – but how do you power it.

             

            Now you have to ask – is there a power source near the GPS which needs to be near a window….a simple RF cable should not be that hard. The old encore GPS’s used very thin coax – thinner than most RF cables around so never saw that as a problem. But each to his own.

             

            If the zigbee is not expensive then I guess its ok, sound like another extra bit of complication but if its easy to implement and low cost – I go with you.

             

            jb

             

            From: smartsockets@yahoogroups.com [mailto:smartsockets@yahoogroups.com] On Behalf Of fixitsan2
            Sent: 11 February 2010 15:28
            To: smartsockets@yahoogroups.com
            Subject: [smartsockets] Re: B7971 6 digit clocks

             

             



            --- In smartsockets@yahoogroups.com, jack <jack@...> wrote:
            >
            > Must be 30-75 quid I guess? Dependant on the module used. New modules costs loads, I bought a serial output all sealed Garmin on Ebay for £15. New probably a lot more. But we don't need the latest and greatest as the clock is being used in a static environment.
            >

            Exactly, so the question is would you happily pay that ?

            www.rfsolutions.co.uk list a very small surface mount GPS unit at about £14, 45mA current draw.

            The only problem I have as a user of GPS is that I don't like the extra coax cable required usually for the antenna, in order to locate it near a window. This is why I installed a GPS in my loft and used 433MHz radios to receive the retransmitted time signal. Using Zigbee is just the modern twist on that, Zigbee transceivers are available at £10 each.

            Chris

          • fixitsan2
            ... I m thinking that maybe a small solar panel, a zigbee radio and the gps could all be brought together with a mobile phone battery or supercap and left on
            Message 5 of 17 , Feb 11 8:24 AM
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              --- In smartsockets@yahoogroups.com, jack <jack@...> wrote:
              >
              > Well I guess a remote GPS module is really fancy - but how do you power it.
              >
              > Now you have to ask - is there a power source near the GPS which needs to be near a window....a simple RF cable should not be that hard. The old encore GPS's used very thin coax - thinner than most RF cables around so never saw that as a problem. But each to his own.
              >
              > If the zigbee is not expensive then I guess its ok, sound like another extra bit of complication but if its easy to implement and low cost - I go with you.
              >
              > jb
              >

              I'm thinking that maybe a small solar panel, a zigbee radio and the gps could all be brought together with a mobile phone battery or supercap and left on any convenient well lit surface (well, one which has a reasonably good view of the sky)

              That's probably another project in it's own right, but the radio modules are very easy to use, I recently incorporated some in another project and can vouch for that.
            • jack
              This is a very neat idea - to power the transmitter by solar power - as it needs to be near a windows anyway...How much is a solar cell large enough to power
              Message 6 of 17 , Feb 12 5:07 AM
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                This is a very neat idea – to power the transmitter by solar power – as it needs to be near a windows anyway…How much is a solar cell large enough to power the GPS receiver though?

                 

                So now we really have 2 projects in one - albeit the timing source – Solar powered – wireless – GPS receiver / transmitter (repeater??) could be used in its own right with other clocks at a later date….so that’s really a one to many very accurate timing source.

                 

                So now whats next….

                 

                 

                 

                 

                 

                 

                From: smartsockets@yahoogroups.com [mailto:smartsockets@yahoogroups.com] On Behalf Of fixitsan2
                Sent: 11 February 2010 16:24
                To: smartsockets@yahoogroups.com
                Subject: [smartsockets] Re: B7971 6 digit clocks

                 

                 



                --- In smartsockets@yahoogroups.com, jack <jack@...> wrote:
                >
                > Well I guess a remote GPS module is really fancy - but how do you power it.
                >
                > Now you have to ask - is there a power source near the GPS which needs to be near a window....a simple RF cable should not be that hard. The old encore GPS's used very thin coax - thinner than most RF cables around so never saw that as a problem. But each to his own.
                >
                > If the zigbee is not expensive then I guess its ok, sound like another extra bit of complication but if its easy to implement and low cost - I go with you.
                >
                > jb
                >

                I'm thinking that maybe a small solar panel, a zigbee radio and the gps could all be brought together with a mobile phone battery or supercap and left on any convenient well lit surface (well, one which has a reasonably good view of the sky)

                That's probably another project in it's own right, but the radio modules are very easy to use, I recently incorporated some in another project and can vouch for that.

              • John Rehwinkel
                ... Depends on your GPS receiver. There are two main approaches, I figure. One is to have a solar cell that can produce enough voltage and current to run the
                Message 7 of 17 , Feb 12 7:25 AM
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                  > This is a very neat idea – to power the transmitter by solar power – as it needs to be near a windows anyway…How much is a solar cell large enough to power the GPS receiver though?

                  Depends on your GPS receiver. There are two main approaches, I figure. One is to have a solar cell that can produce enough voltage and current to run the whole shebang.

                  The other is to use a smaller, cheaper solar cell, along with a supercap and some control circuitry to store up power until there's enough, then fire up the GPS until it gets a lock, then fire up the transmitter and send a few bursts, then shut down again.

                  For one price point, 4V @ 100mA can be had in a nice panel (not just a fragile bare cell) for US$5:

                  http://www.goldmine-elec-products.com/prodinfo.asp?number=G4481

                  - John
                • fixitsan2
                  ... That s more what I was thinking of. A gps like the one mentioned creates a drain of 45mA, the zigbee radio adds another 10mA. The gps gets a lock in 30
                  Message 8 of 17 , Feb 12 11:34 AM
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                    --- In smartsockets@yahoogroups.com, John Rehwinkel <jrehwin@...> wrote:
                    >

                    > The other is to use a smaller, cheaper solar cell, along with a supercap and some control circuitry to store up power until there's enough, then fire up the GPS until it gets a lock, then fire up the transmitter and send a few bursts, then shut down again.
                    >

                    > - John
                    >


                    That's more what I was thinking of. A gps like the one mentioned creates a drain of 45mA, the zigbee radio adds another 10mA.

                    The gps gets a lock in 30 seconds and the radio only needs to turn on for 1 second to transfer the data and receive confirmation. That is less than 1mAh of battery capacity. If that happens every 4 hours then a supply capable of producing 0.25mAh is required, which even a small 5mA solar panel could provide (or two in series to produce a high output voltage on dull days)
                    A small rechargeable lithium cell for power storage and an LDO regulator to convert the voltage to charge it would probably work 'well enough'.
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