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Re: [OAFs] Power supply for G11

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  • Richard McDonald
    Thanks, Bob. I ll avoid the problem and just go straight to 18. (If the mount ever arrives. Been waiting 6 months now.) Thanks Richard
    Message 1 of 20 , Dec 22, 2005
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      Thanks, Bob. I'll avoid the problem and just go straight to 18. (If the
      mount ever arrives. Been waiting 6 months now.)

      Thanks
      Richard
    • Rolf and Linda
      Hi, Until recently, I was using a Canadian Tire Eliminator marine battery pack/supply with the ac adapter plugged in. But now I m using a very small 120V to
      Message 2 of 20 , Dec 22, 2005
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        Hi,

        Until recently, I was using a Canadian Tire "Eliminator" marine
        battery pack/supply with the ac adapter plugged in. But now I'm using
        a very small 120V to 12V adapter from The Source - about $25. It is
        good for 1 amp. Canadian Tire has a slightly bigger one for $30, good
        for 6 amps. I measured 17.5 volts open circuit, but I haven't had a
        chance to check it under load. For portable use of course I can still
        use the Eliminator marine power supply. I got it on sale for about
        $80, but I think the regular price is about $140. I have a C14 on the
        G11. I do need to add a dew heater, which I'll make with a string of
        resistors. For the past 2 months, I've been getting frost on the
        inside of the corrector after about half an hour of use.

        -Rolf

        --- In OAFs@yahoogroups.com, "ericwbenson" <ebenson@s...> wrote:
        >
        > I took the plunge, I'm waiting on Fedex for a G11 with gemini. The
        > thing seems to need electricity to run, what AC/DC power supply are
        > others using with this mount? or a CG-5 since...
        > It will be carrying a C11 OTA which is also on it's way with a CG-5
        > goto mount (C11+CG-5 costs less than C11 OTA, go figure!) which I
        > guess will also need a dew heater, any suggestions here, Kendrick the
        > way to go?
        >
        > Thanks,
        > Eric
        >
        > Eric Benson, B.Sc, Ph.D
        > Picarro Canada, Inc.
        > 495 March Road, Suite 200
        > Kanata, Ontario, K2K 2G1
        > Tel: 613 270 2058
        > Fax: 613 270 9585
        >
      • Rolf and Linda
        ... I suspect that the specified 12-18V range for the G11 is to accomodate the wide range of supplies out there, many of which will be unregulated. I think
        Message 3 of 20 , Dec 22, 2005
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          --- In OAFs@yahoogroups.com, Richard McDonald <richard@t...> wrote:
          >
          > Thanks, Bob. I'll avoid the problem and just go straight to 18. (If the
          > mount ever arrives. Been waiting 6 months now.)

          I suspect that the specified 12-18V range for the G11 is to accomodate
          the wide range of supplies out there, many of which will be
          unregulated. I think the current capability is more important,
          meaning a reasonable voltage under load (13.2 or so). Do the Gemini
          motors run from the raw voltage or is there a regulator in the
          controller? I suspect the latter, but I have no idea.

          -Rolf
        • Douglas B. George
          I think I ve spotted some confusion on this thread. Don t run the Losmandy Digital Controller at 18V! That s the stepper motor version without GOTO. It
          Message 4 of 20 , Dec 22, 2005
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            I think I've spotted some confusion on this thread. Don't run the "Losmandy
            Digital Controller" at 18V! That's the stepper motor version without GOTO. It
            takes 12V at 500 mA. There's zero risk of burning out the stepper motors or
            controller under any conditions... except perhaps putting in too much voltage!

            The Gemini GOTO controler, which uses servo motors, takes substantially more
            power. It's the one with the risk of burning out the motors.

            Doug

            -----------------------------------

            Doug George
            dgeorge@...

            Diffraction Limited
            Makers of Cyanogen Imaging Products
            http://www.cyanogen.com

            25 Conover Street
            Ottawa, Ontario,
            Canada, K2G 4C3

            Phone: (613) 225-2732
            Fax: (613) 225-9688

            -----------------------------------
          • Bob Olson
            Hi Rolf, I think the Gemini servo motors run on the raw voltage of the supply. Don t you have the stepper motor G11? They run on 12 V and maybe don t like
            Message 5 of 20 , Dec 22, 2005
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              Hi Rolf,

              I think the Gemini servo motors run on the raw voltage of the supply.

              Don't you have the stepper motor G11? They run on 12 V and maybe don't like
              higher voltages.

              Bob
            • Rolf and Linda
              ... don t like ... Right you are, Bob. I know the spec is 12V/500mA, but I Losmandy is not big on providing more detailed electrical specs (like min/max). 12
              Message 6 of 20 , Dec 22, 2005
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                --- In OAFs@yahoogroups.com, "Bob Olson" <r.olson@r...> wrote:
                >
                > Hi Rolf,
                >
                > I think the Gemini servo motors run on the raw voltage of the supply.
                >
                > Don't you have the stepper motor G11? They run on 12 V and maybe
                don't like
                > higher voltages.

                Right you are, Bob. I know the spec is 12V/500mA, but I Losmandy is
                not big on providing more detailed electrical specs (like min/max).
                12 V rarely means 12.0000 volts; hopefully it is supposed to run off
                car voltages (anywhere from 11.5-15.5). Anybody got a schematic?

                Regarding the Gemini, is it actually the motors that burn out, or is
                it the driver IC? Again, a schematic would help to figure out the
                problem. I guess Losmandy's area of expertise is mechanical.

                -Rolf
              • Rolf and Linda
                ... Losmandy ... without GOTO. It ... motors or ... much voltage! Hi Doug, Do you by any chance have a spec on the acceptable input voltage range? I m
                Message 7 of 20 , Dec 22, 2005
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                  --- In OAFs@yahoogroups.com, "Douglas B. George" <dg@c...> wrote:
                  >
                  > I think I've spotted some confusion on this thread. Don't run the
                  "Losmandy
                  > Digital Controller" at 18V! That's the stepper motor version
                  without GOTO. It
                  > takes 12V at 500 mA. There's zero risk of burning out the stepper
                  motors or
                  > controller under any conditions... except perhaps putting in too
                  much voltage!

                  Hi Doug,

                  Do you by any chance have a spec on the acceptable input voltage
                  range? I'm assuming a range of at least 11.5-15.5 (car voltages).

                  P.S. I have not spotted the confusion of which you speak (just a lack
                  of specs from Losmandy!).

                  -Rolf

                  >
                  > The Gemini GOTO controler, which uses servo motors, takes
                  substantially more
                  > power. It's the one with the risk of burning out the motors.
                  >
                  > Doug
                  >
                  > -----------------------------------
                  >
                  > Doug George
                  > dgeorge@c...
                  >
                  > Diffraction Limited
                  > Makers of Cyanogen Imaging Products
                  > http://www.cyanogen.com
                  >
                  > 25 Conover Street
                  > Ottawa, Ontario,
                  > Canada, K2G 4C3
                  >
                  > Phone: (613) 225-2732
                  > Fax: (613) 225-9688
                  >
                  > -----------------------------------
                  >
                • Bob Olson
                  Hi Rolf, ... Usually the motors draw too much current and the solder connections let go or the windings burn up. But I have heard of the driver ICs failing and
                  Message 8 of 20 , Dec 22, 2005
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                    Hi Rolf,

                    >Regarding the Gemini, is it actually the motors that burn out, or is
                    >it the driver IC?

                    Usually the motors draw too much current and the solder connections let go
                    or the windings burn up. But I have heard of the driver ICs failing and also
                    the optical encoders on the servo motor shafts. Usually the motors get hot
                    before they fail but I believe that Albert had a motor fail that did not
                    heat. When you send them to Losmandy for repair, they come back filled with
                    heat sink grease to help conduct away the excess heat from the motor. Motor
                    failures is a hot topic on the Losmandy Gemini group.

                    >I have not spotted the confusion of which you speak (just a lack
                    >of specs from Losmandy!).

                    I think that Doug is referring to the difference between the stepper motor
                    and the Gemini servo motor G11 mounts. And Losmandy is pretty clear about
                    what they recommend.

                    Stepper motors 12 V 500 mA.
                    Servo motors 12-18 V 3 A (But they caution that anything else also being
                    powered (eg dew heaters) must be added to the 3 A) Most of the users on the
                    Gemini group (at least those who say what they are doing) use 18 V. This
                    seems to reduce motor stalls and burn outs.

                    Losmandy sells a regulated Gemini power supply which is 13.8 V 5 A.

                    Bob
                  • Douglas B. George
                    ... Motors. It s easy to burn out a permanent magnet motor by overheating. High permeability permanent magnets tend to have very low Curie temperatures --
                    Message 9 of 20 , Dec 23, 2005
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                      Rolf and Linda wrote:

                      > Regarding the Gemini, is it actually the motors that burn out, or is
                      > it the driver IC? Again, a schematic would help to figure out the
                      > problem. I guess Losmandy's area of expertise is mechanical.

                      Motors. It's easy to burn out a permanent magnet motor by overheating. High
                      permeability permanent magnets tend to have very low Curie temperatures --
                      that's the temperature where they cease to have magnetic properties. Bring it
                      over that temperature just once, and they demagnetize for good. End of motor.

                      (That's also how they magnetize them in the first place -- heat the magnetic
                      material above the Curie temperature, put it in a high powered field from an
                      electromagnet, and let it cool.)

                      Doug

                      -----------------------------------

                      Doug George
                      dgeorge@...

                      Diffraction Limited
                      Makers of Cyanogen Imaging Products
                      http://www.cyanogen.com

                      25 Conover Street
                      Ottawa, Ontario,
                      Canada, K2G 4C3

                      Phone: (613) 225-2732
                      Fax: (613) 225-9688

                      -----------------------------------
                    • Douglas B. George
                      ... No, but I ve been inside the box and it s quite simple inside. One of my controllers was damaged by a short circuit a few years ago. It only took me half
                      Message 10 of 20 , Dec 23, 2005
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                        Rolf and Linda wrote:

                        > Hi Doug,
                        >
                        > Do you by any chance have a spec on the acceptable input voltage
                        > range? I'm assuming a range of at least 11.5-15.5 (car voltages).

                        No, but I've been inside the box and it's quite simple inside. One of my
                        controllers was damaged by a short circuit a few years ago. It only took me
                        half an hour to figure out where the problem was and replace the damaged chip
                        with one from my collection of spare parts.

                        The regulator for the digital circuitry doesn't get hot, so it's got lots of
                        headroom. And competent designers always include a 50% margin on the voltage
                        rating of the power supply capacitors. So I'm not at all worried about the
                        electronics. I wouldn't use 18V because I suspect you wouldn't have much margin
                        left. But 15V should be fine.

                        The motor driver is very simple, just a basic driver that puts the input power
                        across the motor windings. No fancy overvoltage drivers or anything.

                        So what really matters is the motor, and I do have the specs for those. There's
                        no problem whatsoever with applying a modest overvoltage, e.g. from a car
                        battery. These motors are very conservatively rated, because their designers
                        fully expected that they'd be subject to things like 4X overvoltage drives (uh,
                        don't get the idea you can put 48V DC on the motor... overvoltage is only safe
                        for a few milliseconds per cycle).

                        > P.S. I have not spotted the confusion of which you speak (just a lack
                        > of specs from Losmandy!).

                        One person quoted 12V 500mA in a discussion about motors burning out. That's
                        the spec for the Losmandy Digital Controller, not the Gemini. Motors only ever
                        burn out on the Gemini, which has much, much higher power consumption. That's
                        the confusion I was speaking of.

                        Doug

                        -----------------------------------

                        Doug George
                        dgeorge@...

                        Diffraction Limited
                        Makers of Cyanogen Imaging Products
                        http://www.cyanogen.com

                        25 Conover Street
                        Ottawa, Ontario,
                        Canada, K2G 4C3

                        Phone: (613) 225-2732
                        Fax: (613) 225-9688

                        -----------------------------------
                      • Rolf and Linda
                        ... of my ... took me ... damaged chip ... That s good to know! I took mine apart before I connected power, just in case, to make sure there was a diode to
                        Message 11 of 20 , Dec 23, 2005
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                          --- In OAFs@yahoogroups.com, "Douglas B. George" <dg@c...> wrote:
                          >
                          > Rolf and Linda wrote:
                          >
                          > > Hi Doug,
                          > >
                          > > Do you by any chance have a spec on the acceptable input voltage
                          > > range? I'm assuming a range of at least 11.5-15.5 (car voltages).
                          >
                          > No, but I've been inside the box and it's quite simple inside. One
                          of my
                          > controllers was damaged by a short circuit a few years ago. It only
                          took me
                          > half an hour to figure out where the problem was and replace the
                          damaged chip
                          > with one from my collection of spare parts.

                          That's good to know! I took mine apart before I connected power, just
                          in case, to make sure there was a diode to guard against accidental
                          reverse polarity (there was, very easy to spot!).

                          -Rolf
                        • pawb63
                          Since things are a little slow, Eric, how do you like your new Losmandy mount? Have you had a chance to use it much? Cheers. Paul WB ... the
                          Message 12 of 20 , Jan 16, 2006
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                            Since things are a little slow, Eric, how do you like your new
                            Losmandy mount? Have you had a chance to use it much? Cheers.
                            Paul WB

                            --- In OAFs@yahoogroups.com, "ericwbenson" <ebenson@s...> wrote:
                            >
                            > I took the plunge, I'm waiting on Fedex for a G11 with gemini. The
                            > thing seems to need electricity to run, what AC/DC power supply are
                            > others using with this mount? or a CG-5 since...
                            > It will be carrying a C11 OTA which is also on it's way with a CG-5
                            > goto mount (C11+CG-5 costs less than C11 OTA, go figure!) which I
                            > guess will also need a dew heater, any suggestions here, Kendrick
                            the
                            > way to go?
                            >
                            > Thanks,
                            > Eric
                            >
                            > Eric Benson, B.Sc, Ph.D
                            > Picarro Canada, Inc.
                            > 495 March Road, Suite 200
                            > Kanata, Ontario, K2K 2G1
                            > Tel: 613 270 2058
                            > Fax: 613 270 9585
                            >
                          • ericwbenson
                            The mount looks great, in my living room, with a 3 C11 dovetail attached, with no telescope on it!!! Celestron shipped a 9.25 OTA in a box marked as a C11 to
                            Message 13 of 20 , Jan 16, 2006
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                              The mount looks great, in my living room, with a 3" C11 dovetail
                              attached, with no telescope on it!!!

                              Celestron shipped a 9.25 OTA in a box marked as a C11 to FocusSci, so
                              I'm still waiting... Although the CG-5goto mount is there. For those
                              who are asking themselves: Why did this guy buy two mounts? The C11-
                              XLT OTA goes for 2180USD (astronomics.com), the C11-XLT with CG-5goto
                              is 2280USD, the CG-5goto by itself is 700USD, go figure! I either
                              sell it, use it as a more portable setup, or find out that it's
                              better than the G11, it is after all billed as: Precision Engineered
                              for Stability.

                              I thought about trying to strap my 120mm Synta refractor OTA onto the
                              G11, but figured I would just drop/smash/break something, so patience
                              rules.

                              I bought a battery from CdnTire, the 60Ah Eliminator with wheels, 12A
                              peak power, 1200W invertor, 5A float charger for 250$. I looked at
                              Kendrick but the 18V/33Ah battery is priced way out there (429$ !!!)
                              and you only get a 1.5A float charger, pay another 157$ for a 6A
                              charger!?

                              Current draw
                              G11 0.5A (0.4 tracking, 1.1A slewing 30sec/5min)
                              Anti-Dew 1.2A ((2.4A:corrector + .5A:finder)*40% duty cycle with
                              Temperature sensing controller, seems Kendrick has got the market
                              cornered here.
                              Laptop 1.5A (5Ah Li-ion battery drains in about 3.5h)
                              ST7EI 2.2A (using battery to invertor to pwr supply, according
                              to SBIG manual)
                              Guide cam 1A (dont know what this is yet, any suggestions?)

                              Total 6.4A = 9hrs to drained, OK in June, need 2 batteries for
                              other months.

                              EB

                              --- In OAFs@yahoogroups.com, "pawb63" <paul.wefers_bettink@s...>
                              wrote:
                              >
                              > Since things are a little slow, Eric, how do you like your new
                              > Losmandy mount? Have you had a chance to use it much? Cheers.
                              > Paul WB
                              >
                              > --- In OAFs@yahoogroups.com, "ericwbenson" <ebenson@s...> wrote:
                              > >
                              > > I took the plunge, I'm waiting on Fedex for a G11 with gemini.
                              The
                              > > thing seems to need electricity to run, what AC/DC power supply
                              are
                              > > others using with this mount? or a CG-5 since...
                              > > It will be carrying a C11 OTA which is also on it's way with a CG-
                              5
                              > > goto mount (C11+CG-5 costs less than C11 OTA, go figure!) which I
                              > > guess will also need a dew heater, any suggestions here, Kendrick
                              > the
                              > > way to go?
                              > >
                              > > Thanks,
                              > > Eric
                              > >
                              > > Eric Benson, B.Sc, Ph.D
                              > > Picarro Canada, Inc.
                              > > 495 March Road, Suite 200
                              > > Kanata, Ontario, K2K 2G1
                              > > Tel: 613 270 2058
                              > > Fax: 613 270 9585
                              > >
                              >
                            • pawb63
                              Patience is a virtue, and according the weather forecasts, there isn t going to be much observing in the next few days. I have heard that the the CG-5
                              Message 14 of 20 , Jan 17, 2006
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                                Patience is a virtue, and according the weather forecasts, there
                                isn't going to be much observing in the next few days. I have heard
                                that the the CG-5 Advanced series mount is a pretty good mount. But
                                with a C11 on it, I am not so sure.
                                Paul WB

                                --- In OAFs@yahoogroups.com, "ericwbenson" <ebenson@s...> wrote:
                                >
                                > The mount looks great, in my living room, with a 3" C11 dovetail
                                > attached, with no telescope on it!!!
                                >
                                > Celestron shipped a 9.25 OTA in a box marked as a C11 to FocusSci,
                                so
                                > I'm still waiting... Although the CG-5goto mount is there. For
                                those
                                > who are asking themselves: Why did this guy buy two mounts? The C11-
                                > XLT OTA goes for 2180USD (astronomics.com), the C11-XLT with CG-
                                5goto
                                > is 2280USD, the CG-5goto by itself is 700USD, go figure! I either
                                > sell it, use it as a more portable setup, or find out that it's
                                > better than the G11, it is after all billed as: Precision
                                Engineered
                                > for Stability.
                                >
                                > I thought about trying to strap my 120mm Synta refractor OTA onto
                                the
                                > G11, but figured I would just drop/smash/break something, so
                                patience
                                > rules.
                                >
                                > I bought a battery from CdnTire, the 60Ah Eliminator with wheels,
                                12A
                                > peak power, 1200W invertor, 5A float charger for 250$. I looked at
                                > Kendrick but the 18V/33Ah battery is priced way out there (429
                                $ !!!)
                                > and you only get a 1.5A float charger, pay another 157$ for a 6A
                                > charger!?
                                >
                                > Current draw
                                > G11 0.5A (0.4 tracking, 1.1A slewing 30sec/5min)
                                > Anti-Dew 1.2A ((2.4A:corrector + .5A:finder)*40% duty cycle with
                                > Temperature sensing controller, seems Kendrick has got the market
                                > cornered here.
                                > Laptop 1.5A (5Ah Li-ion battery drains in about 3.5h)
                                > ST7EI 2.2A (using battery to invertor to pwr supply, according
                                > to SBIG manual)
                                > Guide cam 1A (dont know what this is yet, any suggestions?)
                                >
                                > Total 6.4A = 9hrs to drained, OK in June, need 2 batteries for
                                > other months.
                                >
                                > EB
                                >
                                > --- In OAFs@yahoogroups.com, "pawb63" <paul.wefers_bettink@s...>
                                > wrote:
                                > >
                                > > Since things are a little slow, Eric, how do you like your new
                                > > Losmandy mount? Have you had a chance to use it much? Cheers.
                                > > Paul WB
                                > >
                                > > --- In OAFs@yahoogroups.com, "ericwbenson" <ebenson@s...> wrote:
                                > > >
                                > > > I took the plunge, I'm waiting on Fedex for a G11 with gemini.
                                > The
                                > > > thing seems to need electricity to run, what AC/DC power supply
                                > are
                                > > > others using with this mount? or a CG-5 since...
                                > > > It will be carrying a C11 OTA which is also on it's way with a
                                CG-
                                > 5
                                > > > goto mount (C11+CG-5 costs less than C11 OTA, go figure!) which
                                I
                                > > > guess will also need a dew heater, any suggestions here,
                                Kendrick
                                > > the
                                > > > way to go?
                                > > >
                                > > > Thanks,
                                > > > Eric
                                > > >
                                > > > Eric Benson, B.Sc, Ph.D
                                > > > Picarro Canada, Inc.
                                > > > 495 March Road, Suite 200
                                > > > Kanata, Ontario, K2K 2G1
                                > > > Tel: 613 270 2058
                                > > > Fax: 613 270 9585
                                > > >
                                > >
                                >
                              • Joe Silverman
                                Ed A great place to go for batteries is Total Battery. They sell marine and wheel chair batteries. Cosco sells marine batteries at great prices. A few years
                                Message 15 of 20 , Jan 18, 2006
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                                  Ed

                                  A great place to go for batteries is Total Battery. They sell marine and
                                  wheel chair batteries. Cosco sells marine batteries at great prices. A few
                                  years back, I remember a 70AH marine battery going for around $100. But they
                                  may only be available in Spring.

                                  Joe



                                  Ed wrote:

                                  Total 6.4A = 9hrs to drained, OK in June, need 2 batteries for other
                                  months



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