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Re: How to Imitate a Solaroller's Solar Cell?

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  • wilf_nv
    I have corrected the SIMSC schematic in http://groups.yahoo.com/group/beam/files/simSC1.gif and changed some component values to lower the voltage drop across
    Message 1 of 18 , May 15, 2003
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      I have corrected the SIMSC schematic in

      http://groups.yahoo.com/group/beam/files/simSC1.gif

      and changed some component values to lower the voltage drop across
      the current sensing resistor to give a sharper cutoff at Voc. This is
      primarily useful for battery charging. The original simSC components
      (10 ohm shunt and 200K series resistor)can also be used to give a
      softer cutoff at Voc.

      The 78L12 provides the regulated volatge required at the input of the
      Solar Cell simulator. It limits the voltage to 12V and the current to
      about 100ma. A 15V-24V unregulated voltage is used as the input to
      the 78L12. Any other regulated 9V-12V source can be used.

      The LM324 is a quad opamp of which only two sections are used. A
      LM358 dual opamp (8 pin) can also be used.

      One opamp is used as a current source with the 0-60mV Isc reference
      voltage as one input and adjusts the opamp output current ("+ out")
      until the voltage drop across the 1 ohm resistor (shunt) is equal to
      the reference input.

      The second opamp uses a 0-6V Voc reference as one input and monitors
      the "+ out" voltage on the second input. When the "+ out" voltage is
      equal to the reference, the second opamp output applies a positive
      voltage to the current source inverting input causing the current
      source output to drop while maintaining the "+ out" equal to the Voc
      reference voltage.

      The net result is a constant charging current up to Voc-Vshunt and
      the a rapid tapering off as the "+ out" voltage is limited to Voc.

      wilf

      --- In beam@yahoogroups.com, "wilf_nv" <wrigter@d...> wrote:
      >
      >
      > Have a look at the Simulated Solar Cell (SIMSC) circuit in the file
      > section. Also good for charging small NiCd batteries.
      >
      > wilf
    • J Wolfgang Goerlich
      ... Thank you! Looks like just what we need. I will build this and try it out. J Wolfgang Goerlich
      Message 2 of 18 , May 16, 2003
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        Wilf wrote:
        > Have a look at the Simulated Solar Cell (SIMSC) circuit in the file
        > section.

        Thank you! Looks like just what we need. I will build this and try it
        out.

        J Wolfgang Goerlich
      • Wilf Rigter
        Here is a correction to the original SIMSC1 circuit and some variations on the theme. SIMSC1a adds D2 so that the output current starts at 0 ma. Since the
        Message 3 of 18 , May 16, 2003
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          Here is a correction to the original SIMSC1 circuit and some variations on
          the theme.

          SIMSC1a adds D2 so that the output current starts at 0 ma.
          Since the LM358 opamp output current was limited to 30ma I added an NPN
          output transistor to provide up to 100ma of current. I tweaked some
          component values for the wider output current adjustment range.

          SIMSC2 uses a LM324 with two opamps in parallel to boost the output current
          to 60ma. The 1ohm resistors help to share the current.

          SIMSC3 shows a simpler but less accurate discrete version of a solar cell
          simulator. It uses the relatively stable voltage of a "fresh" 9V battery as
          the "reference", however the current and voltage adjustment will drift when
          the battery voltage drops. For small currents (<10ma) a fresh 9V alkaline
          battery should be good for many hours.

          wilf


          ----- Original Message -----
          From: "J Wolfgang Goerlich" <jwgoerlich@...>
          To: <beam@yahoogroups.com>
          Sent: Friday, May 16, 2003 4:52 AM
          Subject: [beam] Re: How to Imitate a Solaroller's Solar Cell?


          > Wilf wrote:
          > > Have a look at the Simulated Solar Cell (SIMSC) circuit in the file
          > > section.
          >
          > Thank you! Looks like just what we need. I will build this and try it
          > out.
          >
          > J Wolfgang Goerlich
          >
          >
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          >


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        • mycroft2152
          Wilf, SIMSC3 seems the simplest to build. What changes would be needed if a 78L05 wwas used for a more stable reference? Another question, how would the
          Message 4 of 18 , May 16, 2003
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            Wilf,

            SIMSC3 seems the simplest to build. What changes would be needed if
            a 78L05 wwas used for a more stable reference?

            Another question, how would the performance be different between the
            SIMSC3 and the resistor/ dual led circuit you posted last year.

            Myc


            --- In beam@yahoogroups.com, "Wilf Rigter" <wrigter@d...> wrote:
            > Here is a correction to the original SIMSC1 circuit and some
            variations on
            > the theme.
            >
            > SIMSC1a adds D2 so that the output current starts at 0 ma.
            > Since the LM358 opamp output current was limited to 30ma I added
            an NPN
            > output transistor to provide up to 100ma of current. I tweaked some
            > component values for the wider output current adjustment range.
            >
            > SIMSC2 uses a LM324 with two opamps in parallel to boost the
            output current
            > to 60ma. The 1ohm resistors help to share the current.
            >
            > SIMSC3 shows a simpler but less accurate discrete version of a
            solar cell
            > simulator. It uses the relatively stable voltage of a "fresh" 9V
            battery as
            > the "reference", however the current and voltage adjustment will
            drift when
            > the battery voltage drops. For small currents (<10ma) a fresh 9V
            alkaline
            > battery should be good for many hours.
            >
            > wilf
            >
            >
            > ----- Original Message -----
            > From: "J Wolfgang Goerlich" <jwgoerlich@h...>
            > To: <beam@yahoogroups.com>
            > Sent: Friday, May 16, 2003 4:52 AM
            > Subject: [beam] Re: How to Imitate a Solaroller's Solar Cell?
            >
            >
            > > Wilf wrote:
            > > > Have a look at the Simulated Solar Cell (SIMSC) circuit in the
            file
            > > > section.
            > >
            > > Thank you! Looks like just what we need. I will build this and
            try it
            > > out.
            > >
            > > J Wolfgang Goerlich
            > >
            > >
            > > Yahoo! Groups Sponsor
            > >
            > >
            > >
            > > To unsubscribe from this group, send an email to:
            > > beam-unsubscribe@egroups.com
            > >
            > >
            > >
            > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of
            Service.
            > >
            >
            >
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          • Wilf Rigter
            Hi Mic, ... From: mycroft2152 To: Sent: Friday, May 16, 2003 11:31 AM Subject: [beam] Re: How to Imitate a
            Message 5 of 18 , May 16, 2003
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              Hi Mic,

              you wrote:

              ----- Original Message -----
              From: "mycroft2152" <mycroft2152@...>
              To: <beam@yahoogroups.com>
              Sent: Friday, May 16, 2003 11:31 AM
              Subject: [beam] Re: How to Imitate a Solaroller's Solar Cell?

              > Wilf,

              > SIMSC3 seems the simplest to build. What changes would be needed if
              > a 78L05 wwas used for a more stable reference?

              You just need to stabilize the 9V battery voltage. 5V is too low for this
              circuit but 9V and up is fine. So you can use two 9V batteries in series and
              regulate the 18V to 15V changing battery voltage with a 78L12 to give a
              stable 12V supply.

              > Another question, how would the performance be different between the
              > SIMSC3 and the resistor/ dual led circuit you posted last year.

              The SIMSC3 circuit is an adjustable current source with an adjustable end
              voltage closely simulating a Solar cell.

              The resistor/dual LED (9VR2LED) circuit used a 9V supply with current limit
              resistor as a simple approximation of a constant current source. The maximum
              output voltage is set by the LEDs used as a shunt voltage regulator.

              As it is a basic RC network the rate of voltage rise and current changes
              exponentially during charging. When the cap has charged to 3V, the current
              is about 66% of the initial charging current.
              As the LEDs start to conduct and divert more of the charging current, the
              rate of voltage rise taper off rapidly as the charging current approaches
              zero. The LEDs will be on brightly.

              Attached are the I-V curves for a SunCeram Solar Cell and for the 9VR2LED
              circuit.

              For the same Voc and Isc and using Vp1 as the trigger level, a true Solar
              Cell SE and the SIMSC circuits would have a 15% shorter charging time than
              the 9VR2LED circuit for the same size cap.

              regards

              wilf





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            • mycroft2152
              Thanks Wilf, very helpful explanation. Since most BEAMers are familiar with the 78L05 volotalge regulator, how would it s performance fit in when set up as a
              Message 6 of 18 , May 16, 2003
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                Thanks Wilf, very helpful explanation.

                Since most BEAMers are familiar with the 78L05 volotalge regulator,
                how would it's performance fit in when set up as a constant current
                source?

                Since the amount of current would be controlled by a single
                resistor, it would be convenient to set up a bank of switches with
                resitors to select which solar cell to emulate.

                Myc



                --- In beam@yahoogroups.com, "Wilf Rigter" <wrigter@d...> wrote:
                > Hi Mic,
                >
                > you wrote:
                >
                > ----- Original Message -----
                > From: "mycroft2152" <mycroft2152@y...>
                > To: <beam@yahoogroups.com>
                > Sent: Friday, May 16, 2003 11:31 AM
                > Subject: [beam] Re: How to Imitate a Solaroller's Solar Cell?
                >
                > > Wilf,
                >
                > > SIMSC3 seems the simplest to build. What changes would be needed
                if
                > > a 78L05 wwas used for a more stable reference?
                >
                > You just need to stabilize the 9V battery voltage. 5V is too low
                for this
                > circuit but 9V and up is fine. So you can use two 9V batteries in
                series and
                > regulate the 18V to 15V changing battery voltage with a 78L12 to
                give a
                > stable 12V supply.
                >
                > > Another question, how would the performance be different between
                the
                > > SIMSC3 and the resistor/ dual led circuit you posted last year.
                >
                > The SIMSC3 circuit is an adjustable current source with an
                adjustable end
                > voltage closely simulating a Solar cell.
                >
                > The resistor/dual LED (9VR2LED) circuit used a 9V supply with
                current limit
                > resistor as a simple approximation of a constant current source.
                The maximum
                > output voltage is set by the LEDs used as a shunt voltage
                regulator.
                >
                > As it is a basic RC network the rate of voltage rise and current
                changes
                > exponentially during charging. When the cap has charged to 3V, the
                current
                > is about 66% of the initial charging current.
                > As the LEDs start to conduct and divert more of the charging
                current, the
                > rate of voltage rise taper off rapidly as the charging current
                approaches
                > zero. The LEDs will be on brightly.
                >
                > Attached are the I-V curves for a SunCeram Solar Cell and for the
                9VR2LED
                > circuit.
                >
                > For the same Voc and Isc and using Vp1 as the trigger level, a
                true Solar
                > Cell SE and the SIMSC circuits would have a 15% shorter charging
                time than
                > the 9VR2LED circuit for the same size cap.
                >
                > regards
                >
                > wilf
                >
                >
                >
                >
                >
                > ---
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              • Wilf Rigter
                Hi Mic, This is what it would look like. The 10K pot is adjusted for currents from 0.5 ma to 100 ma. Since there is a constant 5V across the pot the current is
                Message 7 of 18 , May 16, 2003
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                  Hi Mic,

                  This is what it would look like. The 10K pot is adjusted for currents from
                  0.5 ma to 100 ma. Since there is a constant 5V across the pot the current is
                  equal to 5V/Rpot up to the internal 100 ma current limit of the 78L05.

                  The 15V supply is needed because the minimum voltage difference between the
                  78L05 input and output pins is 3V and the P1 drop is 5V and the output
                  voltage should be able to rise to about 6V to simulate the 5.5V SunCeram
                  solar cells and you can expect some ripple on the unregulated input voltage.
                  (3V(in/out)+5V(pot)+6V(out)+1V(ripple)=15V).

                  This is just the current source and there is not adjustment for Voc

                  wilf

                  ----- Original Message -----
                  From: "mycroft2152" <mycroft2152@...>
                  To: <beam@yahoogroups.com>
                  Sent: Friday, May 16, 2003 3:51 PM
                  Subject: [beam] Re: How to Imitate a Solaroller's Solar Cell?


                  > Thanks Wilf, very helpful explanation.
                  >
                  > Since most BEAMers are familiar with the 78L05 volotalge regulator,
                  > how would it's performance fit in when set up as a constant current
                  > source?
                  >
                  > Since the amount of current would be controlled by a single
                  > resistor, it would be convenient to set up a bank of switches with
                  > resitors to select which solar cell to emulate.
                  >
                  > Myc



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                • Domenico
                  Hi Wilf, just a question: can I have problem about the pot. power dissipation when the 78L05 s output is near the end of potentiometer (circuit output) ? Can I
                  Message 8 of 18 , May 17, 2003
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                    Hi Wilf,

                    just a question: can I have problem about the pot. power dissipation when
                    the 78L05's output is near the end of potentiometer (circuit output) ? Can I
                    use a trimpot ?

                    Domenico

                    http://www.beamitaly.com
                    (the Italian site for beamers)
                    (visit beamitaly at yahoo groups)

                    ----- Original Message -----
                    From: "Wilf Rigter" <wrigter@...>
                    To: <beam@yahoogroups.com>
                    Sent: Saturday, May 17, 2003 3:32 AM
                    Subject: Re: [beam] Re: How to Imitate a Solaroller's Solar Cell?


                    > Hi Mic,
                    >
                    > This is what it would look like. The 10K pot is adjusted for currents from
                    > 0.5 ma to 100 ma. Since there is a constant 5V across the pot the current
                    is
                    > equal to 5V/Rpot up to the internal 100 ma current limit of the 78L05.
                    >
                    > The 15V supply is needed because the minimum voltage difference between
                    the
                    > 78L05 input and output pins is 3V and the P1 drop is 5V and the output
                    > voltage should be able to rise to about 6V to simulate the 5.5V SunCeram
                    > solar cells and you can expect some ripple on the unregulated input
                    voltage.
                    > (3V(in/out)+5V(pot)+6V(out)+1V(ripple)=15V).
                    >
                    > This is just the current source and there is not adjustment for Voc
                    >
                    > wilf
                    >
                    > ----- Original Message -----
                    > From: "mycroft2152" <mycroft2152@...>
                    > To: <beam@yahoogroups.com>
                    > Sent: Friday, May 16, 2003 3:51 PM
                    > Subject: [beam] Re: How to Imitate a Solaroller's Solar Cell?
                    >
                    >
                    > > Thanks Wilf, very helpful explanation.
                    > >
                    > > Since most BEAMers are familiar with the 78L05 volotalge regulator,
                    > > how would it's performance fit in when set up as a constant current
                    > > source?
                    > >
                    > > Since the amount of current would be controlled by a single
                    > > resistor, it would be convenient to set up a bank of switches with
                    > > resitors to select which solar cell to emulate.
                    > >
                    > > Myc
                    >
                    >
                    >
                    > ---
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                    >
                    > To unsubscribe from this group, send an email to:
                    > beam-unsubscribe@egroups.com
                    >
                    >
                    >
                    > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                    >
                    >


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                  • Wilf Rigter
                    Small trim pots would run hot. Just add a 50 ohm 1/4W resistor and a LED in series with the wiper. It gives a visual indication and reduces power in the pot.
                    Message 9 of 18 , May 17, 2003
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                      Small trim pots would run hot. Just add a 50 ohm 1/4W resistor and a LED in
                      series with the wiper. It gives a visual indication and reduces power in
                      the pot.

                      wilf
                      ----- Original Message -----
                      From: "Domenico" <d.mancini@...>
                      To: <beam@yahoogroups.com>
                      Sent: Saturday, May 17, 2003 7:07 AM
                      Subject: Re: [beam] Re: How to Imitate a Solaroller's Solar Cell?


                      > Hi Wilf,
                      >
                      > just a question: can I have problem about the pot. power dissipation when
                      > the 78L05's output is near the end of potentiometer (circuit output) ? Can
                      I
                      > use a trimpot ?
                      >
                      > Domenico
                      >
                      > http://www.beamitaly.com
                      > (the Italian site for beamers)
                      > (visit beamitaly at yahoo groups)
                      >
                      > ----- Original Message -----
                      > From: "Wilf Rigter" <wrigter@...>
                      > To: <beam@yahoogroups.com>
                      > Sent: Saturday, May 17, 2003 3:32 AM
                      > Subject: Re: [beam] Re: How to Imitate a Solaroller's Solar Cell?
                      >
                      >
                      > > Hi Mic,
                      > >
                      > > This is what it would look like. The 10K pot is adjusted for currents
                      from
                      > > 0.5 ma to 100 ma. Since there is a constant 5V across the pot the
                      current
                      > is
                      > > equal to 5V/Rpot up to the internal 100 ma current limit of the 78L05.
                      > >
                      > > The 15V supply is needed because the minimum voltage difference between
                      > the
                      > > 78L05 input and output pins is 3V and the P1 drop is 5V and the output
                      > > voltage should be able to rise to about 6V to simulate the 5.5V SunCeram
                      > > solar cells and you can expect some ripple on the unregulated input
                      > voltage.
                      > > (3V(in/out)+5V(pot)+6V(out)+1V(ripple)=15V).
                      > >
                      > > This is just the current source and there is not adjustment for Voc
                      > >
                      > > wilf
                      > >
                      > > ----- Original Message -----
                      > > From: "mycroft2152" <mycroft2152@...>
                      > > To: <beam@yahoogroups.com>
                      > > Sent: Friday, May 16, 2003 3:51 PM
                      > > Subject: [beam] Re: How to Imitate a Solaroller's Solar Cell?
                      > >
                      > >
                      > > > Thanks Wilf, very helpful explanation.
                      > > >
                      > > > Since most BEAMers are familiar with the 78L05 volotalge regulator,
                      > > > how would it's performance fit in when set up as a constant current
                      > > > source?
                      > > >
                      > > > Since the amount of current would be controlled by a single
                      > > > resistor, it would be convenient to set up a bank of switches with
                      > > > resitors to select which solar cell to emulate.
                      > > >
                      > > > Myc
                      > >
                      > >
                      > >
                      > > ---
                      > > Outgoing mail is certified Virus Free.
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                      > >
                      > >
                      > > To unsubscribe from this group, send an email to:
                      > > beam-unsubscribe@egroups.com
                      > >
                      > >
                      > >
                      > > Your use of Yahoo! Groups is subject to
                      http://docs.yahoo.com/info/terms/
                      > >
                      > >
                      >
                      >
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