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

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  • wilf_nv
    Have a look at the Simulated Solar Cell (SIMSC) circuit in the file section. Also good for charging small NiCd batteries. wilf
    Message 1 of 18 , May 15, 2003
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      Have a look at the Simulated Solar Cell (SIMSC) circuit in the file
      section. Also good for charging small NiCd batteries.

      wilf
    • 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 2 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 3 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 4 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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            >


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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 5 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 6 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 7 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 8 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 9 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 10 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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                        >
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                        >
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                        >


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