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

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  • 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 1 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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    • 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 2 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 3 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 4 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 5 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 6 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 7 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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                  >


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