On Friday, 3 November 2023 at 15:02:35 UTC, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Why use a zener at all? Its not likely to add much voltage stability at the very
low current available from the optocoupler.
Alternatively, with a low power op-amp, put the optocoupler in series with >the positive power supply and its voltage instability will vanish from the >final output.
John
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
John Larkin <jl@997PotHill.com> wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Looks nice. You’ll want to filter the LED drive carefully, because with a bang-bang phase detector your loop bandwidth will be limited.
Cheers
Phil Hobbs
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
John Larkin <jl@997PotHill.com> wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Looks nice. You’ll want to filter the LED drive carefully, because with a
bang-bang phase detector your loop bandwidth will be limited.
Cheers
Phil Hobbs
Oh, and at 10 uA, the zener noise will probably be a worry.
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
On Friday, November 3, 2023 at 11:02:35?AM UTC-4, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Not seeing the need for a zener...
I take it mean the standard non-inverting OA with the PV in series with OA output, and a high-Z resistor feedback divider from the composite output (PV cathode) to OA (-). Loop gain, which should be very large attenuates noise and the unknowns at thecomposite output.
Is there some reason you can't drive current through the detector? Maybe too non-linearizing...
They datasheet is so fixed on detector Voc Isc with input LED drive, it's almost tempting to use the LED drive to modulate the final output into place.
On Friday, November 3, 2023 at 11:02:35 AM UTC-4, John Larkin wrote:composite output.
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Not seeing the need for a zener...
I take it mean the standard non-inverting OA with the PV in series with OA output, and a high-Z resistor feedback divider from the composite output (PV cathode) to OA (-). Loop gain, which should be very large attenuates noise and the unknowns at the
Is there some reason you can't drive current through the detector? Maybe too non-linearizing...
They datasheet is so fixed on detector Voc Isc with input LED drive, it's almost tempting to use the LED drive to modulate the final output into place.
On Fri, 3 Nov 2023 09:47:09 -0700 (PDT), Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> wrote:composite output.
On Friday, November 3, 2023 at 11:02:35?AM UTC-4, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Not seeing the need for a zener...
The PV voltage has a bad negative tempco, and that could cause us
problems. A zener helps that. An LM4040 bandgap would be great, but
they only come in 5 and 10 volts, too low and too high!
I take it mean the standard non-inverting OA with the PV in series with OA output, and a high-Z resistor feedback divider from the composite output (PV cathode) to OA (-). Loop gain, which should be very large attenuates noise and the unknowns at the
If I have a pretty constant offset added to the opamp output, I don't
need to feed back from the offset, just from the opamp output. If I
use the PV for the offset, I don't have enough current for the opampm feedback resistor.
Is there some reason you can't drive current through the detector? Maybe too non-linearizing...
They datasheet is so fixed on detector Voc Isc with input LED drive, it's almost tempting to use the LED drive to modulate the final output into place.
To slow.
Nice puzzle.
On 03/11/2023 16:47, Fred Bloggs wrote:composite output.
On Friday, November 3, 2023 at 11:02:35 AM UTC-4, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Not seeing the need for a zener...
I take it mean the standard non-inverting OA with the PV in series with OA output, and a high-Z resistor feedback divider from the composite output (PV cathode) to OA (-). Loop gain, which should be very large attenuates noise and the unknowns at the
Is there some reason you can't drive current through the detector? Maybe too non-linearizing...
They datasheet is so fixed on detector Voc Isc with input LED drive, it's almost tempting to use the LED drive to modulate the final output into place.Not clear to me from JL's original post if the op amp has a negative
supply rail so that even after the 7V output offset the varicap can be biased below 7V?
Modulating the PV LED drive could have horrible delays and upset the dynamics?
piglet
On Fri, 3 Nov 2023 09:47:09 -0700 (PDT), Fred Bloggs <bloggs.fred...@gmail.com> wrote:composite output.
On Friday, November 3, 2023 at 11:02:35?AM UTC-4, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Not seeing the need for a zener...The PV voltage has a bad negative tempco, and that could cause us
problems. A zener helps that. An LM4040 bandgap would be great, but
they only come in 5 and 10 volts, too low and too high!
I take it mean the standard non-inverting OA with the PV in series with OA output, and a high-Z resistor feedback divider from the composite output (PV cathode) to OA (-). Loop gain, which should be very large attenuates noise and the unknowns at the
If I have a pretty constant offset added to the opamp output, I don't
need to feed back from the offset, just from the opamp output. If I
use the PV for the offset, I don't have enough current for the opampm feedback resistor.
Is there some reason you can't drive current through the detector? Maybe too non-linearizing...
They datasheet is so fixed on detector Voc Isc with input LED drive, it's almost tempting to use the LED drive to modulate the final output into place.To slow.
Nice puzzle.
On Fri, 3 Nov 2023 09:47:09 -0700 (PDT), Fred Bloggs <bloggs.fred...@gmail.com> wrote:composite output.
On Friday, November 3, 2023 at 11:02:35?AM UTC-4, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Not seeing the need for a zener...The PV voltage has a bad negative tempco, and that could cause us
problems. A zener helps that. An LM4040 bandgap would be great, but
they only come in 5 and 10 volts, too low and too high!
I take it mean the standard non-inverting OA with the PV in series with OA output, and a high-Z resistor feedback divider from the composite output (PV cathode) to OA (-). Loop gain, which should be very large attenuates noise and the unknowns at the
If I have a pretty constant offset added to the opamp output, I don't
need to feed back from the offset, just from the opamp output. If I
use the PV for the offset, I don't have enough current for the opampm feedback resistor.
Is there some reason you can't drive current through the detector? Maybe too non-linearizing...
They datasheet is so fixed on detector Voc Isc with input LED drive, it's almost tempting to use the LED drive to modulate the final output into place.To slow.
Nice puzzle.
On 03/11/2023 19:19, john larkin wrote:composite output.
On Fri, 3 Nov 2023 09:47:09 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
On Friday, November 3, 2023 at 11:02:35?AM UTC-4, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
Not seeing the need for a zener...
The PV voltage has a bad negative tempco, and that could cause us
problems. A zener helps that. An LM4040 bandgap would be great, but
they only come in 5 and 10 volts, too low and too high!
I take it mean the standard non-inverting OA with the PV in series with OA output, and a high-Z resistor feedback divider from the composite output (PV cathode) to OA (-). Loop gain, which should be very large attenuates noise and the unknowns at the
If I have a pretty constant offset added to the opamp output, I don't
need to feed back from the offset, just from the opamp output. If I
use the PV for the offset, I don't have enough current for the opampm
feedback resistor.
Is there some reason you can't drive current through the detector? Maybe too non-linearizing...
They datasheet is so fixed on detector Voc Isc with input LED drive, it's almost tempting to use the LED drive to modulate the final output into place.
To slow.
Nice puzzle.
There is the adjustable LM4041 but the minimum operating current will be
too much for the PV.
Most action in a varicap is in the 1-10V range, can't you simply pad the >varicap capacitance down so you avoid the need to go to 16V?
piglet
I have an opamp with a 10 volt positive supply and need the output toSo, put two lithium coin cells in series with the op amp output (it'll work for years if the load is really light).
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
On Fri, 3 Nov 2023 09:47:09 -0700 (PDT), Fred Bloggs ><bloggs.fredbloggs.fred@gmail.com> wrote:
On Friday, November 3, 2023 at 11:02:35?AM UTC-4, John Larkin wrote:
I have an opamp with a 10 volt positive supply and need the output to
swing to about 16 volts. I was thinking I could add a paralleled 6.8
volt zener, a cap, and a floating power supply at the opamp output.
The power supply could be a PV optocoupler like this:
https://www.digikey.com/en/products/detail/toshiba-semiconductor-and-storage/TLP3905-TPR-E/7809804
My load is obviously light, a varicap in fact.
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