Kevin Weddle
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Posts posted by Kevin Weddle
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Yes the circuit can be done. The problem is the gain has to be at least one. But not more.
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An opamp doesn't source any current.
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Oh, wrong project.
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Pretty.
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I'm satisfied with the design. It's not perfect.
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Yes it makes little sense. Because the potentiometers set the output voltage.
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The 1-25volt power supply design is a better one.
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The 1-25volt power supply is is the latest.
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I'm sorry audioguru. Really I had to delete my last posts.
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I changed the opamp load resistor from 100K to 200K. But of course the voltage regulation is no where near as good as the 30V Stabilized Power Supply.
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Thank you audioguru. I'm wrong. I forgot where 0volts differential occurs.
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U2 doesn't have any differential voltage at higher output voltages. At zero volts ouput, it has more differential voltage because of the -3volt power supply. I'm not sure how this can affect the voltage regulation.
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What about the opamp differential voltage? U2 has almost none. Because the gain is low. The resistance is low.
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Modified. The 1-25volt variable power supply is the preliminary design.
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I have this other 1-25volt variable power supply that may compare to this design. This one is great by design because the change in output voltage is inverted at the opamp input. The 1-25volt supply has higher gain.
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I'm wrong. The voltage regulation looks very good at around a gain of 3.
RV1 doesn't need any offset adjustment unless the regulated output voltage is more than 15 volts. -
The opamp having a very high voltage gain should regulate it's output at the voltage set by the offset RV1. The 0.85 gain of the negative feedback loop transistors combined with R12 is where the loss in load regulation is. However, the voltage response is quick.
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The error amplifier opamp is two transistors away from the output. Low gain and high input current means low beta. So this isn't the best voltage regulator.
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Doesn't he need a good voltage regulator to charge the battery?
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Here's a better circuit.
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1-25 volt power supply
in Projects Q/A
Posted
I know that circuit. The gain must be at least be 1. This circuit has a gain of 6 which has an obsolete voltage divider. Unless you want to get rid of something else.