On Sat, Mar 15, 2025 at 05:00 AM, john23 wrote:
Could you describe how the regulating dinamics works here?
Pull out your analog design books.
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This is a feedback loop.? The two NPN transistors are a differential pair.? ?I trust you know how differential pairs work.? The difference voltage between the two bases drive the collector currents, and thus, the voltage on node 1.
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The PNP transistor further amplifies the voltage on node 1.? When that voltage drops lower than +14.3V, the PNP turns "on" harder and passes more collector current towards the load.
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In operation, it is a feedback circuit that drives the output (node 3) until it roughly equals the voltage at the left NPN's base.? If it drops below +2 V, the left NPN conducts more collector current, node 1's voltage falls, the PNP turns "ON" harder, and sends more current to the load - as needed, to pull that voltage back up.? Hence, it regulates it at about +2 V.
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Andy
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