Ralph’s simple battery charger is essentially this simple voltage regulator circuit. He chose the voltage-setting resistors R1 and R2 to give him 2.5 V on the TL431 when the output sees 3.6 V ...

R5 and Q5 make up the current regulator. When the voltage across R5 exceeds about 0.65V, Q5 turns on and shunts base drive from the power Darlington thus causing the output voltage to be reduced. My ...

In hope of repairing it, I traced out the circuit, but did not like what I found—poor circuit design ... A good battery charger tapers off when the battery voltage is above about 14V. For this to ...

Otherwise, testing may only verify V-I limits in the charger itself. A shunt power voltage regulator with a resistor in series to simulate the ... simplify the circuit design for both functions.