Circuits & Schematics Supply - 7

Frequent contributor, Peter Demchenko, recently published “A safe adjustable regulator” ( Ref. 1 ) discussing the likelihood and consequences of rheostat-connected voltage trimmer failure in three-terminal adjustable regulator ( LM317 , ...

In a three-phase ac system, a power source with three wires delivers ac potentials of equal frequency and amplitudes with respect to a zero-potential wire, each shifted in phase by 120 from one wire to the next. Two possibilities exist for ...

Most battery chargers comprise nothing more than a series-pass regulator with current limit. In solar-powered systems, you can’t count on sufficient headroom to keep a series regulator alive, so a shunt method is preferred. A simple shunt ...

You may lack experience and hardware when designing battery-operated products. The battery life of a product can depend more on the ESR (equivalent series resistance) than the terminal voltage. This situation is especially true when you use ...

Recently available visible lasers can be operated from 1.5 V supplies, given appropriate drive circuits. Because these lasers are exceptionally sensitive to overdrive, power to the laser must be carefully controlled lest it be damaged. ...

When you design a transformer for any power converter, you face several compromises. You must trade off core size against the number of primary turns and flux density. Another trade-off is the number of turns and winding resistance versus the ...

Most circuits are referenced to ground, where relatively low-voltage components can monitor and control the low side of a load but not the high side. For example, nearly any low-voltage rail-to-rail-input op amp can detect a voltage increase ...

Analog circuits for long-term testing of passive components, such as 0.1%-tolerant resistors or high-intensity white LEDs, often require a constant current. Using two op amps and a voltage reference, you can develop a circuit that provides a ...

Linear regulator ICs are commonly used in variable power supplies. Common types such as the 317 can be adjusted as low as 1.25 V in single-supply applications. At low output voltages power losses in these regulators can be a problem. For example, ...

Adding a manual reset to a design usually involves designing in a new part with a manual-reset input. But, by adding a couple of low-value resistors, a standard three-pin-reset supervisor can work in most applications. The circuit in Figure 1 ...