Circuits & Schematics Supply - 8

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 ...

You can build a self-oscillating H bridge by replacing the pullup collector resistors of a classical BJT (bipolar-junction-transistor) astable multivibrator with PNP BJTs (Figure 1). Because this circuit oscillates at supply voltages as low as 0.6 ...

In power supplies or battery chargers, you often need information about the current flowing in the high-side rail. Figure 1 shows a common circuit for obtaining this information. Figure 1. This method for measuring high-side supply current requires ...

Hysteretic voltage regulators offer the potential advantages of simplicity, fast response, 100%-duty-cycle operation, high efficiency at light loading, and low cost. They need no loop-compensation components to add delays; thus, response time to a ...

Designers often use relays as electrically controlled switches. Unlike transistors, their switch contacts are electrically isolated from the control input. However, the power dissipation in a relay coil may render the device unattractive in ...

You can use simple circuits to implement small, regulated plug-in power supplies. In Figure 1, a basic and versatile 5 V supply uses a zener diode and an emitter-follower transistor. You must calculate and design the transformer such that Q 1 is ...

For symmetrical applications, the circuit of Figure 4 works well. It is made up of the positive limiter already seen and a complementary negative limiter connected in parallel. A single positive reference voltage is used to control both voltage ...

I need a circuit to limit the voltage across some dissipation limited devices. It must: limit the voltage to a maximum of 1.5 V, have symmetrical limiting, be capable of accepting a current of 2 A, and leak less than 100 µA at 1 V. Two Zener ...