Circuits & Schematics Digital - 2

Mechanical push-pushbutton switches (also known as alternate-action or push-on/push-off switches) can be bulky and expensive. As an alternative, an electronic version uses a cheaper, NO (normally open), momentary-on switch (Figure 1). Figure 1. ...

When applied to pharmaceuticals, the term “off-label” suggests the (frequently discovered) practical and beneficial uses for a drug that are different from the one it was originally developed for. This happens for electronic components ...

Common designs for touch switches detect a decrease in resistance when a user's fingertip either connects a contact to the circuit's common ground or supplies an injection of 60-Hz ac voltage, resulting from immersion in the electrostatic ...

The control circuit in Figure 1 presents a relatively low input resistance and thus imposes a low value on external pulldown resistor R 1 to provide the desired low-level input voltage. In turn, R 1 wastes power by drawing a relatively high current ...

Interfacing two systems that operate at two arbitrary voltages is a challenging problem; there is no guarantee that one side operates at a voltage higher than the other side. Usually, the interface is an open-collector or open-drain type with just ...

Many designs exist for logic-based astable multivibrators, one of the simplest being an RC feedback loop around a single inverting Schmitt trigger inverter (Figure 1). The output charges the capacitor to the upper switching threshold, at which ...

The circuit in Figure 1 allows you to convert capacitance into a pulse train by using a constant current source and a linear monostable formed by two NAND-gate chips ( 74HC132 ). The circuit also provides two pulses to control external counter ...

The performance of the watchdog circuit in Figure 1 may not match that of a dedicated watchdog circuit, but this circuit is helpful when the only watchdog in the lab doesn’t meet your design’s temperature requirement and when you are in ...

Applications ranging from frequency counting and synthesis to sensor signal conditioning require conversion of RF signals to digital-logic levels. In such situations, designers typically use a high-speed voltage comparator to perform the ...

In this Design Idea, we look at how electromechanical relays display hysteresis behavior that is surprisingly similar to the solid-state Schmitt trigger circuits, and how they can be used for many similar applications. This Design Idea is inspired ...