Circuits & Schematics

When probing digital logic levels on a circuit board, locating the indicator of the logic level near the probe tip is convenient, so that you can keep both the indicator and probe tip constantly in sight. When using a handheld DVM or oscilloscope ...

Switching power supplies can be notorious noise generators. You should prevent this noise, which is conducted, radiated, or both, from returning to the input source, where it can potentially wreak havoc on other devices operating from the same ...

Tachometry, the measurement of the speed of spin of rotating objects, is a common application. Some of those objects, however, have quirky aspects that make them extra interesting, even scary. One such category includes outdoor noncontact sensing ...

A previously published Design Idea describes a practical gadget that has the potential to save a lot with little investment ( Reference 1 ). However, the circuit uses 120 V line voltage and, as such, it is not that convenient for many applications. ...

Of the many types of analog filters available to designers, few allow easy adjustments of the filter parameters. The biquadratic, or biquad, filter is an exception, however. You can change that filter's corner frequency (ω 0 ), Q, and ...

LM317 fans will recognize Figure 1 as the traditional LM317 constant current source topology. It closely regulates I OUT = V ADJ /R S by forcing the OUTPUT pin to be V ADJ = 1.25 V positive relative to the ADJ pin. Thus, I OUT = V ADJ /R S to a ...

Receiving infrared (IR) signals while conserving system power is difficult, and typically requires the inclusion of complex power-management routines in the firmware. You can avoid that problem by disconnecting power to the microcontroller when IR ...

The circuit of Figure 1 is designed for portable-power applications that require white LEDs with adjustable, logarithmic dimming levels. The circuit drives as many as four white LEDs from a 3.3 V source and adjusts the total LED current from 1 to ...

When designing devices with microcontrollers (MCU), I like to use some of the analog-to-digital converter (ADC) inputs to measure onboard voltages along with all the required sensors inputs. This means I often run out of ADC inputs. So presented ...

A colleague asked for the measured jitter number on a single-supply comparator design based on the LM359 IC ( Ref. 1 ). He wanted to know how the jitter performance of the discrete comparator compared to an IC comparator, which was used with an ...