Circuits & Schematics - Measurement - 6

Battery-operated instrument benefited from auto-power shutdown A handheld, battery-operated “fiber finder” measures the light escaping from an optical fiber when clamped in a V-shaped block under slight pressure. A pair of photodiodes ...

Figure 1 shows two large-signal- measurement methods. The first uses a two-resistor voltage divider and an output buffer, and the second comprises an attenuating inverter and a high-value input resistor. Both of these approaches introduce ...

All thermal anemometers work by inferring air speed from measurements of thermal impedance (Z) between a heated sensor and the surrounding air: (1) where P is the power dissipated by the sensor and T is the temperature difference between the sensor ...

Several years ago we were developing a clamp-on photometer, a hand-held instrument that could be clamped onto a communications optical fiber to indicate the presence of light, its direction of travel, and the presence of combinations of ...

Self-heated transistors used as thermal air flow sensors are a particular (obsessive?) interest of mine, and over the years I must have designed dozens of variations on this theme. Figure 1 illustrates one such topology seen here (Reference 1) ...

Anemometers are an important category of environmental sensor. Articles about their design, data capture, and linearization have comprised topics featured in EDN Design Ideas, several quite recently. Less well covered, however, has been the topic ...

An obstacle detection unit is an essential part of a variety of projects, such as robotics and security applications. The infrared sensors are widely used for these types of applications. The main drawback of some circuit designs is that the ...

Awhile back I published a simple design idea for a thermal airspeed sensor based on a self-heated Darlington transistor pair (Ref, 1). The resulting sensor is simple, sensitive, and solid-state, but suffers from a radically nonlinear airspeed ...

At the end of the DI for a Simple log-scale audio meter (Ref. 1), I promised to show how to upgrade it to work better. With these fixes, it now has near-digital performance, with faster response and smoother operation. Even this supersized version ...

The logic probe is powered from the device under test (DUT) it may be any binary logic, which can be powered in the range +2 V to +6 V. This may be a microcontroller or 74/54 series logic chips, including HC/HCT chips. The probe determines 3 ...