Circuits & Schematics - Measurement - 8

While refurbishing an ageing audio mixer, I decided that the level meters needed special attention. Their rather horrible 100 µA edgewise movements had VU-type scales, the drive electronics being just a diode (germanium?) and a resistor. ...

Awhile back I published a simple design idea for a thermal airspeed sensor based on a self-heated Darlington transistor pair ( Ref. 1 ). See Figure 1. Figure 1. Older design idea with self-heated Darlington thermal airflow sensor. In the circuit, ...

Capacitance sensors measure a wide variety of physical quantities, such as position, acceleration, pressure and fluid level. The capacitance changes are often much smaller than stray capacitances, especially if the sensor is remotely placed. I ...

With just one leftover op amp or comparator, you can add a battery-condition indicator to your portable circuit design. To indicate the life in an aging battery visually, the circuit in Figure 1 varies the duty cycle and flash rate of an LED when ...

You often need to measure current during circuit design and debugging. You can perform that task by breaking a path, inserting a shunt resistor, measuring its voltage, and converting the voltage to current. Unfortunately, that approach is sometimes ...

Frequent design idea contributor, Peter Demchenko, recently published “Extending the resolution of a peripheral DAC” ( Reference 1 ). In it, Peter describes an inverting dual-supply amplifier circuit that he says is intended “ to ...

Low-cost monolithic precision adjustable voltage references are available in multiple families from multiple manufacturers, but this isn’t true for adjustable precision current references. That’s unfortunate, because while most ...

It is known that the p-n diode can be the basis of an accurate thermometer for cryogenic temperatures up to about 200 C. A constant current is maintained through the diode and the voltage across it gives an indication of the temperature. The ...

Numerous applications require the measurement of very low resistances, including but not limited to fuse integrity analysis, relay characterization, and superconductor evaluation. There is a wide range of commercially available equipment designed ...

Long ago in a galaxy far away (actually, the same galaxy but the Milky Way is moving so it must logically be far away from where it was way back then), I sketched up a simple circuit for a DC coupled amplifier that I thought (in my youthful ...