Circuits & Schematics - Measurement

I designed and built this thing many years ago. I published the hobby circuit in the now defunct “Radio Elecronics” magazine back in 1992. The electronic circuit injects a precise 1 Amp of current into any unknown resistor, up to about ...

Designing an analog circuit can be a frustrating experience, as noted by Nick Cornford in his Design Idea (DI), “DIY RTD for a DMM” ( Ref. 1 ). With a fortnight’s struggle, I completed the design of 4 mA to 20 mA, two-wire ...

At its invention roughly four decades ago, STM (scanning tunneling microscopy) created a sensation because it was the first technology to make atomic-scale-resolution imaging a routine procedure. An essential requirement for the practical ...

In April 2012, EDN published a circuit by John Fattaruso ( Ref. 1 ) that lets you quickly measure the drain-source saturation current and the pinch-off voltage of both an N-JFET and a P-JFET. The pinch-off voltage (V P ) is measured by inserting a ...

Figure 1’s circuit is not as fast as some other circuits, but its 2.5 MHz output settles from a full-scale input step in only 3 us. This makes the circuit a good candidate for FM applications or any area where fast response to input movement ...

Almost every wall power supply has no indicator showing whether current is consumed by the load or not. It seems that this was a shortcoming that was not only noticed by me: I once saw the solution given in Figure 1. Figure 1. Wall power supply ...

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 ...

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. ...

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 ...