We can use a Wheatstone bridge voltage measurement to determine an unknown resistance value. In part 3 of this series, we used Kirchhoff’s voltage law to derive the branch currents and node voltages for an unbalanced Wheatstone bridge with five known, fixed resistors (Figure 1). Now, we propose to replace R5 with a digital multimeter […]
Bench Test
Making sense of test circuits with Kirchhoff’s laws: part 3
Kirchhoff’s voltage law gives us three equations with three unknowns to solve for loop currents in an unbalanced Wheatstone bridge.
Making sense of test circuits with Kirchhoff’s laws: part 2
In part 1 of this series, we looked at ways to simplify resistor networks by identifying series and parallel combinations of resistors. We closed with a look at a version of the Wheatstone bridge, such as the one in Figure 1. Although it has only five resistors, not one of them is in series or […]
Tryout: two low-cost USB inline meters and a load
Despite their limited use for testing wall chargers and power banks, USB inline testers let you compare power sources. In three videos, we take you through their features, and we also try an inline USB electronic load. When testing a USB charger or power bank, you can connect a phone or other device and see […]
Teardown: HP 8112A pulse generator
This 50 MHz pulse generator was built as solid as a rock. It’s almost all metal. We take the unit completely apart and look at it from a system and board level. On a visit to the MIT swapfest in 2024, I came across an HP 8112A 50 MHz pulse generator. For $20, I brought […]
Modular system combines DMM with DAQ
The DAQ3120 from B+K Precision lets you install up to three measurement modules to create a custom system for your bench. Most engineers have a digital multimeter (DMM) for basic measurements such as voltage, current, and resistance. Sometimes, however, you need the flexibility to add channels and log measurements without or without a computer. That’s […]
How can I quantify a device’s nonlinearity? part 1
You can specify nonlinearity in parts per million or, especially for RF components, in terms of the 1-dB compression point or third-order intercept point.
What’s a half digit and are they all the same?
The most significant digit on a DMM’s display often doesn’t count 0 through 9.
Audio analyzer combines analog and digital domains
The APx516B from Audio Precision comes with built-in analog I/O and a slot that adds wired or wireless digital I/O. With so many of today’s devices having audio capabilities, engineeers designing wired or wireless audio into a device need to verify audio quality. Audio Precision, well known for its audio analyzers, has introduced the APx516 […]
How to locate EMI emissions with near-field probes: Part 1
Near-field probes let you find the sources of near-field and far-field EMI that ruin your design, and your day. You don’t need to know Maxwell’s Equations to troubleshoot your designs.
