Analog-to-digital converters (ADCs) need a reference voltage (VREF) input in order to operate properly. ADCs convert analog inputs that can vary from zero volts on up to a maximum voltage level that is called the reference voltage. The reference voltage determines the ceiling of what the ADC can convert, and is essentially the yardstick against […]
basics
Options for current sensing, Part 2
Part 1 of this FAQ discussed the issue of current measurement, and four transducers which can be used to measure current. The first two – shunt resistors and Hall-effect devices – can be used for AC or DC currents. We will now look at two other transducers – the Rogowski coil and the current transformer […]
Options for current sensing, Part 1
The need to sense and measure current at one or more points is a circuit is very common. In situations ranging from microamps going into or out of a battery, to DC current from a solar panel, to feedback for a power supply controller, to tens or hundreds of amps of AC power to a […]
Power factor and Power Factor Correction, Pt 2
Part 1 of this FAQ discussed power factor and the issues associated with power factors which are not unity, and briefly mentioned power factor correction (PFC). This FAQ explores PFC in more detail. Q: What is PFC? A: PFC is an adjustment of a load’s front-end “appearance” so it presents a resistive-like load to the […]
Power factor and Power Factor Correction, Pt 1
In recent years, considerable attention has been focused on power factor (PF) and power factor correction (PFC) in devices ranging from small appliances to larger systems. Concern about PF and PFC is not new: it has been an issue with AC power delivery in industrial and commercial settings for many decades. The big difference is […]
What is leakage current?
Leakage current flows unexpectedly in almost all circuits, even when the power is off. Current leakage is not limited to electronics, computers, or small signal circuits, and can be found in industrial equipment and three-phase wiring installations, too. Some current will always find a path to ground whether it’s through ground-conducting insulation that’s supposed to […]
Not to be forgotten: the simple, bipolar SCRs and TRIACs
Thyristors or silicon controlled rectifiers (SCRs) and TRIACs are simple bipolar devices which probably get forgotten in this high-tech, CMOS, MOSFET, digital world. A thyristor is a PNPN bipolar device, compared to a normal bipolar transistor which will be PNP or NPN. A common way of explaining their operation is to visualize the thyristor as […]
Passive cooling options and considerations (part 2)
Part 1 looked at the basics of passive cooling. Part 2 explores the specifics of passive cooling in more detail. Q: What is a most common physical arrangement used for passive cooling? Most designs use a combination of conduction and convection cooling, and perhaps some radiation. Conduction is used to draw the heat away from […]
Passive cooling options and considerations (Part 1)
Keeping components and systems cool enough and within their safe temperature zone is a concern for many, though not all, designers and projects. Excessive heat as measured by temperature can cause erratic behavior, inaccuracy and drift due to temperature coefficient-induced shifts, shortened component lifetime, and even outright failure. Q: What are the cooling options? The […]
Reverse polarity protection: how can you provide it?
The reverse connection of a circuit to its DC power source, whether it’s a battery or power supply, can damage and even destroy the electronics. For this reason, many connectors are “keyed” to ensure correct connection. But there are many connections which are directly hard-wired using wires inserted into screw terminals, or ring or spade […]