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 […]
FAQ
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 […]
Basics of power-supply self-protection
AC/DC and DC/DC power supplies are normally relatively rugged in regular operation. Nonetheless, some protection features are built into most of these units to ensure that they do not “self-destruct” or damage associated circuitry – primarily their loads – in the event of a failure or out-of-spec operational mode. (note: in strict terms, a power […]
Power Status: battery monitors matter
For battery powered systems it can be useful to know something about the state of the battery in order to predict remaining battery life. With specific charge/discharge information, you could also manage battery consuming resources to maximize battery life. There are integrated circuits to help with either approach. For simple charge or discharge information, a […]
Stray current and parasitic capacitance in circuits at RF
Strange things can happen at high frequencies. It begins with stray current in your printed circuit board (PCB). What is stray current? Stray current starts with stray voltage, relating through Ohm’s Law (V=IR). Stray voltage refers to a situation where between two points, there exists a voltage potential that should not be there (and wouldn’t […]
