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MOSFET

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A switching voltage regulator is one of my favorite circuits. In school, they were the first circuits I built where I understood how transistors worked. In fact, they were the first circuit I saw an inductor being useful! Switching regulators are incredibly efficient when designed properly. Of course, this detail about design is important. They are not as simple as a linear regulator, which is basically an IC and two caps.

To understand the basics of a switching regulator, I released AddOhms #18 this week. This is video tutorial dedicated the Switching Voltage Regulator. If video tutorials aren’t your thing, then keep reading for my written tutorial.

On every page of my blog, you might notice a chat window. If I’m not busy, we can chat in real-time. If not, the messages come to me by email. Here’s one I got from Matt the other day:

Let’s talk a bit about how (and why) you would use a P-Channel MOSFET. Matt, and he’s not the only one, is probably asking this question based on the “myth” that P-Channel MOSFETs require “negative voltage” supplies.

Keep reading for how-to use only positive voltage in this p-channel MOSFET tutorial.

When your project needs a transistor, there are tons of choices.  Which makes answering the question “Which transistor should I use or buy?” a daunting task.  Fear not, before wading through spec sheet after spec sheet, consider one of these four general purpose transistors.  Every electronics enginerd’s toolbox should have a few of each.

Transistors are one of the most versatile discrete components in electronics.  In digital circuits, they switch on and off while in analog circuits they are used to amplify signals.  For most projects, they are used to turn on a load that would kill the I/O pin of a microcontroller or microprocessor.   For most circuits either a BJT or MOSFET can be used, depending on the load current you need to switch.

[Edit Note]  Jan (comment below) points out that there are European Equivalents that may be more available for those located in that part of the world. For NPN Check out the BC547, for PNP the BC557.

Here are some more details on each of these.