MOSFET on Bald Engineer

What Active Components Do You Need? | Workbench Wednesday #29

Thu, 08 Oct 2020 21:43:00 +0000

Active components like transistors, BJTs, MOSFETs, and integrated circuits (ICs) make it possible to control circuits. This video explains the must-have NPN and PNP BJTs. For MOSFETs there are a couple of N-Channels and P-Channels to consider. Basic ICs include some digital logic stuff from the 7400-family as well as the venerable 555-timer to have on-hand. We did not forget Op-Amps either. Spoiler: We do not recommend the ua741!

Watch this video on YouTube

Measuring a MOSFET's Miller Plateau | Workbench Wednesdays #25

Tue, 07 Jul 2020 21:28:00 +0000

Turning on a MOSFET takes more than knowing the threshold voltage. A special event occurs when a FET turns on, which is called the Miller Plateau. The gate voltage sticks to the threshold voltage while the drain opens up. In this video, James shows how to measure the Miller Capacitance, using an oscilloscope and custom MOSFET test board. This video came from some measurements I did on a live stream. I had intended to demonstrate something else, but the board I created was such a great demo board for the Miller Effect.

Watch this video on YouTube

DCA Pro Transistor Tester Review | Workbench Wednesdays

Wed, 07 Aug 2019 14:19:09 +0000

When it comes to transistors, there are only so many things a multimeter can measure. The DCA Pro from PEAK Electronics makes short work of testing parts like a transistor. This small device can determine pinout, component type, and essential parameters in a matter of seconds. Not only that but it can be connected to a (Windows) PC and draw parameter curves. Check out the video review to see how the device and software work. Then head over to the element14 page where you can download a zip file full of example parts I measured for you. Use the free DCA Pro software to open them.

Watch this video on YouTube

7 MOSFET Myths and Misconceptions Addressed

Wed, 08 May 2019 13:03:24 +0000

The most popular AddOhms video is my short tutorial on MOSFET basics. In the years since I posted the video, people have sent me many questions. While answering those questions I’ve learned quite a bit as well. For example, in that video, I say that Vgs is the threshold to turn on the MOSFET. Well, it turns out, that is not entirely true. It is the threshold to turn it off! Oops. A minor point with a subtle difference, but a common MOSFET misconception.

Low side vs. High side transistor switch

Wed, 10 Apr 2019 13:45:02 +0000

A common task for a transistor is switching a device on and off. There are two configurations for a transistor switch: low side and high side. The location of the transistor determines the type of circuit and its name. Either transistor configuration can use a BJT or MOSFET. In this post, I draw the configuration for both transistor types, discuss which requires a driver, and explain why you would use either. If you are new to transistors, check out the resource links at the bottom. I have a few videos I made and some from element14’s The Learning Circuit, which do a great job introducing transistors.

Switching Voltage Regulator Tutorial

Wed, 13 Apr 2016 13:00:04 +0000

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.

P-Channel MOSFET Tutorial with only Positive Voltages

Thu, 09 Jul 2015 01:20:55 +0000

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.

The 4 best transistors to keep in your parts kit

Mon, 21 Apr 2014 15:00:38 +0000

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.