The Zener diode is often used to create a reference voltage. In tutorials and even college texts, there are mentions of creating a Zener diode based regulator. The idea is that the Zener maintains a known voltage drop. The problem is that current matters. This post looks a quick Zener diode overview and shows what happened when I tried to power a microcontroller using a “Zener diode regulator.”
Sunday September 24, 2017, I will host the 2nd live stream of AddOhms. My first live stream was a test for the technology pieces. I’ve made some refinements and am giving it a second try. For that reason, I’m keeping the topic really simple.
The Agenda for the Live Stream is:
News (3 stories or projects that I found interesting)
Op Amps with the XL741
Whatever surprises pop-up.
In the livestream, I’ll be talking about inverting and non-inverting circuits using an op-amp. But I am not going to use just ANY op-amp. I’ll be using the MASSIVE XL741! (I did a review of Evil Mad Scientist Lab’s XL741 in the past.)
If you need a reason to be an Element 14 member, let me suggest their Road Test program. Companies partner with Element14 to get people to try out their gear. A couple of years ago I got a new microcontroller board. This week I received a new test instrument. Here’s my hands-on Picoscope 2204 review.
The scope is bus powered. With the BNCs and type-B USB connector, it is slightly larger than an external USB hard drive. There is not much weight to the device. It does not feel cheap, just lighter than I expected.
Getting the scope up and running is a breeze. Pico Tech included a CD (or DVD?) to install the software, but I could not find my drive to check it out. Software downloads from Pico Tech’s website work great. It looks like you can even download the software and use it in “Demo mode” if you are curious how it works.
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In this video, I discuss considerations for SSD Capacitors, with a focus on enterprise applications. (No, not the ship kind, the business kind.) As more consumer devices use solid state technology, it gets easier for us to forget the importance of keeping data safe during storage. While solid state drives are more robust than their spinning counterpart, they are not perfect. Just like with spinning drives, there is a small delay from when a write occurs until the data is stored permanently. The highest performance solid state drives parallelize data in a way to minimize this propagation time. However, these drives also keep an active copy of the allocation table in RAM.
Just like the RAM in a PC, when power is lost, so are the contents. So it is critical for a solid state drive to have a reserve bank of energy to dump the RAM contents into permanent storage. Modern drives use huge banks of capacitors to write out any RAM buffers when the system’s rail voltage suddenly disappears.
Here are some ideas of what you can do with the humble voltage divider. This elementary circuit has a few inventive uses. To be upfront, one of these uses is NOT as a voltage regulator. If you need a voltage regulated, get a voltage regulator! At some point or another, I’ve built all five of these voltage divider circuits. For me, the voltage level shifter is the most common.
Arduino tends to call daughter cards shields, while the Raspberry Pi community calls them hats. The Pi Cap is a hat. It plugs into the GPIO header of a Raspberry Pi and provides 13 capacitive touch pads. There is a traditional push button, an LED, and a prototyping area. While the Pi Cap does consume all of the GPIO pins, several are broken out near the GPIO header.
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The first part of the tutorial looks inside of a Brushless DC Motor, or, BLDC. Then I show a discrete transistor circuit that can drive one. Of course, you’ll need a Microcontroller like an Arduino to drive it! Lastly, I briefly talk about an ESC.
Overall, a BLDC is better than a Brushed DC Motor (talked about those on #20) because:
Supplyframe Hardware has published a video of a talk I gave in July 2017. This talk was at HDDG 22. The focus of my discussion was how an oscilloscope’s trigger circuit works. I built on that and talked about some of the behind-the-scenes stuff of what is going on with a digital oscilloscope. (You can download my HDDG 22 slides here.)
Previously, I reviewed the smartphone DMM, Mooshimeter. It is a great meter. One feature I didn’t spend much time on in my review was the ability to graph. Some see it as an “oscilloscope alternative.” The past couple of weeks, I’ve been using Aeroscope. It is a Bluetooth-based oscilloscope about the size of an older active probe. The Aeroscope runs $199 direct from Aeroscope Labs. The question I address in this Aeroscope review: is it better to buy this, a USB-based, or standalone scope for about the same money. How does it measure up?
My Aeroscope review looks at the specifications, the App that runs it and breaks down the key features. Let’s probe deeper.
A question came up on IRC regarding how to PWM a 3-pin PC fan with an Arduino using analogWrite(). Controlling the fan was seemingly straightforward. The problem was that the hall effect sensor, or TACH signal, was incredibly noisy. The noise made it impossible to measure the fan’s rotation. Working through the question, I found three issues to tackle:
You need to use a PNP transistor
Filter capacitors help
Create a non-blocking RPM measurement (with millis())
This post addresses all three issues regarding how to PWM a 3-pin PC fan with an Arduino.