Can you use voltage dividers as regulators? What if you add a Zener Diode? In this AddOhms episode, I show what happens when you try to power a complex circuit like an ESP8266 with a voltage divider instead of a regulator. (Spoiler: Get a voltage regulator.) This video tutorial is related to a write up I did recently on Zener Diodes. For questions or comments visit the AddOhms Discussion Forum.

Behind the scenes

A significant change for this AddOhms Episode is that I moved from Final Cut Pro X to Premiere Pro. I also shot the entire video in 4K, even though the output is 1080p. Animations were still done as 1080p compositions. One snag I ran into, the color corrections I applied in PPro, didn’t seem to get exported. You might notice when the breadboard is on screen, it has a very slight yellow tint to it.

I’ve been changing how I produce the videos. It’s shortening the cycle time. The key is that I’m not trying to animate every scene. The amount of work involved is just too much. I animate practically every frame. So in a 6-minute video, that’s just too much.

By the way, there are two easter eggs in this episode. Can you find them?

Voltage Dividers as Regulators on YouTube

FleaFPGA Ohm is a crowdsource project worth considering

An awesome crowd source project is live.

FleaFPGA Ohm Prototype with case

Previously,  I wrote a FleaFPGA Introduction. This board was about the size of an Arduino Uno with some GPIO pins, a VGA, USB, SD Card, PS2 Style Port, and a USB Host connector. At the time, the Lattice Mach XO2 provided the base logic. It found some success in the emulation community (*cough* x86 *cough*.) Unlike software emulators, the FPGA emulates the actual digital logic of classic computer ICs. Also known as ASICs.

Fast forward to today, well, this week. Valentin Angelovski is at it again, but this time, with a new and improved board the size of a Raspberry Pi Zero. He’s launched an Indiegogo Campaign for the FleaFPGA Ohm. For $45 (plus a bit for shipping) you can reserve your spot for when these start shipping early next year.

As you might have noticed, I don’t often promote or comment on crowdfunded projects. My experience with crowdfunded projects has not been positive. So what makes the FleaFPGA Ohm different? Well first, I know Valentin well. Granted distance has kept us from meeting face-to-face, we talk at least once a week on IRC. I’ve been eagerly watching his progress with the FleaFPGA Ohm. Second, this isn’t his first hardware project. He’s already sold many of the original FleaFPGA boards. While there is always a risk with crowdfunded campaigns, I think the risk here is minimal–and worthwhile.

If you’re interested in advancing your hardware hacking game, FPGAs are the next step. And I think the FleaFPGA Ohm is a serious option to consider. Since you might be new to FPGAs or Valetin’s projects, I sat down to interview him for this project. (Okay, it was Google Docs, but these questions and answers are real!)

Before continuing, in disclosure, I have backed this project. However, no other endorsement or paid promotion has happened. Below here are actual answers from Valentin to questions I asked (and had.)

Back FleaFPGA Ohm on Indiegogo

Continue Reading »

Op Amp Circuits by Bob Pease

TI (Formerly National Semiconductor)
September 2002

TI AN-31 Torn Paper

Op amps are one of the most versatile ICs in electronics. A purely analog device, they can be used for amplification, summing, integration, and a whole host of other circuits. AN-31 from Texas Instruments is 32 pages of op amp circuits. (Note: this document was created before TI acquired National Semiconductor.)

Even more amazing is that the author is Bob Pease. If you never heard of Mr. Pease, please spend a few minutes right now reading this TI page dedicated to him. His contributions to electronics are nearly immeasurable. (Sadly, he was involved in a car accident after attending the funeral of his equally famous engineering friend, Jim Williams.)

Download AN-31 from TI


Zener diode makes for a lousy regulator

Reference and regulation are not the same thing

zener diode regulator

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.”

Continue Reading »

Download AddOhms Live iCal Reminder

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:

  • Introduction
  • News (3 stories or projects that I found interesting)
  • Op Amps with the XL741
  • Q&A
  • 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.)

Download AddOhms Live iCal Reminder

Date:September 24, 2017
Time:17:00-18:00 PST
Appearance:Op Amps featuring the XL741 (and Q&A) on AddOhms Live!
Outlet:AddOhms Live

PicoScope 2204 Review and Hands-On

Initial thoughts on my first hands-on with a USB 10 MHz Scope

picoscope 2204 review

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.

Continue Reading »

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.

Learn how to choose Enterprise SSD Capacitors in the EE Journal Chalk Talk.

This video was created in cooperation with KEMET Electronics, Mouser, and EE Journal.

Date:August 29, 2017
Appearance:Enterprise SSD Capacitor Chalk Talk
Outlet:EE Journal's YouTube Channel

5 Voltage divider circuits that go beyond dividing

voltage divider circuits

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.

  1. Measure Battery Voltage
  2. Signal Level Shifter
  3. Reference Voltage
  4. R-2R Ladder
  5. One Analog Input with Many Buttons

Continue Reading »

Pi Cap Hands On Review

My first impressions of a Raspberry Pi capacitive touch hat

Pi Cap Review

The Pi Cap adds capacitive touch buttons to your Raspberry Pi. Bare Conductive was kind enough to send me one. I do not have a project in mind right now, so here are my first impressions.

What is the Pi Cap?

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.

Continue Reading »

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:

  1. There are no brushes to wear out
  2. No sparks when the motor spins
  3. You can get way faster RPMs out of a BLDC.

Check out the AddOhms #21: Brushless DC (BLDC) Motors. Show notes are available here.