October 2015 - Herdware.com

WE ASSUME CONTROL: SPI AND A DIGITAL POTENTIOMETER

In the last video I demonstrated a Universal Active Filter that I could adjust with a dual-gang potentiometer, here I replace the potentiometer with a processor controlled solid-state potentiometer. For those that are too young to remember, we used to say “solid-state” to differentiate between that and something that used vacuum tubes… mostly we meant

HOW TO BUILD A THERMOCOUPLE AMPLIFIER

A Thermocouple is a terrific way to measure temperature. The effects of temperature change on dissimilar metals produces a measurable voltage. But to make that measurement you need an amplifier circuit designed for the thermocouple being used. Linear Technology LTC 1049 Low Power Zero-Drift Operational Amplifier with Internal Capacitors While researching “Zero Drift Amplifiers” as

DIRECT DIGITAL SYNTHESIS (DDS) EXPLAINED BY [BIL HERD]

One of the acronyms you may hear thrown around is DDS which stands for Direct Digital Synthesis. DDS can be as simple as taking a digital value — a collection of ones and zeroes — and processing it through a Digital to Analog Converter (DAC) circuit. For example, if the digital source is the output

BIL HERD: COMPUTING WITH ANALOG

When I was young the first “computer” I ever owned was an analog computer built from a kit. It had a sloped plastic case which had three knobs with large numerical scales around them and a small center-null meter. To operate it I would dial in two numbers as indicated by the scales and then

INTERACTIVE SOFTWARE TO SOLVE CROSSTALK PROBLEMS

A link to this video demonstrating PCB cross-talk ended up in my mailbox the other day as I tend to stay on the mailing lists of the some of the high end CAD companies. There are some really interesting and powerful “mega-tools” that do things like plot noise density for decoupling analysis and extremely high

HOW CMOS WORKS: MOSFETS, JFETS, IGFETS AND MORE

CMOS opened the door for many if not most of the properties needed for today’s highly integrated circuits and low power portable and mobile devices. This really couldn’t happen until the speeds and current drive capabilities of CMOS caught up to the other technologies, but catch up they did. Nowadays CMOS Small Scale Integration (SSI)

COMMVEX 2015: WHAT HAPPENS WHEN COMMODORE USERS GATHER

I’m not getting any younger, in fact I’m getting older by the day. This fact along with the fact that this year is the 30th anniversary of the Commodore C-128 and the original Commodore Amiga prompted me to attend this year’s CommVEx in Las Vegas lest I not be around for the next significant anniversary.

GATES TO FPGAS: TTL ELECTRICAL PROPERTIES

On the path to exploring complex logic, let’s discuss the electrical properties that digital logic signals are comprised of. While there are many types of digital signals, here we are talking about the more common voltage based single-ended signals and not the dual-conductor based differential signals. Single-ended Logic Signal I think of most logic as being in

MAKING THE CES SHOW… THIRTY YEARS AGO

This year’s CES has dredged up some memories. I had assumed that as one becomes old they are supposed to become used to memories of a young vigorous person that shared their body and memories leaving little else except some scars and some old stale socks lying around plus 2 or 3 pictures to

WIRE WRAP 101

You might notice that many of my writings start with “Back in the day”. Not wanting to disappoint I will say that back in the day we used to use wire wrap technology when we needed a somewhat solid, somewhat reliably assembly. Given a readable schematic a good tech could return a working or near-working unit in a day or two depending on the completeness and accuracy of the schematic.