A Fox Consulting & Design

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A Fox Consulting & Design We are a consulting company engaged in software engineering, system design, and electronics R&D.

We're playing with a 74LS31 Delay Circuit, a not-so-popular or easy to find chip these days. These provided 6ns, 24ns an...
27/03/2026

We're playing with a 74LS31 Delay Circuit, a not-so-popular or easy to find chip these days. These provided 6ns, 24ns and 48ns delays, useful for old-timey computer bus interfaces where interfacing to slower chips was needed. Here, we have it wired up to 1 Mhz clock and have the chip wired to produce its maximum of a 96ns delay. Not a hell of a lot, is it? But it does work out: 0.096 or roughly a 10% shift @ 1Mhz which is about what it looks like.

We do like our old, hard-to-find chips!

We've been working on some triangle waveform generators with the goal of having a square-wave output with INDEPENDENT va...
02/03/2026

We've been working on some triangle waveform generators with the goal of having a square-wave output with INDEPENDENT variable frequency and duty cycle. Independent meaning varying the frequency does not change the duty cycle. First waveform is the best we could achieve with a 555. Second is from a dual op-amp setup (a 358).

It is now officially Stepper Motor season! Back in March of 2025 we purchased many different kinds of stepper motor cont...
27/12/2025

It is now officially Stepper Motor season! Back in March of 2025 we purchased many different kinds of stepper motor controllers, drivers, and a box of miscellaneous stepper motors. We've finally got the time to evaluate all of these purchases and figuring out the motor wirings. This shall continue for some time.

Evaluating some NANKADF power supplies. They aren't without their quirks but they do have good (if a bit over-zealous) O...
10/07/2025

Evaluating some NANKADF power supplies. They aren't without their quirks but they do have good (if a bit over-zealous) Over Current Protection. One has memory storage, the other has USB power readouts so.... whichever you choose.

For the last week we've been playing in the world of single-chip-solution counters/displays. Here we are demonstrating d...
22/12/2024

For the last week we've been playing in the world of single-chip-solution counters/displays. Here we are demonstrating dueling counters: A 74C925 from the late 1990's, and an ICM7217 from the 1980's. Both are 4-digit BCD counters with built-in display circuitry. Only a few external resistors or transistors are needed to drive the displays.

The ICM7217 has a few extra features over the newer chip: it can count up or down, and includes a leading zero blanking option. It can also function as a frequency divider and be programmed to roll over/overflow at any given count. Last, it doesn't require any external components. There's something to be said about older technology.

A couple of Christmas Presents for our lab: a digital microscope, and an integrated circuit tester. Oops, there went our...
12/12/2024

A couple of Christmas Presents for our lab: a digital microscope, and an integrated circuit tester. Oops, there went our profit for the year! :-)

Organizing our Arduino modules.....
19/11/2024

Organizing our Arduino modules.....

We've had an original AY-3-8910 Programmable Sound Generator chip for, oh, 30 years, but were never able to properly int...
27/10/2024

We've had an original AY-3-8910 Programmable Sound Generator chip for, oh, 30 years, but were never able to properly interface with it--that-is, until recently when we purchased a RC2014 module that takes an AY-3-8910 chip. as well as a Yamaha YM2149. Unfortunately the original AY-3-8910 requires a /WR hold time of 1800ns, and even through the RC2014 module has a clock divider, it apparently is only used for frequency calculation, not for slowing down /CS, /RD and /WR signals, so sadly we were unable to use our chip with this module.

On a positive note, we did purchase some AY-3-8910A chips off eBay which did work with our RC2014 system.

27/10/2024

A demo circuit we made some years ago to show off the features of the SN76477 Analog Sound Generator from Texas Instruments.

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