Profile cover photo
Profile photo
Travis Hayes
219 followers -
Identifying the world's problems, designing solutions, implementing nothing.
Identifying the world's problems, designing solutions, implementing nothing.

219 followers
About
Travis's posts

Post has attachment
Free-running a Z80 tonight at 1 MHz, as the trendy people do. The Teensy 3.5 on the right is providing all active signals.
Photo

What if I need to use a 2016 MacBook Pro to ssh to remote system and run vi? No physical and unshifted escape key!

I remember when every self-respecting tech geek in SV seemed to have a Mac. My ex-Apple coworkers at Azul convinced me to switch in 2003. In March of this year I switched back with a Dell XPS 15. I just couldn't justify (slightly) more money for older technology, no upgradability, and challenging software compatibility.

I do wish Apple had been more serious about holding onto the technical and creative niches with true "pro" systems.

Post has attachment
I've been lost without my desktop PC for the last few days. My GTX 660 Ti started glitching on the BIOS splash screen and going to black on the Windows 10 login screen.

This old wide microATX case provides great airflow, access for swapping cards, and handles 11.5" cards with the front fan mounted. Pity I had to spend an hour searching for an extra 8 pin PCIe modular power cable.

The new card is a GTX 1070, which is total overkill for the 6.5 year old processor, mobo, and RAM. I'm hoping to limp along until Kaby Lake is available.

Post has attachment
Generating ---12V from four AA batteries. I built up the inverting example from the TI MC34063A datasheet, and it's shown working here. So many interesting applications require a dual (+/---) DC supply. It's time for me to hack together a usable DC input (laptop power brick) dual output supply on a perfboard.
Photo

Post has attachment
As soon as I open up a new benchtop, this happens! Anyone else identify?

I just might need to reign in my project and exploration multitasking. Maybe.
Photo

Post has attachment
I'm enjoying +John Wiggins' project postings, and would like to do more of my own.

The picture is a prototype of an isolated DC power supply that should meet the needs of a test and measurement device I'm designing. Such devices often have similar requirements:

1. Power for the analog section needs to be galvanically isolated from main power. This prototype alternates 5 volts across the primary side of a small PCB mount transformer at ~400kHz. The switching is done with a dedicated IC, but I'll do this with an AVR micro and a couple 2N7000 FETs in the final device.

2. Power needs to be dual rail: plus, ground, and minus. The secondary side of the transformer goes into a full wave bridge rectifier and output caps to produce unregulated power at something like +/-6.5V.

3. Power needs to be regulated. The unregulated positive and negative supplies need to stabilized around +/-5V and filtered to remove ripple. Low dropout regulators were required for this case. The unregulated voltages simply didn't have enough headroom beyond the desired +/-5V for classic 7805 and 7905 regulators to function decently.

4. There needs to be an additional higher positive DC voltage to drive power FET gates or voltage references. I do this with a charge pump voltage tripler. The oscillating, pre-rectified ~6.5V from the secondary side of the transformer is fed into a ladder of diodes and capacitors. This is shown on the very right side of the breadboard, with the meter showing 19.17 volts with a 100k resistive load.

This was my first time prototyping a charge pump (voltage tripler) to generate low current, higher voltage DC. This is so cheap and easy to do if there's already a switching supply. It's a nice tool to have in the bag of tricks.
Photo

Post has attachment
Not that I'm biased, but w00t!

Post has attachment
Please pardon my joyful ululation, but I have received the surprise gift of an ulu!

I've vaguely wanted one ever since I went to Nunavut. This particular form should be quite practical. Thanks so much mom +Barbara Hayes! My vast array of kitchen gear is now complete.
Photo

Post has attachment
Can a Teensy 3.2 board be used as a quick and dirty function signal generator? All sines point to yes!
Photo

Post has attachment
Low Power Voltage Sampling
The car computer project has taken a big detour for the last few months in lieu of my gaining more experience with microcontrollers and electronics. Carputer 2015 was mostly a system integration design to be achieved by plugging together existing modules. C...
Wait while more posts are being loaded