Ross Robotics

8840a Repair Project

User Rating: 5 / 5

I have been keeping an eye out for a good, name brand bench DMM for personal use for a few months now. Did a bit of research and started looking for a Fluke 8842, 8840, or a 45. Watched some popular auction sites and even CL. These Flukes, especially working ones go for $150+ and well, didn't want to pay an arm and a leg for one. So, during my research, I know that these have VFD (vacuum fluorescent display) that dims after a time. Figured I could get a dimmed display DMM cheap.

I finally came across a 8840a with the AC option 9 and the GPIB options included and had one person bid at $32 with 13hrs remaining! In the description, it stated that they did try some solutions found on the web to get the display working, but couldn't. Long dramatic story short, I placed a bid in the last 2 seconds and won an 8840a!

USB Business Card with USB

Making a USB Business Card

May 25, 2020

I've been kicking around the idea of designing and etching a USB business card. USB business cards have been around for a few years and there is a few designs and software options to choose. My plan is to use an Atmel microcontroller to open a browser and direct them to my website. There is a few issues with this idea as Windows doesn't like to execute code from USB since this could circumvent security. But, I am not at this stage and will tackle that later on.

I have started designing the schematic and there is nothing exciting about the design. It's just a minimal microcontroller circuit, but may add some LEDs for show. I chose the ATTiny85 as it's common with loads of firmware examples.

PCB Etching with Ferric Chloride

So I finally made myself try to etch my own Circuit board. I have put it off for about a year mainly due to PCB Manufacturers getting finished boards out in just a few days. Not to mention the price of a few boards at less than $10.

I made a video of my experience etching a PCB. The board just has a simple 555 blinking some LEDs. But, it will not be populated as the traces between the ground plane didn't etch very well. I think the issue was not leaving it in the etching solution.

My next custom PCB project is laying copper traces on glass. Yes, just clear glass. Should be an awesome journey!

Tricorder

Star Trek TNG Tricorder

So, yes, I'm a Trekkie. I didn't grow up during the TOS series, instead, it was the ST:TNG period. With that useless knowledge, I have a few TNG toys and even though they are great collectors items, I want to make them more detailed like they are on screen. With lots of LEDs, buttons, and even a working LCD screen.

Decade Resistance Box With Display

I figured it was time for a Decade Resistance Box as I am getting tired of using single resistors to test circuits. But, these projects are fairly simple, so I want to complicate it a little bit. Looks like a display will complicate it to satisfy that itch. Yes, I know, these boxes don't need one and reading the dial is really easy.

As of April 6th, 2019, I have started researching what components I want to use. First, I'll need some type of enclosure. Sure, I could go for the really cheap Chinese extruded aluminum projects boxes, but everyone does that! After browsing through page after page of DIY boxes, my eyes seen this box and didn't want to look any further.