Eric Sorensen - esorensen.com

Eric Sorensen

Photo of Comet Neowise

Photo of Comet Neowise

Made it over to Mt. Hood to see Comet Neowise and captured this photo. The Portland city lights are visible on the horizon.

Home Antenna Grounding

Home Antenna Grounding

I recently installed an end-fed wire antenna running from the apex of my garage into a large maple tree in my backyard. I want to get the best performance I can from the antenna and also take the appropriate precautions to operate safely and protect my equipment.

Yeasu FT301D Restore - Part 1

Yeasu FT301D Restore - Part 1

When I first got my ham radio license I purchased a Yaesu FT-301D from another amatuer radio operator on Craiglist. I enjoyed using the radio, but over the years I've ended up using other radios that were either more reliable or matched my requirements better (QRP, portable, etc). At this

MiSTer Case

I've recently been interested in FPGA-based gaming systems. These systems implement the hardware of gaming systems on a programmable FPGA to achieve very accurate "hardware emulation" of the platform. A recent popular example is the Analogue Pocket, which is an FPGA-based handheld gaming system which can interface with Gameboy and

Loop Antenna Copper Jumpers

Loop Antenna Copper Jumpers

I am planning to machine some copper jumpers to go between the copper loop and the vacuum capacitor. These can be soldered (or brazed) to create a solid connection with very low resistance.

LCD Control Board for SX3 Mill

LCD Control Board for SX3 Mill

The LittleMachineShop control board replaces the button board built in to the mill, so when the spindle control board is connected the buttons and LCD built in to the mill are no longer functional. I designed a drop-in replacement for the button board to help add back some functionality.

Full Disk Images of Earth from GOES-17

Full Disk Images of Earth from GOES-17

Geostationary satellites maintain their position relative to earth. This means a parabolic dish can be pointed at the satellite and receive continuous downloads.

Astrophotography, Part 1

Astrophotography, Part 1

Astrophotography used to be a hobby of mine and I would make it out with my camera a few times a year. Over the last few years I haven't prioritized this hobby, but I am ready to start again. Astrophotography typically involves hours of idle time in remote locations (often

Soap Film Photography

Soap Film Photography

After a few photo and brainstorming sessions, we ended up with a repeatable setup to capture the kinds of images we wanted. In this post I hope to pass on some of the things we learned and share some of the resulting images.

Loop Antenna - Initializing the TMC2130

Loop Antenna - Initializing the TMC2130

Continued from part 4. Now that I can read and write across the SPI interface I am going to write an initialization routine for the TMC2130. Fig 22.1 and 22.2 in the TMC2130 datasheet show a "quickstart" routine for the TMC2130. First, here is 22.1: At "SC2"

Loop Antenna - SPI Read and Write

Loop Antenna - SPI Read and Write

Continued from part 3. Now that I have confirmed the stepper driver is working properly, I want to establish SPI communication for configuration and status readback. This will be especially important to enable the stall detection feature I am using for homing. First, I wrote a function to read and

DDS RF Signal Source

DDS RF Signal Source

In 2017 I designed a local oscillator board which can be used to generate an RF signal in the HF range (< 30MHz). I hope that this can become the building block for a more complete radio design, so I included a lot of expansion options including an I2S interface, I2C,

Shopfox M1111 Mill Conversion - Intro

Shopfox M1111 Mill Conversion - Intro

In 2017 I acquired a Shopfox M1111 benchtop mill. It has an intermittent issue with the spindle motor, but is otherwise mechanically sound. This mill is very similar to the Grizzly X3 mills and is suitable for light-duty milling in aluminum. Leadscrews These mills are commonly converted to CNC machines

Loop Antenna - Motor Control Part 1

Loop Antenna - Motor Control Part 1

Continued from Part 2. I am starting to work on the automatic tuner for the magnetic loop antenna. I will implement the various functional blocks in the following order: 1. Motor control and homing 2. SWR measurement 3. Seeking algorithm to store history and tune quickly Component Selection: I am

Loop Antenna - Assembly and First Test

Loop Antenna - Assembly and First Test

Picking up from part 1. Today I finished assembling the loop antenna and ran some tests on it for the first time. The results look great so far and after this I'll be ready to put it on the air. First, I screwed on the plastic clamp pieces to each

Oddwatt Amplifier Assembly

Oddwatt Amplifier Assembly

In 2016 I built a sound system including speakers, preamplifier, subwoofers, and amplifier. I chose a tube amp design based on the "Oddwatt" design by Bruce Heran. If you want your own tube amplifier design, I highly recommend checking out his website here. Bruce is very helpful and active on

Loop Antenna - Annealing Copper

Loop Antenna - Annealing Copper

Continued from Intro. Many people assemble their loop antennas using copper pipe and 45 degree angle connectors to form an octogon. This approximates a circle well enough, but introduces some electrical resistance to the loop. I want to bend a piece of copper into a continuous loop to decrease the

Infrared Photography

Infrared Photography

The sensors inside many consumer cameras on the market today are sensitive to infrared light. This isn't normally desireable, so manufacturers add an infrared-blocking filter in front of the sensor. It is possible to remove this filter and replace it with a visible-light filter to take some images from part

4PI Speaker Build

4PI Speaker Build

This is a build log for my 4PI speakers. These high-efficiency speakers have a 15" woofer and a horn-loaded tweeter.

4PI Speakers and Oddwatt Amplifier

4PI Speakers and Oddwatt Amplifier

In 2016, I set out to design and build a sound system for our house. Going into the project, I knew I wanted to build a tube amplifier. I'm not much of an audiophile or audio "purist", but there is something fun about tube amps that made we want to

Droplet Photos - Part 2

Droplet Photos - Part 2

In Part 1, I showed my setup for taking water droplet photos by using an eyedropper and an IR emitter/receiver pair. After learning from that setup, I created a fully-automated droplet setup which opens the camera shutters, dispenses droplets, and fires the flashes at the appropriate moment. Once its

Droplet Photos - Part 1

Droplet Photos - Part 1

Droplet photography is interesting to me because it combines two interests of mine: photography and electronics. I've done multiple photo sessions over the years with different technical methods of synchronizing the shots. In the beginning, the setup was simple. I used a set of harbor freight "helping hands" to hold

High Voltage Experiments

High Voltage Experiments

Flyback transformers are a great tool for experimenting with high voltage. These transformers were commonly used in CRT monitors/televisions and are designed to generate the high voltage necessary for the operation of the screens. I did some experiments with high voltage when I was in college. I don't have

Ham Radio Loop Antenna

loopantenna Featured

Ham Radio Loop Antenna

Intro to my Loop Antenna Design

Robotic Arm - Part 2 - Assembly

Robotic Arm - Part 2 - Assembly

In part 1, I shared some of my notes about the BOM for the Moveo robotic arm. In this article I'll share some pictures of the assembly. All of the plastic parts on the Moveo are 3d-printable. I experimented with and without support material and found the parts printed generally