Welcome to the N1IR Electronics Website. Totally off the cuff, one take, unrehearsed video projects for anyone interested in amateur radio, electronic design, makers, hardware hackers and science.

Get off your duff and build something!
Training the hand and mind since 1982.

Tuesday, June 4, 2019

Greetings Prospective Employer

Greetings Prospective Employer,

Please feel free to browse my page and projects, any question please contact me at 508-558-2559 or chrisjohnson2003@gmail.com

Click here to see my résumé

ELT/EPIRB Detector - Capstone Project

The design I came up with was a pager size device that would alert a pilot there ELT or Emergency Location Transmitter was on. When we got called out to search for these ELT's they were false alarms in fact over 59 out of 60 of my documented finds were false activation's. I wanted to design a product that a pilot could wear or throw in his fight bag that if there was a signal on 121.500 Mhz (121.775 prototype) and was less than 200 feet away it would beep.
Link below
Narrow Band Emergency Message System Interface
NBEMS is Narrow Band Emergency Message System. Think back to your last public service event, drill, or deployment. You probably passed a lot of traffic best suited for voice communications but...What if you had been asked to pass Roster of evacuees, Required prescription medications, Directions to a disaster scene. The needs of our Served Agencies have changed. They still need voice communications but...There's an increasing need for data communications. We need to be able to provide more than just voice communications from a ham with an HT
Link below
The Ignition Switch Delay for APRS node
"The Ignition Switch" featured in QST Aug09. This circuit provides protection against transient protection when starting your car and proves a delay off time for APRS equipment to send data before shut-down.
Link below

9th Grade Capstone Project Line Following Robot Project - Design of a ultra fast line following robot project for student engineering technology project. Worked in conjunction with Electronics Engineering, Drafting and Precision Machine Technology provided a “canned” project. Robot would follow a black line (electrical tape) on the floor autonomously, via infrared led and infrared photo transistor. The engineering student program an algorithm in the Arduino. Students assemble the electronics and build a custom machined chassis and wheels. Students would “tune” the program to different track conditions.

10th Grade Capstone Project“Blimpy”
Blue-tooth Controlled Blimp Project - Design of a ultra light modular control system for student engineering technology project. Worked in conjunction with Electronics Engineering, Drafting and Precision Machine Technology provided a “canned” project. Students assemble electronics and program the project, both in the Arduino IDE and a custom application on the cell phone using MIT APP inventor, scratch programming. Student would also design custom 3-d printed chassis in Solid Works

Online assembly instructions

Precision LUX Detector
Here is a design I made for a friend who wanted an white LED to turn on when it was dusk, but also wanted so adjustment via a pot. So off to pick a photocell, I picked a VT9ØN3 that was used in many low light applications. 

Once ordered we tested the photocell characteristic curve and found the following: 

Now the circuit we chose was a op-amp comparator type, this was a great circuit because we used a JFET input opamp the TL072 and current consumption was less than 1ma (our target current) and have a very crisp trigger level unlike using a single transistor or FET. We used a 25 turn precision pot to get the accuracy down to +/- 1 LUX at the set-point. In-fact a voltage of 1.625 at pin 3 (reference) was ideal for dusk at 7pm local, the photocell read about 130k ohms indoors at dusk shades open with 5.25 sqft total window area facing east+west (2.625 sqft ea) approximately 3 to 4 LUX