OHARARP LLC

Great New Solder Paste How-To!

ohararp — Tue, 13 Mar 2012 14:18:45 +0000

Our friend Scott over at Curious Inventor and Vmeter posted this awesome tutorial on how to use our Surface Mount Kapton stencils. If you haven’t seen this video, amongst his many others, you are missing out.

http://www.youtube.com/watch?feature=player_embedded&v=xqv9HF_2GlY

ChipKit Arrives!

ohararp — Wed, 28 Dec 2011 02:21:59 +0000

I planned ahead and made sure I was one of the first people to make sure my ChipKit Design Challenge application was in the day registration opened. The initial intent was to work on an improved beer brewing controller for the recent 240V 15 Gallon brewery setup I have built. I am looking forward to the design challenge and getting things going in the development IDE.

PhD Work Featured on NPR

ohararp — Wed, 17 Aug 2011 01:21:00 +0000

Unfortunately, I don’t get to play to on as many fun electronic projects as I used to, now that my PhD is really ramping up. The good news is I have plenty of work related projects to keep me busy and luckily they are all panning out well. With that said, here’s a quick feature on some of what I have been doing as reported today on “All Things Considered” on NPR - http://www.npr.org/2011/08/16/139651358/air-force-eyes-artificial-birds-bugs-that-can-spy

A carbon fiber tobacco hawkmoth wing created by Maj. Ryan O'Hara flaps 30 times per second and was photographed using a strobe

New Logger with 10 Hz GPS and 3-Axis Accelerometer

ohararp — Thu, 05 May 2011 18:15:54 +0000

I have thought about adding a 3-axis accelerometer to the SD Datalogger for quite awhile now. I have recently received a set of 3 prototype boards from Laen to do some testing on this concept. Overall things seem to be working very well. I am now considering adding the ability to do AHRS in addition. The question is whether to do this on board using accels, gyros, and a magnetometer or to use a OSH IMU board like the ARDU-IMU.

Kegerator Controller Prototype Up and Running!

ohararp — Thu, 05 May 2011 18:12:01 +0000

I have had a recent interest in brewing and now kegging of beer. In this quest I have purchased a small 5.3 cu. ft. chest freezer to store 3 kegs. Since the chest freezer is meant to operate at <10F it is necessary to control the kegerator via a seperate controller and temperature sensor. I will be posting a more detailed writeup on how I am accomplishing this control, but in my elation the fact that I got everything working I thought I would post a quick picture in the meantime.

13 APR 11 – Back In Business

ohararp — Wed, 13 Apr 2011 14:26:56 +0000

Well, Denver was a rewarding experience and we really enjoyed the nice mountain air, vistas, and even a little bit of skiing. With that said we are back open for business and will be shipping orders starting today to clear our backlog. We should be all caught up by the end of today!

Closed 1-12 APR 2011

ohararp — Fri, 01 Apr 2011 01:59:12 +0000

Unfortunately, we’ll be closing the doors to the business for a few days so that we can attend the AIAA Structural Dynamics and Materials Conference in Denver, CO from 1-12 APR 2011. Any orders placed during this time will ship on 13-15 April 2011. Sorry for any inconvenience we hope to do business with you upon our return. You can read the technical publication of my work here.

DIY Solder Hot Plate

ohararp — Sun, 21 Nov 2010 02:05:08 +0000

For a longtime now I have been an advocate of the hotplate method that was first introduced to me by the folks at Sparkfun for simple and easy reflowing of solderpaste. Through the use of our stencils this makes for a very simple and easy to use method of preparing SMD products for the marketplace. Trhough some of the research work I am currently performing it had become necessary to prepare our own hot plates. I developed through the guidance of doctek and MightyOhm a very simple “P” Temperature control using an Amicus development board and a solid state relay. Using some simple thermal transfer equations and a matlab script I was able to calculate that for a 8″x8″x1/2″ aluminum plate that I sourced from Metal Express for $32 with local pickup.

clc clear close all l=8; % inches w=8; % inches t=.5; % inches W=500; % Element Size in Watts l=l*2.54; % cm w=w*2.54; % cm t=t*2.54; % cm v=l*w*t; % cm^3 d=2.7; % density of Al in grams/cm^3 m=v*d; % grams m=m/1000; % kilograms Cs=0.9; % Specific heat of AL in Joules/(grams * K) Cs=Cs*1000; % Specific heat of AL in Joules/(Kg * K) Tset=200; % degC = 400 F Tamb=20; % deg C = 68 F Qn=Cs*m*(Tset-Tamb); % Heat Flux required eff=0.5; % Heat Transfer Efficiency (Initial 0.8 - Real 0.5) Q=Qn/eff; t=Q/W; % Time to heat in seconds t=t/60; % Time to heat in mins
Q = 458732.9148 Time in Mins = 15.2911

I chose to use a 500 Watt Ring Heater from McMaster-Carr for my design due to pricing. However, in the future I would recommend a 1000 W heater. Heat time is approximately 10-15 minutes and nearly matches the calculations from the heat transfer analysis.

After getting everything working with the Amicus development board I began to work on the “optimization” and “safety” aspects of this project. Luckily for me I live near Midwest Electronic Surplus in Fairborn, Ohio. This local stomping ground often has everything you need for that prototype project. Luckily, I found 1″ ceramic standoffs here for $0.50. These bad boys cost >$3 from Digikey. I was also able to source >880F wire here for $0.10/ft versus the $3.15/ft Digikey wanted for this stuff. After much debate I finally gave in and moved from the Amicus board to the $35 TET612 – PID controller you see in the images above. The manual is not very good but will get you started. Operation is dead simple and the auto tune PID is a breeze with this configuration. Actual control of the ring heater is through a 25A SSR. Temperature control is through a K-Type Thermocouple that I had here in the office.

This project is by no means complete as I have still to add an inline fuse, proper grounding, and a protective metal enclosure. I plan to update once I get these pieces up and running. Stay tuned for more details in the near future!

Maker Beam KKMulticopter: Build Part 1

ohararp — Sun, 21 Nov 2010 00:09:36 +0000

Next Page ›

One of the best parts of being the owner of your own business is that you get to explore different avenues for product development. In this install I am looking at some open source hardware to build a quadcopter for possible resale/kitting in the near future. In this post I am showing the use of Makerbeam and Captain Kuk’s quadcopter controller. I have been a big fan of Makerbeam since its initial funding via Kickstarter and the delivery of my Beta kit. I have finally found a project where I have made good use of the Makerbeam that I have received to date. I still have many parts on order: radio, batteries, prop savers, etc. I’ll be sure to keep some updates going on the progress on this project.

Harvard Microrobotics Laboratory

ohararp — Sat, 20 Nov 2010 23:52:13 +0000

I recently got to spend a week at the Harvard Microrobotics Laboratory in coordination with some collaborative research that I am working on with them. It was an amazing trip and all very impressive at the same time. It’s really amazing the scale that these folks are working on. I have never been in a place where I felt I needed a microscope to look at anything!