Douglas.Butler

's profile
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consultant

A Design Engineer with over 20 years of experience in Analog, Digital and Optoelectronic Design, Prototype fabrication,and Test. A "total solution" person who finds and implements expedient and cost effective solutions to a wide variety of problems. Specialties: Environmental sensors: temperature, pressure, light, conductivity, rainfall, compass, etc. Industrial sonar Robotic controls Underwater Gliders Buoyancy Gliders Design, prototype construction, field installation, customer training Theatrical props: exploding zombies and stage magic


Douglas.Butler

's contributions
  • 12.11.2014
  • Bad timing
  • My first job out of college was designing an oceanographic release, a device that holds instruments to the sea floor for months until they have collected their data and then releases an anchor so the instruments float to the surface where they can be recovered. So we had a small brush motor that would sit for months in the cold and damp and then had to run or $100,000 of instruments would be forever marooned on the seafloor. On the other hand the motor would only run for perhaps a total of 10 minutes in the 20 year expected life of the release. Our solution was to use as precious metal brushed motor rated for a nominal 6V run directly from our 27V battery. It would not last the manufacturer's expected thousands of hours of run time but it was very likely to move when we needed it.
  • 09.26.2017
  • Who cares that we no longer have privacy?
  • "but why hide if you are not doing anything wrong or bad?" Who gets to decide what is wrong or bad? Is it the current administration? Or maybe the next administration when this one is in prison? It is impossible to predict what may be embarrassing or illegal a year from now. Just ask the Dreamers about the value of privacy.
  • 08.14.2017
  • The weed-eater circuit
  • In my head I came up with 7ish volts in a few seconds. Then I would ask how accurate an answer you need. Most of the time 7ish would be good enough. My favorite question in "What is 5/8" minus 0.050"? Many candidates have to break out a calculator or simply get totally flustered.
  • 04.04.1985
  • 1-bit PROM programmer shows status
  • I remember in the late 1970's or early 80's there were actual non-erasable PROM chips. We built a bit-slice processor for sonar data that used them for its microcode. In production they would be programmed, tested, and if they failed they were thrown away. I had a few dead ones hanging from my rear view mirror in my car.
  • 03.07.2014
  • Competition breeds oscillating amplifiers
  • Many years ago I worked for a company that made sonar survey equipment. Their current well known product was touted as a "16 bit" system, though in truth the only 16 bit parts used were the A/D chips and their LSB was replaced by a sync signal. Worse yet the system had about 1000 counts of noise floor so the effective resolution was only about 6 bits. But that still was enough for many happy customers. However Marketing wanted a new system that had to be clearly better then the old system. Over Engineering's objections they insisted on making the new product 24 bits wide. I left the company three years later and the new 24 bit system still did not offer the user a noticeable signal improvement over the old 6 bit system.
  • 07.29.2016
  • Circuit delivers constant power to a load
  • @Haider, That reminds me of the acoustics lab at WPI. About 1980 there was a previous students project in the back of the lab that was a woofer with a HF LVDT for feedback so the controlled factor was cone displacement. We were told it worked well by the measurements but didn't sound good to the ear.