datasheets.com EBN.com EDN.com EETimes.com Embedded.com PlanetAnalog.com TechOnline.com   UBM Tech
UBM Tech

zeeglen

's profile
image
CC&BW

Old-timer who grew up with vacuum tubes and therefore have been amazed and fascinated by the many advances in the electronics industry since.


zeeglen

's contributions
  • 05.23.2014
  • Milliohm Squawker great at finding shorts and reverse engineering PCBs
  • gordonbrush . com Give them your required dimensions and size of mounting hole(s). The 3 mil diameter phosphor-bronze bristles are held in a crimped-flat copper tube, they can figure out how many bristles needed to fill your dimensions. You do need to use heatshrink to support the bristles and keep them held together.
  • 07.18.2014
  • Could your product be exempt from EMC testing?
  • Wondering if the model rail Digital Command Control (DCC) bit rate of about 8620 Hz to the rails was chosen to be just under the 9KHz exemption? Of course modern decoders use a higher frequency for motor PWM and are not exempt, but maybe the original system designers were concerned about putting digital square waves to the "antenna" formed by the railroad tracks in a Class B residential environment.
  • 05.23.2014
  • Milliohm Squawker great at finding shorts and reverse engineering PCBs
  • I once worked at a place where the technicians (and managers) swore by their Huntron Trackers. Until the day when a tech could not figure out why a power module would not work. The tracker told him the output filter cap was good. I showed him that an ohmeter revealed the filter cap had 40 ohms internal leakage. My oft-repeated adage 'Never trust a Huntron' stayed with him after that.
  • 05.23.2014
  • Everyday household scope uses
  • There was that Samsung microwave mess with fried connectors (2 weeks after the warranty) that I described on The Connecting Edge, and of course that Horrific Hellscope by Atten. For household use, how about checking the drive level and timing to the fuel injectors in your car, or loosely couple a probe to the plug wires (a short antenna wire OUTSIDE the insulation for small capacitive coupling) to see if any sparks are abnormal, as in different from the rest.
  • 05.23.2014
  • Milliohm Squawker great at finding shorts and reverse engineering PCBs
  • Hi Martin, The broom probe is custom made to our design by a wire brush company. I found that phosphor bronze has lower contact resistance than stainless steel, is more flexible, and does not damage 0403 components on the bottomside of boards. I tried both 6mil and 3mil phosphor bronze bristles, much prefer the 3mil. However, if there are no fragile components 6 mil is a bit better if thin conformal coatings are present. Heatshrink holds the bristles together while still flexing, when the ends get too worn we simply trim the wires and heatshrink a bit shorter.
  • 03.25.2014
  • Give me those old-tyme displays
  • "My parts stash includes some incandescent seven-segment displays; but I've never seen them used in an actual product" One of the products in which these were used was a Heathkit Digital (as opposed to rotating disc with flashing neon lamp) Marine Depth Sounder, forgot the model number. IIRC the 8th segment was a little X of incandescent wires to form the decimal point. Can't recall if they were used in any other Heathkit products.