92 Juli/August 2020 http://www.elektormagazine.de
MORE ON VOLTAGE REGULATOR CIRCUITS, POWER SUPPLIES, AND LEDs
Looking for additional info about power systems, LEDs, and voltage regulators? Check out these useful Elektor resources:> Voltage regulators (www.elektormagazine.com/tags/voltage-regulators)
> Power supplies (www.elektormagazine.com/tags/power-supply)
> C. Valens, “How to Calculate an ‘LED Resistor’,” ElektorMagazine.com, August 2019. (http://bit.ly/LED-resistor)
> M. Heine, “LED Booster for Microcontrollers,” ElektorMagazine.com, 2020. (http://bit.ly/LED-booster)
> C. Valens, “Do You Know the Linear LED Driver?,” ElektorMagazine.com, February 2020. (http://bit.ly/linear-LED-driver)faulty but brand new components. These included transistors
with their complimentary device in the package or their marking
switched (not sure which) — that is, a PNP in a case with an NPN
part number, efficiency diodes that measured nearly identical to a
good one but did not work properly leaving the power supply to run
very hot. We even had a diode which had the anode and cathode
swapped. The device the TV manufacture had used (they got them
cheap) had the cathode connected to the metal tab (TO-220 type
case from memory) and that was connecting to the heatsink,
which was grounded (no insulator) but the new part (correctly
made) had the anode connected to the tab, so it shorted when
fitted until you figured out that it needed a mica washer to make itAll Components Are Suspect
Looking for tips about printed circuit board (PCB) design? Chris Clapham
is an Auckland, New Zealand-based hardware engineer with 30-plus
years of experience working with PCBs. He offers some great advice:
always check your components. Even new components can be faulty.“Never remove brand new components from the suspect list! While
working for a TV PCB reconditioning company 30-plus years ago
— where we not only repaired faulty PCBs, but they were recondi-
tioned, electrolytics replaced, dry joints resoldered, etc., and any
stressed looking components replaced — we came across a fewA Case for Voltage Regulator Circuits
Have you ever spent hours on an electronics project only to have it
all go “poof ” due to a simple mistake? Scott Coppersmith — a Senior
Research Engineer at the University of Notre Dame in South Bend,
Indiana, USA — has been there. He recently shared his experience
and offered a tip. “I designed a lighting solution for my boat once by stringingLEDs inside clear tubing. I calculated the voltage at 13VDC based
on measurements while the boat motor was operating. Then
I made the mistake of starting the engine without the battery
connected and every LED burned out in unison when the alter-
nator output jumped to 21 VDC. Hours and hours of work — poof.
Automotive and marine power systems can vary wildly from 8
volts to 18 volts or more depending on charge state and load on
the battery. It’s best to have your own voltage regulator circuits
for these applications.” — Scott Coppersmith Error Analysis
Tips on Voltage Regular Circuits, PCB Design, and More
Compiled by C. J. Abate (Elektor)
Engineers, makers, and students can learn from
their engineering errors, as well as from the mistakes
of their peers. In our "Error Analysis" series, we let
Elektor community members share their engineering-
related errors and experiences.
development