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Simple Variable Voltage
Source - The high current regulator below uses an
additional winding or a separate transformer to supply power for the LM317 regulator so that the pass
transistors can operate closer to saturation and improve efficiency. For good efficiency the voltage at the
collectors of the two parallel 2N3055 pass transistors. . . [Bill Bowden's circuit]
Step Up/Step Down
Converter Takes 2 to 16V Inputs - 07/16/98 EDN Design
Idea (Several circuits in this file. Scroll to find this one) The circuit in Figure 1 is a low-cost
step-up/step-down DC/DC converter. By definition, its input can range above and below the regulated voltage.
The circuit includes a . . . [by Lucian Brodogna andLuca Vasalli. Maximin Integrated Products, Milan Italy]
Step up/step-down current-source charges batteries - 06/06/96 EDN Design Idea For battery charging, the highly efficient step-down (buck]
configuration is usually the topology of choice. However, a different approach is necessary if the following
conditions prevailThe supply voltage is less than the battery . . . [by Michael Keagy, Maxim Integrated
Products, Sunnyvale, CA]
Switching regulator forms constant-current source - 05/30/02 EDN Design Idea Many applications require current sources rather than voltage
sources. When you need a high-current source, using a linear regulator is inadvisable, because of the high
power dissipation in the series resistor. To solve the wasted-. . . [by Stefan Strozecki, Institute of
Telecommunications, bydgoszcz, Poland]
Test UL Ground Resistance - UL requires that an electrical system using a metal chassis earth ground connection have a
resistance of less than 0. 1 ohms. This resistance must be tested with actual line current in excess or 10
amps. The circuit shown uses a couple of LEDs to indicate . . . [Circuit by David Johnson P.E., 04/28/01]
Tests UL Ground
Resistance - UL requires that an electrical system
using a metal chassis earth ground connection have a resistance of less than 0. 1 ohms. This resistance must
be tested with actual line current in excess or 10 amps. The circuit shown uses a couple of LEDs to indicate
if in fact the resistance is less than 0. 1 ohms - modified on july 10, 2006 . . . [Hobby Circuit designed by
Dave Johnson P.E., 04/28/01]
Three-transistor current source covers wide range - 05/31/14 EDN Design Idea This Design Idea is a two-wire current regulator that strikes a
good balance between performance and parts count. Employing three transistors, three resistors, and one LED,
it achieves good regulation (better than 1% over most of the voltage range), lower operating voltage (1. 2V
typical), and better tempco (0. 07%/K) than other circuits of similar complexity. It is designed to operate
in a range of currents from tens of milliamperes to several amps. It does not use any hard to find parts; for
example: an LM10 can be used to make an even higher performance circuit, but this IC is not multi-sourced and
is likely to be discontinued. . . . [by Einar Abell0]
TSM108 Evaluatin Board 12V to 6V
DC/DC Converter - The TSM108 is a step down controller
that features constant voltage and constant current regulation. The Evaluation Board was designed to allow
different converter configurations. Several options for power semiconductor footprints are available on the
PCB in order to make it adaptable to a wide range of converter output power. In a first step, . . .
UL Ground Resistance Tester - UL requires that an electrical system using a metal chassis earth ground connection have a
resistance of less than 0. 1 ohms. This resistance must be tested with actual line current in excess or 10
amps. The circuit shown uses a couple of LEDs to indicate if in fact the resistance is less than 0. 1 ohms -
modified on July 10, 2006 . . . [Circuit by David Johnson P.E., 04/28/01]
Variable Voltage Source - The high current regulator below uses an additional winding or a separate transformer to
supply power for the LM317 regulator so that the pass transistors can operate closer to saturation and
improve efficiency. For good efficiency the voltage at the collectors of the two parallel 2N3055 pass
transistors should be close to the output voltage. . . [Bill Bowden's circuit]
Voltage-To-Current Converter Makes A Flexible Current Reference - 09/18/03 EDN Design Idea The voltage-to-current converter in Figure 1 can both source
and sink current. The circuit isflexible than some traditional current references that require different
topologies for current sourcing and sinking. Also, you can easily. . . [by Art Kay, Texas Instruments,
Tucson, AZ]
Voltage-to-Current converter offers precisely defined dead-band - 07/29/13 EDN Design Idea Dead-bands have application in control loops and other areas.
In the control of nonlinear and linear systems, sometimes a slight nonlinearity is intentionally inserted
into the closed control loop. “Slight” here means that the output of the inserted element starts to vary
linearly, but only once the input exceeds a nonzero threshold value. For inputs from zero to the threshold,
the output of the element has zero value. The result is that adding of this nonlinear element can quench
damped oscillations, which are typical for feedback systems. . . . [by Marian Stofka]
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