DESIGN IDEAS

Design Ideas

  IMPORTANT DISCLAIMER  

The circuits presented here are uniquely designed by me unless otherwise specified. I reserve the right to the information presented here. I am not knowingly violating any copyrights or patents, nor deliberately offending other people by presenting pictures, schematics, ideas and/or other material as my own.


The information presented may not be used commercially, published, copied, transferred or distributed in any way, without written permission from the authorYou are allowed to use the information presented here as the basis for your own private non-commercial construction projects.

Background

Here is a small collection of design ideas and circuits I have developed for serious and even commercial use. All circuits are proven in real products. I publish them here since I believe they might be of relevance and could simplify some of your projects too.


Some of the ideas have been before published in magazines, or on other person webpages (with permission). 


This collection is not complete and will be updated from time to time. Many ideas are awaiting publishing and will be later added here.


ENJOY!

Base Current Error Compensation in Current Sources

You can improve a bipolar transistor current sink’s (or source's) accuracy by at least two orders of magnitude by adding two standard 1% tolerance resistors to an already simple circuit.


As a bonus, you also compensate for errors that a low current gain pass transistor’s base current introduces. To do so, you measure the transistor’s base current and add a proportionally scaled error term to the source’s reference voltage.


This idea can easily be extended to other applications, as current shunt measurement circuits and alike.

Isolated Mains Voltage Zero Crossing Detector

This circuit produces constant and well-defined zero-crossing pulses, symmetrically centered around the zero crossings, using very little power and just a few plain vanilla components. The pulse length is virtually independent of the mains voltage, is stable with temperature, and immune against compo­nent and opto­coupler tole­rances and aging.

Low parts count bridge sensor interface

You can do without the typical differential amplifier consisting of three opamps and matched resistors - when interfacing to Wheatstone-type strain-gauge, pressure or force sensors.


Only one dual opamp is required - and as a bonus - the sensor is also driven by the same circuit. This design idea saves lots of components and space, especially in multichannel circuits.

You can simply set the gain and offset with two non-interacting resistors, and no matching or trimming is required to minimize the common-mode rejection.

Control three loads with two wires

This Design Idea is suitable for applications where power is applied to only one of the three remote loads at a time, and where the available wiring or number of connector pins is limi­ted.

Three remote loads can be independently controlled by just using 3 wires and 2 switches. The loads can be of any kind as long as they are DC-driven and switched at relatively low frequencies (<100Hz). Best suitable for low voltage loads <40VDC.


Non-linear current source

Under construction

Self-locking optical signal receiver and detector

Under construction

Simple power switch

Under construction

Current transmitter for 4...20mA loops

The old and faithful TL431 shunt regulator is a very versatile component. In this circuit idea, TL431 forms together with a +3.3V or +5V voltage regulator a simple and good quality current loop transmit­ter.

Simple solenoid bootstrap

Under construction