dapj Tech Publications

At dapj Tech you will find Tech Blogs related to Electronics Engineering, Hobby and Educational Resources too.

Electronic Design

• Schematics of delabs - Circuit Diagrams, Design.
• Soldermans Basics - Tutorials, Theory, Fundamentals.
• Hobby Hound - Hobby, DIY, Do it Yourself Projects.
• Circuit Design Gopher - Product Design, EDA, ASIC Design.
• Circuits FAQ - Electronics Design Notes and Answers

Electronic Parts

• Electronic Components - Parts, Instruments, Tools.
• Embedded Processor - Microcontroller, SOC, FPGA, ASIC.
• Industrial Electronics - Engineering Products Cladistics.
• RF Wireless and Photonics - Networking, Microwave, Optics.
• Semiconductor Devices - Diode, Transistor, IC Chips.

EE Firms and Resources

These pages of mine and other sections of delabs lists firms and EE design resources around the globe, related to Professional and Hobby Electronics. This work of mine started in 1999 on netscape, geocities and tripod homepages. Now it is distributed over few domains and tech blogs that i own and manage.

Electronics Engineering and Technologies



Some Electrical and Mechanical pages closely related to Electronic Manufacturing and Industrial Engineering are also listed here. delabs lists more than 10K EE Companies & Resources in the Web.

Categories of EE Websites of Firms and Resources

• Circuit Diagrams Archives Reference
• Embedded Microcontroller Resource
• EDA CAD Circuit Design Software Tools
• Electronic Engineering Magazines
• ASIC, SOC, CPLD, DSP and FPGA
• Electronics Resources and Tutorials
• Industrial Automation & Process Control
• Sensors, Actuators and Analytical
• Test & Measurement, Instrumentation
• Semiconductor and IC Application Notes
• Datasheets, Standards & Service Manuals
• Components Parts Kits and Materials
• Power Electronics & Solar Energy

Circuits using only discrete devices

Here are circuits made of Resistors, Capacitors and Inductors which are passive components. Crystals, Thermistors, Varistors, Variable Passive RLC are also Passive Parts.Some circuits documented from my design note book are here with the editable schematics.

Circuits using only discrete devices

Zeners, Diodes, NPN-PNP Transistors, FET, MOSFET, SCR, Triacs are all discrete active devices. ICs and Hybrid Modules are made of many discrete and passive components.



In the Integrated Circuits or ASICs, all parts even passives are derived on the Silicon Wafer. In Hybrid Modules the construction uses SMD or Tiny Chip components interconnected in a small ceramic PCB and Hermetically Sealed if needed.

• Isolated dual power supply from 5V
• Telephone LED status indicator
• Music Sound to light converter
• Simple Water operated relay
• LED Voltage Level Indicator
• Basic Relay or Solenoid Driver
• Mains Voltage Current LED Indicators
• Triac based Lamp Dimmer power control

Parts like Switches, Connectors, Relays and PCBs are ElectroMechanical parts. Nuts, Bolts, Screws, Cabinets and enclosures are Mechanical parts.

For a Systems Integrator or Control Panel Designer, the Timers, Controllers, PLC which are Electronic Products become Components or Modules along with Contacters, Current Transformers, AC-DC Drives etc.

Analog Electronic Circuit Design

The very first designs that came about were analog designs, a Vacuum Tube amplifier is an example. Analog is the representation of data or physical parameter in an accurate and precise decimal number like + 72.182 mV. The greater the resolution required, the more demanding is the design for achieving high accuracy and low drift. Digital circuits have only two voltage levels, high and low, the third state of floating, Hi-Z or high impedance is only for multiplexing or sharing a bus. This is done so that devices dont drive into each other and it is also used in external port drivers.

Analog Design and Circuits

As an analogy, see the conventional water tap as an analog control, an electric light ON-OFF switch as a digital control.



Among the semiconductor products Bob designed are temperature-voltage frequency converters used in groundbreaking medical research expeditions to Mt. Everest in the 1980s. He also designed a seismic pre-amplifier chip used to measure lunar ground tremors in the US Apollo moon landing missions. Among his more memorable designs are the LM331 voltage to frequency converter and the LM337 adjustable voltage regulator. - Remembering Bob Pease

Analog Circuits Instrumentation

• Industrial Process Control Circuits
• Instrumentation Circuits
• Analog Circuits added after 2004
• Temperature Measurement Control

Even in digital, going from a low level say 0V to a high level say 5V is not instantaneous, the side of the square wave or the rising edge is not as straight as it looks. On zooming only the edge, you see that it is also an analog phenomena. The 'square wave' itself appears to be a summation of many sine waves, 'harmonics'. This is because nature is analog, the sine wave is analog, the movements of the planets or even the spin of electrons in an atom too.

Circuits in Above

• Auto ranging 4-1/2 digit digital voltmeter icl7135 of intersil.
• Precision attenuator with digital control - use with above.
• Precision amplifier with digital control - use with above.
• Precision attenuator and amplifier - write up for above two.
• Fluid or water level sensor using reed relays
• Fluid or water level sensor using reed relays - circuit example.
• Voltage to pulse converter, for impulse counter
• Current Source mA for calibration
• AC voltmeter digital
• 8 channel analog mux with sample hold

delabs Technologies

Industrial Control Panels and Instruments

Instruction Manuals of Process Control Instruments and Industrial Automation Solutions, Control Panel Diagrams, Wiring, and Facia.

Temperature and Pressure Controllers form a large part of Process control Instrumentation. Then you have Flow, Humidity and many more custom parameters.

Electronics Theory - Industrial Control Panels

All Real Life Physical Phenomena are reduced to Analog Numbers by Sensors and Transducers. This analog value is amplified and linearized and brought into standardized windows like 1-5 Volts or 4-20mA and more.



These Analog Values go to Analog Closed Loop Controllers or Meters for Measurement and Control. In Embedded Controllers, the Analog is converted to Digital ( At least 12 bit, 8 bits are cheap not used for industrial automation, more than 16 bits is not required as sensor accuracy/linearity never transgress such precision )

• Electrical Control Panel Wiring
• Industrial Process Control Circuits
• Mini RTD Pt-100 Three Wire Transmitter
• Four Channel Temperature Alarm

Embedded Process Controllers may use Microcontrollers with Floating Point Arithmetic, Lookup Table, Logic and Basic Math. Advanced Controllers may use DSP and Complex Algorithms for Adaptive control. (self learn, fuzzy logic.).

Mixed and Interface Circuits

Most of the sensor interface and instrument inputs are analog; even if it event based like a limit switch, analog circuit protection and signal conditioning is required before it reaches the level sensitive digital circuit blocks.

Starting with Schmitt triggers and to the VCO and A-D Converters, are grades of Mixed Circuits. I feel Comparators like LM339, Timers like the 555 and Phase Locked Loop PLL are fundamental mixed circuits as they have a analog voltage detection.

DSP and uC with built in A-D or D-A or even SOC are Public ASICs and Fall in the Embedded Systems Block. Public ASICs are not user specific, they can be branded, numbered and provided with Application notes for the use of the Design Departments of any firm. User Specific ASICs are custom built and have only an application with that manufacturer for a Specific Product type. This also protects the IP of Code and Device Design. Custom ASICs are limited to the Platform and Technologies for which they were designed. Then we have programmable and configurable chips other than uC for logic like PLD, CPLD, FPGA and SOC, there is even some talk of mixed or analog configurable chips.

It would be nice if they made a breadboard chip with 12 opamps, 24 comparators, Some PLD and a couple of uC. Then we certainly need software trimmable or tweakable Resistors and Trimpots. This is the Magnum Opus of EDA. A EDA Chip Printer may be coming soon ! (Affordable by small firms).

Read More - Mixed and Interface Circuits - delabs

Control Interface to PC Ports

A computer can be used to control or automate systems. From turning lights on/off at your home to shutting down motors or heaters in industries. Speed control and PID Control too.

PC based Instrumentation is easy to implement using USB Devices and Plugin Cards for Test and Measurement.  Most instruments can communicate with PC on the GPIB interface.



USB interfaces have made such PC based Data Acquisition and Controls much easier. In the early days it was Printer Port and Serial Port. The future is for Wireless Device Networking.

When Intelligent Devices (embedded systems) are privately and securely networked, it is called the Intranet of Things. This is like a Home-Office-Business private closed Cloud. This is ideal for Home and Infrastructure Automation and even Big Business or SMB Automation.

This can get you started too. The few examples above show an instrumentation - Logic Analyzer 'Like' interface and a relay-display driver circuit. They are examples i tried for students to try out and learn.

Control Interface to PC Ports.

• Simple Printer Port Interface, Input-Output.
• Test Circuit for Logic Analyzer software.
• Printer Port, 256 Relays - 16K Dot Matrix.

A Practical 2018 Engineer

Making Simple, Safe, Sensible and Sturdy Electronic Products should be the aim of any Electronic Engineer. A prototype should be developed to become a Cost effective Solution.

Never ship Beta products or sell them at High Prices. New products if not tested and developed completely should be marked Beta and Sold at lower prices. When a manufacturer is on "The Rising Edge of the Learning Curve" (delabs phrase 1998) for a product line, he has to sell products marked beta at lower price or wait till the development is mature. I have learnt this from my own blunders.

In Software Beta markings are clear, even in Webapps they mention. Hardware Industrial products are never sold in beta state. Then the Smartphones and Tablets boom led to many beta products being sold to consumers at regular prices. This should be avoided to protect the brand name and the reputation of that business segment itself.