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Analog Designers created Spice, Analog Design Professionals are adding their experience in many commercial and free spice EDA tools. When you are creating a new demanding design, a working solution is achieved by combining workbench and simulation work.

The Lab Test Bench and Breadboard work along with simulation works best for analog, power and mixed signal. In a full digital design, simulation does a more complete Virtual Test bench role.

A simulation tool can help you test the blocks and helps catch some design and concept errors. When you build a live breadboard prototype, some real issues facing your design can emerge.

Spice is a analog design aid and helps mixed design circuit simulation, See the Spice homepage.

SPICE (Simulation Program with Integrated Circuit Emphasis) is a general purpose analog electronic circuit simulator. It is a powerful program that is used in IC and board-level design to check the integrity of circuit designs and to predict circuit behavior. - Wikipedia

Spice Resources

• PSpice and LTSpice Tutorial
• Spice 3 Userguide
• SPICE2 and SPICE3 at UC Berkeley
• ngspice: SPICE3 with updates and XSPICE extensions
• WinSpice is a port of Spice3F4 to Win32
• PSpice Simulation of Power Electronics Circuits
• 5Spice easy to use analog circuit simulation
• Intusoft - SPICE Simulation, Analog and Mixed-Signal
• eCircuit Center - free source of SPICE files and tutorials
• NI Multisim Analog Devices Edition
• National Semiconductor SPICE Macromodels
• B2 A/D Spice simulation program

LM335-336 -

LM335 is a temp sensor, LM335 . use it for temp for CJC. Temperature Sensors - RTDs and Thermocouples, - Chapter 6: Temperature Measurement.

LM336-2.5 is an voltage Reference. recision 2.5V shunt regulator diodes, Applied as a precision 2.5V low voltage reference for digital voltmeters, power supplies or in opamp signal conditioning.

Current Loop -

4-20 ma will drive DC drives, motors and steam valves. It is a current loop, for long distance transmission, current loop is not prone to noise and hum, EMI RFI. As it is a small power transmission no loss of data, also many equipments can be in one data loop. A single transmitter with 4-20mA out can drive a strip-chart recorder, motor, controller and SCADA input. all in a series loop.

Current loops, - Current loop - Wikipedia, the free encyclopedia, - 4-20 mA

Opamp Notes and Types

TL062, LF353, TL072, fet input. 1 tera ohm input imp.

OP07 higher price, 1 giga ohm. 75uV offset.

LF353 pin to pin replacement of TL062-72 and 82.

LM358 works on single supply too, low price, inp imp 1 meg. OP07

LM324 Quad, works of batteries well.

All work best with dual +/- 5 V or more. LM7805 -LM 7905.

OpAmps, - 741 Op-Amp Tutorial, op-amps, Operational Amplifier
Analog Electronics: Basic Circuits of Operational Amplifiers

Points to Note -

• Analog ground (opamps), digital ground (CMOS) and power ground (relays and LED) should be separate, (linked at root)
• Glass epoxy PCB have high insulation resistance, above 10 tera ohms, and are not hygroscopic which means they do not drink water vapor, this makes them very suitable for precision instrumentation and sensitive circuits.
• When you measure DC levels in 16bit accuracy or more you need resistors which have temp. coeff. of 10ppm, or you may have to put the entire circuit in a stable 45 deg oven. Thermoelectric effects, EMI, RFI, pA Leakage currents, ground loops, contact resistance all can make the readings drift and unusable.
• High impedance points of circuit like 500 kilo ohm and above can pick up AC noise and DC leakage currents. this will affect the performance of circuit, so for DC you have to put a guard ring of the signal ground around that point in PCB. For RF you have to shield with things related to iron and mu metal, for low signals even a copper shield will do.
• Percentage and ppm: when percentage becomes like 0.001% it is difficult to manage, so we use ppm-parts per million.5% means 5 parts in 100 parts. 23 ppm means 23 parts per million parts. 0.001% - shift the dp-decimal point four places to right it is 10ppm. 0.01% is 100ppm which is the variation of value of mfr resistors on temperature change.

BD139 and BD140 Complementary transistor

This pair is my favorite when driving small solenoids or motors. SOT-32 12 Watts..

BD139 - NPN, 80V and 1.5A, 40 beta min.
BD140 - PNP, 80V and 1.5A, 40 beta min.

This means any small solenoid, relay or DC motor can be controlled with this. I would use it upto 24V DC and max of 1A for applications of full on and full off.

In applications like a regulator or variable motor control, you have to keep in mind the current thru and voltage across the transistor which results in power dissipation. Let us say it is driving 0.5A thru a motor in speed control and the Voltage across is 30V then the dissipation could be 30 x 0.5 = 15 Watts.

That is the reason we use switched regulators or switched controllers. So if we chop the DC and do PWM you have only the Switching losses and also a bit of DC loss. Switched controllers are also green, they save power for the same work done, but generate EMI-RFI and care is required in sensitive uV circuits. The transistors for switching are also special as they have to be fast with less capacitance, hence the mosfets are preferred in those applications. - ananth (san)

Robotics Notebook of Chuck McManis

These pages are extremely useful for an entry into the Robotics Wonderland, a little electronics ability is enough for you to start learning robotics. Robotics is the only science that covers everything almost .. Mechanical, Electrical, Electronics, Embedded, Computing, Networking, Automation and Wireless Technologies. Some advanced robots include probably every science and skill known to mankind. So make a start today. Learn Robotics! - ananth (san)

PIC Programming using USB, Ant Weight Speed Contro ller, LCD Diagnostic Console,

Robotics Projects : Index

• Tools for Robots
• The ARBE-ONE Robot
• The High Power Speed Controller
• H-Bridge tutorial
• The Servo Gizmo

Home Brew Robotics Club - Resurrected from the ashes of the original HomeBrew Computer Club by a group enthusiasts who were interested in the emerging field of robotics. Meets at Carnegie-Mellon West campus, Building 23 inside the NASA Research Park (NRP) complex in Mountain View, California.

Robotics Institute: Publications

This site includes abstracts and bibliographic references for most publications by RI researchers. Additionally, the full text of many of the publications is downloadable in PDF or Postscript format.

• Technical Reports- published by the RI since 1980.
• Projects- Projects, Sorted Alphabetically
• Labs and Groups - Labs & Groups, Sorted Alphabetically

The Robotics Institute - Carnegie Mellon University

School of Analog Design

Switching Regulator Fundamentals
Objective: Be able to identify the three basic switching regulator configurations and know where each one is used. The course includes inductive switching regulator power stage definition, input, output and duty cycle relationships.

Current Feedback Operational Amplifier
Objective: This training module discusses the current feedback operational amplifier (CFB op amp). There will be a brief background of the current feedback op amp.

DC to DC Converter Basics
Objective: This course will teach the basics of linear, inductive, switched capacitor DC to DC converter products from Portable Power Systems perspective.

• Knowledge Base
• Design Tools

Good Earthing Prevents Shocks and Prolongs Appliance Life

Earthing in the olden days was done like this, i have just mixed what i have heard with my common sense and this is what it may be.

Make a deep pit, 4 feet deep, 1/2 feet dia, put long copper rods ( GI pipes or lead pipes were also used). Let the copper rods be driven deeper than the four feet that has been dug. mesh the rods with copper mesh or wire (GI chicken mesh). Fill the pit with all the conductive things which are bio-degradable, non-toxic, non-corrosive and non-soluble. They used coal, charcoal, salt, scrap metals. (now they have a polymer conductive gel). Terminate the copper rods to a thick copper wire run it to your mains box in a way it cannot be cut or broken when gardening etc.

The mains box should be fitted with HRC fuses and MCBs as required, use a ELCB too. The MCB trips when a over current load is drawn, there are both thermal (thermostat technology) and electromagnetic (relay technology) MCBs. The ELCB does not have a earth wire, it trips when the current in the live and neutral paths are unequal. When the difference is say 20mA it trips. This 20mA would have gone thru the ground wire or thru a person giving shock. Also use Over Voltage and Under Voltage Trips if possible, Many equipment fail due to this.

HRC — High Rupture Capacity.
MCB — Miniature Circuit Breaker.
ELCB — Earth Leakage Circuit Breaker.
GI — Galvanized Iron

Also do not forget a lightning rod on the top of the house, whose path to ground is far from the earth pit. Lightning also zaps phones etc. Use Zener barriers for all interfaces between equipment and isolation transformers.

Cable TV wires, phone wires, and mains wires all may get mixed up. During rainy days even a phone line or TV cable may give shock or blow input circuits in equipment. This may be due to mains leakage or lightning.

Before you touch any metal object, cross your fingers, better still buy a long neon tester.

Additional Study

• Earthing system
• Earthing Your Hi-Fi - Tricks and Techniques
• Design of Earth Electrode Systems