How to read schematics for beginners – when starting to learn electronics, beginners need to learn how to read schematic diagrams. Schematic diagrams show the components and electrical connections of a circuit in schematic or diagram format. A schematic diagram is also known as a circuit diagram, or just schematic.
How to Read Schematics for Beginners
Before being able to read a schematic, it is necessary to learn and recognize the symbol for each component in a circuit. Each symbol in a schematic represents a physical electrical or electronic component.
In the circuit above, the schematic is shown on the left and has two symbols representing two components. The symbol on the very left represents a battery. On the right of the schematic is the symbol that represents a light bulb.
On the right of the above image is the physical implementation of the schematic on the left. Here the actual light bulb and battery can be seen.
Electrical connections between the bulb and battery are represented by lines in the schematic. These lines are wires in the actual circuit.
How to Read Schematics
The article on how to read circuit diagrams for beginners on the Starting Electronics website shows the very basics of how to read schematics. This article uses the same light bulb and battery circuit to explain the basics of circuit diagrams. It shows how to recognize when two wires are connected, or whether they are just crossing each other.
After reading this article, a series of tutorials follows to get the reader to recognize electronic components and their schematic symbols. Each electronic circuit can be built on breadboard. A good way to learn how to read electronics schematics is to follow the tutorials, look at the schematic diagrams and build the circuits.
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LM3909 IC 1.5V LED flasher circuit. A circuit that uses the now obsolete LM3909 IC to flash an LED from a single 1.5V cell. This IC and circuit is now a piece of history. I had one of these circuits running on a PCB for years, the circuit finally failed. My attempts to repair the circuit were unsuccessful. It appears that the IC finally failed. Read on for a look at some electronics history.
LM3909 1.5V LED Flasher Circuit Diagram
Below is the circuit diagram of an LM3909 LED flasher taken from an out of print electronics magazine. I built this circuit on a tiny PCB many years ago. The circuit operated from a single 1.5V cell, but could also operate from a single 1.2V rechargeable cell.
LM3909 1.5V LED Flasher Circuit Diagram
Flashing an LED from a Single Cell
I remember the LM3909 being expensive, costing many more times than a 555 IC. The problem with using a 555 is that it could not be used to flash an LED from a single 1.5V cell, but had to operate from a higher voltage. A 555 also drains a lot of current from a battery because of its internal voltage divider resistors.
When the LM3909 became available it was popular with hobbyists because an LED can not be lit up from a single 1.5V cell. Here was an IC that would flash an LED from a 1.5 or 1.2 volt cell, pretty impressive. The cell would last for a long time too.
LM3909 now Obsolete
Unfortunately the LM3909 is not available anymore. It was made obsolete several years ago and has no equivalent or replacement part. There are some transistor circuits available that will flash an LED from a single cell.
Attempting to Revive my LM3909 Circuit
The only LM3909 IC that I have was used in a LED flasher circuit built on a PCB. Fortunately I had used an 8-pin IC socket on the board, so could remove the IC to test it on breadboard. The PCB and breadboard test circuit are shown below. Notice that only two additional components are needed in the circuit – a capacitor and LED.
LM3909 PCB Circuit and Breadboard Circuit
After many years of service, the LM3909 finally failed. After testing the PCB circuit with a new battery and then building the circuit on breadboard and testing it, the LM3909 was finally declared dead.
In this blog post we look at how beginners wanting to start with Arduino can choose an Arduino board. Help is provided for beginners choosing an Arduino. The difference between an Arduino and AVR ATmega microcontroller is also covered.
Choosing an Arduino for Beginners
The recommended Arduino for beginners is usually the Arduino Uno. On the Starting Electronics website, the article on choosing an Arduino for beginners provides more information on which Arduino to choose when starting to learn about Arduino and writing sketches.
Difference Between Arduino and AVR
Many Arduino beginners are confused about the difference between Arduino and AVR, or Arduino and ATmega. Difference between Arduino and ATmega328 explains what the ATmega328 microcontroller is and how it relates to the Arduino Uno. The article also explains more about the AVR microcontroller found on most Arduino boards.
The Arduino programming course originally started in 2014 is being updated and extended. Updates include using the newest version of the Arduino IDE and updating the videos in the course to HD video.
Currently parts 1 to 5 of the course have been updated which cover Arduino sketch structure and flow, Arduino main loop, calling functions, variables, arithmetic operators and relational operators.
Once updates have been completed the course will be extended to include new material and topics. Take a look at the Arduino programming course contents page to see the currently available tutorial parts of the course.
The final part of the Atmel Software Framework tutorial is now available. It covers how to use the ASF help documentation and how to find and use example ASF code. The tutorial uses an Atmel ARM Cortex on an Atmel Xplained evaluation board.
A previous blog post listed the current articles in the tutorial at the time of posting. The tutorial series is now complete.
ASF – Atmel Software Framework Tutorial
The first part of the ASF tutorial series introduces ASF and shows the basic structure of ASF. Each part of the tutorial series explains various parts and usage of the ASF in easy to follow steps.
The final part of this series shows how to use the ASF documentation and ASF example projects in Atmel Studio 7.