Basic electronics

123 Game – All MCU-free (simple electronic game circuits)

This electronic game pits a human player against the ‘machine’. The opponents use a common ‘game token’ and take turns moving along a path by one, two or three steps, and the winner is the first one to reach the goal exactly. Incredibly enough, this simple version of the ‘123’ game can be built without a microcontroller, and it’s almost impossible to beat. The electronics for this is built using only diode logic (Figure 1).

The ‘ input inter face’ consists essentially of 30 miniature sockets to which a probe tip can be connected to mark the position of the ‘game token’. To make the game more compact, the sockets are arranged in a grid so the route along the sockets follows a serpentine path (Figure 2). The starting position is at the bottom right, and the goal is in the middle of the playing area. The electronics becomes the ‘active player’ when the button is pressed…….

This is how the LED display works:
The player touches the right-hand contact with R4 (only LED D3 lights up), the left-hand contact with R3 (LEDs D1 and D2 light up), or the middle contact with diodes D4 and D5 (all three LEDs light up). The two diodes prevent all three LEDs from lighting up if the player touches the left-hand or right-hand contact. The key to all this lies in the assignment of the 30 sockets to the three types of logic, which means the three types of ideal next move.

Working backward from the goal, no further move is possible when the goal is reached. For this reason, the last socket is not connected to anything. At the socket just before the goal, the ‘computer’ naturally wants to be exactly one step in front. Consequently, this socket is connected to R4. At the second socket before the goal, the electronics wants to move by two steps. This socket is thus connected to R3……

Source: http://www.extremecircuits.net/2010/05/123-game-all-mcu-free.html

Simple Micro Ampere Meter Circuit

This simple micro ampere meter circuit can help in measuring small currents in five ranges: from 1 µA to 10 mA. The meter is working in this way: the current being measured Ix shifts the input voltage resulting to an output voltage with an inverted polarity.
The output voltage of the opamp CA3130 is proportional to the measured current Ix.
By selecting the proper feedback resistors through S1, the output voltage by full meter deflection is 1 volt in all measuring ranges.
The value of the series resistor R must be selected for the particular meter being used. For example if a 1 mA meter is used, the total resistance (the sum of the resistor R and the coil resistance Ri of the meter) must be 1k?. If a 100 µA meter is used, the total resistance must be 100 k?. If needed, a potentiometer can be used for the R.
And view images:uA741 .
The Author Name: P. Marian
Source:http://electroschematics.com/6537/simple-microampere-meter-circuit/

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Make and Learning Electronics by Discovery

This is Excellent Beginner Book for Hobbyists/Beginners/Makers Book.

Want to learn the fundamentals of electronics in a fun, hands-on way? With Make: Electronics, you’ll start working on real projects as soon as you crack open the book. Explore all of the key components and essential principles through a series of fascinating experiments. You’ll build the circuits first, then learn the theory behind them!

I recommend this book strongly for anyone just starting out in electronics. Many other books introduce the subject of electronics by talking about the early discoveries concerning amber rods, Leyden jars, and static electricity. This book dives right in using parts that you can pick up at a local Radio Shack, or can easily order on-line. And it uses a fun almost playful approach to experimentation. Your first experiment involves touching a battery to your tongue! Man, that will either annoy you into quitting or completely intrigue you into learning more. My bet is it will spark (pun intended) your interest and excitement as it leaves you with a funny metallic taste.

This is exactly the hands-on approach that I was looking for to teach my son. Something that he can read on his own, or read with me. Easy experimentation, clear steps, good photography. No wondering if any of the experiments will fail because they were written only/mainly to think about. These were all written to be DONE by the reader. Getting into the nitty-gritty of learning is easy when you can actively experiment as you learn.

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