This is the circuit diagram of electronic dice which built based microcontroller chip of Atmel AT89C2051. The application of this electronic dice is similar to the one used in a game of dice. The circuit generates the random numbers which not displayed numerically, but represented by the number of glowing LEDs. The LEDs are the dot representation on the face of a dice. Suggested LED arrangement for the electronic dice display is shown on the right side.

This simple circuit -which come from EFY magazine- demonstrates the capability of an AT89C2051 microcontroller chip to function as a random number generator based on the flying counter principle. The program in the chip constantly updates the counter variable, which, on being interrupted by an external trigger, latches the counter value and displays a random number through its output ports. This method is similar to the one used in PCs or calculators for generating random numbers at any instance.

TL0 and TH0 act as free-wheeling counters in auto-increment mode and constantly count up from the initial value. When the interrupt occurs, the value from the counter is latched and glowing LEDs indicate the random number generated by the microcontroller chip. Assembly language is used for programming the chip. The Assembly code listing is self-explanatory.

Source Code: electronic dice source code

At times, power from a wall socket is neither clean nor uninterruptible. Many abnormalities such as blackouts, brownouts, spikes, surges, and noise can occur. Under the best conditions, power interruptions can be an inconvenience. At their worst, they can cause loss of data in computer systems or damage to electronic equipment.

It is the function of an Uninterruptible Power Supply (UPS) to act as a buffer and provide clean, reliable power to vulnerable electronic equipment. The basic concept of a UPS is to store energy during normal operation (through battery charging) and release energy (through DC to AC conversion) during a power failure.

UPS systems are traditionally designed using analog components. Today these systems can integrate a microcontroller with AC sine wave generation, offering the many benefits.

The PIC17C43 microcontroller handles all the control of the UPS system. The PIC17C43 is unique because it provides a high performance and low cost solution not found in other microcontrollers.

PIC17C43 Microcontroller Benefits:

• High Quality Sine Wave – High throughput allows for high quality output
• Flexibility – core control features and operations can be changed with software modifications only
• Transportability of Design
• Variable Loop Response
• Digital Filtering
• Parts and Complexity Reduction
• Peripheral Integration
• Ease of Interfacing
• Testability
• Time to Market

Download the reference design of Uninterrupted Power Supply with PIC:

UPS with PIC17C43 Microcontroller

1 file(s) 2.41 MB

Download the file here

Bruce Robinson explaination about this circuit:

• I did a few revised drawings for Ian quite a while back, so he could place them up at beam-online. However, they did not get posted inside the midst of the a lot of revisions he was doing.
• Attached (begging Ian’s indulgence), will be the two versions of the circuit, one which turns on having a Positive input, the other (for quadcores) having a Negative input.
• Ian shows 100k input resistors. I’ve been applying 47k resistors with success. Tilden’s report recommends nothing lower than 50k (I assumed 47k was near enough) and up to 20 Meg or so.
• I’ve also observed a slight drop in speed when I use these bridges, but only about 10% or so.

Technical details:

• Until 800 mA capacity (working with PN2222 and PN2907 transistors)
• Not “smoke-proof” (i.e., it cannot deal with drive voltage in both directions at once)
• 30 connections per bridge (so, 30 holes in case you make a PCB)

Original Tilden H-Bridge article can be found here. Read the article for detailed ecplanation and recommendation.

You may download the tutorial of RJ45 LAN tester building include the schematic diagram, circuit explanation, project preview and program source code from the following link:
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