TIMING CALCULATORS FOR LM555

Resistor values are in Ohms (1K = 1000) - Capacitor values are in Microfarads (1uF = 1)

  NOTE: The leakage currents of electrolytic capacitors will affect the actual output results of the timers. To compensate for leakage it is often better to use a higher value capacitor and lower value resistors in the timer circuits.

LM555 Monostable Oscillator Circuit Diagram

The digital voltmeter ICL7107CPL

Here is my lovingly-crafted schematic for the voltmeter module. Note that this could be made as a standalone voltmeter, it will measure up to 20v DC. In our finished product, the +5V will be sourced from an LM78L05 voltage regulator.

And the parts list:

    IC1 – Intersil ICL7107CPLZ
    IC2 – Intersil ICL7660
    D1~D3 – 1N4148 diodes
    LED displays – Agilent HDSP521G 2 x 7-segment green displays (common anode). You can use anything really, as long as it is common anode, and each segment is ~8mA
    R1 – 220 ohm – all resistors 0.25W
    R2 – 10k ohm
    R3 – 1M ohm
    R4 – 47k ohm
    R5 – 15k ohm
    R6 – 100k ohm
    R7 – 1k ohm multiturn potentiometer/trimpot (for calibration)
    C1 – 10nF – all capacitors must be rated for at least 25V
    C2 – 20nF
    C3 – 470 nF
    C4 – 100 nF
    C5 – 100 pF
    C6,7 – 10 uF electrolytic

Please note that this is a work in progress and errors may have been made, or values altered at any time after publication.

An Arduino Compatible - CP2102

Standard Arduino boards use FTDI’s FT232RL to interface with computer’s USB port. Since FT232R is just a USB to UART converter, it is possible to build an Arduino compatible USB interface using other USB to UART chips.

One such alternative is Silicon Labs‘ CP2102. I particularly like this USB to UART transceiver because very few extra components are required for it to work. As an added benefit, this chip is also cheaper than the ubiquitous FT232R. Of course, there are also a few trade offs. First of all, CP2102 does not provide a bit bang interface (the X3 pins on the Arduino board on the other hand can be used for bit bang operations, but the X3 pins are not soldered with header pins by default and thus for the average users no bit bang support should not be an issue). Secondly, CP2102 does not have the configurable general purpose I/O pins to drive the TX/RX LEDs. There are other minor differences as well (for instance the maximum transmission speed for FT232R is 3Mbps while CP2102 tops at 1Mbps. Both chips are more than adequate for the maximum 115,200 baud rate supported in Arduino environment), but they do not affect the performance in our application of interfacing with Arduino.

Here is the schematics for using CP2102 with ATmega328p (the circuit below is compatible with the Arduino IDE):

if you compare the above circuit with the official Arduino Duemilanove board you will see that the interfacing portions (RXD, TXD and TDR) are virtually identical.
Since CP2102 comes only in QFN-28 packaging, some people might find it slightly harder to deal with than TSSOP. Using the prototyping method I mentioned a few months back though, it is fairly straightforward to use the chip on a standard perf-board nevertheless. No special tools or stencils are needed. The following picture shows the USB to UART converter portion of the Arduino, which can be used to replace the FT232 break out board. I chose to break out the converter so that I could use it in other projects that require serial connections.



If you are running Linux, you do not need any third-party device drivers. All recent Linux kernels support CP210x via the usbserial kernel module. Once connected, you should be able to use dmesg and see these messages:

    [ 8333.572512] usb 8-2: new full speed USB device using uhci_hcd and address 3
    [ 8333.744748] usb 8-2: configuration #1 chosen from 1 choice
    [ 8333.785114] usbcore: registered new interface driver usbserial
    [ 8333.785161] USB Serial support registered for generic
    [ 8333.785221] usbcore: registered new interface driver usbserial_generic
    [ 8333.785222] usbserial: USB Serial Driver core
    [ 8333.792419] USB Serial support registered for cp210x
    [ 8333.792460] cp210x 8-2:1.0: cp210x converter detected
    [ 8333.920011] usb 8-2: reset full speed USB device using uhci_hcd and address 3
    [ 8334.076745] usb 8-2: cp210x converter now attached to ttyUSB0
    [ 8334.076760] usbcore: registered new interface driver cp210x
    [ 8334.076762] cp210x: v0.09:Silicon Labs CP210x RS232 serial adaptor driver

If you are running Windows, you will need to install the royalty-free driver from Silicon Labs directly.

Under Linux, CP210x shows up as a a ttyUSB device. You can use the Arduino IDE to program your ATmega328p’s just as you would with an official Arduino. Serial communication via the serial monitor works the same way as well. Like the official Arduino, the above circuit also automatically resets whenever you upload a program.
 

2N2907A Small Signal PNP Transistors

2N2907A

Small Signal PNP Transistors

This circuit shows a synchronous-rectifier-based ac/dc converter which has high accuracy up to about 2.5 MHz. To calibrate, apply a 1- to 2-MHz 1-V pp sine wave and adjust the delay compensation so that bridge switching occurs when the sine crosses zero. Next, adjust both skew compensation pots for minimum aberrations in the ac output signal. Finally, adjust the gain trim for a dc output that corresponds to the ac input.

Circuit diagram ATMEGA64 8-bit Microcontroller with 64K Bytes In-System Programmable Flash

The ATmega64 is a low-power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By executing powerful instructions in a single clock cycle, the ATmega64 achieves throughputs approaching 1 MIPS per MHz, allowing the system designer to optimize power consumption versus processing speed.

The AVR core combines a rich instruction set with 32 general purpose working registers. All the 32 registers are directly connected to the Arithmetic Logic Unit (ALU), allowing two independent registers to be accessed in one single instruction executed in one clock cycle. The resulting architecture is more code efficient while achieving throughputs up to ten times faster than conventional CISC microcontrollers.

TEA2025B bassed amplifier circuit and explanation

A very simple audio amplifier electronic project that can be used in small portable audio applications can be designed using the TEA2025B audio amplifier IC . This audio power amplifier project supports a wide input voltage range between 3 and 15 volts .
Input capacitor is PNP type allowing source to be referenced to ground.
In this way no input coupling capacitor is required. However, a series capacitor (0.22uF)to the input side can be useful in case of noise due to variable resistor contact.
The bootstrap connection allows to increase the output swing. The suggested value for the bootstrap capacitors (100μF) avoids a reduction of the output signal also at low frequencies and low supply voltages.
The voltage gain is determined by on-chip resistors R1 and R2 together with the external RfC1 series connected between pin 6 (11) and ground. The frequency response is given approximated Input capacitor is PNP type allowing source to be referenced to ground.
The frequency response is given approximated : VOUT/VIN= R1/(Rf +R2 +(1/JWC1))
The maximum output power that can be obtained using the TEA2025B audio amplifier in stereo mode is around 2.3 watts on a 4 ohms load .

Design on the basis of electrical home appliances liquid crystal display system MC9S08AW32 and HT1621

Drive the performance characteristic of the chip HTl621 and make up the structure, combine and fly to think of Karl’s little controller MC9S08AW32 according to the liquid crystal, have described the design of a kind of electrical home appliances liquid crystal display system. Have described HT1621 practical application in the display system design of this liquid crystal in detail, have explained hardware forming and software design process of this system especially, and provide interface block diagram of the hardware and software flow diagram. The display system of this liquid crystal reveals steadily, fine performance such as low power dissipation, the interface friendship, and saved little controller I/O port resources. 

The display system of the liquid crystal is the important component of the control system of electrical home appliances. The liquid crystal display system of electrical home appliances reveals the module Liquid Crys-tal Display through the liquid crystal Show important information such as its working state and time out, users assign the operation order to deal with to the little controller according to the information, thus realize the control on function of the electrical home appliances. The liquid crystal reveals the module not merely can reveal figure, Chinese character and character vividly, and the consumption is little, the working voltage is low, so the application in the modern electrical home appliances products is more and more extensive. The intersection of electrical home appliances and the intersection of liquid crystal and display system including liquid crystal reveals the module LCD mainly, backlight source, liquid crystal drive the chip HT1621, flies and thinks of Karl’s little controller MC9S08AW32 and button module etc.. Here, according to the performance characteristic, making up structure and programming method, combine MC9S08AW32 of HT1621, have described HT1621 practical application in the liquid crystal display system of electrical home appliances in detail, have explained hardware design and software design process of this system, and provide hardware interface block diagram and software flow diagram of this system.

A liquid crystal drives the chip HT1621 introduction

1. Characteristic of 1 HT1621

HTl621 is held group HOLTEK in Taiwan 128 sections which the company puts out 32* 4The multi-functional driver of the built-in memory, can drive the multistage LCD character to be its main characteristic. HTl621 can form LCD and reveal module and display system, only needs 3- 4 with the communication of little controller, it also included at the same time the electricity orders in a province, reduced the systematic consumption effectively. SSOP that HTl621 is 48 pins encapsulates, has a lot of fine characteristics, its main characteristic is as follows:

1.Working voltage 2. 4- 5. 2 V;
2.Inlay 256 kHz RC oscillator inside;
3.The order can be used in reducing the consumption economizing on electricity;
4.A LCD driver of 32* 4 sections;
5.32* 4 that inlay in one reveal RAM memory;
6.Mode of three kinds of access to data.

1. Systematic structure within 2 HT1621
The systematic structure includes revealing the memory RAM within HT1621 Systematic oscillator, guard the gate the intersection of dog and timer, the intersection of voice and generator and the intersection of LCD and driver,etc.. Only introduce the display memory correlated to this design RAM as follows With LCD driver.

1. 2. 1 reveals the memory RAM
The static behavior reveals the memory RAM, store the data revealed in the form of 32* 4. The data of RAM can shine upon the driver to LCD; The data stored in RAM can use READ, WRITE and READ-MODIFY-WRITE order to visit. Fig. 1 is the image from RAM to LCD driver.

1. 2. 2 LCD driver
HT1621 is one and 128 sections 32* 4LCD driver. It can dispose from software into LCD driver biasing and 2, 3 or 4 public ports of 1/ 2 or 1/ 3. This characteristic makes HT1621 suitable for many kinds of LcD to employ the occasion. LCD drives the clock to be produced from the frequency division of the systematic clock; LcD drives the frequency value of the clock to keep as 256 Hz, it is 32 by the frequency. The shaking brilliantly of 768 kHz, Rc oscillator or external clock in slice are produced; See Table 1 in relevant order of LcD driver.

Runic 100 is ” 100″ Express the order mode type. If carry out the continuous order, except the first order, mode type of other orders yard will be neglected. LCDOFF orders to make LCD bias the generator and fail, thus close LCD to reveal; LCD ON orders to make LCD bias the generator effectively, thus opened LCD to reveal.