Tag Archive: Project

 Among the final amplifier we called. Regional Power Amp, will it work on several well-known as Class A, Class B, Class AB etc. Each class of the above, to honor the Class A was superior to the sound quality. best. However, class A power output to a low of 20 percent compared with a loss of power or the power consumption of about 5 times the power output. Therefore, the problem of heat Although it has not paid any audio. But anyway, despite the low-watt power, it also provides crystal clear sound quality than Class B and Class AB.

      Principles of integrated amplifier class A is IC1 – NE5532 to extend signal input through the C1 to increase 15-fold. The signal output from the pin 1, signal hemisphere positive through C2 to access Q1-BD139 and Q3-2N3055. is powered by Darling ton, amplifiers and signal the intensification of the negative side of C3 through the amplifier with the Q2-BD140 and Q4-MJ2955. This is the Darling ton, too.

Then the output signal from the positive side of the pin E of the Q3 and the negative side of the pin out of the E in Q4 through R10 and R11, to prevent short circuits and then output to the speakers. This will power up to 5 watts. The D1-D4 acts as a rectifier in the DC bias for Q1 and Q2. And VR1 is adjusted to a constant current bias is at work. The Q1-Q4 will be attached sheet cooled, Q3 and Q4, especially the thermal plate must be large. Because the circuit has high energy loss.


My H-Bridge consume 3ma@3.3v when there is no load and both inputs are zero,

    How can i reduce it ?
    my goal is <100uA
Q2 and Q8 are SS8550 and Q3 and Q9 are SS8050, other Qs are 2N2222A


  The following CD4017 circuits have not been tested and is presented here as a possibility only. If you experiment with this circuit, please send me any problems found so that the circuit can be updated.

  The following circuits are designed to change the duration of each positive output pulse from the astable timer. The circuits use a CD4017 Decade Counter / Decoder to provide nine or ten steps in the cycle.

  The first circuit operates with a repeating ten step cycle. Each output pulse is longer than the previous until a count of ten is reached at which time the cycle will repeat.

  The second circuit has a nine step cycle that stops at the end of the cycle. The cycle is restarted or reset when the RESET input is briefly made high.

  The CD4017 can be configured to give count lengths between 1 and 10. Refer to the timing diagram in the CD4017 data sheet for a better understanding of the IC’s operation.

The MAX705CSA is a microprocessor (μP) supervisory circuit which reduces the complexity and number of components required to monitor power-supply and battery functions in μP systems. The device significantly improves system reliability and accuracy compared to separate ICs or discrete components. The applications of the MAX705CSA include Computers, Controllers, Intelligent Instruments, Automotive Systems, Critical μP Power Monitoring.
MAX705CSA absolute maximum ratings: (1)VCC: -0.3V to 6.0V; (2)All Other Inputs: -0.3V to (VCC + 0.3V); (3)Input Current, VCC: 20mA; GND: 20mA; (4)Output Current (all outputs): 20mA; (5)Continuous Power Dissipation, Plastic DIP (derate 9.09mW/℃ above +70℃): 727mW.
MAX705CSA features: (1)μMAX Package: Smallest 8-Pin SO; (2)Guaranteed RESET Valid at VCC = 1V; (3)Precision Supply-Voltage Monitor, 4.65V in MAX705/MAX707/MAX813L; 4.40V in MAX706/MAX708; (4)200ms Reset Pulse Width; (5)Debounced TTL/CMOS-Compatible Manual-Reset Input; (6)Independent Watchdog Timer—1.6sec Timeout (MAX705/MAX706); (7)Active-High Reset Output (MAX707/MAX708/MAX813L); (8)Voltage Monitor for Power-Fail or Low-Battery Warning.

I know how to build a big digit but how the heck did you control that much current with such few ICs and such few control lines? Ahh, I’m glad you asked. Here are some fun pointers about how to control large numbers of seven segments LEDs.

Now if you’re not a hardware person, get ready for some technical jargon.

A PIC 16F877A has quite a few I/O pins (around 32). But if you start doing the math, you see just how limited we are.

6 digits * 7 segments = 42 channels

Sure, we could find a microcontroller that has 42 available I/O pins, but there’s got to be a better way! This is actually an age-old problem. Turns out there are chips out there! The 74HC4511 is the magical chip that takes a Binary-Coded-Decimal (BCD) input and outputs the correct pins to create that binary number on a seven-segment display.

Okay, so we go from seven lines down to four, big deal? There is a latch on the 74HC4511. This latch allows us to share the 4-bit bus with all the channels, and then just toggle the latch pin on the digit we need to talk to. Maybe a schematic will help:


You can see four Control lines. This is the BCD bus. There is also six Driver lines. These Driver lines activate the latch on each ‘channel’.

U6 is the 74HC4511. U7 is a ULN2003A. JP1 is the RJ45 jack. Just stick with me a bit longer!

The ULN2003A is a high-current Darlington array. Darling what? This IC has seven channels. Each channel can control up to 500mA. When 1B goes high, current is allowed from the ‘1C’ input to ground.

So when the Num1_f pin goes high, current flows from RAW, through the LED Light Bars in the big digit, into 1C, and then out through GND. This may seem a little bit odd at first. Maybe this will help:

Okay so now for the chain of events.

The PIC parses out the GPS time from NMEA sentences coming out of the Lassen iQ receiver at 4800bps.
The PIC decides that the time is 6:45:33, so a ‘3’ needs to be displayed on channel 1.
A binary three (0b.0011) is put onto the bus.
Driver1 is pulled low, then driven high. Because all other driver lines are kept high, the other drivers ignore this bus data.
The 74HC4511 for channel 1 sees this binary number, notices that it’s been latched, and then outputs the correct segments to light up a three. Segments A, B, C, D, and G go high.
The ULN2003A detects these lines (Num1_a, b, c, d and g), goes high and allows current to sink through 3C, 4C, 5C, 6C, and 2C.
The LED Light Bars inside the digit (located farthest to the right) light up the correct bars to display a three.

It’s really pretty slick. The system is completely scalable. To add another seven-segment display requires only one additional I/O pin for another DriverX line. The PIC 16F877A could control as many as 28 digits. Have you ever seen 28 digits next to each other? How about 18″ wide and on a wall? That’s really huge.

That’s it! Sorry the tutorial ended up being so long. This project took about two weeks of cutting and figuring out how to best create the digits. The firmware took about an hour and hardware layout took about three (we’ve used most of the basic components before). Let us know what you think.

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.

The following picture shows this Arduino compatible circuit in action.


An ATmega64 is used for the controller. The MCU has an external memory interface, it benefits the applications that require a certain memory. The waveform data is loaded from a memory card and stored it to the wavetable located in the 256 Kbit external memory. The wavetable, 16 bit word, 8192 samples and two channels, fits to the entire memory. The system clock is supplied from DAC. The frequency exceeds maximun allowable working frequency of the MCU, however it works with no problem.


The figure shows the MAX773 connected to provide 100-V output at 10 mA, with 24-V to 28-V input. Figure shows the calculations for selecting the RSHUNT vaLue. RSHUNT should be selected so that ISHUNT is greater than 1 mA, but less than 20 mA. If the calculated shunt regulator current exceeds 20 mA, or if the shunt current exceeds 5 mA, and less shunt-regulator current is desired, use the circuit of Fig. This provides increased drive and reduced shunt current when driving N-FETs with large gate capacitances. Use an ISHUNT of 3 mA. This provides adequate biasing current for the circuit, although higher shunt currents can be used. Notice that the shunt regulator is not disabled in the shutdown mode, and continues to draw the calculated shunt current. To prevent the shunt regulator from drawing current in the shutdown mode, place a switch in series with the shunt resistor.See Fig. for component suppliers.


MAX773 MUR115 SI9420DY 2N2222A 2N2907A

Microlab ATX 400w KA7500 Power supply micro lab 400watt atx ka7500 lm339 2sc2625 st3040 st1020 sbl2040 microlab atx 400w 2sc5027 fr107 2sc5344y atx tamir şema atx smps circuit, atx smps repair schema.


USB-to-1-wire adapter with galvanic isolation


Using long wires through workshops or buildings connected to the precious computer’s ground line is not the greatest idea concerning EMI and noise impact as well as operators’ safety. A system with separated grounds, the 1-wire-bus isolated from the USB and the computer, would improve reliability and availability of that measuring system even under influence of electrical noise, lightning or ground voltage disturbances.

The isolated transfer of power uses a transformer and rectifier assembly, here build with a digital bus driver circuit 74HC245 and a 1:1:1 ferrite transformer (3 identical windings). This provides low power, high efficiency and utilisation of readily-available low-cost parts.
The transfer of RS232 information uses high speed optocouplers 6N136. A low-cost hex Schmitt inverter HCMOS IC 74HC14 is used on the isolated side for the processing of the filtered 1-Wire-signals and LED drive to reduce the overall component count.