Mutchus

In this tutorial I am going to brief you on how to establish a communication between two arduino boards through SPI(Serial Peripheral Interface). SPI is also called as 4 wire interface, because it uses four pins to transmit and receive data, they are MISO (Master In Slave Out), MOSI(Master Out Slave In), SCK – This provides the clock signal for data transfer, usually from master to slave. And SS pin- It selects the slave device, it is an active low signal given by Master device. After completing the data transfer with one slave device, the master device pulls up the SS pin to high. In SPI protocol, it is possible to connect more than one slave to a master device. The master device can communicate with any slave connected to the bus at any time, but the slave can communicate only to the master. Whenever the master device wants to send a data to slave, it pulls down the SS Pin and the slave will listen to data. The master device is controlling the clock signal for data transfer, so the s...

The circuit in Fig 1 supplies both 3.3 and 5V to transitional circuits that employ both the new 3.3V and older 5V devices. Additionally, because the regulator accepts either 3.3 or 5V inputs, you could plug it into either a new 3.3V system or an old 5V system.The circuit consists of two sections: a dc/dc converter and a double-pole, double-throw (dpdt) switch. The dpdt switch comprises a pair of dual n-channel MOSFETs (Q2 and Q3) and their associated high-side drivers. Upon power-up, the comparator in IC2 determines the state of the circuit. The comparator’s output, IC2 pin 6, goes to the input of the MOSFET driver, IC1. The driver internally generates a gatedrive voltage 8.8V above the device’s supply voltage. This high voltage drives the appropriate MOSFETs in Q2 and Q3. IC2 is also the heart of a flying-capacitor, buck/boost dc/dc converter. Unlike other switching- regulator schemes, this topology needs no transformers. Transistor Q1 controls this section’s output voltage, VS. When...

Description  This circuit is designed on request and can be useful to those whishing to have, say, a red LED illuminated when an appliance is on and a green LED illuminated when the same appliance is off. Any mains operated appliance can be monitored by this circuit provided a suitable mains switch, capable of withstanding the full load current, is used for SW1.When SW1 is closed, the load and D4 are energized, Q1 is saturated and shorts D3, thus preventing its illumination. Circuit Diagram: Parts: R1 = 27K-1W R2 = 27K-1W R3 = 6.8K D1 = 1N4007 D2 = 1N4007 D3 = Green D4 = Red Led Q1 = BC337 SW1 = SPST Mains Switch Notes: Change R1 and R2 to 15K 1W for 115Vac mains operation. SW1 must be capable of withstanding the appliance's full load current and volage Source- http://www.redcircuits.com/#home

This little circuit provides a surprisingly spectacular bright strobe flash which is adjustable with P1, the 200K trimmer potentiometer. P1, R1, R2, and C1 provide the flashrate. R1 sets the upper flashrate. The flashrate for the above circuit was measured at 12Vdc. If the supply voltage is steady or regulated, the flashrate is very stable. Capacitor C2 on pin 5 of the IC is to filter off noise when used in motorized vehicles. For battery power it can be eliminated. Resistor R3, 47 Ohm, is there to protect the Leds for burn-out. Depending on your application and power source, increase or decrease the value of R3. Like, for a 9V power source decrease the value to 22-33 ohms or so. For a 15V power sourse increase the value to 680-1000 ohms. Circuit Diagram: The duty-cycle is about perfect at 50% so will give a nice strobe when adjusted with P1 to a fast flash. I experimented with several color Leds and basically they all strobe very bright especially the white ones. Current draw of this ...

The circuit provides a 10MHz cutoff frequency. Resistor R3 ensures that the input capacitance of the amplifier does not interact with the filter response at the frequency of interest. Circuit Diagram: An equivalent low pass filter is similarly obtained by capacitance and resistance transformation.

Here are two simple 12V DC motor speed controllers that can be built for just a few dollars. They exploit the fact that the rotational speed of a DC motor is directly proportional to the mean value of its supply voltage. The first circuit shows how variable voltage speed control can be obtained via a potentiometer (VR1) and compound emitter follower (Q1 & Q2). With this arrangement, the motor’s DC voltage can be varied from 0V to about 12V. This type of circuit gives good speed control and self-regulation at medium to high speeds but very poor low-speed control and slow starts. The second circuit uses a switchmode technique to vary motor speed. Circuit diagram: Fig.1: a very simple motor speed controller based on a compound emitter follower (Q1 & Q2). Here a quad NOR gate (IC1) acts as a 50Hz astable multivibrator that generates a rectangular output. The mark-space ratio of the rectangular waveform is fully variable from 20:1 to 1:20 via potentiometer VR1. The output from the ...

This is the Simple Two 555 Timers Bell Circuit Diagram. This simple scheme uses two Bell 555 timer. The frequency controlled capacitors, which should be preserved are almost identical in value with each other to achieve the best results. Fine tuning is done with the R1 and R2. The decay time is controlled by R3.   Simple Two 555 Timers Bell Circuit Diagram    

This constant current circuit is designed to drive two 3-watt Luxeon LEDs. The LEDs require 1,000mA (1Amp) and have a characteristic voltage-drop across them of about 3.8v. Approximately 4v is dropped across the LM317T regulator and 1.25v across the current-limiting resistors, so the input voltage (supply) has to be 12.85v. A 12v battery generally delivers 12.6v. The LM 317T 3-terminal regulator will need to be heatsinked. This circuit is designed for the LM series of regulator as they have a voltage differential of 1.25v between "adj" and "out" terminals.