Showing posts with label build. Show all posts
Showing posts with label build. Show all posts
Friday, October 17, 2014
Build a MHz Oscillator using an ATtiny15
Most engineers will recognise the problem: Your circuit needs a stable 1 or 2 MHz clock generator (in the author’s case it was for a Pong game using an old AY3-8500). A suitable crystal is not to hand so you cobble together an RC oscillator (there are plenty of circuits for such a design). Now it turns out that you don’t have exactly the right capacitor so a preset pot is add e d to allow some adjustment . Before you know it the clock circuit is taking up more space on the board than you had hoped.
Providing the application does not demand a precise clock source a tiny 8-pin microcontroller may offer a better solution to the problem. It needs no additional external components and an old ATtiny15 can be found quite cheaply. Another advantage of the solution is that clock frequency adjustment does not involve changing external components and is not subject to component tolerances.
The microcontroller’s internal RC oscillator is already accurately calibrated to 1.6 MHz. With its inbuilt PLL, internal Timer 1 can achieve up to 25.6 MHz [2]. By configuring internal dividers the timer can output a frequency in range of roughly 50 kHz up to 12 MHz from an output pin. The difference between calculated and the actual output frequency increases at higher frequencies. A meaningful upper limit of about 2 MHz is a practical value and even at this frequency the deviation from the calculated value is about 15 %.
MHz Oscillator using an ATtiny15 Schematic
The circuit diagram could hardly be simpler, aside from the power supply connections the output signal on pin 6 (PB1) is the only other connection necessary.The example program, written in Assembler is just 15 lines long! With a program this short comments are almost super fluous but are included for clarity. The code can be downloaded from the Elektor website [1].
The program only needs to initialise the timer which then runs independently of processor control to output the clock sign al . The processor can then be put into sleep mode to memory used up the remaining 99 % is free for use for other tasks if required.
The OSCCAL register contains a calibration byte which allows some adjustment of the CPU clock. This gives a certain degree of fine tuning of the output frequency. A recommendation in the Atmel data sheet indicates that the CPU clock frequency should not be greater than 1.75 MHz otherwise timer operation cannot be guaranteed.
The more recent ATtiny45 can be substituted for the ATtiny15. In this case the CK SEL fuses should be set to put the chip’s Timer 1 into ATtiny15- compatible mode [3]. After adjustment to the program it will now be possible to obtain a higher (or more exact) frequency from the timer, the ATtiny45’s PLL can operate up to 64 MHz.
Thursday, October 16, 2014
LM380 Build 2 Watts Audio Amplifier Circuit Diagram
LM380, Build 2 Watts Audio Amplifier Circuit Diagram. Small audio amplifier is useful for audio troubleshooting or simple audio projects. It should be a low cost and easy to build. Using integrated circuit for this purpose is the right choice. With LM380 audio amplifier integrated circuit, 2 Watts power can be delivered. For better thermal endurance, a large copper track can be printed in the board to provide heat sinking, this copper track should be soldered to pins 4, 3, 10, 5, 12 and 11. Here is the schematic diagram of the circuit.
LM380, Build 2 Watts Audio Amplifier Circuit Diagram
Wednesday, October 15, 2014
Build a Rain and Water Alarm Circuit Diagram
This is the circuit diagram of Rain and Water Alarm circuit. This circuit generates alarm sound when its sensor is witted by water which make a short circuit (connection) between X and Y. A tone of about 1kHz which can be hear while detecting water, is provided by a stable multivariate from timer IC 555.
The sensor when witted by water completes the circuit and causes the 555 oscillate at about 1kHz. It has to placed generating an angle of about 30 – 45 degrees to the ground. This tends to make the rain water to flow over it towards the ground and prevents the alarm from going on because of the stored water on top of the sensor.
The metal implemented for making the sensor is required to be aluminum and not copper. This is simply because copper forms a blue oxide on its layer on prolonged exposure to moisture and needs to be cleaned on a regular basis.The aluminum foils may be secured to the wooden / plastic board via epoxy adhesive or small screws. The connection between X and Y from the sensor may be obtained by small crocodile clips or you could possibly use screws.
Build a Rain and Water Alarm Circuit Diagram
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The sensor when witted by water completes the circuit and causes the 555 oscillate at about 1kHz. It has to placed generating an angle of about 30 – 45 degrees to the ground. This tends to make the rain water to flow over it towards the ground and prevents the alarm from going on because of the stored water on top of the sensor.
The metal implemented for making the sensor is required to be aluminum and not copper. This is simply because copper forms a blue oxide on its layer on prolonged exposure to moisture and needs to be cleaned on a regular basis.The aluminum foils may be secured to the wooden / plastic board via epoxy adhesive or small screws. The connection between X and Y from the sensor may be obtained by small crocodile clips or you could possibly use screws.
Build a Rain and Water Alarm Circuit Diagram
Saturday, September 13, 2014
Build a Precision Narrow Band Tone Switch Wiring diagram Schematic
How to Build a Precision Narrow Band Tone Switch Circuit Diagram. This is a simple Precision Narrow Band Tone Switch Circuit Diagram. This signal tracker and lock detector combine to make a precision tone switch. Filter R3/R4/C2 determines signal capture and tracking range, as well as settling time. Max. VCO frequency: R& Min. VCO frequency: + Pin 9 voltage affects both.
Precision Narrow Band Tone Switch Circuit Diagram
The minimum at pin 9 is 0 V and the maximum at pin 9 is VDD. In the lock detector, the PC (phase comparator) outputs are pulses whose width is proportional to the phase difference between the two PC inputs. At lock up, the two PC outputs are almost mirror images. The output of IC1A remains low and IC1B is high. This lights LED1. If the loop is unlocked, the LED will not light.
Build a High voltage Bucking Regulator Wiring diagram Schematic
This High voltage Bucking Regulator Circuit Diagram is basically tbe classic bucking regulator, except it uses a TMOS N-channel power FET for the chopper and creates its own supply for the gate control. Tht unique aspect of this schema is how it generates a separate supply for the gate schema, which must be greater than Vvv.
When power is applied, C2 charges, through D2, to +12 V. At this time, Q1 is off and the voltage at point A is just below zero. When the pulse-modulated signal is applied, the optoisolator transistors, Q2 and Q3, supply a signal to Q1 that turns it on. The voltage at point A then goes to Vvn. C2 back-biases D2, and the voltage at point B becomes 12 V above Vnn· After Q1 is turned on, current starts to flow through L1 into C1, increasing until Q1 turns off.
High voltage Bucking Regulator Circuit Diagram
The current still wants to flow through Ll, so the voltage at point A moves toward negative infinity, but is clamped by D1 to just below zero. Current flows less and less into C1, until Q1 turns on again. Q2 and Q3 drive Q1 `s gate between the voltages at point A and B, which is always a12 V swing, so Vcs max. is never exceeded. For proper operation, the 12-V supply has to be established before the pulse-width modulator signal is applied.
Monday, September 1, 2014
Build a 1 2 36V 5A Adjustable Power Supply with LM317
Build a 1.2-36V 5A Adjustable Power Supply schema diagram with LM317. This schema is a simple power supply schema. 1.2 - 36V adjustable bench power supply with 5A of output current. Max input voltage is 37V and output is adjustable via potentiometer between 1.2 up to 36 volts. TIP147 PNP darlington transistor boosts the current of LM317 from 100mA to 5A. LM317 is the most useful and inexpensive adjustable regulator and for this schema you can also use LM317 L that can give 100mA, thats enough for transistor bias.
1.2-36V 5A Adjustable Power Supply Circuit Diagram
D1 and D2 are protection diodes because when you turn the schema off the output capacitors are discharging and can damage the transistor or regulator. 100nf capacitors are in parallel with electrolytic capacitors to remove high frequency noise because large value electrolytic have large ESR and ESL and cant remove high frequency noise.
Tuesday, August 26, 2014
Build a Pulse Generator using Basic Operational Amplifier
How to build a pulse generator schema using operational amplifier, very basic, it is the schema stable multi vibrator or square wave oscillator. It uses a dual operational amplifier IC, one in 1458. The output frequency set by the value of R1 and C1. The calculation is Frequency = 1 / (2R1.C1.ln3)
The capacitor C1 1uF to change capacitance value by the frequency of 8 Hz, = 0.1uF 50Hz, 700Hz = 0.01uF, 0.001uF = 6kHz. In place of 1458 4558 may be used, LF353, etc.
Pulse Generator using Basic Operational Amplifier Circuit Diagram
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Saturday, August 23, 2014
Build a Bang Bang Controllers Circuits Wiring diagram
Bang-Bang Controllers Circuits Diagram Just one chip, the PWR-DRV1 from Power Integrations, builds a `bang-bang` controller that switches 275 mA and runs off the rectified 115-Vac mains. An on-chip zener diode powers the chip from high voltage through a dropping resistor.
Bang-Bang Controllers Circuits Diagram
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Bang-Bang Controllers Circuits Diagram
Thursday, August 21, 2014
Build a Variable Bandpass Audio Filter Wiring diagram Schematic
Build a Variable Bandpass Audio Filter Circuit Diagram. This Variable Bandpass Audio Filter Circuit Diagram is a variable audio bandpass filter that has a low cutoff variable from about 25 Hz to 700 Hz and a high cutoff variable from 2.5 kHz to over 20 kHz. Roll off is 12 dB/octave on both high and low ends. R2-a-b and R6-a-b are ganged potentiometers for setting lower and upper cutoff frequencies, respectively.
Variable Bandpass Audio Filter Circuit Diagram
Tuesday, August 19, 2014
Build a Low Cost Line Receiver Wiring diagram Schematic
Build a Low Cost Line Receiver Circuit Diagram. This is a simple low cost line receiver schema diagram. This timer makes an excellent line receiver for control applications involving relatively slow electromechanical devices. It can work without special drivers over single, unshielded lines.
Build a Low Cost Line Receiver Circuit Diagram
Sunday, August 17, 2014
Build a Simple Single Chip Dc Supply Wiring diagram Schematic
How to Build a Simple Single-Chip Dc Supply Circuit Diagram. This Simple Single-Chip Dc Supply Circuit Diagram Direct derivation of 5 to 24 Vdc from ac mains, without a transformer is possible with this schema. Note that a direct mains connection to the dc output exists. Suitable safety precautionary must be taken.
Simple Single-Chip Dc Supply Circuit Diagram
Monday, August 11, 2014
Build 12V to 9V DC Converter
To get a more precise output voltage, replace zener diode Z1 with 10V and R1 with a 1Kilo ohm potentiometer. A Coolrib for Q1 is optional but highly recommended. You can replace Q1 for a more robust type to get more output amps depending on your requirements. Simple schema to power your 9 volt cassette recorder and other stuff.
Parts List:
R1 = 560 ohm
C1 = 1000uF/40V, Electrolytic
C2 = 10uF/25V, Electrolytic
C3 = 330nF, Ceramic
Z1 = 9.1V, 1watt zener
Q1 = ECG184, NTE184
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