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Key Code Combination High Security Door Lock
This project is an electronic lock with many combinations that you can easily change and opens only with the correct combination of four consecutive numbers. The big advantage of the electronic lock is that the four numbers must be entered in the correct order one after the other. If a number is wrong then the circuit automatically resets to its...
Decimal to BCD Convertor Keypad
When any particular key is pressed, its value will appear in BCD form at the outputs (A, B, C & D). It will remain there until another key is pressed. The 12 keys produce outputs up to "1011". Extended to 16 keys, the circuit will give the full HEX to BCD conversion.
If your application uses a relatively powerful microcontroller, you can use several free I/O pins or an unused input with an ADC to effect an easy keyboard connection. But, if the microcontroller in your system has too few free I/O pins and no on-chip ADC, you can be in trouble. However, if your system doesn`t require a high-performance...
LCD & Keypad drive
No description available.
Keypad activates relay
Moreover, the method does not entail programming and the concomitant, almost inevitable, debugging. A CD4016 CMOS analog switch, IC1, forms the heart of the system. Depressing the key labeled "1st" closes the topmost switch (between pins 1 and 2), which latches itself via the diode connected between pins 2 and 13. The same topology repeats three...
Implementing Wake-up on Key Stroke
The circuit, shown Figure 1, depicts an application with two keys. The PIC16C54 is normally in SLEEP mode consuming very little operating current. If either of the two keys is pressed, the PIC16C5X wakes up, scans the keys and turns on one or both of the LEDs.
Multiplexing LED Drive and a 4x4 Keypad
Typically applications having LEDs and keypads also keep track of real-time, in order to synchronize certain related events. An Industrial Clock/Timer example has been used in this application note as a demonstration of these functions. The software overhead to keep track of real time is minimal and the user can modify the code to...
Keyboard links to microcomputer
You can divide a large keypad or keyboard into sections of 12 keys each (Figure 1). Each section connects to a separate comparator circuit, which detects a keystroke and generates a trigger pulse using the monostable circuit of IC4, and you can add more sections in the same manner. Diodes D1, D2, and D3 couple and isolate the comparators`...
Security Lock with keypad and LCD (PIC16F84A)
Finally I was able to control an LCD Hitachi display and a 12-key matrix keypad with only one 16F84 or 16F628. In a near future, I will be able to control a full QUERTY-type keyboard and a LCD display. The biggest improvement on this projects was the compatibility with the Microchip PIC 16F84 and the 16F628, also the 16x1 or the 8x1 LCD Hitachi...
Remote IR controller
This unit provide 2 way IR communications using a numeric keypad and an LCD display. Data is sent and recieved in ASCII with no regard to what the data means to any particular device. The ASCII data still needs some form of encoding. For this I chose 10-pulse coding of 38Khz IR using a nifty 99 cent receiver chip , TSOP4838 The transmitting is...
CMOS Combination lock
his Electronic Lock circuit is not only simple but it is also very good. It can easily be configured to provide either momentary or continuous output. Key sequences of up to 9 digits are possible. You can pre-enter part of the combination and then have someone else enter the last few digits at a later time allowing for one-time access. This...
Door electronic lock with Keypad
It is a relatively simple circuit of electronic lock of safety with code of 7 digits. It should is given attention in the time that will be stepped the keys, that shape code and it does not exist it delays. With the right step of keys and if code is right then is activated exit Q7 for roughly 4 seconds, driving the transistor Q2, which with the...
Keypad Combination Lock circuit
This simple circuit is the electronic version of the combination lock. Using the special purpose LS7220 digital lock IC, the circuit allows a 4 digit combination of your choice to activate a relay for a set period of time. This relay can then be used to trigger a lock solenoid, enable a starter button, open a motorized door, or many other tasks...
4-key keyboard using ATtiny85
A good while back, I made the 1-key-keyboard project. Ever since it has always been in the back of my mind that the ATTiny microcontroller.
Keypad Talking To LCD Via AT89S51
In few previous post, I showed schematic for interfacing Keypad and LCD using 8051 architecture. This blog post shows complete implementation of the interface using AT89S51 Micro-controller with programming in assembly. Considering that one understands the technical background for Keypad and LCD. Now, follow the schematic given above and solder th
Electronic Keypad Combination Lock
When wired to a ten-digit keypad, the circuit will recognize one 4 digit combination out of a possible 5040 codes. When the programmed four-digit combination is entered from the keypad, in proper sequence, LOCK turns on and Lock Status turns off. The lock combination is set by pins 3, 4, 5 and 6 on the LS7220. These correspond to the digits on...
microcontroller Which schematic is better for keypad connection to an MCU
4x3 4x4 Matrix Keypad Interface with Atmel AVR Microcontrollers
Many application requires large number of keys connected to a computing system. Example includes a PC keyboard, Cell Phone keypad and Calculators. If we connect a single key to MCU, we just connect it directly to i/o line. But we cannot connect, say 10 or 100 keys directly MCUs i/o. Because :- We want to avoid all these troubles so we use some...
nokia 5130 keypad ic solution 1000% working
nokia 5130 keypad jumper just follow the diagram.. tested just now.. after doing the jumper.. all keypads working well ..
Alarm Circuit Using Keypad
This is a design circuit for alarm circuit. This circuit is controlled by keypad. For the core of the circuit is using a single transistor with BC547 series. This is the figure of the circuit. For operation, on a 12-key pad, look for 13 terminals. The matrix type with 7 terminals will NOT do. The Alarm is set by pressing a single key. Choose the k
ft817 keypad circuit diagram
understanding keypads circuit
interface keypad with pic12f675
This post provides a simple method to interface any keypad (e-g 4x4 or 4x3 etc) with PIC12F675 microcontroller. The code for PIC12F675 is written in C lang..
interface keypad with pic16f877
This PIC microcontroller tutorial provides a simple method to interface any keypad (e-g 4x4 or 4x3 etc) with PIC16F877 microcontroller. This code is writte..
how to repair nokia 6500 keypad problem
nokia 1110 keypad failure
Enhanced 5 digit alarm keypad circuit
keypad interfacing connection diagram
learn to interface 4x4 matrix keypad with AVR and 8051 microcontroller and program AVR microcontroller and 8051 microcontroller in C and assembly for keypad matrix..
2x16 lcd and 4x4 keypad interfacing 8051
Microcontrollers are just silicon wafers until we tell them what to do, program them according to our requirement.Read More..
4 digit alarm control keypad
This Keypad is suitable for the Modular Burglar Alarm. However, it has other applications. Pressing a single key will energize the relay. Entering the Four-Digit code of your choice will de-energize it..
5 digit alarm control keypad
This Keypad is suitable for the Modular Burglar Alarm. However, it has other applications. Entering the First Four Digits of your chosen Five-Digit code - will energize the relay. Entering the Full Five-Digit code - will de-energize it..
4 digit keypad controlled switch
This is a Universal version of the Four-Digit Alarm Control Keypad. I have modified the design to free up the relay contacts. This allows the circuit to operate as a general-purpose switch. I`ve used a SPCO/SPDT relay - but you can use a multi-pole relay if you wish..
555 Timer Circuits
RC Model Toy Circuits
H Bridge Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial