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AC to DC & DC to DC
Solar Cell Circuits
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Switching Power Supplies
Light Laser LED
Digital to Analog
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Data Bus Circuits
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RF Converter Circuits
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Video Wall circuits
TV Video Circuits
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8051 / 8052
PCB CAD Software
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555 Timer Circuits
Remote Control Toy
H Bridge Circuit
Interconnection & Timing
Digital Signal Integrity
Transmitters & Receivers
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4 Band Resistor
5 Band resistor
6 Band resistor
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
Recording circuit of phone conversations using PC
This circuit is used to record telephone conversations on your landline telephone. All you will need is this small circuit and subscription of your PC. There are few times when we forget what we said or told us. So we need recording. Sometime, not many years ago, recording of this kind of conversation was done with a small tape recorder. The...
FM Micro-Transmitter Bug Surveillance Circuit
The transmitter we recommend to build is quite simple. It can even be built by a beginner. However, unlike the ease of construction and its small size, it is almost certain that it will impress you with its outstanding performance. Its autonomy is 12-15 hours, with a 9 volt battery and its range is from 100 to 300 meters depending on the...
Construction of 50Watt 8Ω two-way Hi-Fi Speakers
The presented speakers are distinguished for their small dimensions and their extraordinary sound. Our home space is often limited and prohibitive for large speakers. This limitation does not mean that we will stay without high Sound Quality. Its design is simple, low cost and is easy to construct. Speaker types are too many and are designed in...
GSM modem circuit with Wavecom WMOi3
Modems are devices that connect either remote devices to a computer, or two or more computers to each other. Their connection is usually wired. The GSM modem we present is wireless. It can connect two computers, a computer with the internet or even be the central unit for a data acquisition system. Generally the construction is a GSM phone...
1W UHF Linear Amplifier with BLW33
This circuit is an amplifier for small transmitters operating in the UHF band, specifically in the 450-800MHz range. The amplifier works in class A and we used the well-known Philips BLW33 transistor for its manufacture. The construction, although simple, can be said to be quite critical due to the high frequency singularity. To achieve this, a...
8W Amplifier with TDA2003 circuit
Many times a small amplifier is needed to meet the needs of small spaces. This amplifier can be either mono or stereo, with this circuitry you can comfortably drive two small speakers. To build the amplifier you do not need anything but a few materials and a small power supply. The power of the amplifier, although low power, will solve many...
FM Linear Amplifier 400mW
This amplifier is intended for amplifying low signals from oscillators in the FM band. It does not have frequency regulators with variable capacitors and coils, it has a wide range and moderate power capable of driving several linear amplifiers. The whole construction is based on the two low-power 2N4427 transistors, which are designed for the...
50 Watt Hi-Fi power amplifier circuit
SGS Thomson's integrated TDA7294 is a high-frequency acoustic power amplifier, with true high-precision specifications, suited for all relevant applications. Its main feature is much higher output power than is usual in amplifiers with similar distortion performance. According to its manufacturer, the output stage of this 15-pin integrated can...
RF Remote Control Switch Rx-Tx circuits
This circuit consists of a 2048 radio remote control transmitter and the corresponding wireless receiver with very high reception sensitivity and low consumption. The combination of the two above gives a high-reliability remote control, ideal for security systems, alarms, automation, etc. At home, in the car and elsewhere. Using the wireless...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial
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