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8051 / 8052
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555 Timer Circuits
Remote Control Toy
H Bridge Circuit
Interconnection & Timing
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Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
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...
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...
Telephone electronic lock circuit
Electronic lock using the telephone key (resistor connected plug) is inserted after the oscillator circuit start-up circuit, and the oscillation frequency is accurate or not to
Three-dial combination lock
Here's an effective little combination lock that you can put together in one evening's time. To open the lock, simply dial in the correct combination on the three rotary or thumbwheel switches. With the correct combination entered, current flows through Rl into Ql's gate terminal, causing the SCR to latch in a conductive state. This sends a...
Electronic combination lock
When button S12 (#) is pressed, a positive voltage fed through Rl appears at the base of transistor Ql, turning it on. When Ql is conducting, pin 1 of Ul is brought to ground 0ow) or the battery's negative terminal. With pin 1 low, two things occur: Pin 8 of Ul goes high ( + 9 volts dc), turning on LED 1â€”indicating that the circuit has been...
The door opener derives its power from a 9-V battery. A momentary-contact switch, 52, is provided in the event that manual opening and closing is required. Relay Kl is a 9-V type and relay K2 is a 117"Vac latching-type, which automatically latches with the first burst of current and opens on the second burst. The gate lead of the LASCR is...
Digital Entry Lock
A keypad enters a four-digit access code, which is programmed via jumpers on a 24-pin plug-in header and socket. Ul is a
The circuit uses a four-bit latch (Ul). What makes the circuit sequential is that the set input of the first bit latch is tied
Digital Entry Lock Circuit
A block pinout diagram of the LS7220 keyless-lock IC is shown. The keypad must provide each key with a contact to a common connection. In this case, the common connection goes to the positive supply rail so that when a key is pressed, a positive voltage is passed through to the wire associated with that key. Each of the 12 keys are brought out...
Simple lock circuit can alarm
Circuit works: Figure 5 -2a in S. Alarm switch. If you press S, after the relay K. Electrical work, two normally open contacts Pull,
Secure lock circuit (CD4017) schematic
Circuit as shown by the two and four decimal counter CD4017 password switch composed by the output terminal of the key switch logic combination of components to another feature of the electronic code switch.
Enhanced AE1169 made lock circuit diagram
As shown in Figure is a circuit diagram of an enhanced lock the AE1169. AE1168 enhanced when the lock button is pressed, AE1168 through the keyboard scan to determine the corre
Super lock circuit diagram
As shown in the lock circuit by a decimal counter CD4017 composed by ten its output terminal is connected through a combination of the number of passwords the group consisting
Electronic lock using the 4022 octal counter
The heart of the lock is the 40022 octal counter. When first powered C2 is charged via R5 so the reset input of the counter is kept high. That causes output Q to go high while all the other outputs are low. With the switches wired as shown, when S4 is pressed, the BS170 mosfet is switched on via debouncing network R2/C1, and the 4022 recieves a...
This circuit emits a beep and/or illuminates a LED when someone touches the door-handle from the outside. The alarm will sound until the circuit will be switched-off. The entire circuit is enclosed in a small plastic or wooden box and should be hanged-up to the door-handle by means of a thick wire hook protruding from the top of the case. A...
Electronic combination lock with PIC
This is my electronic combination lock to use with an outdoor gate. The functionality is implemented in software. It turns on a relay (usually to open a door) for a few seconds if someone enters the valid code. This relay can operate a power-to-open type electric strike with a shorting contact or a power-to-hold type electromagnetic lock with a...
Digital Code Lock with 555
A low-cost digital code lock circuit is presented in this article. Here the keying-in code is rather unique. Six switches are to be pressed to open the lock, but only two switches at a time. Thus a total of three sets of switches have to be pressed in a particular sequence.
Combination Lock Circuit
This circuit is very basic to build. To open a the lock which is connected to the K1 Load you must press each momentary switch in the correct sequence. The sequence used in this circuit is S1,S2,S3,S4. If any of the other switches are pressed the circuit will reset and you will need to start over. Depending on how you wire the switches, you can...
Simple Code Lock circuit
The circuit described here is of an electronic combination lock for daily use. It responds only to the right sequence of four digits that are keyed in remotely. If a wrong key is touched, it resets the lock. The lock code can be set by connecting the line wires to the pads a, b, c, and d in the figure. For example, if the code is 1756, connect...
Door lock Circuit
This circuit can be used to operate an electric strike or an electromagnetic lock on a door. It is not the door being opened/closed, but a small electromagnetic strike which unlocks the door. The opener has the following features currently programmed in software:
CodeLock AVR electronic combination lock is realised with Atmel AVR microcontroller AT90S2313 or ATtiny2313. Program in hex code is 2 kB long. User code is consisted of 1 to 4 digits. If you buy the chip than user code is consisted of 1 to 8 digits. If the code is entered in the correct sequence, then after 1 second the relay and the electric...
Card Lock System
The circuit presented here can beused as a lock for important electronic/ electrical appliances. When card is inserted inside its mechanism, depending upon the position of punched hole on the card, a particular appliance would be switched on.
Password Based Door Locking
Security is a prime concern in our day-today life. Everyone wants to be as much secure as possible. An access control for doors forms a vital link in a security chain. The microcontroller based Door locker is an access control system that allows only authorized persons to access a restricted area. The system is fully controlled by the 8 bit...
Digital code Lock with AT89C2051
Security is a prime concern in our day-today life. Everyone wants to be as much secure as possible. An access control for doors forms a vital link in a security chain. The microcontroller based digital lock for Doors is an access control system that allows only authorized persons to access a restricted area. The system is fully controlled by the...
The simplest Electronic Door Lock
To put the relay in tension the 4 buttons S1 S4 must be pressed. If anyone of the 4 butoons S5 S8 are pushed the relay donts tension ( dont receives supply voltage ). The supply voltage must be equal to the working voltage of the relay. One transistor like BD135 can commute up to 0.5A, in the same tine 2N2222 can do only 0.2A.
iButton DS1990A Lock
This electronic lock can be used with any type of iButtons you may already have, since the only thing needed is the internal serial number, that's different for every iButton. The command used to read the serial number is the same for all iButtons. The iButton family code that goes with every iButton, can be anything and is calculated as part of...
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...
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...
Programmable Code Lock circuit
A programmable code lock can be used for numerous applications in which access to an article/gadget is to be restricted to a limited number of persons. Here is yet another circuit of a code lock employing mainly the CMOS ICs and thumbwheel switches (TWS) besides a few other components. It is rugged and capable of operation on voltages ranging...
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...
1 button Security locking circuit
The Button Code is a system that allows a single button to act as a keypad. The user enters a 4 digit code into the system using button taps. The button can be placed where the public can access it since like a keypad there are many combinations to keep guessers from activation the system. When the correct code is entered a form-C relay is...
Surveillance Bug 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
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