Keypad Circuits
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A very simple circuit forexperiments with AT90S2313, 2x16 LCD display and 4x4 keypad. The clock is based on 4 MHz crystal, but you can use any other crystalbetween 1-4 MHz. The keys with the name "A", "B". "F" are typed to the LCD with numbers 10-16. Because.... -
Keypad Controlled Switch No2 Circuit The circuit is drawn with a 12-volt supply - but it will work at anything from 5 to 15-volts. All you have to do is choose a relay suitable for the supply voltage you want to use. Replace the.... -
This is a universal version of the Four-Digit Alarm Keypad. I`ve modified the design of the output section - to free up the relay contacts. This allows the circuit to operate as a general-purpose switch. I used a SPCO/SPDT relay - but you can use a.... -
This is a simplified version of the Universal Keypad-Operated Switch. I have modified the design to reduce the complexity of the circuit - and the number of components required. As a result - the code is somewhat less secure. However, there should be lots of.... -
When a keypad switch is pressed - this circuit will reproduce its value in Binary Coded Decimal from. I`ve used a 12-key pad. But it may be expanded to 16 keys - to provide Hexadecimal to BCD conversion. The circuit is constructed in two parts. There`s a.... -
The prototype of Keypad Switch No. 2 was built using only the Stripboard Layout as a guide. So - if you have faithfully reproduced that layout - you will have a working circuit. Once you`re satisfied that your layout is correct - and you have made a careful.... -
This circuit is designed to operate an electrical door-release mechanism - but it will have other applications. Enter the four-digit code of your choice - and the relay will energize for the period of time set by C4 & R4. Use the relay contacts to power the.... -
Pressing a single key on the keypad - will energize the relay. Entering a four-digit code of your choice - will de-energize the relay. The circuit was designed to control the Modular Burglar Alarm System - but it will have other applications. If you require.... -
This circuit is designed to be used with the Universal Keypad Operated Switch. A few genuine mistakes - made during code entry - will not activate the device. But repeated attempts to find the correct code by trial and error - will cause the keypad to.... -
This is a universal four-digit keypad-operated switch - with a difference. Instead of entering the security code one number at a time - the four keypad buttons must be pressed simultaneously. In other words - the four numbers must be entered in parallel. The.... -
The key you`ve connected to "E" is used to energize the relay. And the four keys you`ve connected to A, B, C & D - are used to de-energize it. All the other keys on the keypad are connected to "F". = When "E" is pressed - current from the "Com" terminal....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
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.... -
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.... -
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.... -
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.... -
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,.... -
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.... -
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.... -
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.....
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