Doorbell Circuits
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Sometimes you have to do it the hard way, even if doing it the easy way is an option. That is the case here. The intention is to add a second doorbell in parallel with the existing bell. This does not, in principle, require any electronic components. You.... -
If you`re expecting an important visitor but you just have to step out for a moment, an electronic doorbell memory can come in handy so you can see whether someone rang while you were out. Of course, you can`t tell whether it was the visitor you were.... -
.jpg "Remote Doorbell Controller")
I usually can`t hear the doorbell when I`m in the basement. This project describes how to add an inexpensive remote doorbell to your existing household doorbell. My doorbell runs off of a 24VAC transformer that is live all the time. Someone presses the.... -
When you press a start button, the arduino picks a random 4 diget code and flashes lights to show the code. When you repeat the code in the other buttons, the XBee will send a message to the other XBee, which will ring the bell. int bell=5; void setup(){.... -
Timing doorbell circuit with CW9300: As shown is Timing doorbell circuit diagram with CW9300. It has timing function, when we push the button,it will play musicforsome seconds, if we re-push the button immediately after loosing it, the doorbell will not ring.... -
As the figure 15-24 shows, the controller circuit is composed of the switch type Hall integrated circuit DN838 and the astable multivibrator (composed of the 555), this circuit can be used in wide range of applications such as the automatic door opening,.... -
As the figure 15-22 shows, the doorbell is composed of the monostable timing circuit, the password switch, the NAND gate circuit and the sound circuit.etc. In the limited time, the circuit uses the program to press the password switch, the doorbell circuit.... -
Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply. IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate.... -
Use the 48V (60V) DC feedback electric current which is provided by the phone feedback line as the working energy of the electronic doorbell is very economical and practical. Now I introduce one kind of two-tone doorbell circuit with out battery. The circuit.... -
The ding-dong electronic doorbell circuit is composed of the power supply circuit, trigger control circuit, audio oscillator output circuit, and it is shown in Figure 3-125. Power supply circuit is composed of the power transformer T, rectifier diodes.... -
The inductive electronic doorbell circuit is composed of the inductive electronic switch and music generator circuit, and it is shown in Figure 3-115. Inductive electronic switch circuit is composed of the inductive electrode A, transistor Vl-V4 and the.... -
The password electronic doorbell circuit is composed of the electronic password circuit and music occurred circuit, and it is shown in Figure 3-118. Electronic password circuit consists of integrated circuits lCl and keys Sl-S6, diodes VDl-VD5. lCl is the.... -
The password electronic doorbell circuit is composed of the trigger circuit and music generating circuit, and it is shown in Figure 3-119. Trigger circuit is composed of the buttons S1-S9, four NAND gate Schmitt trigger integrated circuit IC1 and the.... -
The electronic doorbell circuit is composed of the pickup amplifier, monostable trigger circuit, pulse counter circuit, music generating circuit and audio amplifier circuit and other components, and it is shown in Figure 3-113. Pickup amplifier circuit.... -
The politely welcoming electronic doorbell circuit is composed of the trigger control circuit, audio amplifier output circuit, music circuit, voice delay control circuit, and it is shown in Figure 3-122. Trigger control circuit is composed of the doorbell.... -
The three-tone electronic doorbell circuit consists of buttons Sl-S3, transistors Vl, V2, speaker BL, resistors Rl-R3, capacitors Cl, C2, diode VD and battery GB, and it is shown in Figure 3-109. Rl-R3 use the 1/4W carbon film resistors or metal film.... -
The three-tone electronic doorbell circuit consists of the coding triggered circuit, multi-tone generator and audio amplifier circuit, and it is shown in Figure 3-110. Coding trigger circuit is composed of the buttons Sl-S6, two four-input AND gate (DI, D2).... -
The two-tone electronic doorbell circuit is composed of the input trigger circuit and audio output circuit, ans it is shown in Figure 3-107. The input trigger circuit is composed of the doorbell button S, transistor V1, resistors Rl-R3, capacitor Cl and dual.... -
The two-tone electronic doorbell circuit is composed of the trigger control circuit and doorbell generating circuit, and it is shown in Figure 3-108. Trigger control circuit consists of doorbell button S, resistors Rl-R3, electrical wear devices Cl-C3,.... -
Transmitter: Pressing the SB will make the transmitter circuit work. D1, D2 and R2, R3, C4 constitute a low-frequency oscillator to control the audio oscillator composed of the D3, D4 and D5, D6, then it works alternately. The generated audio signal is added.... -
The doorbell operates on the 303MHz band and the 30 metre range (100ft) is obtained without the use of an antenna! The circuit is actually radiating from the printed track of the tank circuit. The Tank Circuit is a single-turn coil and a small capacitor (5p.... -
This circuit uses a synthesized sound chip from Holtek, the HT-2811. This reproduces the sound of a "ding-dong" chiming doorbell. Additionally, the circuit includes a CMOS 4026 counter display driver IC to count your visitors. The Holtek HT-2811 is available....
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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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