The simple conjuring trick in Figure 1 is intended to provide some enjoyment for the beginner in electronics or conjuring, and should take only an hour or two to build. The trick works as follows: a wand (with a magnet mounted in one end) must pass in a 1-2-3 sequence over reed switches S4 to S6 before the bulb LP1 will light. If the wand passes o
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ver reed switches S1, S2, or S3, the 1-2-3 sequence will be reset (that is, cancelled). Or, if the bulb is already burning, the activation of reed switches S1, S2, or S3 will extinguish it. All the reed switches - S1 to S6 - are glued just beneath the surface of a 10 cm² box (Figure 2). A general purpose adhesive is suggested, so that the reed switches may later be moved if necessary. The bulb, LP1, is mounted in the centre of the box. A small PP3 9V battery may be used. The prototype box was built using balsa wood. The wand may be waved back and forth in various motions over the box, on condition that it finally passes in the correct 1-2-3 sequence over S4 to S6 (at which point LP1 will light). This should thoroughly confuse any onlooker and make it virtually impossible for another person to repeat the correct motions with the same wand. The wand may also be lifted just high enough over reed switches S1 to S3 so as not to trigger them. The operation of the circuit is fairly simple. Three AND logic gates of a 4081 CMOS IC are employed, with gates IC1a to IC1c being configured as a standard cascaded latch circuit. S1 to S3 serve as reset switches. The output at pin 10 will only switch to logic high when reed switches S4 to S6 are closed in sequence. Power transistor TR1 amplifies the output current to light bulb LP1. In "stand-by" mode (with the bulb extinguished) the circuit will use very little current. Therefore a...
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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