At this point you whistle into the receiver and the Infinity Bug will pick up the line. The high-gain amplifier in the Infinity Bug will pick up the audio at the place where it is located. It can only be assembled on the PC board supplied in the kit as the Latching Circuit is already soldered to the board and the project will not work with substit
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ute components. When the Infinity Bug is connected to the line, the "line voltage" will drop to about 36v, due to the current drawn by the bug. This will not upset the operation of the phone system. The bridge on the front-end allows the project to be connected either way around and allows for the annoying feature of some phone lines. They create a voltage reversal as soon as the phone is picked up and this would defeat a Bug that requires a polarized voltage. The only two sections drawing current during quiescent conditions is the whistle-detecting circuit made up of the BC 547 and its surrounding components. This section draws less than 0. 25mA. It is frequency sensitive and will not detect the 33Hz ring frequency. The other section is the "timing section, " made up of the 40106 IC. This is a hex Schmitt trigger (the same as 74C14). When a phone (that is connected to the same line as the Infinity bug) is picked up, the line voltage drops to about 12v and the whistle-detecting circuit does not see any voltage, as the 8v2 zener drops nearly all the available voltage. The transistor amplifies the signal to produce a 2v p-p signal that is turned into a DC voltage by the 10u. This turns on the latch circuit and the base of the BC 639 is raised to produce a voltage on the emitter of about 4. 5v The actual voltage on the emitter of the BC 639 is determined by the 120R in the emitter leg of a BC 547. The BC 547 is almost fully...
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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