This circuit uses a conventional spring loaded mouse trap, available from hardware stores. However when a mouse is caught, the circuit triggers and transmits an interrupted tone on the commercial FM band to a nearby radio receiver. This circuit is a small battery powered transmitter which is activated by vibration from a mechanical mouse trap. Thi
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s can be done using a microswitchpositioned so that the circuit is off (not transmitting). When the mouse trap is triggered the microswitch lever is moved and activates the transmitter. The transmitter is a standard hartley oscillator, designed to transmit across the FM band approximately, 87 to 108MHz. The transmit frequency is adjustableby means of trimmer C8. The combined capacitance of C4 plus C8 and L1 set the resonant frequency. IC1 is a CMOS quad 2 input AND gate. Gates U1a and U1b create a square wave astable oscillator ofabout 2Hz. The output of gate 1b is wired tothe input of gate 1c. Similarly gates 1c and 1d form another astable oscillator, this time about 2kHz. The 2kHz oscillator is activated only whengate 1b is high, all gates forming and interrupted oscillator. The tone of this oscillator is adjustable via the preset R2. The output of the oscillator now directly drives the transmitter comprised of Q1 and associated components. The transmitter will be on when the output fromgate 1c is high and off when gate 1c is low. As the input signal is a sqaure wave, there will be some cross modulation and the transmitter signal willbe heard at more than one point across the FM band. As the output power is limited, this is not really a problem and with just 5 inches of wire as anantenna, I could hear the transmitter with an ordinary radio 15 metres away. The antenna is connector to Q1 collwctor and will work with just 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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