The Test Transmitter (A3020) is a combination of three circuits. Its purpose is to allow us to test the Subcutaneous Transmitter ( A3019 ) and to investigate SAW (surface acoustic wave) VCOs (voltage-controlled oscillators). The A3020 contains the complete A3019 circuit in its center section. The circuit is almost identical to that of the Subcutan
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eous Transmitter ( A3013 ). The most significant changes are as follows. Replace reed switch with Hall Effect Switch. The old magnetic switch was easy to break and large, not to mention its being discontinued by the manufacturer. Magnet turns off all power to circuit except Hall Effect Switch. The transmitter is either ON or OFF. When it`s OFF, the only current drain is the Hall Effect Switch. When it is ON, it is transmitting. Two op-amps used for amplification and filtering instead of three. We reduce the DC gain of the main amplifier stage by adding a capacitor to its feeback loop. The capacitor sets the lower limit of the operating bandwidth at around 1 Hz. Power supply decoupling done so as to favor analog circuits. We use the battery and regulator directly for analog circuits, and supply current to the digital circuits and VCO through resistors that keep transmission noise off the analog supplies. The SAW VCO circuits continue the earlier work we did with our RF Tester ( A3014 ) and RF Combo ( A3016 ) circuits. In the new SAW circuits, we are able to vary the feedback track length in order to provoke oscillations, and we are able to short a stub track to ground in order to cause phase changes. Figure: The A3020A Circuit. The middle section provides the circuit drawn in S3020_1, the test transmitter. The right section, which we have cut off because it is independent, provides S3020_2, the SAW oscillator. The left...
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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