The Panasonic transducers are no longer available, but the design is still interesting as an example. J1 is the connection to the RCX. D1 - D4 form a bridge rectifier to obtain local power from the RCX which is stored on C7 and regulated to 5V by U1, a low power, low dropout regulator. The microcontroller, U3 is programmed to generate a burst of 8 x 40KHz pulses on pin 6. Q1 switches current into L1 creating
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a "flyback" voltage output to Y2, the ultrasonic transmitter, of about 20V peak. The 40KHz is based on a software division of the 10MHz reference (the ceramic resonator, Y1, in this case). Y3, the ultrasonic receiver, is band-limited by L2, to stop normal sound and vehicle vibration from being the dominant input. L2 is chosen to form a resonant circuit with the self capacitance of the receiver piezo. It should be peaked for 40KHz. U2D and U2A are the primary gain stages to get the millivolt level signals up to a couple of volts. Use of a rail to rail amplifier with symmetrical (1/2 rail) biasing makes overload recovery very efficient for large input overloads from very reflective targets. D8 rectifies the returns on C9. D9 generates a exponential waveform on C6 driven from the initial pulse burst. This forms a comparison input to U2B which outputs a logic "1" whenever a return exceeds a range sensitive threshold. This design is only interested in the first return (closest object) since the RCX cannot handle a series of returns from different ranges. Both the analog and logic level returns are input to the microcontroller via analog input pin 7 and digital input pin 4. The current firmware only makes use of the logic input. The microcontroller times the returns and converts them into a varying mark/space squarewave on digital output pin 5. This squarewave is converted to a voltage on C1 and presented to the RCX analog input...
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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