The expansion board had 6, but I didn`t think that 6 servo ports were worth the price of the expansion. I ended up making a fully reversible modification to my handyboard that gave me 16 servo ports costing a total of about $2, two of the motor ports and a digital input. Aservo motor doesn`t just turn when we apply voltage. instead, it is a positional motor -
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it exerts effort to maintain a particular position. We tell it which position by supplying a string of pulses, where the time that the pulse is positive defines the position we want the motor to hold. 0. 8ms is 90 degrees left, 1. 5ms is center, and 2. 2ms is 90 degrees to the right. Digital input #9 is connected to a special pin on the 68HC11. It is connected to a bi-directional timer pin which can have its digital level read, throw an interrupt when it changes and record the time, be a digital output, or make a pulse that goes for a specific length of time (of either polarity), and throw an interrupt when the pulse ends! I did a little bit of maths, and worked out that this timer has a resolution (or accuracy) of 500ns! this means 3, 000 counts for center position - well within our maximum time of 65, 535 counts. The fact that we can ask the 68hc11 to tell us when its done is great too - we can use this to trigger the pulse again without ever having to check if we need to start again! Instead of making the board wait until its ok to pulse again, I wondered if I could get it to pulse a different servo in that time instead - enter the 4514 ic. The 4514 ic basically decodes 4 bits and sends the relevant one of 16 pins positive. Each motor port uses two bits - direction and enable. I decided that I wouldn`t need more than two motor ports, and could use the other two to talk to the 4514. The signals to the L293D are latched...
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....
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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....
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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....
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