A newer version of this circuit board is available. Rev 4 includes a faster CPU, more memory, more I/O and an optional LCD. We recommend you use Rev 4 for new projects. Even though this older board is no longer available, we are keeping these old pages on-line for reference to assist people who purchased or build the older version. This i
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s the complete schematic for the development board. Address and Data bus wires are drawn separately (not in a bus), so that it`s easy to color over them on a printout, if you choose to manually connect the wires. It really is easier to buy a bare circuit board, though. This design and its schematic have been placed in the public domain. They are distributed in the hope that they will be useful, but are provided without any warranty, not even a warranty of merchantability or fitness for a particular purpose. The address bus in this schematic is connected in an unusual way, which is optimized for simpler point-to-point wiring. For anyone building the board using wire-wrap or hand soldered point to point construction, this wiring scheme makes for much less clutter in the wiring if the chips are positioned similarily to the layout on the printed circuit board. Very few wires cross over one another. This also makes the PC board layout a bit simpler, allowing wider traces and fewer vias. This unusual address bus wiring works. The 74HC373 chip (U2) is 8 identical flip-flops, so it does not matter which one is used for each line. On the RAM (U3) and Flash ROM (U4) chips, all data that is stored in these chips is written by the 87C52 chip (U1), so it does not matter which physical location within the chip is mapped into each location within the CPU`s address space, because each read from these chips will return the same data that...
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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