This was my first published article, and fell out of my work on the homebrew 8008 system that is now in the Computer History Museum (that link includes four detailed photos). It`s basically a one-way simple UAR/T, though those devices were pricey back then and the design induces the host micro to wait while a character is sent (an interrupt wou
Click here to download the full size of the above Circuit.
ld be better, of course, but my primitive software wasn`t doing anything else at the time). Of course, now one would eschew expensive external hardware and just use a port bit, but this was 1974 and static RAM locations were a scarce resource. This article had the effect of kindling the crazy notion of writing about my projects, and that became a career. I was 22 at the time, living in an apartment in Kentucky, doing all I could to escape employment. A photo of my living room, including the machine and the amazing Model 28 teletype, is below the article. The lengthy software service routine generally required to interface a teletypewriter and an IC microprocessor, such as the Intel 8008, can be eliminated by the circuit shown here. A shift register and some control logic are all that it takes, bringing total component cost to only about $6. 50. In the 8008 system, synchronization with the central processing unit is accomplished through this microprocessor`s READY line, making modification of the teletypewriter itself unnecessary. The hardware configuration given in the figure is designed for a 10 character-per-second Model 28 Teletype, which uses the five-level Baudot code. If the intended application will not easily accommodate data storage in the Baudot code, conversion may be accomplished with a read-only memory, such as National`s MM5221TM. (A Model 33 Teletype presents no decoding problem. ) During the time that the...
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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