So, after yesterday`s post about The Demon Machine I decided it would be fun to play around with the BBC Micro Model B and so I plugged it in and powered up. The familiar two-tone boot sound played and the machine was on. About 15 minutes after power up there was a fizzing, popping sound from the computer and I ran to cut the power. Too late! A pl
Click here to download the full size of the above Circuit.
ume of blue/grey acrid smoke poured out of the left hand side of the machine right by the power supply. I cut the power and moved the machine away from anything that might burn quickly and waited for the smoke to stop. It quickly dispersed and so I did the only thing a self respecting software engineer would do. I decided to turn it back on again. Warning. I don`t recommend that you do this sort of thing yourself. There are high voltages there, plus a bunch of electrolytic capacitors that can do nasty things if they feel like it. I was doing this while wearing my safety glasses. You`ll notice that there doesn`t seem to be anything burnt in the supply and when I powered on the machine worked perfectly. Close examination shows that one of the capacitors used for power supply filtering had cracked open and burnt up. If you look carefully you can see the cracking on the case of the capacitor and fresh capacitor juice running across the circuit board (most visible on the top photograph). A quick Google tells me that this is one of the most common failures on the BBC Micro power supply and easily repaired. It`s interesting to note that the capacitor used is rated by safety agencies because of the potential for failure leading to a short at mains potential and the metallized film is designed to self heal or fail safely. The device is also meant to fail safely at a peak potential of 2. 5kV without burning with a flame. 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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