A radio that was stored for years on a dusty shelf must be awakened gently to return to its reliable operation and provide us with warm and pleasant sounds for years to come. Here are few generic notes on how a radio can be easily returned to life. Of course, more details can be found looking at each specific model. In addition to common tools, as screwdrivers,
Click here to download the full size of the above Circuit.
pliers, soldering iron and some brushes, we need few basic instruments. Some of the types, commonly in use in the past, are no longer manufactured. Some of the instruments still in production today can be more or less unsuitable for vacuum tube sets, where voltages could well be in the order of several hundreds volts. Anyway in many cases, old instruments still operating can be easily find at reasonable prices. Here an overview of instruments usually found in old service shops and their usefulness. A step-down transformer, a Variac or even an incandescent lamp, to reduce the mains voltage during the early power-on, is the most useful tool. The step-down transformer is to be preferred when servicing radio sets with chassis directly connected to the AC mains. When a transformer is used, a 2 to 1 voltage ratio can be selected. We will start at half voltage and switch to the full voltage after the reforming of filter capacitors. A soft start-up procedure is advisable even for radios already serviced in the past, if left inoperative for several months or years. Most of the digital multimeters, today available, have high input impedance, in the order of 10 Megaohms. and are suitable to measure voltage and resistance inside our radio. Unfortunately the voltage range of modern multimeters is limited to few hundreds volts, unsuitable for some old electronic sets. I burned some digital multimeters, attempting to calibrate the HV...
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.....
characters left: