A battery charger is nothing more than a constant current source connected in series with the battery you want to charge. Nicad small batteries have load currents of 15 mA to 45 mA, depending on the size and type. In most of them, indications of charge current and time are recorded in the enclosure itself. The circuit shown in Figure 1 is a constant current source which serves precisely for this purpose.
A system, based on a piezoelectric transducer, can generate enough power to power a small wireless sensor system. This article is from 2007.
Response speed, sensitivity and immunity to external factors, such as pollution, are some of the characteristics of Hall sensors that make them ideal for critical applications. Learn in this article the TLE 4921-3U.
Here is a device that the modern detective or spy who deals with documents and money: a fake documentary and money detector with ultraviolet radiation.
The detective or spy may feel the need to protect some object with some kind of electric shock that is both strong and harmless at the same time. The circuit we describe can be triggered to any type of sensor or even activated by a reed-switch when the object is removed or if it tries to do so.
Taking advantage of the notions that we had in our book Electronic Course, of the configurations of the transistors, we can elaborate a simple amplifier of audio. Its performance is not comparable to the best hi-fi amplifiers, but it can be used as a stage for radios, intercoms or as benchtop amplifier.
This circuit uses a sensitive reed relay to control external loads. The time delay is given by the...
This circuit was found in an old publication about transistor. The original trasistors are...
This conventional astable uses two NPN transistor and was found in a publication of the year 1968. The...
This basic configuration of an astable multivibrator was found in a publication of the year 1968....
This oscillator can run in frequencies up 10 MHz depending on the Power supply voltage. The 1 µF...
This one-digit counter is part f the samples bench of the MultiSIM in one of its versions. The...
This simple timer can be used in many applications such as egg timer. The LED glows up when S1 is...
The circuit shown by the figure below can produce signals in the range between 20 kHz and 30 kHz....