One of the most important problems of mobile robot platforms is associated with the power supply. With exception of some special systems, batteries, dry or rechargeable, are the most commonl... Read more
This circuit performs a similar function to the ‘sleep’ button on a radio alarm clock; pressing the button connects the battery supply to some external equipment or circuit (represented by R... Read more
The adjustment control for the contrast of an LC-Display is typically a 10-k potentiometer. This works fine, provided that the power supply voltage is constant. If this is not the case (for... Read more
The technical demands on microphones used with radio equipment are not stringent in terms of sound quality: a frequency response from around 50 Hz to 5 kHz is entirely adequate for speech. F... Read more
After buying a number of DECT telephones, we noticed that these became quite warm while charging. That surprised us, because the manufacturer wrote in the manual that the batteries had to be... Read more
It sometimes comes as a bit of a shock the first time you need to replace the batteries in an LED torch and find that they are not the usual supermarket grade alkaline batteries but in fact... Read more
Professional (directional) microphones often require a phantom supply of 48 V. This is fed via the signal lines to the microphone and has to be of a high quality. A portable supply can be ma... Read more
This circuit was developed to power an AVR microcontroller from a 12 V leadacid battery. The regulator itself draws only 14 μA. Of course, there are dedicated ICs, for example from Linear Te... Read more
This small but very effective circuit protects a lead-acid battery (12-V solar battery or car battery) against overcharging by a solar module when the incident light is too bright or lasts t... Read more
Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver te... Read more
