More about phone (291)

1-07-2005 | Many ‘busy’ indicators for use in telephone systems present undesirable loading of the telephone line. Some circuits are very simple indeed...

1-07-2005 | After buying a number of DECT telephones, we noticed that these became quite warm while charging. That surprised us, because the manufacture...

1-07-2005 | The technical demands on microphones used with radio equipment are not stringent in terms of sound quality: a frequency response from around...

1-07-2005 | Designs for good-quality headphone amplifiers abound, but this one has a few special features that make it stand out from the crowd.We start...

1-07-2005 | The main ideas behind the lock described here are minimum obtrusiveness and minimum user interface.A typical code lock is operated with a fo...

1-07-2005 | Circuits have been published on earlier occasions that keep an eye on the telephone line. This simple circuit does it with very few componen...

1-02-2005 | When the ISM frequency band was made available in Europe for audio applications, Circuit Design, a manufacturer of professional RF modules,...

1-09-2004 | Bluetooth is a huge commercial success but so far hobbyists and lab workers have been barred from access to ready-made modules for this wond...

1-01-2004 | A headphone amplifier with outstanding sound quality can be built using readily available modern components. Omitting the output transformer...

1-12-2003 | Depending on local regulations and the telephone company you happen to be connected to, the voltage on a free telephone line can be anything...