dbp lists writes: >I've been thinking for a while about setting up my debian box to >record some AM radio programs... sort of a Tivo for radio. A lot of >mp3 players come with FM radio and recording function, but not AM
-------------------------------------------------------------------------------- >So I've been thinking about just using a radio (with AM capability, >obviously) and using an 8mm plug (male conneciton on both ends) and >connecting the output of the radio to the input (microphone socket) of >my soundblaster sound card on my linux box. THen I can use some bash >scripts and "at" commands or cronjobs to record the shows I want. You're almost there. First, be sure the alsa drivers are built in to your kernel and that they are for _YOUR_ particular sound card. Being a SoundBlaster makes life easier for you since there is lots of support for SB's. Second, the Microphone jack is a 3-conductor stereo-type miniature phone plug that is actually used in a somewhat special manner. The tip of the plug is the audio input, all right, but the first ring is a low-level DC power source from your sound card whose purpose is to supply DC to the FET-based preamp in most computer microphones. That gets the impedance down to a lower level for the audio output and amplifies the condenser-type mike element that is in most computer microphones. Also, microphone inputs only need a few millivolts to work, like 3 or 4, and your radio probably puts out that much audio with the volume turned all the way down. If it is a tuner, it will probably be putting out up to 2 or 3 volts which is about 500 to 1,000 times more audio than your sound card's microphone input is expecting and you'll discover that you can't turn it down enough to get good sound without distortion. You can either try to procure or build an attenuator to knock off about 50 DB of output from your radio or you can feed the sound in to the Line inputs on your sound card. That doesn't even require anything but the patch cord. If you get alsa working, your /dev/dsp standard device will work as will amixer and other alsa-compatible programs. A couple of final thoughts. The sleeve or ground connection on your audio card may be common to the case or frame of your computer. This has some safety implications when connecting it up to external devices plus some related sound-quality issues. Sometimes, there will be a little bit of AC power current flow between the Earth ground of your computer and the audio source you are feeding to the sound card. If there is a lot of flow, it can actually be dangerous to you and to your equipment. Usually, however, the effect is to put a hum on the audio that you can't get rid of to save your soul. The fix is to do what the pros do and buy little transformers called audio isolation transformers to go between your sound card and the audio source. If you get a 3-conductor mail to mail patch cord, that would patch a stereo headphone output to the two input channels of your Line inputs. If you can get the level right and there is no hum, you are home free. There's still no way to tune the radio from your computer, but you certainly can use at and cron jobs to start and stop your recording on a schedule. Read the HOWTO's about Linux audio for more good information. Martin McCormick WB5AGZ Stillwater, OK OSU Information Technology Division Network Operations Group -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]