Archive for July, 2008
uA739 datasheet specifications
uA739 and uA749 are dual audio operational amplifier/preamplifier and consists of two identical High-Gain Operational Amplifiers constructed on a single silicon chip using the Fairchild Planar epitaxial process. This 3-stage amplifiers use class-A PNP transistor output stages with uncommitted collectors. This enables a variety of loads to be employed for general purpose applications from dc [...]
Dynamic mic preamplifier
This mic preamp uses the low noise IC uA739. The circuit is an example of how a good preamplifier can be designed for dynamic microphones. The IC houses two identical integrated preamp circuits. The second preamp is used in identical manner for the second channel of the stereo microphone.
Diagram bellow shows the pin numbers (in [...]
Cardiophone
The human heartbeat can be made audible by using this cardiophone circuit. It is basically an audio circuit coupled to a probe made specially for the purpose of picking up electric signal from the human heart.
To get the best signal, place the probe’s electrodes to a point close to the heart. The preferred point is [...]
