Apr 042017
 
1 Input - 4 Outputs Stereo Audio Splitter

1 Input – 4 Outputs Stereo Audio Splitter

This 1 Input – 4 Outputs Stereo Audio Splitter has a single input and 4 independent outputs, each amplified with an operational amplifier.

Each operational amplifier is configured as an emitter follower, to take advantage of its high input impedance and low output impedance, thus avoiding distortion in sound.

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Mar 282017
 
Audio level indicator using LM339

Audio level indicator using LM339

This audio level indicator using LM339 circuit is very interesting, because it allows us to visualize the audio level intensity by connecting this circuit to the output of a loudspeaker.

The LM339 integrated circuit has 4 comparators that operate completely independently but share the same voltage source.

Mar 212017
 
Logic Probe with 7 Segment Display

Logic point using 7 segment display

This logic probe with 7 segment display is designed with TTL technology and does not use LEDs to display the high and low logic levels found in many of the logical probes on the market. The circuit shows the capital letter “H” when there is a logical “1” or the letter “L” when there is a logical “0”.

Feb 092017
 
Light sensitive alarm using LDR

This light sensitive alarm is very simple and works using, as main components, a transistor, an LDR and a relay.

The alarm activates when the illumination level changes from almost total darkness to a moderately high illumination level. When this happens the alarm is locked and the alarm signal, be it a light or a sound, remains active.