Content for 74HC4515


The 74HC4515 is a 4-to-16 line decoder/demultiplexer having four binary weighted address inputs (A0 to A3) with latches, a latch enable input (LE), an enable input (E) and 16 inverting outputs (Q0, to Q15). When LE is HIGH, the selected output is determined by the data on An. When LE goes LOW, the last data present at An are stored in the latches and the outputs remain stable. When E is LOW, the selected output, determined by the contents of the latch, is LOW. When E is HIGH, all outputs are HIGH. The enable input E does not affect the state of the latch. When the device is used as a demultiplexer, E is the data input and A0 to A3 are the address inputs. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of VCC.

Arduino Typewriter

“I modified a vintage type writer to function as a USB keyboard using an Arduino and 50 phototransistors. The typewriter is a German Olympia Monica that I bought at a local flea market. For this project I created a simple …