I want to make a circuit which inputs a 4 bit number from a parallel port, into a 74HC15N multiplexer (4 to 16 decoder) and the activated output pin will switch on an LED, via a transistor.
I have made the parallel port output a controlled binary number and the multiplexer is responding correctly by making the selected active output low and all others high.
However, the Multiplexers output voltage and current is unpredictable because it is being influenced by the 4 parallel data input signals coming from the connected parallel port.
Should only the supply signal be affecting the Multiplexers output power?
I have made the parallel port output a controlled binary number and the multiplexer is responding correctly by making the selected active output low and all others high.
However, the Multiplexers output voltage and current is unpredictable because it is being influenced by the 4 parallel data input signals coming from the connected parallel port.
Should only the supply signal be affecting the Multiplexers output power?
