Mux Question

[redcrusher]

I am trying to figure out a way to make an AV switch. I decided to kinda tinker around to see what i would do...

I took 2 Mux (74HC151N) and attempted to pass a video signal through it.
It seems to work with an Audio signal ( with static ) BUT not with video AT ALL...

Please help me out here...

The switch i want to make consists of 8 inputs and 1 output...
For the time being, i just want to use RCA.

If you have any idea, please let me know. And i realy want to know why video did not work at all...

--redcrusher

 

[ericgibbs]

I am trying to figure out a way to make an AV switch. I decided to kinda tinker around to see what i would do...

I took 2 Mux (74HC151N) and attempted to pass a video signal through it.
It seems to work with an Audio signal ( with static ) BUT not with video AT ALL...

Please help me out here...

The switch i want to make consists of 8 inputs and 1 output...
For the time being, i just want to use RCA.

If you have any idea, please let me know. And i realy want to know why video did not work at all...

--redcrusher

hi,
The 74HC151 is a digital mux, not analogue.

For analog look at HEF 4051, 4052, 4053 and 4067

 

[audioguru]

74HC4051, 74HC4052 and 74HC4053 ICs are high speed analogue and digital MUX ICs and can also be used.

 

[ericgibbs]

74HC4051, 74HC4052 and 74HC4053 ICs are high speed analogue and digital MUX ICs and can also be used.

hi,
How can a digital mux be used to gate analogue signals.?

 

[audioguru]

The 74HC151 is a digital MUX. The others are analogue and digital MUXes.
An analogue MUX passes digital data perfectly.

 

[ericgibbs]

The 74HC151 is a digital MUX. The others are analogue and digital MUXes.
An analogue MUX passes digital data perfectly.

hi agu,
This is the point I made in my reply to the OP.

The 74HC151 is a digital mux, not analogue.
For analog look at HEF 4051, 4052, 4053 and 4067

I thought you may have a method of using a digital transmission gate for analogue signals.

 

[audioguru]

You can chop an analogue signal with PWM, use a digital MUX on it then smooth it back into an analogue signal.

 

[ericgibbs]

You can chop an analogue signal with PWM, use a digital MUX on it then smooth it back into an analogue signal.

Yes, I know that technique, also works with PCM.

 

[crutschow]

When you pass an analog signal through an analog mux, make sure the plus and minus peak voltages of the signal are within the voltage range of the mux input. Thus if if the mux is operating from a power source that is +5V and ground , then the analog signal may need a DC bias offset so that its limits are within 0V to +5V, since analog signals are often symmetrical ± around ground.