help with s-video 4x4 video matrix switcher

Thread Starter

p4ntb0y

Joined Apr 19, 2011
33
Hi I did it in eagle

been playing with eagle and express pcb.

I am in the progress of redoing my pcb as I can tidy it up more have less jumpers and anyway I got the 4314 layout wrong its SO14 and not a DIP14.
Also I have taken on board what you said about having the ground plane on the bottom of the board, is it good to have one on the top as well?

I just wanted to make sure my circuit is ok.

I have attached a png screen shot.

My head hurts so much reading so much about this! staring at the screen all day and night :(

anyways please let me know if I am on the right track I am a bit worried about pin 12 on the 4314 as I am not sure what this does.

again thanks for your time.

On a side note I was reading sgt wookies posts on 7 Segment leds but I should do one step at a time ;) maybe I can add this in later.

ahh I forgot the 1uf caps on the cd4093.
 

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Ron H

Joined Apr 14, 2005
7,063
You have multiple errors, some of which were a result of errors I made.:(
Attached is my latest version of what I think you are trying to do. Notice that, since the MAX4314 runs on ±5V, the logic gates also have to run on ±5V. The switch common (wiper) must return to -5V, and unused gate input pins must be tied to -5V.
Note also that the MAX4314 has internal feedback resistors, and as such does not have a FB pin.
 

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Thread Starter

p4ntb0y

Joined Apr 19, 2011
33
Many Thanks

I did receive 8x DG540 today thanks to vishay japan :)

So I might try and do the same project with these well I need the pratice :)

I will correct my circuit and pcb layout once finished I will post
 

Kermit2

Joined Feb 5, 2010
4,162
I am still wondering why all this is needed.

You could simply boost the signal going into your current switcher and overcome the degradation problem you have when using all four on the same signal.

They make signal boosters and most have a bypass function(or switch) that lets you turn off the boost without disconnecting the cables. So you wouldn't over drive a single output if you only use one output.

??
 

Thread Starter

p4ntb0y

Joined Apr 19, 2011
33
@ron

sorry i was lookiing at a old schematic

@kermit

if you saw my first attempt you would be horrified hot glue and plastic with cables solder to each other :)

I am just having a bit of a battle with the software to have the least amount of jumps.

I thought it be nice to start me off in the world of trons :)
 

Ron H

Joined Apr 14, 2005
7,063
@ron

sorry i was lookiing at a old schematic

@kermit

if you saw my first attempt you would be horrified hot glue and plastic with cables solder to each other :)

I am just having a bit of a battle with the software to have the least amount of jumps.

I thought it be nice to start me off in the world of trons :)
A 555 flashing an LED would have been a lot simpler.:D
 

Thread Starter

p4ntb0y

Joined Apr 19, 2011
33
:yes it would but i have done this on my iphone :)

I have posted to ask for help with my PCB layout in eagle.

Been doing it all day so I am going to take a rest ;)
 

Thread Starter

p4ntb0y

Joined Apr 19, 2011
33
I have a load of DG540s which I got for free I am trying to work out the datasheet.

I just wanted to know the pin Descriptions like

N1,N2 etc

D1,D2 etc

S1,S2 etc

maybe I am being a bit thick.
 

Ron H

Joined Apr 14, 2005
7,063
It seems to me that crosstalk would be lower if you connect the video inputs to the D pins, and connect all the S pins together for the output. The IN pins are the switch controls.
 

Thread Starter

p4ntb0y

Joined Apr 19, 2011
33
Ok

D1 -D4

Are the switches to turn on my video output yeah?

looking at the truth table Logic "0" off will be zero on anything less than 0.8v
Logic "1" on will be anything more than 2v

so I have a quad nand gate cd4093 so each gate will go to each D pin to turn on or off the video is that right?

so I just need to work out the math for the rotary switch to the chip using the nand gate.

feel free to punish me for being a noob
 

SgtWookie

Joined Jul 17, 2007
22,230
On your schematic, you are not using junctions. Junctions need to be used when one wire connects to/terminates at the middle of another wire, or when two wires connect at a pin. Apparently, you don't know about the Erc function; there are buttons on the toolbars to run Erc in the schematic (see near the bottom) and Drc in the board. You need to make Erc happy before starting a board. This means getting rid of all of the errors by fixing them. If you have errors and try to create a board, you will not have the air wires that you need. Use Erc early, and use it often. Don't wait until you have a bunch of errors, or you will get burned out trying to fix them all.

You show +5v and GND symbols, but you do not have them connected to either wire pads nor some type of off-board connector. Unless you add them, you will not have an easy way to connect Vcc and GND to your circuit board.

You are using 4093 CMOS IC's. Usually, the library models use Vdd for +5v. If you don't have a Vdd symbol on the schematic somewhere, the power to the IC won't get wired up.

You also need to find out what the power pin on the MAX4311 is labeled as.

You can't have more than 1 signal on a wire, so you can't connect Vdd, Vcc, and 5+ all together. You need to use 0 Ohm resistors or solder jumpers to connect the same voltage but different signal names together, or you will have problems.

In your schematic, try to run wires most of the time either horizontal or vertical. If you really have to go at angles, try to just use 45° off from horizontal or vertical. Wires at odd angles make your schematic harder to read.

Below IC2N1 (your MAX4311) you have two capacitors; the reference designator (name) fields are overlapping so I can't tell for certain what they are. The one on the right is connected to +5v on one end, but the other end is not connected to ground.
 
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