Hello, I have Arduino Duemilanove since one week and I can't solve the problem of transfering analog signal.
I know that this arduino doesn't have analog out pins but maybe there is any other way to solve my problem.
I'm trying to send two or more composite video signals which are analog signal and let the arduino choose one of ther and send to TV.
Something like this:
Can anybody tell me what do I need to do to make this possible ?
Sorry for my english if there are any langage mistakes.
Try interfacing a 4051 analog multiplexer IC to the Arduino (which can switch one of eight signals); the Arduino alone won't be able to do it - see also:
http://www.arduino.cc/playground/Learning/4051
A simple DPDT relay would allow the Arduino to switch between the two video sources.
Lefty
i toss my hat in for the mux also, it may be more complicated to understand (at first) but it seems easier than dealing with relays transistors diodes etc
4051 is a decent choice, the 4052 is similar but its a dual 4 port switch, which I like cause you can use it for 2 signals at once (ie video and audio, or stereo audio)
Can you tell me what kind of relay will be quite small and good enough to to this ?
any relay could work, but most are not going to be able to be directly driven from the arduino (transistors and resistors) + there is the back emf pulse when the magnet cuts off, that could kill your arduino also (diode), I suggest you search the forums for more info (topics about normal motors are the same)
where as a analog mux like the CD4052, you only need to worry about power ground your signal hookups and 2 wires (probably 3 on the 4051)to the arduino to select which channels you want connected in the mux
For security cams and such, you can switch video/audio just with an NPN transistor and resistor.
Here is a simple relay that would work. It can be driven directly from an Arduino output pin without using a switching transistor. You should wire a reversed biased diode across the relay coil terminals.
http://www.allelectronics.com/make-a-store/item/RLY-532/5-VDC-DPDT-MINI-SIGNAL-RELAY-2A/1.html
and you would need 2 at a buck forty each, a CD4051 cost 55 cents at digikey
Im not trying to battle it out with lefty, the mux is a more practical choice from cost to wiring, but its up to you, both would function
and that is a good resource zoom
and you would need 2 at a buck forty each,
Ah, one would accomplish what the OP wanted, to be able to switch betwen two sources to one monitor. The two video sources wire to the NO and NC contacts, the monitor wires to the common contacts. One pole used for the active signal, the other pole for the ground side.
I don't have a problem with anyone building a analog switch, just think the relay is a quicker simpler solution. It's good for the OP to have choices.
I would go the solid state rout for AV switching. Relays tend to degrade and not work well with such low level signals.
The problem in using AV switches is that they tend to be a lot more expensive and involve a lot more construction than a relay. If the op is having to ask such a question I suspect he is not up to the task of making an AV switcher. If he is then a good one is a AK4704.
I bought HCF4051 HTTP 301 This page has been moved
And problem is that TV needs to have camera GND, not board GND.
And second problem, even if I connect camera GND to TV and video through multiplexer the screen is darker and have little interference (very little)
Maxim has some composite video muxes. Sorry, I don't recall the part numbers, but there are 2 input and 4 input models, and unity gain and 2x gain models. They are SMT parts.
Except for the SMT part, they should be as easy to use as the 4051, except they're actually designed for video, so your signal loss should be less.
-j
And problem is that TV needs to have camera GND, not board GND.
This problem is called black level clamping and is caused when the bottom of the sync pulse is a negative voltage and the black level is ground. The way round this is to ac couple the video signal. The use a sync separator and a transistor to short the signal on your side of the capacitor to ground during every sync pulse. This will then allow you to switch both the sync and video signals without affecting the brightness.