I recently purchased an Antari z-800ii fog machine that comes with a push button remote that connects via a 1/4" stereo cable. The current button is a depress to close, depress to open style switch. I'd like to modify the function by having it close for a specified amount of time (maybe 5-7 seconds) when a button us pushed.
I guess the root of my question is: can I use my Uno to close a circuit for a specified amount of time without putting power to the circuit?
You would still have to power the Arduino.
Not sure what you mean about putting power to the circuit. Additional power? Then no.
But yes, Arduino can be used to open and close that circuit in any fashion you please.
First step is to get a multimeter and see what voltage and current is getting passed across that button.
I guess the root of my question is: can I use my Uno to close a circuit for a specified amount of time without putting power to the circuit?
Yes. A relay is an electrically-isolated, electrically-controlled switch so a relay is a perfect replacement for a manual switch, especially if you've got an unknown circuit..
You generally need a transistor or MOSFET to drive the relay coil (the relay "input") because the Arduino can only put-out 5V at 40mA or less and most relays require more than 40mA, and relays with 5V coils are not as common as 12V coils. (You can drive a 12V relay with the Arduino using a transistor/MOSFET, but you'll need a 12V power supply.)
They make relay driver boards/shields for the Arduino that include the driver circuit and those are easier to wire-up, especially if you're new to this stuff.
A relay has to two "ratings". There's a voltage & current rating for the coil and your power supply has to supply "exactly" the rated voltage and it has to supply at least the rated coil current (which usually isn't much and usually not an issue).
The contacts also have a voltage & current rating, and in this case these are maximums. i.e., The relay contacts may be rated for 220V and 10 Amps, and it would be OK to switch 12V at 1 Amp.
Are there any voltage & current ratings on the manual switch? I'd imagine it's low-voltage & low-current, so just about any relay would work, but it would be better if you know what you're starting with. (The switch may be over-rated too... It might be labeled as 120 or 220VAC, but I'm sure there are no dangerous voltages coming out of that 1/4" plug.)
connects via a 1/4" stereo cable.
If it's really "stereo" (a 3-conductor TRS plug) you'll have to figure-out the connections. Do you have a multimeter?
Optocoupler does what a relay does and is a better option if it's just a signal current. Bit brash to jump headfirst into a bulky relay solution when it could be unnecessary.
INTP:
You would still have to power the Arduino.
Not sure what you mean about putting power to the circuit. Additional power? Then no.
But yes, Arduino can be used to open and close that circuit in any fashion you please.First step is to get a multimeter and see what voltage and current is getting passed across that button.
I understand I'll have to power the arduino; sorry for not being more clear.
I checked the button and it looks to be 12v DC. Are there any the built-in examples that would be a good jumping off point for this project?
DVDdoug:
If it's really "stereo" (a 3-conductor TRS plug) you'll have to figure-out the connections. Do you have a multimeter?
You are correct. it is a mono-cable, not stereo. Looks just like a guitar cable.
The very first example pretty much everyone sees, Blink, is the core.
Then a button example. The rest is hardware.
You measured voltage, but also need to know current (amps/milliamps)