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Topic: Need a small program written (Read 2078 times) previous topic - next topic


I imagine this should be quite easy for someone with experience.  I have an Uno, but I am unfamiliar with programming it.

I would like use the Uno to take the place of two switches for two different devices that I want to start simultaneously.

The first switch when closed sends a 3v signal for 3 seconds.  It is open by default.
The second switch is closed by default with a 3v signal (the circuit opens when the switch is pressed).

The input to the Uno would be a momentary switch as 'start'.  Maybe a half second at most.

When the input signal occurs it should output a 3v signal for 3 seconds on one output.  On the other output, it should output a 3v signal until the input signal occurs.  Then it should stop sending the signal for a 1/2 second before resuming.

This project is for non-profit use; your generosity would be appreciated.  Let me know if there are any questions.


I imagine this should be quite easy for someone with experience.  I have an Uno, but I am unfamiliar with programming it.

I hope this doesn't sound too rude - but why don't you experiment with it yourself?

Have you even tried?  :smiley-slim:


The USO is a 5V device. It can output 0V or 5V. Nothing else. Using a PWM pin, the UNO can toggle that pin on and off, relatively quickly, so that some devices like LED and motors think that they are getting 3V. But, at no time does the Arduino output 3V.
The art of getting good answers lies in asking good questions.


Normally I would, but I do not have the time.


As PaulS said, a 3V output is not the usual thing. If you can tell us what the 3V signal is used for, and how much current is required, then it may be possible to make some suggestions.


Sounds like two relays controlled by and arduino could accomplish that task even without having to understand all the electrical properties of the circuit being controlled. First relay's contacts would wire in parallel with the first switch and the second relay's contact would operate in series with the second switch.



What I was trying to do was simultaneously send a signal to a start gate and a timer used on a pinewood derby track.  As of right now I don't have a way for them to talk to each other.

The start gate switch plugs into a selenoid unit and sends the 3 second signal which fires the selenoid for that amount of time, allowing the cars to clear the gate before it goes back up.

The timer is a Newbold DerbyStick which has a trigger switch.  As an update to the original post, the timer sends the 3V on the line and the switch breaks the connection, which signals to the timer to begin.

After thinking about it, I thought that perhaps it might be simpler if the Uno was programmed to be the timer itself and also sent the signal to the start gate.  I don't know but suspect that the selenoid unit might be fine with a 5V signal.

I did find at least one person who was working on using the Uno as a timer, and so the code that he had looks like a good start.

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