Audio Input to trig a relay

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi all

I need to connect a audio input from a laptop to my arduino.

the laptop is not always the same, and that is not possible to install software at the laptop, the laptops is i a car, and supplyed by a 12VDC til 230VAC inverter thats suppply the normal charger to the laptop.

My arduino will be supplyed from the car with 12VDC.

someone told me, to use a op-amp with a optocoupler, and supply it from the USB port at the pc, and then use the optocoupler to trigger a input.

The whole thing is, that i want the arduino to measure the length of the played sound, (between 3 and 6sec, or so) and then trigger a relay output.

It is fore use with som mobile dispatch system, where drive orders is sendt to the pc by GPRS connection, and a ring tone is played when the order cames, but somtimes there is hours between orders, and then the driver must stay in the car to watch the pc, and in the car there is already mounted a auto-pager, (call system) with a usable input. then it is possible fore the driver to leave the car, until 200meters

Anyway.. since iam pretty new to this, i do not now if the way with op-amp and optocoupler is the rigth wany, and also i do not know how to connect it..

Can sombody please help me? how to connect it, what op-amp do i need, and so, om..

If sombody have even better ideas, you are werry welcome

thanks.

Brian, Denmark

2

and that is not possible to install software at the laptop,

So without installing any software on the laptop how do you expect to talk to an arduino?

someone told me, to use a op-amp with a optocoupler, and supply it from the USB port at the pc, and then use the optocoupler to trigger a input.

So what goes into the input of the op amp is it the audio output from the laptop? If so you could use this:-

3

Sorry... I'm just not clear on what you want where....

Please recap the underlying problem, without too much about proposed solutions yet.

I "get" that there is a car with a driver.

The car is receiving messages by a telephone link, and you have a way to connect to the speaker of the "telephone"?

And you want to make a signal go from the car to a driver, who might be having coffee 100 m away from the car?

Where is the laptop? Is that in the car always, or does it go with the driver to the coffee place?

And where would the Arduino be? Does that stay in the car to handle the "come back to the car" message, or go with the driver to receive that message?

and in the car there is already mounted a auto-pager, (call system) with a usable input.

Is this the "telephone link" between the boss who wants to send the driver somewhere and the car? Or a way to connect the car to the driver in the coffee place? Did you mean INput, or OUTput? The "thing" on the autopager: Could you, say, connect it to a speaker to hear a noise, or is it more like something you would connect a microphone to, to feed someting IN to the auto-pager.... this is what I would call an input. If it is an input, what sort of thing would you connect, what would the arrival of something through the input cause to happen?

4

The Car is a taxi, in the car there is a pager system, if the driver revices a drive order from the taxi central, and the driver is not in the car, hes pager is bipping up to 200m away from the car.

On the pagere (transmitter), there is a not-used input (short these and the pager is bipping)

Sometimes, the taxi is driving for the hospital with a doctor for 8 hours, when this happens, the taxi is equipped with a laptop (not always the same, there is several laptops fore use) with a external minitor and keyboard, so the doctor can use the laptop, and the driver also.

when there is no need fore the doctor, he will be leving the car. maybe for hours until the next order.

The order is delivered to the laptop by a internal GSM/GPRS DataCard (internet).

When the pc recives a order, a ringtone is played in the laptops loudspeaker, and the drivers have to call (phone) the doctor, and then pick up the doctor.

sometimes there is hours between the orders, and the driver must stay in the car, to watch the pc. or often tjeck the pc. some of the drives, some of the drivers live nereby the doctor, and want to go home, watch tv, and so on, and not have to go out and tjeck the pc every 5 mins.

Then i think, if the ringtone is trigging a relay, that shorts the pager, the driver will be "bippede" up to 200m away from the car..

-Thats my problem..