audio sensor project design thoughts

Holy shit, just hook the amp's remote wire up to an accessories wire, and wire the power to the battery (fused). Or wire both pwr/remote to accessories, like mine are.

Wayy too much effort there for a simple result!

For the record, my amps are wired directly off the accessories, with a bridge between Pwr & Remote on the amps. And i'm only running a 30a fuse where a 50a should be for the 'main' accessories fuse - no problems whatsoever so far. Blew a fifty, had a thirty so rigged it up, never got around to putting the new 50 in as it's working fine.

Basically wired it like that due to the pain-in-the-arse factor of running a single wire to the amps after i'd put all the trim back in and the dash back together.

-mark

to drive the optocoupler LED at low volume directly.

so the amp is not needed at low volume ?

a diode across the opto diode to protect against reverse voltage is also needed

back

I was going to do that but I would slightly miss out on some of the functionality of the radio. The radio is able to be turned on without the accessories on, and I would still like the amp to turn on at this time as well. (sorry to be picky)

enough

needed

I'd still like the amp to be on at low volume.

I thought that the opto diode would not need another diode to protect it. But I'll wack it in anyway, thanks.

Then how about a current sensor on the radio +ve? 'standby' and 'on' will have substantially different draw levels, should work a treat and be a bit simpler than the speaker output.

I've got my accessories hooked up to both the ignition and a seperate switch, so I don't need to leave the keys in for the radio on... perhaps you would be better off with the switch? didn't bother me all that much when my amps were hooked up thru a seperate switch, good for h/free phone calls and the like - quick whack and silence!

-mark

... Second thoughts, why not wire up that convenient switch you have via a relay to turn the accessories on/off? Should be cheap, quick and easy to do.

-mark

Does the stereo have a wire for a power aerial, if so use that to power the amp whenever the stereo is on. Regards John

What about when he's listening to CD?

They generally only have power down them on Radio... at least, all the ones i've come across have only had power on radio, stock and aftermarket.

-mark

Thanks all for your thoughts. They are all valid thoughts but not suitable for my needs. I should explain myself a bit more. The player that I have in the new car is an integrated unit. It has wired in controls on the steering wheel, and uses the dash display to display the MP3 info and Radio info. The CD drive is separate and fully moulded into the center console with no display at all.

The car is fitted with dual air bags, and is only two weeks old, so I don't want to take the whole dash assembly apart to find out exactly what the connections are between the screen, steering wheel, and integrated dash readout are. I have a feeling in any case that this would be time wasted, as if there was provision for an amp remote, it would have already been wired out of the console to a place where it could be accessed. The manual makes no mention of this, so my best bet is that it is not there.

The antenna is a fixed antenna on top of the car, so no possibility of using an auto antenna wire.

The remote switch that I currently have is not actually a remote switch. It sits in the boot, so I have to open the boot to turn on the amp (and remember to turn it off !!)

So since I have the power cables, and speaker connections where I want them (in the boot), and I have limited means of wiring any more cables, I was thinking of a system which would simply sense whether audio was being played through the speakers, and turn the amp on/off accordingly.

While tapping into the accessory wire may be physically possible, I'd prefer not to, as these new vehicles are quite complex little beasts. There is excellent functionality built in but adding a trick such as inducing power down the accessory wire might cause more problems than it solves. For instance, currently, if I turn off the ignition with the key, but keep the key in the ignition, the radio keeps playing. Only when I remove the key does the radio stop playing. (nice little feature) Also, as I mentioned earlier, even with no key present, I can still turn on the radio, and it stays on for an hour. Gone are the days of simple "off" "acc" "on" states.

Just out of interest, I might state that the power windows have some tricky little power control features themselves. For instance, they do not move when the key is out of the ignition, but if you have set them to go up, and then take the key out of the ignition, they continue to go up till fully closed. It's not a simple timer. It is all individually controlled by the onboard computer.

The main thing is that I really would not want to muck with the cables. I think I have all that is necessary in the boot to make a perfectly functional system. I just need a sensor circuit that will be on 24/7 that monitors whether there is audio coming from the speaker connections, and turns on the amp.

The sensor circuit would of course have to use minimal power. I swear I have seen this type of kit somewhere. I think it was used to turn on a remote subwoofer or something. Can anyone remember the source?

What is the car? If the controls are on the steering wheel leave it alone. I was offered the complete data base of customers of Lexus if I could work these controls out, as you can imagine, I bent over backwards and contacted every Lexus repair shop I could find so I could get my hands on the customer list.

If his equipment doesnt have a volume control, he should trade it in.

hmmm.. bit of a privacy breach if you would be successful in getting that list!!

I would be ready to kill someone if I had found out they contacted me by getting my details from a leaked list of buyers.

-It's a holden barina. The CD player etc... is all standard these days.

I have bitten the bullet and am designing an op-amp circuit now. I don't know why but I am quite averse to op-amps. Something about analogue electronics in general that I detest. Sorry if I offend anyone here but digital electronics is so nice and black and white!

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