Power Drain??? Help needed...

Discussion:

(too old to reply)

VentureOverland

2006-09-04 14:06:08 UTC

Hi All,

I have a JBL GTO 75.4 II amp connected and Im wondering about the REM
feed.

My head unit doesn't have a remote feed to auto switch on (via the
REM) so I can either wire in a seperate switch and feed from the +12V
side or leave it on all the time. I dont want a switched live
otherwise the key will need to be in the ignition...

Question is how many Amps will the amp draw when its switched on but
not being driven by a head unit? In other words will it flatten my
battery over the weekend if i dont use the vehicle?

Thanks
Jon
Regards,

Jon
VentureOverland
http://www.ventureoverland.com

Colin Stamp

2006-09-04 18:12:47 UTC

Permalink

On Mon, 04 Sep 2006 15:06:08 +0100, VentureOverland

Post by VentureOverland
Hi All,
I have a JBL GTO 75.4 II amp connected and Im wondering about the REM
feed.
My head unit doesn't have a remote feed to auto switch on (via the
REM) so I can either wire in a seperate switch and feed from the +12V
side or leave it on all the time. I dont want a switched live
otherwise the key will need to be in the ignition...
Question is how many Amps will the amp draw when its switched on but
not being driven by a head unit? In other words will it flatten my
battery over the weekend if i dont use the vehicle?

It depends on the amp, but it'd be marginal at best. I don't know
about your amp specifically.

What type of head unit do you have that doesn't have an electric
aerial wire?

Cheers,

Colin.

VentureOverland

2006-09-04 19:21:11 UTC

Permalink

On Mon, 04 Sep 2006 19:12:47 +0100, Colin Stamp

Post by Colin Stamp
On Mon, 04 Sep 2006 15:06:08 +0100, VentureOverland

It depends on the amp, but it'd be marginal at best. I don't know
about your amp specifically.
What type of head unit do you have that doesn't have an electric
aerial wire?
Cheers,
Colin.

Colin,
Its actually a 12V car computer thats connected. I have tried to take
a line from the power supply that feeds the actual computer to the REM
input and this does switch the amp on and off with the computer but
that introduces a large pop in the speakers when it starts up.

My other option is to introduce a timer into this REM wire such that
the PC starts up and then say 5s later the REM line is made live
starting the amp..

If the PC is switched on first and then the amp (5s or more later)
there is no problem, only when the amp turns on at the same time as
the PC and it begins to boot.

Jon
Regards,

Jon
VentureOverland
http://www.ventureoverland.com

Colin Stamp

2006-09-04 20:27:16 UTC

Permalink

On Mon, 04 Sep 2006 20:21:11 +0100, VentureOverland

Post by VentureOverland
On Mon, 04 Sep 2006 19:12:47 +0100, Colin Stamp

Post by Colin Stamp
On Mon, 04 Sep 2006 15:06:08 +0100, VentureOverland

It depends on the amp, but it'd be marginal at best. I don't know
about your amp specifically.
What type of head unit do you have that doesn't have an electric
aerial wire?
Cheers,
Colin.

Colin,
Its actually a 12V car computer thats connected. I have tried to take
a line from the power supply that feeds the actual computer to the REM
input and this does switch the amp on and off with the computer but
that introduces a large pop in the speakers when it starts up.
My other option is to introduce a timer into this REM wire such that
the PC starts up and then say 5s later the REM line is made live
starting the amp..
If the PC is switched on first and then the amp (5s or more later)
there is no problem, only when the amp turns on at the same time as
the PC and it begins to boot.

Ah, I see. In that case, a timer would probably be the neatest option.
It doesn't need to be anything fancy - A resistor, a capacitor and a
12V relay should do for this job since there's no need for any kind of
accuracy.

Let me know and I'll scratch out a circuit.

Cheers,

Colin.

VentureOverland

2006-09-05 07:05:46 UTC

Permalink

On Mon, 04 Sep 2006 21:27:16 +0100, Colin Stamp

Post by Colin Stamp
On Mon, 04 Sep 2006 20:21:11 +0100, VentureOverland

Post by VentureOverland
On Mon, 04 Sep 2006 19:12:47 +0100, Colin Stamp

Post by Colin Stamp
On Mon, 04 Sep 2006 15:06:08 +0100, VentureOverland

It depends on the amp, but it'd be marginal at best. I don't know
about your amp specifically.
What type of head unit do you have that doesn't have an electric
aerial wire?
Cheers,
Colin.

Colin,
Its actually a 12V car computer thats connected. I have tried to take
a line from the power supply that feeds the actual computer to the REM
input and this does switch the amp on and off with the computer but
that introduces a large pop in the speakers when it starts up.
My other option is to introduce a timer into this REM wire such that
the PC starts up and then say 5s later the REM line is made live
starting the amp..
If the PC is switched on first and then the amp (5s or more later)
there is no problem, only when the amp turns on at the same time as
the PC and it begins to boot.

Ah, I see. In that case, a timer would probably be the neatest option.
It doesn't need to be anything fancy - A resistor, a capacitor and a
12V relay should do for this job since there's no need for any kind of
accuracy.
Let me know and I'll scratch out a circuit.
Cheers,
Colin.

Colin,
Sounds like a timer of some description would be just the thing. A
circuit diagram woud be much appreciated.

Many Thanks.
Jon
Regards,

Jon
VentureOverland
http://www.ventureoverland.com

Colin Stamp

2006-09-05 20:37:45 UTC

Permalink

On Tue, 05 Sep 2006 08:05:46 +0100, VentureOverland

Post by VentureOverland
Colin,
Sounds like a timer of some description would be just the thing. A
circuit diagram woud be much appreciated.
Many Thanks.
Jon
Regards,
Jon
VentureOverland
http://www.ventureoverland.com

Here you go. It's quick and dirty, but hopefully, it'll do the job...

Loading Image...

The components are :-

Resistor - 390R 0.5W - Farnell 9340513
Capacitor - 6800uF, 16V - Farnell 8767203
Relay - 12V 2250R coil - Farnell 1175000

The delay should end up at about 2.5 seconds. The choice of relay is a
bit critical, I'm afraid, since it's such a simple circuit. The coil
resistance does need to be high or it won't pull in with the 390R
resistor.

Cheers,

Colin.

VentureOverland

2006-09-07 07:35:30 UTC

Permalink

On Tue, 05 Sep 2006 21:37:45 +0100, Colin Stamp

Post by Colin Stamp
On Tue, 05 Sep 2006 08:05:46 +0100, VentureOverland

Here you go. It's quick and dirty, but hopefully, it'll do the job...
http://www.stamp.plus.com/temp/TimeDelay.JPG
The components are :-
Resistor - 390R 0.5W - Farnell 9340513
Capacitor - 6800uF, 16V - Farnell 8767203
Relay - 12V 2250R coil - Farnell 1175000
The delay should end up at about 2.5 seconds. The choice of relay is a
bit critical, I'm afraid, since it's such a simple circuit. The coil
resistance does need to be high or it won't pull in with the 390R
resistor.
Cheers,
Colin.

Colin,
Many thanks for this, its great... Is it possible to get the 2.5s
stretched out to about 5s as 2.5s is just a little too quick? I
reckon the "pop" from the pc is about 4s after switching on.

Thanks,
Jon
Regards,

Jon
VentureOverland
http://www.ventureoverland.com

Colin Stamp

2006-09-07 17:38:40 UTC

Permalink

On Thu, 07 Sep 2006 08:35:30 +0100, VentureOverland

Post by VentureOverland
On Tue, 05 Sep 2006 21:37:45 +0100, Colin Stamp

Post by Colin Stamp
On Tue, 05 Sep 2006 08:05:46 +0100, VentureOverland

Colin,
Many thanks for this, its great... Is it possible to get the 2.5s
stretched out to about 5s as 2.5s is just a little too quick? I
reckon the "pop" from the pc is about 4s after switching on.

You could just add another 6800uF cap in parallel with the first,
which should work, but the values are starting to get a bit silly. It
might be worth going to a slightly more sophisticated circuit for
extra versatility. A quick Google found this:-

http://home.cogeco.ca/~rpaisley4/LM555.html#30

Try circuit #2, with :-

C1 = 100uf, 16V
R1A = 1K
R1B = 100K preset

That should give you a variable delay up to about 10ish seconds.

Cheers,

Colin.

John Greystrong

2006-09-04 21:06:26 UTC

Permalink

It will if you leave it parked at Stansted for a week. You wont know
this until you fly back at 2am though. DAMHIKetc.

Oh and that was on a switch which I obviously forgot to turn off.

John