Too Many Switches?

vijainair · 11-06-2009, 08:32 PM

I want to install a series of switches in my project. The first switch (SPST) would be up front near the steering wheel, would control the main signal. The second switch (SPST) would be hidden away (most likely in the glove box), would be like the first, except it would be the real valet switch; meaning valets, service techs and the like would be unable to operate my carputer (since my glovebox would be locked

). This switch would normally remain closed.

The third switch (SPDT) would be in the back, directing the remote signal to either the carputer (in turn, connected to the amp and HD radio tuner) or the amp (with the HD Radio connected).
The reason why this switch exists is for the times when I'm servicing my carputer, or it doesn't work, or whatever. Since I'm going headunit-less, and in case my carputer becomes inoperable, I can fall back on HD radio (connect radio to amp and plug in LCD controller).

The question is: are there any problems or concerns I should be aware of before I go through with this? Below is a quick diagram of what I said earlier.

justchat_1 · 11-06-2009, 10:10 PM

you will need to put a diode between the amp and the carPC

vijainair · 11-07-2009, 06:00 AM

Quote: Originally Posted by justchat_1

you will need to put a diode between the amp and the carPC

Would this be more appropriate? I changed the first switch after getting ideas from a few other threads. I'm guessing the diode would for when I change the rear switch from the CarPC to the Amp directly, right? What rating diode would I need then?

soundman98 · 11-08-2009, 06:29 PM

very similar to how my system is setup--- the major differnence is that i have a switched computer turn on lead, and the amps will always turn on with the key(different idea, same result)

also, in case you havent thought of it, i would also recommend running power and reset switches to the front to control the computer-- in case anything were to happen...

justchat_1 · 11-08-2009, 06:42 PM

Quote: Originally Posted by vijainair

Would this be more appropriate? I changed the first switch after getting ideas from a few other threads. I'm guessing the diode would for when I change the rear switch from the CarPC to the Amp directly, right? What rating diode would I need then?

Missed the reply...yup thats how it should be. Since the diode only has switching current any sized diode should be fine its only drawing a fraction of a watt at best.

vijainair · 11-09-2009, 12:03 AM

Quote: Originally Posted by justchat_1

Missed the reply...yup thats how it should be. Since the diode only has switching current any sized diode should be fine its only drawing a fraction of a watt at best.

Thanks for the confirmation!

Quote: Originally Posted by soundman98

very similar to how my system is setup--- the major differnence is that i have a switched computer turn on lead, and the amps will always turn on with the key(different idea, same result)

Don't you get that amp "thump"? I was told that the best way to avoid that is to wire the amp remote line to the M2-ATX.

Quote: Originally Posted by soundman98

also, in case you havent thought of it, i would also recommend running power and reset switches to the front to control the computer-- in case anything were to happen...

I plan to have the main valet switch, a reset button, a power LED and an HDD activity LED. I'm considering two options on the front switch:
1) Use a SPDT rocker switch and take up a switch spot, and put the LEDs/reset button elsewhere.
2) Using my non-existent fabrication skills, put the switch, the button and the LEDs into a switch panel blank.

Most likely will go with the second route. Even though the first would give me an OEM look, it's a lot more expensive. Also, would I be able to use a 125V AC rocker switch? Finally, any suggestions as to where I can get switches for cheap?

Thanks!

soundman98 · 11-09-2009, 09:39 AM

i don't have problems with amp thump. it seems it is more a issue with how the OS loads the audio drivers for the soundcard-- out of 3 cards i have used, 1 of them had amp thump. to correct this, you could either use the amp thump pins on the power supply, or use a separate turn on delay, i beleive that directed electronics makes one- its intended use is for remote start on deisel motors, but would work...

for switch sources, there are loads of them (i usually end up at the local radio shack/auto parts store though): from what i have read, digikey, and allied-electronics are both good sources.

usually, any switch will work(the writing on the side is the max that it will take). i would recommend using momentary switches for startup/reset buttons-- spdt switches could cause problems if you accidentally switched them on.

vijainair · 11-09-2009, 10:28 AM

Quote: Originally Posted by soundman98

i don't have problems with amp thump. it seems it is more a issue with how the OS loads the audio drivers for the soundcard-- out of 3 cards i have used, 1 of them had amp thump. to correct this, you could either use the amp thump pins on the power supply, or use a separate turn on delay, i beleive that directed electronics makes one- its intended use is for remote start on deisel motors, but would work...

for switch sources, there are loads of them (i usually end up at the local radio shack/auto parts store though): from what i have read, digikey, and allied-electronics are both good sources.

usually, any switch will work(the writing on the side is the max that it will take). i would recommend using momentary switches for startup/reset buttons-- spdt switches could cause problems if you accidentally switched them on.

I'm going to be using onboard sound. I guess the only real way to see if there is thumping is to test for it. I'd like to avoid separate timers/delays. I barely got very basic electrical down, and since I'm modding my daily driver, I don't want to end up causing even more problems.

I'm not sure if a switch rated at 15A--125VAC would be the same as 15A--12VDC. Just in case something goes wrong, I don't want anything burning/melting/whatever. The types of switches I listed were for the remote line.

The reset button is a prewired momentary pushbutton to the board directly (in case the PC hangs or something, so that I don't have to put up with the PSU delay) Also, I believe that's all that the intel d945gclf2 board can handle anyways.

I'll take a look at those stores. Thanks for the info!

Extide · 11-09-2009, 11:42 AM

Quote: Originally Posted by vijainair

Would this be more appropriate? I changed the first switch after getting ideas from a few other threads. I'm guessing the diode would for when I change the rear switch from the CarPC to the Amp directly, right? What rating diode would I need then?

I already have the switch up front but lack the switch to turn on just the carpc (without turning on the amps). I will probably be adding a switch and diode like in this pic. Setup looks good to me.

soundman98 · 11-09-2009, 12:47 PM

Quote: Originally Posted by vijainair

I'm not sure if a switch rated at 15A--125VAC would be the same as 15A--12VDC. Just in case something goes wrong, I don't want anything burning/melting/whatever.

good link for ya on how switches are rated:
http://www.tpub.com/neets/book3/9f.htm

as long as you are only using the switch for turning the remote line on and off, you should not have a problem-- the link you posted was about using a small, low amperage switch to control the main power line-- which can cause issues with smaller switches-- though i see where some of the posts can be troublesome. while it is better to have a switch rated for the same type of voltage you will be using, i really haven't had problems in the past using ac-rated switches in dc circuits.

as a general rule of thumb, the remote turn on line of a device should be pulling about 100-500mA @12volts DC.

if you get extremly concerned about the amperage that is going through the switch, install a relay that is controlled by the switch to turn the devices on and off.

Extide · 11-09-2009, 02:08 PM

Yeah the remote line should not have much current at all going thru it so in reality just about any switch will matter.

AC vs DC on a switch doesnt matter (At least in this case it shouldn't matter), and the ratings are max ratings, so you can use a 125v switch for 12v just fine.

vijainair · 11-10-2009, 03:05 AM

I always gotta make things more complicated than they already are. It's a really bad habit. I forgot to take into consideration my rear view camera (connected to lilliput LCD). So I've updated the switch diagram. Which brings me to my next questions:

I understand why I'll need a diode between the PC and the Amp, but will I need a diode between the Amp and the HD Radio Tuner? What about the camera: should I put a diode between it and the switch? Would this even be necessary? Will the tuner and camera need fuses (the PC and Amp already are fused)?

The updated diagram adds the camera into the fray, but also shows where the power line from the headunit harness goes. Will this end up becoming a problem? I've decided to go with the multiple-switch-in-one-panel option, meaning I will now need two SPDT switches, one momentary pushbutton, and two LEDs. I'm going to definitely a lot of 18AWG wiring...

BTW, anybody got a spare Toyota dash switch blank?

Extide · 11-10-2009, 01:50 PM

So, you can actually simplify this and remove the diode.

Remove the SPDT switch in the rear, and just connect your black line to the blue one.
Put a SPST switch where the diode is.

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