electronic projects
 

Ok, time to bring this forum back to life. I know some of you are working on some projects. Lets start talking about them. How is everyone coming with alarm/turbo timer/door lock thing?

On a side note, I fried my trunk actuator yesterday and nearly burned down my car. Good thing fuses work! https://www.rx7club.com/ubb/cwmsmilies/cwm1.gif It was my own fault for changing (accidently) an option in the alarm. Next project: fix my own screw-up!

thats nothing. when my car got towed due to alarm going off all night, the cops cut a few wires that shorted all my amps, deck, and alarm. this short caused a white soke from my hatch area. i thought my car was on fire. total damage $1500 bucks. https://www.rx7club.com/ubb/cwmsmilies/cwm23.gif

That's making me what to rage! https://www.rx7club.com/ubb/cwmsmilies/cwm23.gif

Please, please, please tell me insurance or something covered your loss. I am getting tired of hearing stories about people getting short of the stick with their FDs.

was a loss cause. https://www.rx7club.com/ubb/cwmsmilies/cwm45.gif

that bites it . . . . have you been able to rebuild it?

Real cool project man. I can't to see what you come up with. I might even want to get in on it with you! I'll answer your question in the other thread... I am an electrical engineer and I think I already have an answer for you!

On the computer's power supply, tell me how you envision this thing working ... meaning always powered ... powered like the radio, but only need those few additional seconds to shut down the hard drives, etc. That will help me out.

One thing to ask that might seem wierd, but do you have turbo timer or aftermarket alarm?

Hey, thanks for answering my question in the other thread. I know a couple guys locally who are car audio types, so I was asking them, and was shocked to find they had no electrical knowledge. Not knowing either, I figured you needed the electrics to get to the car audio...


For the computer, my thinking is to get a UPS that runs constantly off the battery (the UPS battery, not the car battery...) in order to provide clean power to the computer, while charging from available power (in the form of a DC->AC convertor). I could do the same thing with a nice surge supressor/line conditioner, but I want the UPS there to trigger the shutdown on the computer. The idea that I'd have to remember to always power down the computer before turning off the car didn't appeal to me at all. And I didn't want to just cut the power, even though all harddrives auto park these days anyway, I didn't want to risk the OS being in the middle of anything and corrupting data. So, the UPS I'll wind up with will be smart, meaning it works with the OS's power management, and tells the computer when it's not able to draw power to recharge the battery. The computer will then auto-shutdown.

The DC->AC convertor I haven't quite researched enough yet. I was just going to go with a cigarette lighter adapter, but, in order to trigger the auto shutdown, I need it to only be getting power when the accessories are on, and I think (but I'm not sure) that the lighter gets power always (if I'm wrong, I'll be happy).

The monitor would be powered just off the car, since it doesn't need a shutdown sequence. Tying it into the radio power supply should work fine (thanks).

I'll be photo-documenting the whole project once I start really getting it together (of the hardware I need, I've only got the LCD display and a spare HVAC panel) and start doing the install.

Oh, yeah, I forgot. I do have a turbo timer and an alarm, though the alarm isn't wired properly for the turbo, so I only use it when racing.

yeh. now my sound is ten time better than the way it was, plus lot cvleaner install. https://www.rx7club.com/ubb/cwmsmilies/cwm41.gif

I am going to go digest what you just wrote so I'll respond to it later. Check my alarm/turbo timer thread for info on how to make a turbo timer work with an aftermarket alarm. I can paste the info if you can't find it or I can clarify it for you.

Alright, I'll buzz in.

I'm working on an in car multimedia system. Made up of a very small PC, a small numeric keypad, an intelligent UPS (for auto shutdown), a 4" color LCD (thank you EBay), HVAC guage relocation, and some custom MP3/AVI/MOV/MPG/DVD player software I'm writing with a nice big clean user interface so it'll show up well on the screen.

Still very early in the project, though. Nothing is actually in the car, but I've got some of the parts, and the software is coming along nicely.

My only stumbling blocks so far have been the power needs of the computer (I need it to continue running for a couple seconds after the car is turned off so that it can safely park the harddrives), and the power for the LCD screen (which I'm asking about in another thread on this forum in, like, two seconds).

I think you build your own power supply easily and without going to all the troble of DC-to-AC and back and using that UPS. I can generate the signal needed to shut down your CPU for you. If you can somehow figure a way to get it into your CPU, then you are in business. I believe you only really need +5V for you CPU . . . and I wrong do you need the +15V and -15V too?

You lost me when you started talking about the power requirements of the computer.

The UPS is actually a fairly cheap part. With the size of the computer, and the fact that it's only powering the computer, and not the computer plus a big ass 21" monitor, I can get away with a lower end unit for <$100.

Building the part, rather than buying, seems like it'd take way too much effort. Especially when you take into account that the signal the UPS sends to the computer to tell it to shutdown is actually a communications protocol running on a USB connection to the computer, and interacting with software provided by the vendor. The R&D time getting that going would suck, compared to just dropping the $100 for the ready made part.

And a DC->AC convertor isn't that big a deal, either. I just don't know how to attach one to an accessory line rather than just the cig lighter.

While researching, I did find a computer power supply that was just straight DC, rather than an AC->DC convertor. But it was prohibitively expensive ($200, if I remember), and it was for a full ATX form factor case/motherboard, while the computer I'm using is a special purpose job designed to be very small (~12"x~12"x~4"), and won't take a non-OEM power supply.

You're wrong, cigarette lighter in the FD is switched...turns on when ACC or CAR is on.
~Tom

Well that special CPU has to have power supply requirements .... can you get me those? In a desktop computer, you have a power supply that converts 120V AC to +5,+15, & -15V DC and it comes on an adapter that plugs into the motherboard . . . .do you have something like this for the special CPU you have? You can build something really cheap and easy from a kit . . . . made specially for your power requirements.

If the cigarette lights is switched, that's brilliant, then, and I've got my solution! Excellent.

Spyfish, the computer is just a normal PC. It's a desktop PC, taking any Socket 370 up to 800Mhz, yadda yadda yadda. http://www.directron.com/bookpc.html has a nice little description of the lower end model. It's a small motherboard with all the peripheral hardware built in, and then jammed into that tiny case. So, power needs are whatever is needed for a regular desktop PC. Nothing fancy about it.

I am still looking into some things ... get back to you later tonight .....

Spyfish is talking about the Computer motherboard requiring low DC voltage.. The computer's power supply puts out +12, -12, +5, -5, and +3.3 Volts... The negative voltages aren't needed anymore, and are just there to maintain backwards comaptibility with serial port cards from the early 1980's... You can actually power the computer off the car battery using less than $20 in Radio Shack parts. (I have tested it, although it was on a 486 motherboard, only running 12 and 5 volts... No 3.3...)

My take is have the computer powered constantly off the car's battery, but go into standby mode. (Parks hard drive, kills all perhipherials, keeps ram and processor alive usinge VERY little power. Starts right back up to where you left it.) Good stuff.

When you make the software, send me a beta test of it, I'd like to try it out.

Another idea for the computer, real time car system management... Not only use it to configure your Haltech or Wolf3D or whatever Engine management computer, but control anti knock and anti flooding systems, mount small stepper motors to your adjustable shocks and have it control them without even getting out of the car. Have it record events in your driving like a black box in a plane. Monitoring RPM, speed, acceleration, deceleration, wheel lockups, steering position... That way when you get a ticket or accident, you can have evidence to back you up... Provided that you were infact not doing anyhting illegal... https://www.rx7club.com/ubb/cwmsmilies/cwm4.gif

I have plenty of ideas for car mounted computers. I was planning on mounting my old P133 laptop in my car.