planned power button...what do you think?

**alienmanfc6** · 09-24-2007, 10:25 AM

Here is my plan for turning on my carpc. just putting this up here to see what you guys think. and to ask if useing the usb ports power to keep the relay on will work and not blow up the port. just a quick explaination - the in dash switch is a momentary switch so i will push and hold it for a few seconds and it will turn the inverter on and the compuer on. then when i let go if the computer turned on the power from the usb port should keep the power inverter on. this way the inverter will never shutdown while the computer is on. Then to turn it of i could hit the button or shutdown through windows and as soon as the computer goes off so will the inverter...or so i think.
and also the monitor will go on and off with the computer.

**trebuchetguy** · 09-24-2007, 01:01 PM

You might want to try taking the 5 volts off your computer's power supply rather then the USB ports. The power supply can usually put out alot more amprage with out damaging it then the USB can.

**alienmanfc6** · 09-24-2007, 01:24 PM

Originally Posted by trebuchetguy

You might want to try taking the 5 volts off your computer's power supply rather then the USB ports. The power supply can usually put out alot more amprage with out damaging it then the USB can.

O i think i forgot to mention that it is a laptop so there is no other place to get any power from when the computer is on, that i know of. if you know of any where please tell me cuz i would like to not have to use the USB.

**Robyn** · 09-29-2007, 03:03 AM

Originally Posted by alienmanfc6

O i think i forgot to mention that it is a laptop so there is no other place to get any power from when the computer is on, that i know of. if you know of any where please tell me cuz i would like to not have to use the USB.

My suggestion is to open the laptop case and find somewhere inside, if that's an option. It appears that you'll have to anyway to interface with the power switch?

**FC3S** · 09-29-2007, 03:22 AM

you shouldnt need that much amperage to just open a relay..

if a usb port can charge a phone, or power a fan i dont think it would be that big a deal

**billmee** · 09-29-2007, 07:38 AM

What kind of relay do you plan on using?

A Bosch/Automotive type relay will energize at 8 or 9 volts and hold if the voltage drops to 5. The isolating diode will drop your holding voltage to less than 5volts and may cause your relay to drop out.

I'd suggest a solid state capable of handling different levels of DC which your circuit will supply. They are also very low load 90% less than coil type.

Crydom makes a line of solid state relays that would work well here.
This is copied from the spec sheet of the 1-DCL

Control Voltage Range 3.5-32 Vdc
Maximum Turn-On Voltage 3.5 Vdc
Minimum Turn-Off Voltage 1.0 Vdc
Typical Input Current 10mA