I am wanting to make a simple circuit that would allow me to softly turn on a 5vdc power.
Let me explain more. I am wanting to put a usb powered device in my car and hard wire it to a 12vdc to 5vdc usb output. I know when starting the car it turns off most accessories and then turns them back on when the car has started. I am wanting the arduino to detect the acc on and count down xx seconds before to unlatched the relay to send the 5vdc to the usb device.
I just want to avoid it wearing down the device if it comes on for a split second and then goes off then comes back on etc..
Would something like this already exists that I could purchase? I’ve seen the 555 timer but it seems to just do xx on then xx off.
How about this?
[Timer relay](CenryKay DC 6V-30V Timer Relay Module Trigger Cycle Delay Timer Switch Turn On/Off Relay Module with LED Display(2PCS) Amazon.com)
I think You overdo things.
35 years ago a 7805 on a heat zink, and a few caps, worked well for 10 years powering a Z80 single card wired computer, 4 digit 7 segment LED display...
Not all vehicles disconnect the "cigarette lighter socket" at startup.
Apart from that, if everything turns off, where will your Arduino power come from...?
There has to be permanent power somewhere in the vehicle when the key is off, otherwise nothing would come on when the key was turned, or, in modern day vehicles, when you press the unlock button.
Where you have a "start" (/stop) button, it has almost nothing to do with starting the engine as the engine just starts and stops whenever it wants to, according to how you are driving. It's a "whole different ball game".
