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12 volt delay timer

Autowraith

May 5, 2022
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Hello there, I am new to the forum and electronics.
I am trying to make a 12volt delay timer for mini fridge/ cooler box for insulin.
I know on GM vehicles the radio has a delay, but shuts off after opening a door.
I need it to stay on for 10 to 30 minutes after vehicle shut off. Just looking for some ideas.
 

AnalogKid

Jun 10, 2015
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Sounds like you need a circuit or device that is powered directly from the battery, so the timer has operating power when the vehicle is off, and feeds battery power to the cooler through a controlled switch. If so, what are the specs for the cooler? Min and max voltage, and max current?

30 minutes is a loooooong time for a simple R-C (resistor-capacitor) timer circuit like a 555. A better choice is something based on a counter or divider like the CD4060.

If you have any programming experience, a microcontroller solution could be easier for you. There still is some circuitry involved, but not as much.

ak
 

AnalogKid

Jun 10, 2015
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I almost said something about fishing around on ebay for a timer module. $10 and free shipping - that is sick.

ak
 
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Martaine2005

May 12, 2015
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It’s a teenagers term for ‘great’, a little like ‘buff’ for a good looking man!.
And how a sentence is started with ‘So’. And ‘like’ every other word in a sentence. A USA thing exported again!.

Martin
 

Bluejets

Oct 5, 2014
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I need it to stay on for 10 to 30 minutes after vehicle shut off

So is it already "on" during engine run..??
If so, what turns it on and off there..?
You may need to look at how you will trigger the timer shown.
You might need to sketch up a wiring diagram of your requirements.
 
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John Canon

Jun 1, 2022
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Jun 1, 2022
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Also Rad (approximately).
You are so lucky, my scientific calculator will only show 12 digits. I am stuck with 57.2957795130, and I never know if the trailing zero rounds up or down. My Archer antenna rotator is getting confused.
 

crutschow

May 7, 2021
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My HP42S (virtual) calculator on my computer gives 57.29577951308232087679815481410517 degrees.
Good enough for government work. ;)
 
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