Reddit reviews 10 Amp Mini Timer Time Delay Relay .2 Sec to 400 days 6V 12V 18V. Power On Off Delay, Cycling and Trigger
We found 1 Reddit comments about 10 Amp Mini Timer Time Delay Relay .2 Sec to 400 days 6V 12V 18V. Power On Off Delay, Cycling and Trigger. Here are the top ones, ranked by their Reddit score.
UNIVERSAL TIMER - Universal Timer delay module allows delaying power or disconnecting power after preset period of time.PRECISE - The circuit utilizes an embedded micro controller so the time delay is precisely repeated every time.TIME SETTINGS - Can be set to delay On or Off or cycle power and much more.MADE IN USA - Made in the United States.MULTIPLE USES - Ready to use 12v 10 amp timer. Great for amplifier delay, industrial control, hobby projects, etc.
I use a standard SPST NC 12V relay and a 12V timer to shutdown the RPi gracefully once the ignition is switched off. The solution is based on this youtube video - https://www.youtube.com/watch?v=rknBevexOcU&t=554s)
The timer powers a 12V-5V converter (which in turn powers the RPi and external USB hub etc.)
​
Setup diagram - https://imgur.com/a/o64l4gW
​
The timer is connected directly to the battery as well to the IGN line. The 12V - 5V converter is connected to the output of the timer. When IGN is on the timer switches on it's output which powers the 12V - 5V converter. When IGN goes off the timer starts it's countdown (e.g. 10 mins), when complete it switches off the output (and the 12V - 5V converter switches off). When the timer is off it draws a very small current.
To enable a graceful shutdown of the RPi (i.e. for the RPi to shutdown before the timer) I use a standard SPST NC 12V relay (connected as per wiki posting - https://github.com/opencardev/crankshaft/wiki/Boot,-reboot-and-shutdown-the-Pi-with-ignition-key). Pin 86 is connected to the IGN line, pin 85 to GND, 87A to a GPIO pin (e.g. 23) and 30 to GPIO GND. A script on the RPi is monitoring the status of GPIO 23.
When the IGN switches off pins 87A and 30 are connected sending GPIO 23 low. The RPi will power off after the shutdown delay (this should be less than the shutdown delay for the timer - e.g. 9.5 minutes).
​
Parts list
12V - 5V converter - https://www.ebay.co.uk/itm/24V-12V-to-5V-5A-Step-down-Buck-Power-Supply-Module-4-USB-Converter-Board-Case/173349930955
This has 5A output which is more than enough to power the RPI, screen and a powered USB hub (for high speed charging of my phone).
​
12V Timer - https://www.amazon.com/Timer-Delay-Relay-Cycling-Trigger/dp/B01HNDOCKK/ref=sr_1_6?
Timer needs to be programmed with an off delay (e.g. 10 minutes), set to Function #12 and Trigger to #2 - http://timers.shop/Timer-Cook-Book_ep_43-1.html#example12
​
Timer wiring
Black - ground
Red - battery
Blue (trigger) connected to IGN
Yellow (load) connected to +12V on 12V - 5V converter
​
Relay wiring
Pin 86= SWITCHED power(ignition/ACC)
Pin 85= Chassis Ground (Vehicle electrical system ground)
Pin 30= GPIO Physical Pin 6 or USB ground(Raspberry Pi/USB Ground)
Pin 87a= GPIO Physical Pin 16 (RPI GPIO 23)