- This topic has 3 replies, 2 voices, and was last updated 2 years, 11 months ago by techcoze.
2017-07-24 at 09:15 #2040techcozeGuest
What are the possible options to add short circuit protection to the kit? I have been thinking of adding some kind of protection to the kit to safeguard cases like some wire short, etc.2017-07-24 at 09:53 #2041techcozeGuest
Addition to my earlier post: I guess short circuit protection is mainly required for solenoid valve circuit (12v). I guess Arduino 5v circuit part does not need any special protection (correct if I am wrong). If solenoid valve wire shorts, then it can be problematic (if my 12v adapter does not have in-built short circuit protection, I am not sure about it).2017-07-29 at 12:09 #2044MartynKeymaster
Disclaimer: I am not an Electrical Engineer…
There is some basic protection already in the circuit. The diode on the power in line, the diode on the power regulator output, the mosfet on the Arduino 5v in line, the optcouplers on the flash and camera triggers. Better spec’d optocouplers could be used though.
An additional layer of protection could be added by having optocouplers before the TIP120s but I believe this is only really required if you also wanted to add separate power supplies for each valve. Using one power supply for everything adds convenience but also means nothing is truly isolated.
My main concerns when developing the device were protecting the camera and the flashes, and not trying to pull too much current from the Arduino at any one time.
If you want to look in to this further, look at the guides on the Rugged Arduino site (https://www.rugged-circuits.com/10-ways-to-destroy-an-arduino/).There is another good site that I can’t find/remember. If I do I will add a link.2017-08-07 at 09:29 #2045techcozeGuest
Thanks for valuable inputs!
I think opto-isolator before TIP120 is very much essential in your design. Let me share my experience. For many days i was facing the strange issue of flash triggerring abruptly even though no signal was sent by Arduino. After lot of head banging, found that 1N4007 fallback diode after TIP120 was leaking small amount of reverse current which was causing my flash to trigger (since both are sharing same ground). After opto-isolating TIP120 my issue was solved. Now I am using separate power supplies for valves and Arduino with the separate ground.
Hope this helps for your next version of drop controller.