Recommend non-volatile Flag/Fault Indicator

hi all,

I'm trying to source for a non-volatile flag/fault indicator to hook up with Arduino to show certain status when the device is in power down mode. I found one from L-3 Electrodynamics that can be SMT mounted, Model CI 25 but unfortunately, it has been obsoleted.

Anyone out there knows of any available alternatives? Thanks in advance!

Can it just be an LED? I found out by accident that you if you write an output High and then go into power down sleep mode, the output will drive at least an LED with 680ohm current limit resistor (all that I happened to try, was sourcing 4mA measured with multimeter). I suppose writing Low with an LED connected to your VCC (3.3 or 5V) with a current limit resistor will work also, that's how the keypads are able to create an interrupt.

You can just use any type of register chip that has a latch (i.e. a 74hc595 shift regester). When the Arduino goes to sleep, the register status will remain as long as the output is latched (in other word, even if the input changed the output will not change).

Thanks for both of your replies. Unfortunately, I need the indicator to be visual and work even when the entire board has been unplugged from power supply.

Sorry for not being clear earlier.

You could wind a little electromagnet, when it has current flowing it would be energized and pull a little flag on a hinged arm over, and when power was lost it would release it and a small spring could pull it back. Basically a relay but with an external indicator. Plenty of google hits on them (magnet wire around a nail basically,with strength determined by # of winds and amount of current). Probably want to control it indirectly from the arduino (via transistor).

Thanks for both of your replies. Unfortunately, I need the indicator to be visual and work even when the entire board has been unplugged from power supply.

So you want some kind of non-lit indicator?

hi Crossroads,

That is exactly what I was looking for in the Model CI 25 that was obsoleted by EDI. It uses a electromagnet to flip the status drum, almost the same as what you have described.

My issue is that I may need a few thousands of these so hand-building them will be quite difficult.

hi mowcius, Yes, I need non-lit indicator.

Well it sounds what is required is a latching relay that has some kind of mechanical indication of which state it is in. That is, rather then making and breaking contacts you want the relay bail to be visible to show it's position, like raising or lowering a colored extension rod. I'm sure such an animal has been made for special applications, but can't recall ever seen one as a standard component in a catalog.


Correct. The pic below shows what was previously available but now obsoleted. I need something that is similar and commerically available due to the high volume required.

Why not just wire an LED & resistor in its place? If power is flowing, the LED will be on, and if not it will be off. If the voltage is too high, then drive a relay that can turn the LED on & off as the power goes on & off. If you just gotta have a mechanical solution, try these guys. They have a 1/2" x 1/2" solenoid that they could probably fit with some kind of flag for the quantity you are interested in. "DC Open Frame"

Try Googling “flip dot”, those are the electro-mechanical “pixels” used for displays on busses etc. I’m pretty sure you can get small individual ones though.


Here's another source for miniature solenoids

There's even a bunch of hits for flip-dots within the forums!

hi Crossroads and Graynomad,

Thank you so much! I think the flipdot is a suitable replacement!

I see they have a few small sizes. When you find out how much they are, I'd like to find out, be something interesting to put in a project sometime. Or if you can get a great price on a couple thousand, offer to buy a few extra and sell them here.

AZ30NR - round disks 0.30" in dimeter. AZ36NR - round disks 0.35" in diameter AZ54NR - round disks 0.53" in dimater