Brads Electronic Projects Forum

Are there any resettable circuit protectors on the web that are breadboard or project friendly?

http://www.allelectronics.com/make-a-st ... MP//1.html

Hey that's pretty cool.

You posted this for me didn't you?

Hey that's pretty cool.

You posted this for me didn't you?

I posted it because I thought of you.

Someone was powering a board with a 9v @2600 lithium-ion battery with (i'm guessing) a 12 volt motor and they said anyone using a Lithium-ion battery pack without a fuse or voltage sensing board is asking for big trouble.

I don't know the right voltage / amperage for this resettable circuit protector or which ones I could use for each project but you got me thinking that I should think ahead and save myself future headache for the future. I hope to do some asking and looking to see if there are other more appropriate resettable circuit protectors or fuses. It is probably a future project for Brad's University and something I would need people to help me on. It is also a good idea to promote this as a safety project because I posted about the multiple LED drivers (chips) and I think we may need it eventually if we go on and use a lot of them.

I know that Parallax sells a Digital I/O board / kit which is designed to allow a microcontroller to interface high voltage circuits and I probably need to learn about optically isolated inputs and outputs and relays.

Yes, this is a good idea - thank you!

It's always been in the back of my mind that I should consider some sort of protection because most my circuits are powered via the PICKit2 (i.e. my usb port on the computer).

I have built a few circuits that I know are pushing the current limit of the port but never really bothered to think about protection.

Stacy

http://www.protostack.com/index.php?mai ... Path=14_38

I learned about these in a newsletter and they have different ratings:

These resettable fuses are polymeric positive temperature coefficient (PPTC) device, which is used to help protect against harmful overcurrent surges and overtemperature faults. Like traditional fuses, these devices limit the flow of dangerously high current during fault conditions. However, the fuse resets after the fault is cleared and power to the circuit is removed.

The PPTC operates like a resistor. During normal operations it has a resistance of about 1.5Ω letting more than enough current flow through. During a fault condition the temperature and resistance of the fuse increases letting much less current through. When the fault has been rectified and the fuse cools down the resistance returns to its normal level.

I know this does not really have much to do with circuit breakers but I thought I would mention it.

I use a LED sometimes in a reversed mounted position, with the Anode connected to the Ground and the Cathode connected to Power, serves as a limited safety diode incase of an accidental reversed power connection.