Might be a polyfuse - which of course is a thermistor, specifically a PTC type.I would say a thermistor rather than MOV.
http://shop.rabtron.co.za/catalog/thermistor-p-3163.htm
It is in series with the load.
Max.
I think this is the exact PTC used:
http://no.mouser.com/ProductDetail/...qs=Xf1FcTN93g4QNCdKPv3sng==#.UznUNOauDHU.link
When I opened the link it said no image available.I think it's the picture and the part number.
Or sometimes once is all it takes, if the Pulse Energy Rating (Joules) of the device is exceeded.Note that these kinds of devices have a lifetime. Each overcurrent event changes their response.
The same is true of MOVs, an overvoltage protection part. They offer real protection for only a few hits, and after 10 or so are pretty much worthless.
ak
Apparently sidacs are all the rage nowadays - but once triggered they clamp at a low voltage and blow the fuse.Or sometimes once is all it takes, if the Pulse Energy Rating (Joules) of the device is exceeded.
Max.
Click on the datasheet link, and notice that one of the parts on page 2 is Type C985. Now where have I seen that before...
Your device is a 15 ohm resistor in series with a thermistor that's around 4.6 ohms. When the thermistor gets hot from too much current, its value snaps up to over 1K (chart on p. 4). Compared to 15 ohms, that's basically an open circuit. Your device current now flows through the LED, illuminating it. When the thermistor cools off it returns to its original value like a self-resetting circuit breaker. A PolySwitch is a similar device with different metallurgy and switching characteristics.
Note that these kinds of devices have a lifetime. Each overcurrent event changes their response. The cold resistance creeps up and the hot resistance creeps down, exactly the opposite of what you want. The same is true of MOVs, an overvoltage protection part. They offer real protection for only a few hits, and after 10 or so are pretty much worthless.
ak
At less than 12V - there probably aren't many MOVs about.Thanks for your reply. I have been using the device for about three years and assumed it still worked, are you saying that it was worthless after about the 10th time the LED flashed?
What can i replace it with? Or would you say i don't need to replace it as it was worthless to begin with?
It was only used to indicate if the voltage i was using was too high or if the items i was plating were in contact with the anode bar etc, wrongly connected to the tank, like a trip switch signified by the flashing LED..... i think!
What other device / cut out circuit could i use to show that the voltage i am using is too high, i electroplate at between 1.5v-9v, depending on how big the part is. I use a standard variable power supply.
by Duane Benson
by Aaron Carman
by Jake Hertz
by Jake Hertz