Help identfying a current regulator

Thread Starter

dasitmane

Joined Mar 31, 2014
10
I have one of the below regulators that i used with a variable power supply with a 5.5mm plug and i need to get another one, unfortunately i do not have the skills to build one myself and i am having trouble sourcing one.


Does anyone know where i can get a replacement?

Thanks

 

Thread Starter

dasitmane

Joined Mar 31, 2014
10
Hi Max,

On the blue item i can make out what looks like

0985 but it could be 0885 or c985

(a triangle shape) next to the number "120"

1336

Yeah there is not much to it.

If i were to google to try and find a replacment what would i be searching for?
 

Thread Starter

dasitmane

Joined Mar 31, 2014
10
I got it with an electroplating kit years ago. The led flashes if the voltage is too high and it works as a cut out circuit.

Does this help?
 

AnalogKid

Joined Aug 1, 2013
10,986
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
 

MaxHeadRoom

Joined Jul 18, 2013
28,617
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
Or sometimes once is all it takes, if the Pulse Energy Rating (Joules) of the device is exceeded.
Max.
 

ian field

Joined Oct 27, 2012
6,536
Or sometimes once is all it takes, if the Pulse Energy Rating (Joules) of the device is exceeded.
Max.
Apparently sidacs are all the rage nowadays - but once triggered they clamp at a low voltage and blow the fuse.

You could always double up with MOVs as well - rate the MOVs so they just stop the sidacs from triggering - once they fail to do that (you know because the fuse blows) its time to replace the MOVs.
 

Thread Starter

dasitmane

Joined Mar 31, 2014
10
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

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.
 
Last edited:

ian field

Joined Oct 27, 2012
6,536
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.
At less than 12V - there probably aren't many MOVs about.
 

Thread Starter

dasitmane

Joined Mar 31, 2014
10
MOV as in in Metal oxide varistor? What do you mean there are not many about at less than 12v? You mean not many manufactured? I know very little about electronics or their workings.

Also is it correct what Analogkid said about this device only being of use for about ten times and then it will be unreliable?
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
28,617
Last edited:
Top