Electromagnet - overheating

Alec_t

Joined Sep 17, 2013
11,529
Welcome to AAC!
It's always a good idea to include a fuse or thermal cut-out, but if the solenoid is rated at 2.5W continuous power (check the datasheet) it will draw ~200mA (not 1.2A), get warm/hot, but should still be safe.
 

Kermit2

Joined Feb 5, 2010
4,162
It will only draw as much current as the wire resistance and voltage allow. 12 volts will make 1 amp of current flow through a 12 ohm resistance.
Voltage divided by resistance is equal to current.
Your magnet should have a resistance of about 48 to 50 ohms cold and resistance will increase with heat till the stated 200 milli amps of current is all that can flow when supplied with 12 volts.
 

wayneh

Joined Sep 9, 2010
16,399
If I power it using normal adapter 230AC to 12V DC (1,2 A) will I risk overheating magnet due to high amperage?
Check the voltage quickly when it is first connected. An old wall wart (transformer) supply with those ratings is likely unregulated and may be a much higher voltage when not loaded to its labelled current. In this case 15V or more would not surprise me. This could indeed risk overheating your magnet if left connected for an extended time.

There are many options: Use a 9V AC/DC converter, use a modern (regulated) 12V supply, use your existing converter with a voltage regulator IC such as 7812.
 

cmartinez

Joined Jan 17, 2007
7,062
Hi, I'm kinda new to this stuff. I acquired electromagnet 12V DC, 2,5W, 200mA, like here:

https://www.conrad.nl/nl/intertec-its-ms-2015-elektromagneet-20-n-12-vdc-25-w-502290.html

If I power it using normal adapter 230AC to 12V DC (1,2 A) will I risk overheating magnet due to high amperage? Should I use some safety circuit?

Thanks!
What are you using the electromagnet for? Sometimes magnets like that are driven at full capacity at startup, and then a PWM goes in effect in order to reduce current and heating. Another strategies are current limiting, or a simple disconnect timer.
 
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