Author Topic: What is this device in a little 1970's bench power supply?  (Read 979 times)

0 Members and 1 Guest are viewing this topic.

Offline jakeisprobablyTopic starter

  • Regular Contributor
  • *
  • Posts: 168
  • Country: us
    • Upcycle Electronics
What is this device in a little 1970's bench power supply?
« on: June 08, 2019, 07:44:14 pm »
I took apart a little 12v power supply I picked up from a local thrift store. Inside it's very simple but I've never seen a device before like this little bulb in the pictures. It looks like a bimetallic strip based current limiter. It was in series with the output positive voltage terminal. What are these devices called, and why are they not used (much/if at all) today?
 
The following users thanked this post: Neomys Sapiens

Offline ciccio

  • Frequent Contributor
  • **
  • Posts: 659
  • Country: it
  • Designing analog audio since 1977
    • Oberon Electrophysics
Re: What is this device in a little 1970's bench power supply?
« Reply #1 on: June 08, 2019, 07:47:51 pm »
You are correct: it's a self resetting fuse.
Last time I've seen one I was much younger..

It is very similar to the bimetallic  fuses that are placed inside motor's windings.
An example: http://www.miottisrl.com/en/prodotto/sw1/
They are current and temperature sensitive (for motor or transformer protection).
The glass body make it less temperature sensitive, so it is in effect a simple current limiter.

Best regards
« Last Edit: June 08, 2019, 08:01:56 pm by ciccio »
Strenua Nos Exercet Inertia
I'm old enough, I don't repeat mistakes.
I always invent new ones
 

Offline Towger

  • Super Contributor
  • ***
  • Posts: 1646
  • Country: ie
Re: What is this device in a little 1970's bench power supply?
« Reply #2 on: June 08, 2019, 07:57:47 pm »
I have also seen them used as a flasher, in ET (phone home) toys!
 

Online floobydust

  • Super Contributor
  • ***
  • Posts: 7679
  • Country: ca
Re: What is this device in a little 1970's bench power supply?
« Reply #3 on: June 09, 2019, 01:38:42 am »
It's a self-resetting thermal circuit breaker.
They are kind of neat, they trip at say 5A and take almost a minute to reset (cool off).
 

Offline strawberry

  • Super Contributor
  • ***
  • !
  • Posts: 1199
  • Country: lv
Re: What is this device in a little 1970's bench power supply?
« Reply #4 on: June 09, 2019, 06:02:16 am »
old scool cristmass lights
contacts in vacuum can hold more current
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf