A mystery component you probably never have seen - Page 1
Forum section: electronics / general

author: SeanB
author_rank: Super Contributor
timestamp: October 03, 2023, 11:57:46 am
content: Mystery part, which, unless you are greybeard, and in this field, you would never have seen, but probably have used at some point or the other in your life.

author: xrunner
author_rank: Super Contributor
timestamp: October 03, 2023, 12:20:20 pm
content: Does it have to do with telecom equipment?

author: macboy
author_rank: Super Contributor
timestamp: October 03, 2023, 12:38:19 pm
content: I've never seen such a thing before, but neither has google image search - it gives a wide array of interesting guesses, none even close.It looks like it could function as a circuit breaker with broken indicator. If so, this one has broken.

author: Bud
author_rank: Super Contributor
timestamp: October 03, 2023, 12:51:06 pm
content: A burned fuse with Normal Open signaling circuit.

author: darkspr1te
author_rank: Frequent Contributor
timestamp: October 03, 2023, 01:02:15 pm
content: As soon as i read the fuse comment I could see the Idea and function, between the two solder blobs would be fuse wire, short in length to hold the red cones away from the upper metals strips and when it blows it open one circuit and closes another or two.neat but never seen one myself

author: soldar
author_rank: Super Contributor
timestamp: October 03, 2023, 05:51:13 pm
content: My guess is telephone line protector fuse. When it blows a light lights up in the panel.

author: Gregg
author_rank: Super Contributor
timestamp: October 03, 2023, 10:25:44 pm
content: It is an indicator fuse. Similar fuses are widely used in the telecom industry. The fuse wire would be soldered between left side of the lower terminal and the next one up keeping the spring tension of the one with the red tips from closing the auxiliary contact (the upper two terminals). When the fuse wire opens, the far left red button protrudes from the case giving visual indication that the fuse has blown.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: October 03, 2023, 10:27:31 pm
content: Definitely a Rueckloetsicherung (resolderable fuse). There is no fuse wire - the solder blob is the fusable element, with the composition of the solder determining the trip temperature. There were variations of the topic in use internationally. The German variant was cylinder-shaped, with a spring-loaded nipple protruding after trip, so the monitor contact was external. The re-soldering took place in a device which heated the solder and held the contacts in position after the heat was turned off. Usually it was combined with a position for testing if the re-soldering was successful.The assumption that most devices of this type were in use as telecom line protectors is correct.

author: SeanB
author_rank: Super Contributor
timestamp: October 04, 2023, 05:59:47 pm
content: Yes telephone exchange line fuse, there to protect against high voltage applied to the line, think a power cable drop on it, and then the fuse blows, lighting a LED on the row to indicate a fault. This one came from my stint as overnight phone operator, where there was one faulty line, which was annoying, in that it kept on cycling the old mechanical relay PBX, it only had pulse dialing, none of this new fangled DTMF around, and in any case your upstream connection was via an operator connected call, and pulse dialing was only used internally. Thus after 4 hours of listening to the Cerchunk......cerlunk, of the exchange behind me cycling, and the corresponding lamp flashing on and off, I went and pulled this fuse, wrote the fault in the log, and had a much quieter night. 10PM town operator called in, they were going to sleep, and thus dropped me all the town lines to handle, as it was likely the calls would all be inbound to me. Farm lines went to the one remote operator 120km away as well, which was fine, as I did not have a ring generator there to use them, or the list of cadences per line for each farm. Morning I put the fuse back, and found the broken one dropped in a corner, so kept it.Not the greatest 18 hour duty around, and with only typically 3 calls per night out, one from the Food Factory to place the fax call to send the order they had, and the others being calls from the Officers mess, to what I assumed were girlfriends, as the calls were around an hour each. Just write down the officer, time and length, and leave the day operator to send the chit for payment through.

author: pcprogrammer
author_rank: Super Contributor
timestamp: October 04, 2023, 06:51:35 pm
content: Works a bit like what big clive shows in this video.Only here it is a surge protection for lightning on your house mains.

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: October 29, 2023, 07:13:16 am
content: Incidentally, the test device for the German version showed up on Ebay.First picture shows the whole device. The Rueckloetsicherung (resolderable fuse) is inserted into the receptacle at the upper right. Then the other contact is connected to 'P' by means of a short test lead.The second picture shows the instrument. For each nominal current value, there is an allowed voltage drop marked. This is the criterium to judge whether the 'resoldering' was successful.