Introduction: Holder for a Glass Fuse

Picture of Holder for a Glass Fuse

This is a free multimeter I got at Harbor Freight with a coupon. It came as a surprise, but there is a fuse inside.

See the second photo. Details about the fuse are included on the back of the meter's case, but it is easy to miss them. See the yellow arrow. The fuse is 0.5A at 250 volts. The size is 5mm x 20mm.

See the third photo. This is the fuse in the factory supplied holders.

See the fourth photo. The factory fuse holders are more flimsy than any I have ever before seen. When the fuse is removed, the holders move. The holder on the right feels especially loose and marginal. If they were made of heavier material, I would simply resolder them. But, I want to replace them. (I could just solder the fuse to leads, but I want replacement of a blown fuse not to require a soldering iron.)

Step 1: First Steps

Picture of First Steps
Cut two sections of brass tube the length of the end caps on the glass fuse.

See the second photo. Ream away rough edges and clean the inside of the brass tube with a round file.

Tools
  • Tubing cutter
  • Round file
  • Soldering iron and solder
  • Small scissors
  • Pair of pliers
  • Heat source (hair dryer, match, etc.)
Materials
  • 9/32 O.D. brass tubing
  • Heat shrink tubing

Step 2: Fitting the Tubing

Picture of Fitting the Tubing

I found I needed to remove nearly one-fourth of the circumference of the brass tubing so it could fit snugly around the end cap on the glass fuse. I used a small stainless steel scissors.

See the second photo. I used a pair of pliers to make the tubing fit the fuse. It was still a little loose, so I crimped the tubing just a little without the fuse to get a closer fit. Caution: These little glass fuses are delicate. I broke one by pushing too hard on it.

Step 3: Solder Leads

Picture of Solder Leads

When the fitted brass tube sections fit the fuse end caps nicely, tin each with solder and solder a short piece of insulated wire to each for a connecting lead. Cut two short pieces of heat shrink tubing and heat to shrink.

I had hoped the heat shrink tubing would add the right amount of tension to the brass tubing, but that proved an invalid hope. Before I tried the brass tubing, I thought about using some thinner sheet brass I would bend around the end caps. It is flexible enough that the heat shrink tubing probably would have made the brass fit snugly around the end caps. Because the heat shrink tubing did not add tension, I tweaked the fit by crimping just a little with a pair of pliers. 

Step 4: Solder Leads in Place

Picture of Solder Leads in Place

Solder the leads on your improvised fuse holder in place. Check with a continuity tester on another meter to be certain there is an electrical path through the brass tube and end cap junctions. The heat shrink tubing also insulates the metal parts of the fuse so they do not short anything on the circuit board. I also bent the connecting leads a little so the fuse and its holders are suspended above the circuit board.

See the second photo. This shows that the improvised fuse holders can be removed easily when it is time to change a fuse. I should get an extra fuse or two, cover them with tape to keep them for shorting anything on the circuit board, and store them inside the case of the meter. 

This Instructable may fix something that was not completely broken, yet. But, I just did not like the very flimsy factory fuseholders. A fuse holder like this could be used anyplace a fuse is needed.

Comments

tutdude98 (author)2013-05-28

Nice instructable Phil
What if i use slow instead of fast fuse? fast fuse will blow just when i put 260 ma on 250 ma fuse i need to replace them and if i will use slow fuse i can put maybe 300 ma before it will actually blow

redkcir (author)tutdude982017-08-23

Fuses are about protecting your device. A fast blow is designed for just this purpose. A slow blow is used when there may be a higher current for a short time, like starting a motor, that will go back to normal afterwards. A delay keeps you from replacing the fuse every time you use it. Because you are checking current that is already or may be flowing your device uses a fast blow to protect its self. You might get away with using the slow blow for a while, but it is designed to have some leeway (allow a higher amperage for a short time) than your device may be able to stand.

Phil B (author)tutdude982013-05-28

Thank you for looking and commenting. I think I am not really qualified to give you a reliable answer. I do not know what parameters the circuit's designer had to consider in his selection of a slow blow versus a fast blow fuse, or vice-versa. I suppose you could try it and hope the device passes the "smoke test."

phmadore (author)2014-05-08

on first glance I thought this title was in making fun of the meter, which would have been hilarious. In the end, it turned out to be a useful instructable with a wide, wide array of applications. Thanks!

Phil B (author)phmadore2014-05-08

Thank you. It did not work quite as well as I pictured in my mind, but it is still useful.

arkangel1975 (author)2013-05-23

Oh wow I think I paid too much for mine... about .99 cents.... LOL

On the up side pretty good for a buck except its margin of error seems to vary 1-4.5 "points" depending on the settings (as compared to my 4 year old fluke)

Phil B (author)arkangel19752013-05-23

Well, do not feel to bad. I paid $15 for one that looks exactly like this one, except that one has fewer features and is black. But, I needed it in that place at that time. It would be hard to beat a Fluke.

explosivemaker (author)2013-05-23

Finally had to get a 9V charger since mine kept running out of power...the irony.

bobzjr (author)2013-05-23

Phil, Even as bad as I am with solder, I think I could pull this one off. Thanks for sharing. I have that meter too - somewhere in my garage.

Phil B (author)bobzjr2013-05-23

Bob,

I used a little 15 Watt pencil point soldering iron for attaching the leads to the circuit board. That helped a lot. If I had not disturbed the fuse all would likely be well for all time. I would like to try a fuseholder with the thin brass sheet I mentioned sometime.

Thanks.

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Bio: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying ... More »
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