Dim-Bulb / Current Limiter Prototype

[Wil_Bloodworth]

I've been working on designing a chassis for a new dim-bulb box and I'm glad I did exactly what I knew I should do... prototype it first!  Sometimes, I think to myself, "Eh, it will be fine... just cut it!" but I know better.

I cut the faceplate prototype on my laser and the parts all seem to fit fine... but there are two unforeseen issues.  I was not aware that the enclosure I ordered would have as much of a "lip" as it does.  Therefore, I'm going to need to move the volt/amp meter down about 1/8" (~3mm for you gents across the pond).  Also, the power outlet on the bottom right is way too far down so that is going to need to come up or I'll need to trim that part of the enclosure.

I'm thinking about replacing the two rocker switches on the far right (on/off & bypass) with their thinner counterparts so I'll have a bit more breathing room on that side.

All in all, it's coming along.  Comments and suggestions welcome!



Hope you enjoy!

- Wil

[Veteran68]

Very nice! I built one recently. Not as fancy as yours, but I was pleased with the result.

[tautech]

Don't overlook KISS principles.



https://www.eevblog.com/forum/repair/suggested-for-a-sticky-part-one-comments-or-additions-please/msg470686/#msg470686

[Wil_Bloodworth]

Very nice! I built one recently. Not as fancy as yours, but I was pleased with the result.

Nice!  Is that one of those heavy duty enclosures from Home Depot?  I was looking at some there a week or so ago.  They were quite heavy.  This blue enclosure is not so sturdy.

- Wil

[edpalmer42]

The bulbs in a dim bulb tester will almost never burn out.  At worst, they'll spend a bit of time at full power until you hit the power switch.  Normally, they'll be ... uh ... dim ... for a short period until you hit the bypass switch.  So you really don't need to put them on the front panel.  Mount them internally to free up front panel space.  Maybe leave one on the front panel for a special custom option.  Leave a small hole in the panel for each bulb so that you can visually confirm that the bulb is working.

Ed

[Wil_Bloodworth]

Hi Ed, the bulbs don’t mount to the front panel. Only the tips of the bulbs will protrude through the front panel; maybe by half an inch.  I’m 3D-printing a mount for the four bulbs and this mount will be deep inside the case.

Oh, and I’m using straight bulbs; not the conventional-shape ones.

- Wil

[Veteran68]

Very nice! I built one recently. Not as fancy as yours, but I was pleased with the result.

Nice!  Is that one of those heavy duty enclosures from Home Depot?  I was looking at some there a week or so ago.  They were quite heavy.  This blue enclosure is not so sturdy.

- Wil

Not from HD, this one came from Amazon. It is pretty heavy duty. Cutting out all the holes was a bit of a pain for a plastic box. A laser cutter or CNC would have been nice to have! I used a jigsaw, drill with step bits, and a deburring tool.

[Wil_Bloodworth]

Not from HD, this one came from Amazon. It is pretty heavy duty. Cutting out all the holes was a bit of a pain for a plastic box. A laser cutter or CNC would have been nice to have! I used a jigsaw, drill with step bits, and a deburring tool.

I thought about going this route was fairly certain I would completely screw it up!

[CaptDon]

Of course you will be using 'real' incandescent light bulbs and not the LED filament analogs of an incandescent lamp.

[Wil_Bloodworth]

Of course you will be using 'real' incandescent light bulbs and not the LED filament analogs of an incandescent lamp.

Yes, if you scroll up a bit you'll see a photo of the incandescent bulbs I'm (currently) planning on using.

- Wil

[thephil]

Very nice! For a long time, I used not much more than a lamp socket and some wire, but recently I built a proper one for myself, and I'm very happy with it.



I wrote a little blog post about the build, too (sorry, only in German ...):

https://techbotch.org/blog/current-limiter-lamp/index.html.

[Wil_Bloodworth]

Very nice! For a long time, I used not much more than a lamp socket and some wire, but recently I built a proper one for myself, and I'm very happy with it.

https://techbotch.org/blog/current-limiter-lamp/index.html.

That is nice and clean Phil!  I will take a look at your blog post.  Thanks!

- Wil

[MarkF]

Mine is very basic.
But I did get some fancy Edison bulbs.

[Wil_Bloodworth]

Mine is very basic.
But I did get some fancy Edison bulbs.

Simple/effective, but I really like that enclosure.

- Wil

[MarkF]

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Mine is very basic.
But I did get some fancy Edison bulbs.

Simple/effective, but I really like that enclosure.

- Wil

It's a 3D print that I designed just for it.
Sorry, I don't have exact 3D models.

[Wil_Bloodworth]

It's a 3D print that I designed just for it.

Very nice. Fusion360 is my go-to tool for 3D design and printing. However, I don't use it often enough to become "good" at it. Seems like I have to relearn it every time I do something new.  I am toying with the idea of designing mine in Fusion but the jury is still out on that as it is quite time consuming.

- Wil

[MarkF]

I've been using FreeCAD.  I'm not big on Fusion 360 cloud-based design.

Recently, I've been building tunnel walls and tunnel portals for my HO model railroad.
Burning up a lot of filament.  Looking back, it's not the cheapest way to go about it.
But, I don't have to mess with plastic cloth and it's structural for the mountain over the top.

[Wil_Bloodworth]

I received some smaller, yet higher-watt (60W vs. 40W) bulbs today and was able to redesign the layout a bit so I can use a much smaller case.  Haven't decided about labels yet so this thing will probably go through a few more revisions.  Although I did get some thinner toggle switches, I think I'll end up using the larger ones.  We'll see.



- Wil

[edpalmer42]

I don't recommend going to higher wattage bulbs unless you have a specific reason to do so.

If your Device Under Test is a small, low power device, you'll need a small bulb to protect it.  My dim bulb tester includes bulbs rated at 7.5, 15, 25, 40, 60, and 100 watts.  It's nothing fancy, I just screw in the bulb I want to use.

Ed

[enut11]

Another take on a mains safety overload box. With mine I need to change bulb wattage for different limit levels. I found the panel meter very useful, especially when the bulb is bypassed.

https://www.eevblog.com/forum/projects/upgrade-of-a-tried-and-true-bench-ac-mains-overload-monitor/msg4430722/#msg4430722

[Brad808]

Don't overlook KISS principles.

That was my thoughts as well 🤣. I just use a bulb with some gator clips on it. Works great.

[Wil_Bloodworth]

   

   Don't overlook KISS principles.
   

That was my thoughts as well 🤣. I just use a bulb with some gator clips on it. Works great.

I'm sure that is fine and will work for most people.

I do not deal well with things that are not clean/tidy/neat.  For example, here are two of my workspaces in the house:



- Wil

[Wil_Bloodworth]

Well, the newer (smaller) enclosure arrived today.  The faceplate prototype rework still needs some minor modifications but it's getting there. I'm going to change the label below the fuse to read 1.6 A.  The labels across the bottom need to be lowered and I'm going to switch YES/NO to opposite sides so that Yes goes with 1 and No goes with 0.  Also, the bulbs across the top need to move to the left around 4 mm.  I'll cut this out (of either acrylic or wood) soon... since this is about 1/4" too wide for my 3D printer.  The internal bulb mount needs to be designed but those sockets haven't arrived yet.



- Wil

[thephil]

Don't overlook KISS principles.

Hey – I'm a nerd! I don't want simple. I want hopelessly overengineered! 

[jonpaul]

The bulb has many limitations.

Since 1960s we use a Variac or Powerstat variable mains trsf on powert electronics, mains powered devices, design and debug of PS, SMPS, HV PS, electronic ballasts.
  avail in all sizes 100VA>>20 kVA

The metered powerstats of Staco and GenRad are especially useful with VRMS, IRMS and/or wattmters included.
I Found at Ham Radio fleas, auctions, silentt keys
For epay, etc, these are Heavy to ship, easily damaged!

Jon

[thephil]

Yes, the dim-bulb is no miracle device. However, it serves a different purpose than a variac. Some devices will refuse to do anything if you feed them a lower voltage than they desire. So I have both and use one or the other, depending on what I want to accomplish and the device I am working on.

[Jwillis]

Dim bulb current limiters are safety devices when working on high voltage low current devices. So if an unintentional short occurs theirs only a few milliamps instead of the full 12 to 15A coming from mains supply.They make a difference between a small spark and a really bad day.

[Shock]

Of course we'll leave "safety, high voltage low current" to be totally ambiguous so no beginner has any idea what you're talking about.

[PlainName]

Wouldn't "a few milliamps" as opposed to "the full 12 to 15A"  tell even a dim (ho ho) beginner the crux of it?

[thephil]

Dim bulb current limiters are safety devices when working on high voltage low current devices. So if an unintentional short occurs theirs only a few milliamps instead of the full 12 to 15A coming from mains supply.They make a difference between a small spark and a really bad day.

Exactly!

[tautech]

Dim bulb current limiters are safety devices when working on high voltage low current devices. So if an unintentional short occurs theirs only a few milliamps instead of the full 12 to 15A coming from mains supply.They make a difference between a small spark and a really bad day magic smoke.

FTFY

Even tried to catch that stuff and put it back in ?