Dim-Bulb / Current Limiter Prototype - Page 1
Forum section: electronics / beginners

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 01:58:46 am
content: 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

author: Veteran68
author_rank: Frequent Contributor
timestamp: November 21, 2023, 02:11:57 am
content: Very nice! I built one recently. Not as fancy as yours, but I was pleased with the result.

author: tautech
author_rank: Super Contributor
timestamp: November 21, 2023, 02:14:42 am
content: Don't overlook KISS principles.https://www.eevblog.com/forum/repair/suggested-for-a-sticky-part-one-comments-or-additions-please/msg470686/#msg470686

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 02:15:51 am
content: Quote from: Veteran68 on November 21, 2023, 02:11:57 amNice! 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

author: edpalmer42
author_rank: Super Contributor
timestamp: November 21, 2023, 02:22:25 am
content: 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

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 02:28:19 am
content: 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

author: Veteran68
author_rank: Frequent Contributor
timestamp: November 21, 2023, 02:32:53 am
content: Quote from: Wil_Bloodworth on November 21, 2023, 02:15:51 amNot from HD, this one camefrom 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.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 02:36:16 am
content: Quote from: Veteran68 on November 21, 2023, 02:32:53 amI thought about going this route was fairly certain I would completely screw it up!

author: CaptDon
author_rank: Super Contributor
timestamp: November 21, 2023, 02:41:41 pm
content: Of course you will be using 'real' incandescent light bulbs and not the LED filament analogs of an incandescent lamp.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 02:58:09 pm
content: Quote from: CaptDon on November 21, 2023, 02:41:41 pmYes, if you scroll up a bit you'll see a photo of the incandescent bulbs I'm (currently) planning on using.- Wil

author: thephil
author_rank: Regular Contributor
timestamp: November 21, 2023, 03:30:30 pm
content: 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.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 03:36:02 pm
content: Quote from: thephil on November 21, 2023, 03:30:30 pmThat is nice and clean Phil! I will take a look at your blog post. Thanks!- Wil

author: MarkF
author_rank: Super Contributor
timestamp: November 21, 2023, 03:49:01 pm
content: Mine is very basic.But I did get some fancy Edison bulbs.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 04:03:59 pm
content: Quote from: MarkF on November 21, 2023, 03:49:01 pmSimple/effective, but I really like that enclosure.- Wil

author: MarkF
author_rank: Super Contributor
timestamp: November 21, 2023, 04:09:51 pm
content: [ Specified attachment is not available ]Quote from: Wil_Bloodworth on November 21, 2023, 04:03:59 pmIt's a 3D print that I designed just for it.Sorry, I don't have exact 3D models.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 04:22:49 pm
content: Quote from: MarkF on November 21, 2023, 04:09:51 pmVery 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

author: MarkF
author_rank: Super Contributor
timestamp: November 21, 2023, 04:29:27 pm
content: 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.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 22, 2023, 09:07:23 pm
content: 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

author: edpalmer42
author_rank: Super Contributor
timestamp: November 23, 2023, 03:50:32 am
content: 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

author: enut11
author_rank: Super Contributor
timestamp: November 24, 2023, 12:40:34 am
content: 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

author: Brad808
author_rank: Contributor
timestamp: November 24, 2023, 03:15:26 pm
content: Quote from: tautech on November 21, 2023, 02:14:42 amThat was my thoughts as well 🤣. I just use a bulb with some gator clips on it. Works great.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 24, 2023, 06:32:29 pm
content: Quote from: Brad808 on November 24, 2023, 03:15:26 pmI'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

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 24, 2023, 11:36:22 pm
content: 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

author: thephil
author_rank: Regular Contributor
timestamp: February 01, 2024, 10:14:28 am
content: Quote from: tautech on November 21, 2023, 02:14:42 amHey – I'm a nerd! I don't want simple. I want hopelessly overengineered!

author: jonpaul
author_rank: Super Contributor
timestamp: February 01, 2024, 11:08:15 am
content: 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 kVAThe metered powerstats of Staco and GenRad are especially useful with VRMS, IRMS and/or wattmters included.I Found at Ham Radio fleas, auctions, silentt keysFor epay, etc, these are Heavy to ship, easily damaged!Jon

author: thephil
author_rank: Regular Contributor
timestamp: February 10, 2024, 01:27:57 pm
content: 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.

author: Jwillis
author_rank: Super Contributor
timestamp: February 10, 2024, 02:04:43 pm
content: 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.

author: Shock
author_rank: Super Contributor
timestamp: February 10, 2024, 04:11:44 pm
content: 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.

author: PlainName
author_rank: Super Contributor
timestamp: February 10, 2024, 05:07:55 pm
content: Wouldn't "a few milliamps" as opposed to "the full 12 to 15A" tell even a dim (ho ho) beginner the crux of it?

author: thephil
author_rank: Regular Contributor
timestamp: February 10, 2024, 06:51:43 pm
content: Quote from: Jwillis on February 10, 2024, 02:04:43 pmExactly!

author: tautech
author_rank: Super Contributor
timestamp: February 10, 2024, 07:17:38 pm
content: Quote from: Jwillis on February 10, 2024, 02:04:43 pmFTFYEven tried to catch that stuff and put it back in ?