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Silly Job Title: Current Conjurer. I am the Current Conjurer!

In this video we build a variable brightness LED for use as a circuit for testing an ammeter which we will be making next week as we continue through Learning the Art of Electronics. This circuit will draw between 3 and 18 mA which should meet our requirements.

(Update: the project where we use our variable brightness LED is now available online. Check it out if you’d like to see how we put this circuit to use: Learning the Art of Electronics: 1L.4.3 10 mA Ammeter | In The Lab With Jay Jay.)

This humble build shows how to make a simple circuit from components connected to each other with DuPont cables, no circuit board required. Using the DuPont cables allows us to make the circuit in the air first for assembly and testing then allowing it to be installed in the project box piece by piece after it has been tested.

During testing we discover a problem whereby the circuit doesn’t power on. Investigation with the voltmeter indicates the problem is in the wiring of the DC barrel power socket. Once that gets fixed the circuit works and is ready for installation.

The convention I used to help me remember what connects to what is that a male DuPont connection is for an output and a female DuPont connection is for an input; things which connect to each other will preferably have the same colour wire.

After testing I use heat shrink around the various leads and wires. I also use a number of different sizes of drill bit in order to make the holes in the project box for the DC barrel power in, LED, potentiometer, and banana sockets.

The DC barrel power in, potentiometer, and banana sockets are bolted in with washers and nuts, whereas the LED is held in place with hot glue. If I need to remove the LED in future isopropyl alcohol is the antidote for hot glue.

I labeled the box as “5V LED”, which should help me remember what this thing does so I can use it again in the future, should I find myself needing to draw a few milliamps in a pinch.

The circuit diagram looks something like this:

And the finished product looks something like this:

We use the METCAL PS-900 Soldering Station for soldering.

We use the AiXun H314 Hot Air Gun for shrinking our heat shrink.

We use the Riden RD6006 Bench Power Supply for supplying voltage for testing.

We use the EEVblog BM2257 Digital Multimeter to measure voltage.

We use the Fluke 17B+ Digital Multimeter to measure voltage and current.

We use the Brother P-Touch D210 Label Maker to label our project.

We use the Carpenter Mechanical Pencil to make notes.

We use the Hakko CHP 3C-SA Precision Tweezers for tweezering.

We use the Plato Model 170 Wire Cutter for cutting.

We use the Kaisi S-160 45x30cm Repair Mat as our workspace.

Thanks very much for watching! And please remember to hit like and subscribe! :)

p.s. today I added potentiometer, isopropyl, milliamps, multimeter, and tweezering to my spell check.

Following is a product I use picked at random from my collection which may appear in my videos. Clicking through on this to find and click on the green affiliate links before purchasing from eBay or AliExpress is a great way to support the channel at no cost to you. Thanks!

Yum Cha Drill Extension

Let’s go shopping!