Learning the Art of Electronics: 1S Supplementary Notes: Investigating Thevenin equivalent of voltage divider | In The Lab

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Silly Job Title: Luminary Luminar. I am the Luminary Luminar!

In this video we continue to work our way through Learning the Art of Electronics. In this video we finish 1S Supplementary Notes: Resistors, Voltage, Current and do Exercise 1.10 from The Art of Electronics which has us investigating a voltage divider.

In this video I recommend to you the book Schaum’s Outline of Basic Circuit Analysis, 2nd Edition and Gary Tuttle’s website gtuttle.net where you can find Thevenin & Norton practice problems.

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

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

We use the Pro’sKit SS-331H Desoldering Pump to fix up some of our mistakes.

We use the Tenma 72-10505 Bench Power Supply to provide 15 and 30 V DC to our circuits.

We use the EEVblog BM2257 Digital Multimeter to measure voltage.

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

We use eight of the cheapo Yum Cha DT830B Digital Multimeters as ammeters and voltmeters.

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

We use the Sharp EL-546L Scientific Calculator to do some basic calculations.

We use the Bysameyee Head-Mounted Magnifier to light up our life.

We use the nmsafety Nitrile Gloves to protect our fingers.

We use the ElectroCookie PCB Prototype Solderable Breadboard to make our circuit on.

We use the WilliamKlein Music Stand to hold our tome.

We use the Scotch Titanium Scissors to snip, snip, snip.

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

We use the Plato Model 170 Wire Cutter to cut, cut, cut.

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 Luminar, Pro’sKit, Desoldering, Tenma, Yum Cha, Multimeters, Bysameyee, nmsafety, ElectroCookie, Solderable, WilliamKlein, and Hakko 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 10pcs Glue Removal Razor BladesThis is an image of the product.

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Voltmeters and ammeters

In this photo we see three voltmeters (across the top) and five ammeters (across the bottom) attached to a voltage divider connected to a load.

30 V is applied then 2 mA flows through R1 and then splits with 1 mA going through R2 and 1 mA going through Rload. 20 V drops across R1 and there is 10 V across R2 and Rload.

Five ammeters and three voltmeters connected to a voltage divider attached to a load

The circuit on the left in the schematic below is the one being tested. In this case R1, R2, and Rload are all 10 kΩ. As R2 and Rload are connected in parallel their effective resistance is 5 kΩ. R1 being 10 kΩ gets two thirds of the voltage because R2 || Rload is 5 kΩ getting one third of the 30 V being 10 V.

The schematic of the voltage divider being tested

The Bang Preventer – aka DIY Current Limiter with isolation transformer

I asked Tony359 about his current limiter and he referred me to the video below in which he explains his home made contraption. Very cool. I think I should make one of these.

Update: I also found a video covering a similar topic:

The voltmeter used in the second design is this one: Digital AC Voltmeter.

Oh, and here’s another one!

Help with Thevenin equivalent circuit

I was doing some prep work for the upcoming LAoE video and learning about Thevenin equivalent circuits, something I need to understand better than I do, particularly how to calculate Vth and Rth. I built the circuit on my bench, but then got readings I didn’t understand, so I asked about it over on the EEVblog Forum: Help with Thevenin equivalent circuit. In the end it turned out that my initial readings were wrong for some unknown reason, but when I repeated them they came out right the second time…

The Beacon Light | Project 11/30 | Maxitronix 30in1 | Learning Electronics In The Lab With Jay Jay

You can support this channel on Patreon: patreon.com/JohnElliotV

This post is part of my video blog and you can find more information about this video.

Silly Job Title: Transistor Troubadour. I am the Transistor Troubadour!

In this video we do the 11th project from the Maxitronix 30in1 Electronics Project Lab Kit: The Beacon Light.

We use the Rigol MSO5074 Mixed Signal Oscilloscope to examine the waveform.

We use the UNI-T UTi260B Thermal Imager to check the thermals (there wasn’t much to see).

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! :)


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!

MECHANIC Hard BrushThis is an image of the product.

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The Highs and Lows of Oscillation | Project 10/30 | Maxitronix 30in1 | In The Lab With Jay Jay

You can support this channel on Patreon: patreon.com/JohnElliotV

This post is part of my video blog and you can find more information about this video.

Silly Job Title: Volt Vanguard. I am the Volt Vanguard!

In this video we do the 10th project from the Maxitronix 30in1 Electronics Project Lab Kit: The Highs and Lows of Oscillation.

The spreadsheet with our measurements is here: Maxitronix-30in1-10.ods.

We use the Rigol MSO5074 Mixed Signal Oscilloscope to measure the period of our circuit’s oscillations.

We use the UNI-T UTi260B Thermal Imager to check the thermal properties of our circuit. There was nothing exciting to see.

We use the Carpenter Mechanical Pencil to take notes.

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 Rigol and Imager 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 CrowbarThis is an image of the product.

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Learning the Art of Electronics: 1L.6 I versus V for some mystery boxes | In The Lab With Jay Jay

You can support this channel on Patreon: patreon.com/JohnElliotV

This post is part of my video blog and you can find more information about this video.

Silly Job Title: Code Warrior. I am the Code Warrior!

In this video we continue to work our way through Learning the Art of Electronics. In this video we continue with 1L Lab: DC Circuits and investigate two mystery boxes.

The values we measure in this video are available in this spreadsheet: LAoE-01L.6.ods.

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

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

We use the Riden RD6006 Bench Power Supply to provide test voltages of 0.1 V through 10 V.

We use the EEVblog BM2257 Digital Multimeter to measure current.

We use the EEVblog BM036 Digital Multimeter to measure current.

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

We use the Brother P-Touch D210 Label Maker to make labels.

We use the WilliamKlein Music Stand to hold the text book.

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 to cut, cut, cut.

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 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 Corner CutterThis is an image of the product.

Let’s go shopping!