Category Archives: Design

High-Water Indicator | Project 16/20 | Maxitronix 20in1 | In The Lab With Jay Jay

Posted on by
Reply

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

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

In this video we do the 16th project from the Maxitronix Sensor Robot 20 (20in1) Electronics Project Lab Kit: High-Water Indicator.

After we build the circuit we dump the sensor in a glass of water which causes the alarm to trigger. To avoid the obnoxious noise we put an LED in place of the buzzer.

Please be aware: while talking about this circuit I said that the astable multivibrator “flip flops” between states. And that’s kind of true in one sense, but I should be clear than an astable multivibrator is not a “flip flop” circuit. A flip flop circuit is a different type of circuit known as a bistable multivibrator, which is a different kind of thing. In this experiment we use an astable multivibrator to generate a 1.62 kHz square wave which provides our tone, we do not use a flip flop or bistable multivibrator circuit.

We use the Rigol MSO5074 Mixed Signal Oscilloscope to measure and visualize the 1.62 kHz square wave which generates our tone.

We use the UNI-T UTi260B Thermal Imager to investigate the circuit thermals. We see that the 1K resistors in the astable multivibrator generate the most heat.

We use the Fluke 17B+ Digital Multimeter to measure the voltage across Q5. Between about 500 mV and 750 mV is enough voltage to enable the output.

We use the Riden RD6006 Bench Power Supply to deliver the 9V DC required for the project. We use the current measurement from the power supply to see that when the LED is active the circuit draws about 23 mA compared to about 11 mA when the LED is not active.

We use the Horusdy Soldering Station with Hot Air Gun to dry the sensor after it got wet.

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!

Ausum 25 In 1 Precision Screwdriver SetThis is an image of the product.notes

Let’s go shopping!

Glass Organ | Project 15/20 | Maxitronix 20in1 | Learning Electronics In The Lab With Jay Jay

Posted on by
Reply

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

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

In this video we do the 15th project from the Maxitronix Sensor Robot 20 (20in1) Electronics Project Lab Kit: Glass Organ.

We had some trouble getting this circuit to work. It turned out that the instructions omitted one necessary wire. After we added that the circuit worked.

The salty water and the clean water didn’t have hugely different effects. It was hard to get a resistance reading because the resistances seemed to just continually increase. In the end I didn’t really understand that.

The products I purchase from AliExpress in the video are these:

We used the Rigol MSO5074 Mixed Signal Oscilloscope to inspect the output of the astable multivibrator.

We used the METCAL PS-900 Soldering Station to solder some jumpers onto a 10K potentiometer which we use to alter the frequency of the astable multivibrator.

We used the UNI-T UTi260B Thermal Imager to inspect the heat profile of the circuit. We see the resistors in the astable multivibrator get warm, along with other components.

We used the Fluke 17B+ Digital Multimeter to continuity test our point to point links, to test various resistances, to check for capacitance (there was none), and to measure the current draw. It was interesting to see the current draw increase with frequency.

We used the Riden RD6006 Bench Power Supply to provide 9V for the circuit. The RD6006 also reported current draw.

We used the Horusdy Soldering Station with Hot Air Gun. We used the hot air gun to shrink the heat shrink we used on the potentiometer jumpers.

We used the Brother P-Touch D210 Label Maker to label our salt jar.

The Goo & Adhesive Remover product I recommend is Goo Gone.

The cheap but excellent wire cutters I mention are these. I got a five pack for ten bucks.

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!

Fluke 17B+ Digital MultimeterThis is an image of the product.

Let’s go shopping!

Square mesh holders installed

Posted on by
Reply

I’m waiting for some more of these to arrive: Office Desk Pen Pencil Pot Ruler Scissor Cup Mesh Organize Container.

While I wait you can see in the bottom photo the bunch of tools without a home. In the pictures below I have circled in red the four mesh holders I have recently installed. They’re black on black so hard to see, sorry about that.

The two on the left are clipped on with zip ties. The other two are screwed in, one screwed into the second drawer and the other to some load bearing dowel I also installed today.

I’m a bit paranoid about the shelf my oscilloscope is installed in will come away from the wall, so I have buttressed it with a dowel I had them cut to size for me today at the shop (307mm, exactly).

Ferromagnetic Substance Detector | Project 13/20 | Maxitronix 20in1 | In The Lab With Jay Jay

Posted on by
Reply

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

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

In this video we do the 13th project from the Maxitronix 20in1 (the Sensor Robot 20): Ferromagnetic Substance Detector.

In this project we use the reed switch to detect magnetic material. We use an astable multivibrator to generate a tone which sounds when magnetic material is detected.

We use the Riden RD6006 Bench Power Supply to provide 9V for our test circuit.

We use the UNI-T UTi260B Thermal Imager to inspect the circuit board during operation and see the transistors for the astable multivibrator dissipating the most heat.

We use the Rigol MSO5074 Mixed Signal Oscilloscope to inspect the 1.5 kHz square wave which generates the tone for the buzzer.

We use the Fluke 17B+ Digital Multimeter to investigate some currents and some voltages into the base of transistor Q5.

We use the METCAL PS-900 Soldering Station to tin some wire for the DuPont-female jumper.

We also use a breakout board to add a volume control to the buzzer and to substitute a LED for the buzzer.

I really enjoyed this project, I think it’s the best one so far!

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!

PowerShield Defender 1600 UPSThis is an image of the product.

Let’s go shopping!

Electronics Project #10: TJ-56-428 4-Digit Digital DIY Clock | In The Lab With Jay Jay

Posted on by
Reply

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

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

Silly Job Title: Switch Sleuth

Happy New Year!

In this video, my first video for 2025, I construct a 4-digit digital clock I recently purchased from AliExpress: TJ-56-428 4-Digit Digital DIY Clock Kits with Acrylic Shell, DIY Alarm Clock Soldering Practice Kit for Learning Electronics.

I thought it might be nice to kick off the new year with an actual electronics project, as that is what this channel is supposed to be mostly about!

I translated the instructions from Chinese to English, and those are here: TJ-56-428. These include instructions for use of the complete and fully assembled clock.

This was a great chance to try out my new METCAL PS-900 Soldering Station and I am pleased to report that I am very happy with my new soldering iron! It is a pleasure to use.

The heart of this circuit is the STC15W404AS which is a microcontroller! It has been pre-programmed with the clock functionality, there was no software or source code that shipped with the kit.

Update: my mate @sadata777 pointed out that there was a protective coating on the acrylic and I remove that in this video: https://youtu.be/y9btakLOCHc

Update: my mate Joe pointed out that I had the case on back-to-front which you can see me fix here: https://youtu.be/IyJ3IHgRfiw

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!

Yum Cha IC Chip Pickup ToolThis is an image of the product.

Let’s go shopping!

Magnetism Detector | Project 12/20 | Maxitronix 20in1 | Learning Electronics In The Lab With Jay Jay

Posted on by
Reply

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

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

In this video I do the 12th project from the Maxitronix 20in1 (the Sensor Robot 20): Magnetism Detector.

In this project we control a BJT transistor with a magnetic reed switch.

We use the thermal camera to observe heat in the transistors and LEDs during operation.

This is a plain DC circuit with no signals so there was no call for measuring anything with the oscilloscope.

I got myself a little confused about normally open and normally closed circuits during the video, but I think I was clear enough about that in the end.

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!

Yutiars Round Paint BrushesThis is an image of the product.notes

Let’s go shopping!