Category Archives: Design

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

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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.

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

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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.

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

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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!

ESP-NOW instead of WiFi

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Today I learned about ESP-NOW over here: Forget WiFi! This Wireless Method is WAY Better?

This looks like exactly what I need for a project I’m planning. I want to connect my WiFi router with a relay between its power source. I can then trip the relay to reboot the router. I need to do this every couple of months and doing it manually is a pain because I have to walk into the other room to do it.