Author Andrei
21/05/2019

The awesome YouTube channel GreatScott! just posted a new project. He now made a new PCB that could control the paower of AC voltage. So, please, if you want to try this same circuit, be careful working with high AC voltage because this could be lethal. That been said, let's see this new PCB. First of all, he explain us how we could control AC voltage using TRIACs with a DIAC circuit that will apply a small pulse at the TRIAC gate each zero-cross of the AC signal. We could add a potentiometer to this circuit and it would work just fine for normal incandescent AC light bulbs. But he also wants to control the power for LED high voltage lights and with this simple circuit that won't work.

So, a more digital and precise control is needed and is that why he designed a new PCB and compare it with a commercial product that dose the same.

He wanted a digital control and that involves a microcontroller. But he also wanted a small PCB so he used the ATtiny85 microcontroller that could be easily programmed using an SPI connection from an Arduino and the needed libraries. So he started making the circuit and this ATtiny85 will read the value from a potentiometer and then apply small pulses to a photocoupler. In this way he will separate the high AC voltage from the low DC voltage of the microcontroller. And about that low DC voltage. To get around 5V DC for the digital part he used a small transformer module that could provide the needed voltage and enough currnet and also keep this PCB quite small.

We can see the design of the PCB in this photo and how he placed all the components. The input and output are just two PCB terminals for that 220VAC main input and the light output. There is also an SPI port so we could program the PCB using an Arduino.

So, he finally made this PCB and it works quite good with normal AC light but also with those new LED based bulbs. If you want to see more, chec the video he posted and read all the information. He is sharing all the schematics and the PCB with us and also gives his final results between the commercial module or the homemade one and it seams that buying the module will be better in this case because that circuit has more protection, the price is almost the same in both cases and it also has a good case for the PCB.

Apart this post, if you have your own project and you need good quality PCBs, consider using the services of JLCPCB.com which will offer you quite good services, I use their services a lot of my PCBs.

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