DIY Solid State Relay

Ever wanted to get rid of that tic-tac sound electromagnetic relays make? Electromagnetic relays require significant power to turn the electromagnet on/off and need a driver circuit for that, oh! wait! also they need a flyback diode to avoid the risk of inductive spiking which may not be suitable for projects running on battery or projects which you want to be power efficient.

If you want to get rid of all those things in once you are at the right place, here I will show you how to make Solid State Relay using just couple of components.

WARNING:- THIS PROJECT DEALS WITH HIGH-VOLTAGE (AC MAINS) USE FULL PRECAUTIONS. I WILL NOT BE RESPONSIBLE FOR ANY KIND OF DAMAGE CAUSED TO YOU.

LET's GET STARTED!!

DOWN HERE IS THE COMPLETE VIDEO TUTORIAL FOR THE SAME.

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Step 1: THINGS WE NEED

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Triac- BT136

Optocoupler- MOC3021 (used to isolate high-voltage from low-voltage input)

Resistors- 220 ohms and 470 ohms

LED - Just for indication of state

Breadboard- For making prototype

Jumpers

5V power supply ( I will use my arduino for this)

Finally the Schematic.

Step 2: OPTOCOUPLER

Add it to the breadboard.

Step 3: Add Negative Pin of Led to Pin 1 of Optocoupler

Step 4: Add 220 Ohm Resistor to +ve Pin of LED

Step 5: Add Jumper to Pin 2 of Optocoupler Which Will Go to -ve Power Supply

Step 6: Join Source of Triac to 4th Pin of Optocoupler

Step 7: Add 470 Ohm Resistor Between the Drain and 6th Pin of Optocoupler

Step 8: Add Two Jumpers, One to Drain and Another to Gate

Step 9: BINGO! Time to Test

Step 10: Add Power Supply

I used my arduino mega with blink sketch.

Step 11: Print the Final PCB

Don't know how to print PCB's? Watch this

From HERE you can download the PCB file in .pcb extension.

Don't know how to print PCB's?

PAY ATTENTION- you need to make the traces thick because it is a high-voltage project, to know how to tin PCB see this instructable

To see the working watch the video I linked in Introduction.

Thanks to DIY bloke for my inspiration for this project.

Thank You for coming here

see you again,

Tanishq Jaiswal

Comments

[tycon4]

Can I use the MOC3023 so I can do dimming?

[Tanishq Jaiswal]

No, Dimming is a completely different concept, have a look at this excellent instructable for more details about dimming - https://www.google.co.in/amp/s/www.instructables.com/id/AC-PWM-Dimmer-for-Arduino/%3famp_page=true

[gid204]

Hello, what is the load voltage and current?
Thanks

[Tanishq Jaiswal]

Load voltage I used is 220V and Load is a 100W bulb, I do not recommend going beyond that without a heatsink on triac, but remember that heatsink will be connected to AC mains, don't do the mistake of going near it.

[EdwardL8]

I have a question regarding the polarity on pin 1 and 2 of the Opto coupler. You say that pin 2 is positive, but in the data sheet I downloaded for the MOC3021, pin 2 is the negative side. Am I mistaken in my understanding?

[Tanishq Jaiswal]

Opps a huge mistake, I reversed the polarity everywhere, Thank you very much for pointing it out, edited it.

[KISELIN]

Good enough! But for the beginer's safety.. the breadboard you made: The ACV (230V) side, ALL wiring and isolation requiers at least 5mm. spaceing, (in Europe), + it should be isolated in other method's too. Make absolutely sure to have the AC side fused, (recommend a fault leakage current circuitbraker 20mA). There are Triacs that you can turn ON/OFF directly with logical levels = no need of the opto. Can't recall them types right now, but they are not expensive. These ON/OFF, (direct logik control triacs), differe's in use from the usually used zero crossing methods in that their effience is much higher.

[AhmedE41]

i build one last week ;) and its very easy thank you

[Tanishq Jaiswal]

Glad that you tried! :)

[JC41]

Good ible. I would recommend using a software such as Fritzing to draw a schematic and layout, instead of spending so many steps on how to do the wiring. You could instead use those steps to explain how the circuit works, or explain the code, etc.

[rafununu]

This relay isn't exactely synchronized with mains. If you send a pwm signal, this time synchronized at 50 or 60Hz, on the moc, you'll have a dimmer !

High intensities will need a dissipator for the triac which produces 1.4 x Int watt.

[Tanishq Jaiswal]

I think by saying synchronization you mean zero cross detection, yes you can use it as dimmer in that way, but it is very complex for beginners to code microcontroller to detect zero cross and also because power MOSFETS(like irfp460) are cheaply available, so for the simplicity of code and circuit, I use them instead of using triacs.

[ahmet_024102]

where is code

[Tanishq Jaiswal]

It is a simple blink sketch, you can get it in examples in IDE, I used microcontroller only for testing, you just have to supply 5V to turn it on.

[spacepymp]

Great job on this... Funny because i had done something very similar for a steam punk ish spark gap "macro" logic gate( just for visuals).... My one suggestion for clarity is to make a diagram for the breadboard, some of the placements are tricky to see, esp for circuit noobs:)

[BeachsideHank]

Good explanation, this may be useful to some.

[Tanishq Jaiswal]

thanks!