Make Your Own Solid State Relay

In this project we will have a look at solid state relays, find out how they work and when to use them and in the end create our own DIY Solid State Relay. Let's get started!

Step 1: Watch the Video!

The video gives you all the information you need to create your own Solid State Relay. In the next steps though I will present you some additional information.

Step 2: Order the Components!

Here you can find a parts list with example seller (affiliate links):
Aliexpress:

1x MOC3020 Optocoupler: https://s.click.aliexpress.com/e/_dZQvjs7

1x BT138 Triac: https://s.click.aliexpress.com/e/_dXjBcRH

1x 330Ω, 3x 1kΩ Resistor: https://s.click.aliexpress.com/e/_dTPpXjt

2x PCB Terminal: https://s.click.aliexpress.com/e/_dYbstfZ

1x Heatsink: https://s.click.aliexpress.com/e/_dXwflOP

Ebay:

1x MOC3020 Optocoupler: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x BT138 Triac:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 330Ω, 3x 1kΩ Resistor:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x PCB Terminal:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x Heatsink: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

Amazon.de:

1x MOC3020 Optocoupler: http://amzn.to/2jEy2NG

1x BT138 Triac: http://amzn.to/2hLuQQ1

1x 330Ω, 3x 1kΩ Resistor: http://amzn.to/2hMZ7h7

2x PCB Terminal:http://amzn.to/2jEq8ns

1x Heatsink: http://amzn.to/2hLJpCT

Step 3: Build the Circuit!

Here you can find the very simple schematic of my DIY solid state relay along with pictures of my finished board. Feel free to use them as a reference.

Step 4: Success!

You did it! You just created your own Solid State Relay!
Feel free to check out my YouTube channel for more awesome projects:

http://www.youtube.com/user/greatscottlab

You can also follow me on Facebook, Twitter and Google+ for news about upcoming projects and behind the scenes information:

https://twitter.com/GreatScottLab
https://www.facebook.com/greatscottlab

Comments

[attanayaka]

i want to control 230v 15A water pump.i can use it?

[gangaaarr]

Just swap the triac with a bigger one... And add snubber circuit

[SeanB10]

I suggest using a relay for the benefits mentioned in the video. Slow but nothing complex about them. Just use a flyback transistor across the solenoid coil and use an NPN transistor between the coil and ground to switch it. 15A is big, pumps switch slow, and ratings are reliable. Sainsmart relay boards are nice because they have optoisolators, protection diodes and relays, and little leds, all packaged pretty cheap. To get a sizable relay for your use, spec it out.

[JohnC430]

"Just use a flyback transistor across the solenoid coil" you mean use a diode across the solenoid coil

[JohnC430]

How do you
know it is 15 amps? 230Vx15A = 3460VA/746 W/HP = 4.6 HP. (approx 5HP) Is that the rating of your water pump motor?
If so then, No you cannot use this one. You
will also need to start the motor slowly, so you need to add phase control to
the motor starter. Hence this circuit is
not applicable to that. Also be aware
that he is he is teaching you the basic concept to show how the SSR works and
is not supplying you with a circuit for you to build and connect to your water
pump motor. If you want something for a
5 HP motor you need to use something more sophisticated than that. You also need to add circuit protection Fuses
and Circuit Breakers for your motor which is much more expensive then this SSR.
The Triac also needs a
heatsink. So there is a lot more to
using an SSR for motor control.

[dcalado1]

You can use BTA41, not for sure in this project.

[jimvandamme]

Be careful of current ratings. Measure the peak current of the pump as it turns on, and the steady state current. You need to pick your triac for both conditions. The instantaneous current rating will take the starting current, then the heat rejection will deal with the steady load.

I'd think that the 15 amps is probably the inrush current rating of the motor, so the 12 amp continuous rated one might work.

Don't expect a fuse to protect your triac. As a rule, solid state blows in nanoseconds "to protect the fuse". At least use a spike protector (MOV, a LC filter, or both) to keep voltage below dangerous levels.

[jfranke]

Good comments! However, a fuse is useful if the load fails and or the triac fails in a mode that maintains enough power to cause a fire or other damage. When things go bad, it is best to remove power at the source and that is where the fuse should be. A fuse is used to protect life and home, not the triac and or load.

[SeanB10]

My experience with zero crossing detectors and triacs to switch any device that induced a phase shift would destroy the triacs and leave them running, or short them out so to speak. The problem is that the triac is switch on at the wrong time because zero crossing detector couldn't handle the phase shift. This is motors, old CRTs, the like. You could tune the detector for a given phase shift. My solution was a relay.

[KEDam]

You would need to finde a more powerful triac, this one is only rated for 12amps but rest would be the same.

[samir021]

Thanx for Your great videos. Is there any way to explain and make single phase shaded motor speed controler with phase angle control with arduino.

[gangaaarr]

Give a pwm signal instead of vcc on optocoupler..... And add a snubber circuit on the ac side... 👍

[ranganatennakoon]

dear @GreatScott! sir,
this diy ssr can handle inductor loads? if answer is no how can i modify it ? I saw the internet they added additional two capacitors, and sometimes added inductor, how its works, thankyou !

[gangaaarr]

We call it a snubber circuit....

[swamijotirlingj]

Will this circuit works with the ESP8266 Node MCU [with 3v as the input voltage].

[gangaaarr]

Yes... Just reduce the R1 value accordingly... 😊

[agungpriamb2000]

wow, you made a 12amp relay
amazing instructions
I thought you were going to make an actual 40 amp relay using the bta41-600b triac or the bta40-700

[aladdinf]

Great instructable thanks.

[EhteshamN]

Why you didn't use RC circuit at secondary or AC side....could you please tell me what is the difference with RC and without it...
One more question...how we can protect our AC side in case of any short circuit..
Because, I have faced many time this issue and this shorten results in blow or short the TRIAC...
Plz reply whatever solution in your mind.
Regards

[gm280]

Mechanical Relays, Solid State Relays and even MOSFET switches all have their place in the scheme of things. Picking the proper one is the option of the person designing the circuit. They all have their pros and cons.