DIY Solid State Relay

About: I am a electronics hobbyist from india. Youcan visit my youtube channel "AviPrink" for more detailed information.

Hello Friends today i am going to make a isolated SSR, As we know treditional relays provide galvanic isolation but it is electromechanical switch as its contacts damaged over time,so i decided to make a Solid State Relay For load switching.

Step 1: Optocoupler Triac AC Output 1 Channel 400VDRM 6-Pin PDIP

MOC3021 is a Otocoupler this component is responsible for switching main triac BT136 and also provide Optical Isolation.

Step 2: BT136

BT136 is a 4A 500V Triac used in this module to switch ON/OFF AC loads,

Step 3: Schematic Diagram

Assemble all the components according to circuit diagram, on PCB


As optocoupler gets 5v DC from Any MCU or Power Source its internal LED illuminates, then other Side PhotoTriac(Transister) turns ON( Optocoupler can either switch AC loads but it can handle only few mA current, so we utilize BT136 it can handle 4 Amps with heatsink, ) then BT136 also turns ON , NOW our entire SSR is Active,


  1. Not Robust as Conventional relays,


  1. consume less power
  2. provide optical isolation
  3. faster response time
  4. longer life
  5. no noice

Step 4: All Assembled Together

Assemble your own if you have any problem related to this project leave a comment, you can also visit my channel Click here for more projects.

thank you

c u soon



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