ROBOT.LK

hi experts,

I received a project from a client to automate one of his machines that are operating with almost obsolete electronics. I can figure out a program for the Microcontroller but there are certain mechanical (4 Amp) relays that are operating in the A/C side to replace as well. I heard about Solid State Relays (SSR) but I have no idea on usage at the moment.

1. Is there anybody who can help me to drive a I/O pin directly to a SSR.
2. I have seen the SSRs are bit expensive. Is there any cheaper solution to drive A/C with a triac circuit?

Regards,

Leo

Hi Friend ,

It seems you want to control some bit large amphere range. So you will have to use a solid state relay , atleast
which is operating from 12 V. Normally microcontroller I/O output 5 V and it is not good to use them as a current source for operate a relay. So you can switch a FET from the microcontroller siganl and that FET can be use to operate the SSR
You can use a FET such as IRF540 , which is very common in the market. feed the MCU I/O signal to FET Gate and conect the SSR control pin to souce of the FET. Suppy voltage to Drain though a resistor ( 12 V)

I think SSR is very reliable and easy to implement compare to TRIAC for this knid of application. And SSR is cheap also , as if you are going to use a TRIAC , you have to implement a gate controlling circuit also. SO I think the best option is use SSR