Relay question

[Pcinacan]

So i am amking my first Christmas light show and i need help with getting the relays. I am going to running them off a MEGA board and want them to be demable. I have been looking at normal ones like this https://www.amazon.com/gp/product/B0057OC66U/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER, but people where saying to get a SSR like this  https://www.amazon.com/gp/product/B017LR5NT2/ref=ox_sc_act_title_4?ie=UTF8&psc=1&smid=A1A5FQE7R5RISB. Can both dim or what. also what is even the difference of SSR and R? 

[W-L]

1 hour ago, Pcinacan said:

So i am amking my first Christmas light show and i need help with getting the relays. I am going to running them off a MEGA board and want them to be demable. I have been looking at normal ones like this https://www.amazon.com/gp/product/B0057OC66U/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER, but people where saying to get a SSR like this  https://www.amazon.com/gp/product/B017LR5NT2/ref=ox_sc_act_title_4?ie=UTF8&psc=1&smid=A1A5FQE7R5RISB. Can both dim or what. also what is even the difference of SSR and R? 

Well just off the bat those solid state relays are much lower amperage at a max of 2Amps (AC) where the mechanical ones are 10Amps (AC). In certain applications solid state units tend to be desirable as they don't spark and have quick open and close times compared to an electro-mechanical relay. 

[straight_stewie]

In addition to what @W-L has said a solid state relay has a faster cycle time than a traditional relay. It's important if you want really fast, blinky lights.

[dany_boy]

Engineering student here:

"Normal" or mechanical relays have a physical switch controlled by an electromagnet, meaning that they are large, noisy, relatively unreliable, and slow. However they are also fairly forgiving, since they are just a physical switch they can control AC an DC in a wide variety of voltages and currents. SSR on the other hand, operate purely based on silicon semiconductors (thyristor or SCR). This means that they are ridiculously fast (micro second for good ones), and fairly long lasting. The downside is that they can only work with AC current within specifications, and they are susceptible to ESD.

 

Because of the coil in a relay, they need additional circuitry to be driven by a micro, the one you point out at amazon has this circuitry. SSR on the other hand needs pretty much nothing to use with a micro and most are opto-isolated, which in a nutshell means that they are super safe to use.

 

Finally, if you want dimming you are gonna have a hard time, since you need to do phase cutting of the AC wave to sync with the relay and it will only work with the SSR. I would suggest you stay out of AC dimming if you have no knowledge in electronics for the time being. Stick to DC and use a MOSFET, simple PWM will do you good.

If I can help you in any way don't hesitate to ask.

Cheers!

[johnny5c]

I'm currently using pre-built LOR controllers in my display but built my own Renard controllers in the past that used separate SSRs.  The 4 channel Dirkcheap SSRs handle a 2 amp AC load on each channel.

 

http://digwdf.com/store/product.php?id_product=228

 

For all the info and help you'll ever need check out DIY Christmas,

http://doityourselfchristmas.com/

[DragonTamer1]

Neither really works as a dimmer. The only way to get a dimming effect is to switch them on and off at high speeds (PWM) and the SSRs are going to be better at this than a mechanical relay. However if you are using traditional Christmas lighting then you should look into the mechanical relays since they will pull more power (especially if there are several strings connected together). With LED lights you might be able to get away with the SSRs but you would need to check the supply current first.