Which relay - Mechanical or Solidstate?

Question

Anyone familiar with relays mechanical or otherwise? I would like to be able to switch on/off up to 250W (120V) load using a microcontroller.

Will be used to control lighting to an aquarium.

score 8 · Accepted Answer · edited Jun 16 '10 at 22:44

8

Solid-state relays are easier to use than electro-mechanical ones. They can be controlled directly by MCU outputs and you don't have to worry about things like putting diodes across coils. I've used lots of them with an ARM to control motors and valves in a complex piece of medical equipment.

edited Jun 16 '10 at 22:44

pingswept

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answered Jun 16 '10 at 20:56

Leon Heller

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What should I look for in a solid-state relay? Is it possible to get a latching solid-state relay? – Vineeth Jun 17 '10 at 16:21

score 7 · Answer 2 · answered Jun 16 '10 at 21:14

Mechanical relays require gobs of current to keep the coil energized, much more than you can directly get from a microcontroller, and when you want to switch them off, you have to contend with all the flyback energy too (i.e., the diode thing).

Solid state is the way to go.

score 2 · Answer 3 · answered Jul 09 '10 at 16:45

You can see a list of advantages and disadvantages here: http://en.wikipedia.org/wiki/Solid_state_relay#Advantages_over_mechanical_relays

In your case, whatever. Both solutions work. It will depend on the variable that you take into account, such as price, life cycle, etc.

Which relay - Mechanical or Solidstate?

3 Answers3