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### Topic: Solid State Relay (Read 2231 times)previous topic - next topic

#### Daught

##### Apr 25, 2008, 01:59 amLast Edit: Apr 25, 2008, 02:00 am by Daught Reason: 1
Hello. I have a project where I need to switch on and off a 110VAC 200mA device using Arduino. Since I have to switch it on and off many times quickly for extended periods of time, regular relays are not an option(they would die too quickly). I am looking at G3MC-101P-DC5 SSR. I think this would work very well in my situation. Can I safely connect this SSR to directly to Arduino, or do I need some kind of protection circuit(I dont think so)? From my calculations(some one please double check) these use ~17mA so I dont need to use any outside power supply, right? Also what is the zero-cross function on these relays? Do I need it?
Also I have another question on the side. I read that Diecimila can supply 40mA per output pin. Can it supply 40mA to all the pins at the same time?

#### worapoht

#1
##### Apr 25, 2008, 07:31 am
You can use this SSR on project, direct connect to Arduino pin.
and this spec. is Zero crossing type.. mean AC current will ON at 0V. of AC sine wave timing after input signal was trigged. that reduce AC transient to device and circuit.. (if no zero crossing, it can be ON at any time and cause large AC transient to device)

another, Absolute maximum spec., pin port current is 40mA per pin and total current is 200mA
but normal condition should not draw current more than 20mA per pin. at 5V. supply (refer so AVR ATMega168 / 8 datasheet), that's safe for chip.

#### sparky2

#2
##### Apr 26, 2008, 06:26 pm
We are using a SSR too and works fine, but how can we turn the AC OFF again?
We tried sending HIGH and LOW from the Arduino Board, but the SSR stays ON.

thx.

#### worapoht

#3
##### Apr 26, 2008, 07:49 pm
Quote
We are using a SSR too and works fine, but how can we turn the AC OFF again?
We tried sending HIGH and LOW from the Arduino Board, but the SSR stays ON.

thx.

Assume your SSR circuit is active HIGH,

The AC output is ON while output stay HIGH. (on zero cross, it'll ON when AC sine wave at 0 or 180 degree)
until output LOW, AC will OFF after sine wave cycle 0 or 180 degree .. (zero volt position).

then code must force output LOW to turn SSR circuit OFF.

#### mrmeval

#4
##### Apr 27, 2008, 06:50 pm
I'm using an Omron that works find. Don't do compact fluorescents as they die if the cylce rate is too high.

On mine high is on and low is off. Check your datasheet which you didn't include for what it needs.

#### Daniel2

#5
##### Apr 28, 2008, 05:59 amLast Edit: Apr 28, 2008, 06:01 am by Daniel2 Reason: 1
Quote
We are using a SSR too and works fine, but how can we turn the AC OFF again?
We tried sending HIGH and LOW from the Arduino Board, but the SSR stays ON.

thx.

That's weird- it usually happens when using an SCR or triac to switch DC rather than AC.

If the load ( the thing you're trying to switch) is DC powered, SSR's based on triacs and SCR's will latch in the "on" position.

Use something like an Omron or OPTO brand ODC5 in that case, or just a plain old relay if the load is under 24V or so.

D

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