Switching AC

[ScuzZ]

Is there any device, like a relay, that can switch AC quickly?

Sort of like transistor like behaviour?

 

[Speakerguy]

A solid state relay?

 

[jpanhalt]

If you are after a solid state relay, try searching on TRIAC. Here is one of the first hits I got:
**broken link removed**

Your question implies that a conventional relay will suffice, but for some reason you believe they only work on DC. AC relays are very commom.
John

 

[dknguyen]

A relay will do it. BUt if you need something like an "AC MOSFET" that can switch at high speeds, you need a triac or an alternistor (and it might be easiest to get an triac driver IC as well since they switch a bit more complicatedly than a MOSFET).

 

[kchriste]

Is there any device, like a relay, that can switch AC quickly?
Sort of like transistor like behaviour?

How much AC current and voltage are you trying to switch?
For high power line voltage AC loads, you would use a triac.
If you want to switch low level AC audio signals, then there are IC's that do this with minimum distortion. You can also build your own AC "switches" out of FETs.

 

[Nigel Goodwin]

Is there any device, like a relay, that can switch AC quickly?

Sort of like transistor like behaviour?

Perhaps you might try asking what you really want?, your current question is completely meaningless.

 

[ScuzZ]

I was just wondering whether there was another way to switch AC on and off quickly.

Something that would be easier to use and would not need protection diodes etc.

Switching AC at 240v 15Amps.

It was just a general question, I wasn't chasing any specific information.

Just as a relay will allow you to use DC to switch AC current and is isolated from the AC current to a point; will a TRIAC allow the same?

 

[jpanhalt]

I was just wondering whether there was another way to switch AC on and off quickly.

It was just a general question, I wasn't chasing any specific information.

It seems your "general question" has been answered. There are two categories of device, solid state and mechanical. Mechanical would be a relay, and they are readily available. Solid state would be something like a triac-based relay as suggested already.

Your comment that you want, "Something that would be easier to use and would not need protection diodes," seems inconsistent with your request for general information.

Where did you get the idea for needing protection diodes? Whatever you used needs to be designed properly, but since you have no specific use in mind, it is impossible to say what the design will need.

If you are just going to switch 240 V at 15A for something like a motor, I would use a standard starter switch or starter relay designed for motor use (check out industrial supply places like McMaster Carr). A simple on/off switch that is properly rated will work fine. You probably do not need a low-voltage control, unless it is for an industrial application. John

 

[eblc1388]

It seems your "general question" has been answered. There are two categories of device, solid state and mechanical.

There is another category of device, a hybrid one.

I have several "module" that look like solid state devices. It is labelled as "Solid State Relay" and manufactured by company "Gordos Arkansas". But when I cut one open, it actually uses a reed switch to operate a component which looks like a TRIAC.

 

[jpanhalt]

There is another category of device, a hybrid one.

I have several "module" that look like solid state devices. It is labelled as "Solid State Relay" and manufactured by company "Gordos Arkansas". But when I cut one open, it actually uses a reed switch to operate a component which looks like a TRIAC.

Thanks for the correction. One must always consider the hybrid -- like steam ships with sails.

On a lark, I did a search on Gordos Arkansas. Apparently, the part is obsolete and was made so long ago, the term "solid state" was more popular than "hybrid."

John

 

[ScuzZ]

So just like a mechanical relay can use DC to switch high AC.
Will a solid state relay allow the same?

Protection diodes -> to allow the surge from a collapsing electromagnetic field to flow, reducing or eliminating the chance of damaging components.

And adding to the original question: If you use any of these components, do you get a 'bounce' ?

 

[eblc1388]

So just like a mechanical relay can use DC to switch high AC.
Will a solid state relay allow the same?

Yes, except there is no electrical moving contact carrying load current. Depends on different construction by various manufacturers, some can also switch DC loads. The ones I mentioned above can switch an 240V AC load upto 30A.

And adding to the original question: If you use any of these components, do you get a 'bounce' ?

There is no moving part so there is no bounce. It can be used straight away on common AC loads. With difficult loads like high inductance, one must refer to the manufacturer datasheet to see if additional external components are needed to ensure correct operation.