Switch ac

raschemmel:
You didn't say whether you needed to switch them individually or simultaneously.

Single 5V Relay Module

Switching 10 relays on/off simultaneously may cause unexpected power fluctuations.
Even if they are required to come on at (about) the same time, It may be a good idea to stagger by a couple ms each one, rather than a us.

… I couldn’t even buy the relays for that.

I figured this shift register controlled relay shield would be great to replace all the troublesome opto-controlled relay cards out there. 8 G5T-1A relays are just under $8 if I stock up on 12 boards worth, plus the board, shift register, and other SMD parts. Fighting a losing battle trying to compete in a commodity market for that.

Is that an actual product available or is that a prototype for a potential product ?
What is the price ?

Just an aside about using transistors instead of TRIACs to switch AC.

You can of course use a - suitably rated - transistor (or FET) inside a rectifier bridge with a - suitably rated - optocoupler to control it. You can in the same fashion emulate a TRIAC with a SCR.

raschemmel:
If you said this:

The normal response from ANYONE would be this:

What are your qualifications for electronics ? (or rather I should say "The fact that you asked that question suggests that you have none".)

Why ?

Well, let's look at what you said:
An NPN transistor is normally biased with the collector biased positive with respect to the emitter.
It is turned on by a voltage on the base, which is also positive with respect to the emitter.
A PNP transistor works just the opposite with the base and collector biased negatively with respect to the emitter. You have suggested putting them in PARALLEL.

Given the above, what is the likelyhood of THAT working ?
What does that say about your electronics experience ?

Post a schematic of what you suggesting .

In my opinion, your response didn't need to be so patronizing. I was asking a legitimate question on why such a circuit isn't used in practice. Nobody learns without asking questions.

Granted, I should have been more specific.

The PNP would conduct during the positive half of the cycle and the NPN would conduct on the negative half of the cycle. The bases would need to be driven with isolated DC.

Did you ever look for a 600volt/5Amp PNP power transistor.

Compare that to a 600volt/5Amp triac.

Also Google "thyristor with transistors" (images).
Leo..

Wawa:
Did you ever look for a 600volt/5Amp PNP power transistor.

Compare that to a 600volt/5Amp triac.

Also Google "thyristor with transistors" (images).
Leo..

Maybe not a disadvantage for the OPs situation, but it may be for some people.

Thristors and triacs can not be switched at any point during the AC waveform (they will hang on until zero crossing). I would still like to know if a variant of the proposed circuit could work

To be honest, I don't know why transistors are not popular for switching AC, other than the fact that they were designed for dc. The Triac, on the other hand, as far as I can tell, was specifically designed for switching AC. It would be my first choice.
AC Lamp dimmer

smeezekitty:
Thristors and triacs can not be switched at any point during the AC waveform (they will hang on until zero crossing).

Which is exactly what you want to do.

Your proposed circuit would not work because you can not get transistors that can handle the reverse base and collector voltages.