IC version of a relay

OK... this is the dilema... I want to control something via an arduino, and it's basically replacing the buttons that ground an internal signal. As an electrician, my mind automatically goes to relays, but the problem is the relays that I find are big and bulky, which is great for mains electricity, but not for a small signal being sent to ground; it's just not practical.

So, is there small IC version of a relay, where I input a signal from an arduino, and this closes a secondary circuit as if it were a simple switch? It doesn't matter if it is a multiple "switch" IC, as I want it to control a total of seven buttons.

I've been googling for days, not finding what I am looking for except for those huge relays, and 7 of those for a tiny signal, it's not very practical to say the least!!

Thank you!!

Describe the signal: AC or DC, maximum voltage and current.

What sort of "internal signal"? Internal to what? Voltage/current/impedance/frequency? Details are often important.

For some applications a simple transistor might be what you need or even just a connection to an Arduino digital pin. Or there are hundreds of different types of IC switches in all sorts of configurations.


It really depends on the kind of signal that is involved.
In some cases, the smallest solution is using a single optocoupler. This requires that the signal be DC and can tolerate the slight voltage drop.
In other cases, using a transistor as a switch is kind of a big deal and replaced electromechanical relays and vacuum tubes.
The relays you're talking about are probably the cheap big blue box types. Raw relays come in much smaller sizes but you'll probably have to make your own circuit to control them.

It all depends on the signal and it's your job to figure out its characteristics. AC or DC, voltage, current, duration/timing, etc. Once you know those, you'll know your options.

Think of the insides of an Atari controller… all DC, no voltage or amperage worth writing home about…

It just bridges a pin to ground

NPN transistor, with a 10K base resistor.

try searching for "solid state signal relay"

Think of the insides of an Atari controller... all DC, no voltage or amperage worth writing home about...

It just bridges a pin to ground

You grossly underestimate what's involved.

You're halfway down the assume road.

You grossly underestimate what’s involved.

You’re halfway down the assume road.

I would beg to disagree… you open up a controller, you see that when a button is pressed it connects a signal wire to ground, and there is no circuitry involved… where is the assumption?

The assumption is about everything on the other side of that wire.

Is an Atari controller your actual project? Or is that an analogy that is going to mislead everyone trying to help?

RS components sell small relays - some only 12mm long

As alluded to in post #5 polarity will figure in the solution. A mechanical switch normally isn't polarity sensitive. A transistor switch? Muchly.

try searching for "solid state signal relay"

This is definitely a more compact solution... I'll put it to the list, thanks!!

NPN transistor, with a 10K base resistor.

Interesting... I'll try this out on a breadboard, see what results it gives. Thanks!!

It's not an Atari controller, because I don't have an official one to use, but it's an equivelent. It will be on an Atari, though... but you can think of it for what it's worth that I am misleading you, because the controller doesn't say "Atari" on it...

And I think I'm going to ignore you from now on... I don't care for your tone; first the holier than thou attitude at the beginning, then the whole deception issue after.

Have a nice day, INTP.

@dougp, yes, I agree, they are different... that's why I thought it better to ask. I can visualise in electrical terms what I want, but if I don't know the specific name of what I am looking for in the electronics world, then I'm just ending up all the time with the same huge blue box, one per channel!!

@hammy, thanks for the heads-up!

Anyway, I have a couple of things to try out, and see which is the best option to go for. I thank you all for your very quick responses, time to do a little shopping!!

first the holier than thou attitude .....

Have a nice day, INTP.

Ouch, the irony and hypocrisy is unbearable.

To everyone else trying to help this guy, since he's assuming that it's DC and 'no voltage or amperage worth writing home about', just hope there's at least enough voltage to overcome any solid state options. But I guess he prefers the blind trial and error approach so keep the underinformed options flowing.

How about the gender assumption? Interesting...

And of course, the "ringleader" attitude.

And yes, it's DC, I checked...

How about taking the term 'guy' personally? Would you be happier if I assumed you were female based on the way you expect us to read your mind? Should I assume you have a traumatic past involving the circus because you have an emotional response to a 'ringleader'?

Why not outright mention in your post that you're a lost female in need of help since you're not above such sensitivities ::slight_smile:

Since you've used an oscilloscope to check that it was indeed DC, why not share with us the voltage and amperage as well? It would literally allow people to give you a guaranteed answer as to an approach that will definitely work without having to involve your feelings.

It's not the "guy" thing, there are a lot of people that use the term in the gender neutral... but the "he" is a little hard to miss...

I'm trying to point out that for someone that doesn't like assumptions...

And the "lost female"... would you like a side of misogyny?


PS, "ringleader" is a metaphor... it's the "come on guys, do what I say" part...

Look at an H11F3 opto FET.