yup that's true, i usually do my work with 5VDC , but i will switch to a Darlington transistor if i need to work with 3.3VDC in the future, thank you for the advise. 👍

Looks fine. Mayyyyyyybe the 1k resistor is a little high, depends on the gain of the transistor. 5 volts would feed it with 5mA on its base, which might not be enough to fully switch it on. However, as it's only driving the relatively high resistance coil in the relay it's nothing to worry about if it works.

If you were driving it with 3.3V, I'd probably swap that transistor out for a Darlington pair to make sure the gain is high enough to fully switch on at that kind of drive voltage. You can get Darlington pairs in the same pinout as normal transistors so it would be a straight swap on the board.

Having said all that, if it's working in your application, leave it. 🤷

for 240V AC this relay can handle 5 Amps

The manufacturer has rated this relay for nominal motor (ie inductive) loads of 0.5 A, with peak surge of 2.5 A, at 120 VAC. The flyback diode should be sufficient, since the switching rate would not be very high to control a relay. The terminal block supports a max wire diameter of 1.5mm2 (~16 AWG) which would be more than plenty for a 0.5 A load.

If you're actually running >60 VAC through the relay, then it's good practice to add a slot that prevents creepage currents between the low-voltage DC section and the higher-voltage power section.

For smaller applications, this seems reasonable enough, at least to me.

forgot to include this

yeah sure

I already added solder to the relay contact tracks to increase it's thickness

those are for the low voltage control pins for a gpio (to control the transistor and the supply +5v and GND)

I think it would help us if you included the part designators for components on the board, and then what your design criteria was. After all, this might be fine for 1A at 5vdc but fall apart for 10A at 67vac.

(squints)

Looks fine up to about 6 amps I reckon, judging from the size of that relay. Not a huge high power coil on that so a simple npn transistor switching the coil to ground would be fine. Got a diode across the coil to catch the back-EMF, looks like all the basics are covered .Would only bother adding extra solder to the tracks for the relay contacts if I was doing it but that's neither here nor there.

Dunno what those eevblog folks are on about 🤷

I think the connected wires would vaporise before those tracks ..

My thought as well. If you get 9 switches that have thin levers, and drill 9 holes in a piece of wood, you'd end up with a wide bar that can move 9 switches at once

but I’m not sure how to find one of these with name brand relays that id actually trust in a commercial setting.

I suppose that comes down to "what is the worst case scenario assuming the board fails". If you simply can't have it fail the design should have redundancies built in. If you're looking for build quality/established MTBF ratings then piggyback on top of someone elses regulatory approvals where those tolerances are built in. I just did a quick google search for "relay board FAA approved" not even knowing what the regulatory rules are of aircraft. Apparently those are FAA-PMA and TSO. Plugging that in with "relay board" and you get something like this:

Sandia Aerospace 12 Pole Switching Relay

This level of build quality and certification comes at a much higher price of $524 for one board though. Another choice I might chase would be "medical".

Using the NC side of the relays would be the best way too, but I’m not sure how to find one of these with name brand relays that id actually trust in a commercial setting.

That would be 1 pole 10 throw, OP wants 9 pole 1 throw

They are rare but they do exist, eg: https://www.salecom.com/en/product/wpt.html Hope that gives you some idea of what they look like and what search terms to use

Is this using a 24v AC setup or is it DC? I feel beyond the logic of what you're trying to do, this could be important.

Search for “10 position rotary switch” - there are lots of options :)

If I understand what you're describing, I'd probably use a relay board. They're not expensive:

You could wire all of the control circuits to one wire, and with the flip of one switch on the control circuit turn on/off all 10 relays on their load circuits.

Not sure exactly the size of switch you're working with, but couldn't you get or fashion a coupler that mechanically links multiple switches together...

I'm thinking like they do with circuit breakers like this:

The few items I have in mind have hard boards with a little rubber foot that touches either two half circles or two wiggly lines, though I do have one of those plasticy ones you're taking about. What if I trace the lines back to the board and replicate it with wire?

Are you a student in Istanbul too?

One question is if you will be using some Xilinx IP, in which case the simulation models likely will be encrypted. If your project doesn't, I don't see why it would be an issue using Icarus, etc.

If all you depend on from the IP is data over an AXI/AXI-stream or the like you can use open-source bus-function models (which I understand as librarues you can use that will take care of properly driving something like an AXI interface for you) in your testbench.

I'm a student myself, Im sharing what I know but this might not be how industry does it.

And I'm criticizing the criticizer of the criticizer of the helper. ☝🏼