Thanks! The video was a bit of a struggle more than I thought it would be as well on my end so I think it’s time to try something a little simpler. Maybe I’ll get that temperature humidity sensor going soon.

@@GadgetReboot Great ! Looking forward to see it.

Next goal, 100k play button. Maybe I better set some more realistic expectations first. I have to place a lot more eBay orders between now and then.

@@GadgetReboot I hate to encourage, but maybe you should conciser a commercial? Big Clive says it's needed and it's the only reason FranLab doesn't have more because she doesn't. Supposedly KZfaq doesn't suggest you to non-subs if you don't. I really don't know how that works, but everyone else comments about it on their channel.

Monetization , yes now that I reached 1000 subscribers I have been automatically put in the queue to have the channel reviewed to be monetized so it estimates currently it might take up to one month so then there will be ads. I’ve noticed a lot more subscriber growth in the past two months so I’m not sure how that started taking off but hopefully it keeps going.

@@GadgetRebootIve tried to plug you on the comments of other channels, but I dont know how many people read that. Good luck, and please keep at it - your videos are great.

@@GadgetReboot In my experience, you should take that 1 month estimate with a few grains of salt... They can take far longer for random (and unexplained) reasons.

The current at the control input for the relay isn’t the same current that the relay is actually getting on its coil, the input is just driving the optocoupler LED so you should measure the current powering the relay coils

Glad I could help!

@@GadgetReboot sir, does 250 VAC and 10 amps mean that a single relay can handle load upto 2500 watts ?

It sounds like I2C would be sufficient for all of that because they are all slow communicating devices. If you have 5 or 10 sensors on the same bus including relays that only need to be read or activated in the macroscopic timeframe, everything should be able to run adequately and getting the most out of the available limited resources is always good design practice as long as it’s implemented within the normal constraints for example if there’s a maximum number of devices allowed on a bus or a certain maximum cable length for signal integrity. If you had something else on the I2C bus that needed more frequent access like trying to generate an output waveform with a DAC, that’s where limitations might be exploited and it would’ve been better to use SPI or even just 8 bit parallel data to get things running smoothly. I chose the discrete relay board for no particular reason but mostly I had in mind that I might want to try building some sort of PLC device and that’s why I got eight relays to start instead of a board with 1, 2 or 4. Although I am waiting for a shipment of a smaller relay board with 2 on it. It’s a little more practical when I just want to control one thing. So I2C would’ve been probably more efficient and perfectly suitable to control eight relays but I was imagining some sort of big circuit with all kinds of separate logic gates or transistors turning them on rather than having a tighter package.

It depends on the solenoid. The solenoid I just replaced on my dishwasher is engaged for many minutes at a time. If you want no noise, you may want to use transistors. There are solid state relays but I believe they are typically AC only.

Are you using one of these relay boards or is it your own component project with an LED connecting to the expander separately? Two things immediately would come to mind. If you connect an LED directly from the expander without a resistor, the LED will regulate the voltage around its own forward voltage so a red LED might be around 2 V. But if you have an LED and a resistor on the output, it should not drag it down. Also, the expander is intended to really only drive an output low rather than an output hghi, so whatever is connected to the expander output should ultimately go to VCC. For example an LED and resistor up to VCC and then to the expander output so the expander can connect it to ground. If you try the other scenario where you have an LED and resistor connected to ground and then you have it on the expander and intend to drive it high to turn it on, that’s more current than the expander can do so that would also drag the voltage down and not work. The expander just has weak internal pull-ups with no high output drive capability, just a sink current drive capability.

@@GadgetReboot oh wow thank you very much for the explanation I dealt with it maybe a little funny but I used a transistor that drives just an Expander

With the opto-coupler driving the relay, the LED in it needs to be powered to turn on the relay, so if there's no power on the Arduino controller outputting a definite high or low, the LED is off and relay is off. Then when arduino is powered up, initially its outputs are floating (still nothing driving the LED), and software should properly configure the lines to avoid unintended power-on

I don't know if it's a standard outside of these modules to have active low control on industrial setups or if it's arbitrary, but if the action needs to be changed so that the relay is engaged when there is no Arduino controlling it (so there is a low already on the control input and then Arduino can come online and set it high to turn it back off if it wants or keep it low if that's desired), then maybe a simple transistor NPN switch can be added to the relay control input like this first NPN circuit: learn.sparkfun.com/tutorials/transistors/applications-i-switches The LED and 100 ohm resistor going to 5v are basically what's already on the relay board so the transistor collector just goes to the relay control input directly, the emitter goes straight to ground as shown, then the base 1K with the control label is where Arduino would connect. Now add another pull up resistor from that 1K "control" side to the same 5V that's powering the relay, maybe between 1K and 10K, so there will be both an arduino output and a resistor to 5V going to the transistor Control. Now if there is no Arduino controlling the transistor, the pull up resistor turns on the transistor and brings the relay control pin to ground as soon as possible when power is applied and the Arduino can over-ride it later.

​@@GadgetReboot Everything seems to be acting in reverse to how your module is working even though its the same one, when I power the module all the lights blink up by default and I have to connect electrical devices in normally closed for them to not run by default. Subbed for the knowledge, keep it up!

@@mariusnorheim1697 I wonder if there's different designs of the module that work with the backwards logic. I have 3 or 4 different ones that all operate the same. But the other solution is maybe one of those hex inverter logic chips like 74HC4049 assets.nexperia.com/documents/data-sheet/74HC4049.pdf So putting an inverter in line with each relay control input, then the inverter input goes to an Arduino control output, and also a pull up resistor to 5V so that it forces the relay into the opposite mode on power up with the resistors and inverters, and Arduino can then take over later.

I think it’s awkwardly laid out as well and misleading. It’s also misleading that the jumper can go in two positions and if you put it in the isolated position instead of totally removing it you would be shorting VCC to ground. It should just be a two pin jumper on its own to bridge the +power and another two pins for the isolated relay VCC and ground.

That video took a long time to make including some re-filming here and there and lots of editing. I think it’s time for a mail bag next.

@@GadgetReboot - you did a great job regardless. Congratulations, you are about to hit 1k! edit: Congratulations on 1K - I was going by the subscriber counter in the video!

Thanks! The counter actually hit 1000 during the yet to be released mailbag coming soon.