First time poster many years lurker. Never expect to enter the microcontroller world but, here i am ...
Project is PID espresso heating element. Seen lots of builds and mesed around with AI and any search i could lay my hands on and i get conflicting info...
In the schematic you can see that i want to controll a heating element. Because the SSR can not be driven directly with the Waveshare2040 (as suggested by the AI's) im going to add a MOSFET. I found this mosfet to be suited for my purpose.
In seedstudio i see that the plus ( + ) and the ( - ) of the Grove Mosfet is connected to the Power supply + and - and the Out and GRN of the GroveMosfet is connedted to the small DC Motor.
AI's suggest that i connect it differently.
So i am in a dead end.
If anyone could shed some light, i would appreciate it a lot.
The Seeed Studio connection looks right to me, but without knowing the internals of the MOSFET module, it's a bit of a guess. Start by leaving the SSR output disconnected, including the Red/Green/Blue thing in the middle. Connect 5V and G (-5VDC) to the pins labelled 5V and G or VCC same as both diagrams. Connect the logic pin and the SSR input. Now toggle the control pin and measure the SSR output.
The SS relay should work, it has a min of 3V and a max of 32V. Your Pi will deliver 3v3 or enough to drive the relay. You can use a logic chip as a level interface, they are very inexpensive but typically only work in one direction. Using a 74HCT08 would give you a level conversion to 5V for a MOSFET or your SSR, power it with 5V and the Pi output can can connect directly to the input.
+---------------———+------------+–-----------+--—----------+-—----------+
| Logic Family | VIL max | VIH min | VOL ma) | VOH min |
| | Input Low| Input High| Output Low| Output High|
+---------------———+------------+–-----------+--—----------+------------+
| TTL (74xx) | 0.8 V | 2.0 V | 0.4 V | 2.4 V |
| LS (74LSxx) | 0.8 V | 2.0 V | 0.5 V | 2.7 V |
| HC (74HCxx) | 0.3VCC | 0.7VCC | 0.1VCC | 0.9VCC |
| HCT (74HCTxx) | 0.8 V | 2.0 V | 0.1VCC | 0.8VCC |
| AC (74ACxx) | 0.3VCC | 0.7VCC | 0.1VCC |
Its the internet so we cant be sure if someone asks genuinely a question or is been condescending. I wish i had your knowledge in electronics though, it would make things easier for me. Thankfully i am good at other things.
Regarding your question :
Waveshare says input range is 3.3-5v. So that tells me that you can run it with these two voltages.
Output of the GPIOs is far to low (miliamps) to drive motors or anythng else that maybe some LED . Relay will drain too much power continuesly so i need mosfet in my case the best fit and the most wide spread after searching the internet.
Yes i have given all the links and specs to AI so as far as my understanding goes, all components should be compatible.
I currently stumble on how to connect the SSR to the GroveMosfet since i get two different ways when only 1 of them makes sense to me. The one that Seed Studion (the manufacturer of the GroveMosfet board).
Is connecting the GroveMosfet for driving a small DC motor so much different than connecting a relais ?
I dont know what to think. That is why i ask.
I dont know if the RP2040 running a PID program, reading Temperature probes comparing them and driving relais is going to work. The relais specs say the following. But wont all this be a problem ? Is the Mosfet not a more safe solution ? I would like the relay to be a bit more isolated from the electronics. Fuses are going to be a safety feature for sure but adding a mosfet might be an extra "distance" from the mains circuit.
Its all due to the "just in case" something happens... it adds some extra buffer zone. (in my limited understanding of the electronics)
I certainly hope this attitude doesn’t apply to the rest of your life. How do you get out of the house in the morning without a personal body guard in your armored car.
There are millions of commercial products running right now with solid state relays using 3.3 volts and they seem to work consistently 100% of the time.
How large of a power supply are you going to use, just in case?
I guess you don't wear helmet/seatbelt nor take some health or any other insurance in consideration.
Seems to me your attitude (towards me at least) posts more threat than running my tongue on a transformer...while it's live.
I am asking in order to learn and i receive ricochets, imagine having a different opinion...
As i said before, i don't know, so i am asking to learn.
So far, i have learned that an SSR is basically an LED, there are millions of commercial products that are working fine with SSRs running on 3.3v, don't ask questions in forums tif you want to learn things and keeping my mouth shut, wait at least a couple of decades until i have enough knowledge and only then i can reply to new commers in an aggressive and condescending manner, and most importantly don't piss off Paul_KD7HB.
Mean Well 5V 3A PSU RS-15-5 More than enough to power everything.
Any more questions or suggestions ? I do like that aggressive old school type of learning.
I would use a simple and reliable 2N3904 NPN transistor to switch 5V to the SSR input pin, 2mA from MCU output to the transistor base should be plenty.
Nice. So throw everything in the trash and start from the beginning.
Google "fake fotek ssr" for entertainment.
Then post what you really want to approach, so guys here can give suggestions.
It's easier to find water in Mars than genuine Fotek SSR on Amzn /Ae.
Can you consider normal relay module or spend more on "serious" SSR?
Since your load is resistive, normal relay would be my first choice.
I have experience with the mean well PSU which are found in a very very large number of machines.
Plus, the sum of all the electronics running on that PSU wont exceed 1A let alone 5A.
About the Fotek, i do not reject the 3-32v spec.... i have zero experience with Fotek, and i always like to be above the minimum and under the maximum. More inside the margin.
The PSU is 5 volts the PR2040 is going to be 5volts , display is going to be 5volts i am trying to keep everything in the 5v range.
So throw everything in the trash and start from the beginning.