Hello folks,
new member and first post here, so please be kind
I'd appreciate your comments and guidance on my project and whether the teensy (v3.6) is the right choice for me and how to solve a particular problem switching on a high current AC load safely.
To start with, I am a total newbie to DIY electronics, but I know how to code and have a fair level of architectural thinking (owning a degree in engineering, I know a bit of everything, I suppose) but here my knowledge is very limited as are my soldering skills.
My project is to replace a programmable thermostat for my hot water boiler, as the original just went dark and there is no replacement on the market with the features required.
This is what I have in mind for my solution ATM:
While I think the teensy has the headroom for the complex programming, I am worried of driving the relais or using one of these cheap relais boards at all.
First, the teensy 3.6 only supplies 3.3V to its output pins, while the common boards run at 5V or even higher.
I learned, that one needs to use an extra small transistor/diode setup in order to drive the relais with the appropriate 5V and prevent higher voltage to run back to the controller pins when the relais is active
Second, all the relais boards I found, are so small that I think these are build electrically incorrect, meaning they don't keep the correct safety distance between the lines, carrying 230V(AC) load and 5V(DC) switching power.
So i came to the conclusion, that I'd rather not risk a fire in my (wooden) home with one these.
Nailing the problem down to safely driving the Heat-Pump with the 3.3V output pins from the teensy is what my problem seems to be ATM.
There are other professional (and safe) switches out there, that can be driven by 8-230V UC (like this: http://www.eltako.com/fileadmin/downloads/en/_bedienung/ESR61M-UC_61200301-1_gb.pdf) but these need +10VDC control power (and possibly will draw more current than the teensy can supply anyway).
As said before, any comments on my solution setup in general, with a teensy 3.6 and on how to solve the challenge to switch the high current AC load safely is very much appreciated.
Many thanks in advance for your time & efforts.
greetz,
Hominidae
new member and first post here, so please be kind
I'd appreciate your comments and guidance on my project and whether the teensy (v3.6) is the right choice for me and how to solve a particular problem switching on a high current AC load safely.
To start with, I am a total newbie to DIY electronics, but I know how to code and have a fair level of architectural thinking (owning a degree in engineering, I know a bit of everything, I suppose) but here my knowledge is very limited as are my soldering skills.
My project is to replace a programmable thermostat for my hot water boiler, as the original just went dark and there is no replacement on the market with the features required.
This is what I have in mind for my solution ATM:
- driving 1 or more temperature sensors/probes
I am looking into 1wire DS18B20 sensors - using a convenient input/output method, thus securing the WAF
I am looking into employing an I2C based, pre-assembled kit with LCD and keypad from here: http://byvac.com/index.php/BV4612
This will fit / can be mounted on a standard box.
In that shop, there will be a new product available in a couple of weeks, using a rotary knob for all the input, which is the most convenient way of I/O for my use-case, i think. - driving a relais (230V/AC, 10-16A) to remotely switch power to the boilers heating element, which is a small heat pump and this is what makes it more complicated
Most common relais boards I found are like this: https://www.amazon.com/SunFounder-C...712010&sr=8-2&keywords=arduino+relay+board+5v - employing a micro-controller that is
- easy to code, with a plug&play IDE (arduino sketch style or C)
- upgradable with wifi to integrate into a smart home environment (i.e. using IP based transport with MQTT)
OK, this will be a real new feature after everything else is up&running - can be integrated safely with the relais / remote switch from above
- has enough headroom for the (fairly) complex program, that needs to self adjust to the heating curve of the HP in order to optimize run-time of the HP and supply the desired water temp at the programmed time of day.
While I think the teensy has the headroom for the complex programming, I am worried of driving the relais or using one of these cheap relais boards at all.
First, the teensy 3.6 only supplies 3.3V to its output pins, while the common boards run at 5V or even higher.
I learned, that one needs to use an extra small transistor/diode setup in order to drive the relais with the appropriate 5V and prevent higher voltage to run back to the controller pins when the relais is active
Second, all the relais boards I found, are so small that I think these are build electrically incorrect, meaning they don't keep the correct safety distance between the lines, carrying 230V(AC) load and 5V(DC) switching power.
So i came to the conclusion, that I'd rather not risk a fire in my (wooden) home with one these.
Nailing the problem down to safely driving the Heat-Pump with the 3.3V output pins from the teensy is what my problem seems to be ATM.
There are other professional (and safe) switches out there, that can be driven by 8-230V UC (like this: http://www.eltako.com/fileadmin/downloads/en/_bedienung/ESR61M-UC_61200301-1_gb.pdf) but these need +10VDC control power (and possibly will draw more current than the teensy can supply anyway).
As said before, any comments on my solution setup in general, with a teensy 3.6 and on how to solve the challenge to switch the high current AC load safely is very much appreciated.
Many thanks in advance for your time & efforts.
greetz,
Hominidae