Bare sensors vs. module sensors

[pawel]

Hi,
Sorry if the question is silly but it's my starting point with ESP,
What's the point of buying sensors in "module version" instead of connecting bare sensors. For example if I wanted to connect temperature sensor I could connect to my ESP8266 either "bare" DHT22 using 3 out of 4 it's pins (https://goo.gl/DnXaRp) or "module DHT22" (https://goo.gl/0ZDWz9). The same with relays for example (bare SRD-5VDC relay vs relay board) or voltage regulators (e.g. AMS1117 based) and so on and so forth. So the question is what's the difference except of course the easy of use in case of module items? I guess the modules are somehow better secured but does it make any sense if we are talking about the hardware worth a few $ each?
Thanks,

[data]

Depends.

Basically, most modules are breadboard friendly so you don't need a soldering iron.
Adding e.g. a DHT11 without module is fine, adding a plain relais without diode is not!
So what is your goal, what sensors do you want to attach?

[Shardan]

Hello,

well, it is possible to connect a sensor or a relay without using a breakout board.

But let me give some examples.

With a DHT11 or DHT22 it does not matter much if you use the sensor directly or on a breakout board.
It might need a pullup resistor, that's all. The Sensor is somewhat big and nicely to handle.

Now take a look at usual environment sensors like SI7021, BMP180 or BME280.
They need some external parts, resistors, capacitors and so on.
The sensors themselves are very small. A BME280 for example is 2,5 x 2,5 mm²...
https://image.slidesharecdn.com/yolebos ... 1427114210
On this small area it has eight soldering points. Soldering a 0,65mm-pitch with a soldering iron
is a pain in the ass if possible at all, it needs a hot air soldering at least... not the hobbyist's all days tool.

Now let's have a look at a relay.
A relay usually needs another voltage, 3.3V is too low.
Besides that it usually needs a higher current then a ESP8266 can provide.
So you need a transistor or FET for switching the relay's voltage and current,
you need some resistors and a flywheel-diode to cut voltage peaks from the relay coil.

So if you build your own sensors or actors on your own PCB and if you can handle tiny SMD parts like the BME sensor,
then without doubt you can put up your own series of sensors or actors.
But for most of the DIYers a small sensor breakout board might be a cheap and easy way to a selfmade sensor.

Besides all of that there is another reason for using the breakout boards.
For myself i create my own PCB's, and i can solder those parts. Nevertheless i use the sensor breakout boards.
As i use BMP180. SI7021 and BME280 with all the same pinout and more or less same size, it is very easy
to make them pluggable. Just a 4x1 pin Header on the breakout board and a fitting plug on the PCB - that's it.
Advantage: I can use the same basic PCB for whatever i need - just plug in the sensor that fits my needs.
Even changing later to another sensor is just plugging another sensor (and changing config, of course).

Regards
Shardan

[pawel]

Many thanks to all of you. These replies finally clears my doubts. Currently I was using DHT22 breakout board and probably that's why this question came into my mind. My next project however will be 220V bulb control using ESP-12 and a relay board with both - manual latch switch and Domoticz timers. And from this point of view it's very important what Shardan mentioned about relays required current and voltage peaks. I was almost sure I can solder it myself using 220AC->12DC step down power supply and a bare (not breakout board) relay. Now I understand the need of relay "shield". Thanks again all and best regards,

[toffel969]

Many thanks to all of you. These replies finally clears my doubts. Currently I was using DHT22 breakout board and probably that's why this question came into my mind. My next project however will be 220V bulb control using ESP-12 and a relay board with both - manual latch switch and Domoticz timers. And from this point of view it's very important what Shardan mentioned about relays required current and voltage peaks. I was almost sure I can solder it myself using 220AC->12DC step down power supply and a bare (not breakout board) relay. Now I understand the need of relay "shield". Thanks again all and best regards,

I would also recommend to use relay boards with optocopplers, they provide full electrical isolation of MCU and Mains. All the 4-16 relay boards I have seen actually have that, but some of the single relay boards don't

[Shardan]

I would also recommend to use relay boards with optocopplers, they provide full electrical isolation of MCU and Mains. All the 4-16 relay boards I have seen actually have that, but some of the single relay boards don't

Hello Toffel,

These optocouplers are senseless in most cases.
Usually these relay boards need 5V for the relay coils. Most users won't use a completely separated power supply for the relays (even if that would be a good idea for some reasons)
but will use the same 5V line for relays and the ESP (WeMos, NodeMCU).
If you use the same power supply, the 5V-wire connects both sides of the optocoupler, which ruins the isolating effect of the coupler..

As long as you don't use strictly separated power supplies I think it is more important if the board has the cutouts to Isolate mains relay contacts from the 5V-circuit.

s-l500.jpg (34.47 KiB) Viewed 6014 times

The cutouts are marked red.
Interesting note: They placed a lot of copper under the optocouplers instead of a cutout necessary for Isolation.
Says a lot about how important These optocouplers are.....

Regards
Shardan

[toffel969]

I would also recommend to use relay boards with optocopplers, they provide full electrical isolation of MCU and Mains. All the 4-16 relay boards I have seen actually have that, but some of the single relay boards don't

Hello Toffel,

These optocouplers are senseless in most cases.
Usually these relay boards need 5V for the relay coils. Most users won't use a completely separated power supply for the relays (even if that would be a good idea for some reasons)
but will use the same 5V line for relays and the ESP (WeMos, NodeMCU).
If you use the same power supply, the 5V-wire connects both sides of the optocoupler, which ruins the isolating effect of the coupler..

As long as you don't use strictly separated power supplies I think it is more important if the board has the cutouts to Isolate mains relay contacts from the 5V-circuit.

s-l500.jpg

The cutouts are marked red.
Interesting note: They placed a lot of copper under the optocouplers instead of a cutout necessary for Isolation.
Says a lot about how important These optocouplers are.....

Regards
Shardan

Hi shardan

I was not aware, but i makes good sense, thanks for the info.... and yes im one of the most Users that used the same 5v psu