PCB for ESP 8266 controlling 2 or 4 relays with or without I2C connection

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Patou
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PCB for ESP 8266 controlling 2 or 4 relays with or without I2C connection

#1 Post by Patou » 29 Apr 2020, 22:08

Hello
I could read a lot of topics in this forum and learn from it but until now I did not publish a project.
Reaction is always very quick on questions and bugs .... Thanks for all
I have develloped a PCB able to control shutter with 2 relays, push button inputs (opto isolated) and I2c connection. As an extension you can add 2 more relays using D1 and D2 but then no more I2C !!
If you are interested in the project I can share the gerber file so you can order the pcb by yourself.

With this link you find a pdf document describing the project https://drive.google.com/file/d/1zjuZrh ... sp=sharing

Good reading
Patou

TD-er
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Re: PCB for ESP 8266 controlling 2 or 4 relays with or without I2C connection

#2 Post by TD-er » 29 Apr 2020, 22:31

Just had a quick look at the schematics.
Why isn't the output of the bridge rectifier not used as input for the 7805?
When powered via AC in, the voltage on the "5V" line may be higher than 5V.
So the relay may act different (dissipate more heat for example) and the linear regulator on the Wemos may also have to dissipate more heat.

You could have a look at the existing GPIO expanders so you can still maintain I2C functionality.

Patou
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Posts: 106
Joined: 21 May 2018, 10:33

Re: PCB for ESP 8266 controlling 2 or 4 relays with or without I2C connection

#3 Post by Patou » 29 Apr 2020, 22:53

Hello
This board wants to have different power supply possibilities
1. Ac power supply with Hlk pm01 give 5 V supply
2. 12 VDC used in other applications
If opto isolator is used for the digital inputs the DC/DC converter must also be isolated so use of B1205S 2W
3. Use of 12 VDC without isolation with a simple 7805
Hope this is now better explained

TD-er
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Re: PCB for ESP 8266 controlling 2 or 4 relays with or without I2C connection

#4 Post by TD-er » 29 Apr 2020, 23:13

Then why the diode bridge if it is already 5V= ?
That will reduce the voltage by about a volt, as it needs to go through 2 diodes.

Patou
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Posts: 106
Joined: 21 May 2018, 10:33

Re: PCB for ESP 8266 controlling 2 or 4 relays with or without I2C connection

#5 Post by Patou » 30 Apr 2020, 08:15

There is no diode bridge
On the pcb there is the choice to integrate
Or the Hlk pm1
Or the Dc/Dc converter B1205S2W
Or the 7805
Hope this clear
Patou

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