ESP8266 Community Forum

- Sat Dec 28, 2019 12:04 pm #85082 Hello,

I came across this relay expansion module on eBay the other day.
https://www.ebay.com/itm/401960095748

ESP8266 Relay KZ-M1.jpg

It looks different than most of the others that are readily available with the addition of a 5v/12v jumper and another 2x6 header, most of which you can't see any markings on.

For my application, being able to power directly from a 12v source would simplify things a lot, so I'm interested in more information about it.

The only reference I could find online was to a site in Persian, but it doesn't appear to have any technical information.
https://redronic.com/product/kz-m1/

What I am most interested in is first whether it can indeed run from a 12v source, but equally important is how the relay is controlled. I need a board that just does simple control of the relay directly from one of the GPIO pins rather than going through another controller like some of the other boards do. It would also be nice to know what the rest of the pins on the header are for. I assume maybe TX/RX, and perhaps a reset?

They're a little pricey compared to others, so I'd hate to order one only to find out it's not what I think it is. If anyone has any information on these modules, please share it here. They look like they have the potential to be a really nice implementation of an ESP8266 controlled single relay.

Thanks.

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- Thu Feb 06, 2020 10:52 pm #85567 So I was never able to find anything about this board and obviously no one here had anything to add either, so I took a gamble and ordered a couple.

Good news! They work!

They are exactly what they appear to be. They do work from either a 5v or 12v source with the switch of a jumper. They also have TX and RX and GND pins available on a header, making it convenient to connect a serial monitor.

I don't know what firmware they came with, mainly because I didn't really care. I have my own custom firmware I use. There is a silkscreen on the ESP8266 that says "AI-Cloud Inside" if that means anything to anyone. I still have one that I haven't overwritten the firmware on, so if anyone wants to know more about it and knows a way to find out via the serial terminal, let me know.

I am happy to report these are wired to control the relay simply by toggling GPIO2. This is perfect because my custom firmware expects just a simple GPIO toggle to control the relay. All I had to do was change which GPIO pin it used since most of the other single relay ESP-01 boards that you find all over the place use GPIO0.

I think GPIO0 may be unused and available for other purposes (I will probably wire it as an input for my application) but I haven't confirmed that yet.

The only disappointing part is power consumption. When connected directly to a 12v supply, it draws a whopping 182ma with GPIO2 low and 81ma with it high. In contrast if I switch it to 5v mode add an external 5v converter to the same 12v supply, it only draws 84ma and 49ma for low and high including what the converter consumes. Obviously the on-board regulator is not very efficient.

In comparison, the "other style" ESP-01 relay boards I have that can only run from 5v draw 103ma and 48ma for low and high including the converter.

So this one is slightly more efficient than my other board when in 5v mode and the relay is not activated, but much worse both ways when running from 12v directly. This is really disappointing because I was hoping to eliminate the need for an external voltage converter to conserve space and maybe conserve a little power. But it's probably not worth the tradeoff if I am doubling the power consumption.

Anyway, maybe this will help someone in the future that is trying to figure out how these things work. I really like the implementation better than the others. If only it had better efficiency at 12v I'd be thrilled with it.

- Fri Jan 28, 2022 9:24 am #93483 So, I found your post while searching for solution to a boot problem, and I registered to this forum just so I could post a reply.

I bought this unit this week, and manage to get it going. GPIO0 is unused, GPIO1 is the LED, GPIO2 is relay, GPIO3 is put as contact sensor.

My problem is that GPIO2 is high on boot, and this triggers the relay during boot. In range of GPIO0 to GPIO3, only GPIO0 is not high on boot. This explains why most other models use GPIO0 to control relay.

Do you have any solution to make sure the relay remain untriggered during boot?