N**7
Good value but poor documentation
I agree with the other review, the solder is not the cleanest but it is opto-isolated from your microcontroller. The relays are heavy duty and the board is quite solid. No documentation was included, but this board appears to be the same as SainSmart 8 channel relay controller.To use it, you need to supply 5v (VCC) and ground (GRD) to the respective pins. It's a 'LOW ACTIVATED' circuit, meaning you need to connect each pin to ground to activate the relay. Use a resistor and NPN transistor in combination with a pulldown resistor to activate each channel. Raspberry PI uses 3.3v and Arduino outputs 5v, so you'll need to adjust the resistor accordingly. Also, Arduinos have an internal pulldown resistor so only PI users need to add it.Wiring example circuit: [...]I also found the schematics here: [....]Hope this review helps others.
A**W
Addressing more than one of these boards
I have an Arduino Duo R3. I bought 3 of these boards. With 8 channels each and only 13 digital I/O I planned to use the VCC as a way to address each board. This method is unreliable since the I/O pins do not provide exactly what the boards are looking for in a VCC source. To accomplish using 3 boards and applying the same 8 channel signals to each board, I had to buy a 4 channel board as well. I used the 3 inputs that I tried to address the boards VCC and instead used those signals on the 4 channel board. And applied an external 5V source, to ensure that each board receive the power it needed. the 4 channel board conned the 5v source to the VCC on the 8 channel so that only the correct 8 channel board was on.
J**4
Extremely Loud, But Works Great for What it Does
Man is this loud. So loud. If you're looking to automate home appliances or anything you use on a daily basis, look away from the mechanical relays (or at least this one). That being said, I use mine for Halloween effects so I could care less how loud it is since it's hidden away in my garage. Does as advertised. Easy to use and wire. DO NOT WORK WITH ELECTRICITY IF YOU DON'T KNOW WHAT YOU'RE DOING. And even then, be sure to check your connections before you fire this baby up. But if you know what you're doing and want a cheap way to switch DC household items on and off, this is for you.
B**9
Kootek 8 Channel DC 5V Relay Module
This was a very cheap alternative to me designing and spinning a board for my testing purposes. The only thing not convenient for me was the ground signal triggering the circuit. I modified the board to work off a 5VDC signal after searching Google for a schematic.UPDATE 5/14/2015:I've been using 27 of these boards in very aggressive conditions for 5 months straight now, and have around 35,000 relay cycles (on and off) for each board. These mounted to fixtures inside an environmental chamber where we ramp the temperature from ambient to -5C, hold for 22 minutes, ramp to 55C in 3 minutes, hold for 22, ramp to -5C in 3 minutes (loops until we stop it). 3 separate times, we have ran the chamber with the boards on down to -110C and they survive. Like I mentioned before, these are a great board. I did have 1 relay go bad, it appears the internal contacts are what failed (120VAC on one side, only 25VAC on the other). I've included the rework schematic to make these trigger on a 5V signal. I'm using a National Instruments DAC to control the relay board channels.UPDATE 3/25/16:These relay boards are still running strong after a year and a half. We had a 3 month fixture shut down but we started the test back up and they still worked like new. We're currently using them in ambient temperatures with approximately a relay activation every 25 seconds. The most commonly used relays on the boards have a cycle count in the range of 110,000 cycles +/-5%. These board have worked great and have put up with more than expected. This test will complete in May and I fully expect all 18 boards to make it without any problems.
M**A
Appears to be pretty solid
I purchased one of these for use in a project where I trigger 1 relay at a time with a high current DC load. I was able to wire these up to an Arduino with no issue at all. I simply connected the 5V and GND pins and the 8 relay inputs to 8 available digital output pins, initially set the state of the output pins to HIGH, and set them to LOW to trigger them. The relays themselves appear to be very rugged and can be triggered with very high frequency ( a few milliseconds). As others have noted, the board itself is not pristine, there are some errant solder splashes and extra/burnt flux. However, I experienced no functional issues. The relays are audible, but what I expected from a physical relay (on par with your TV clicking on or The Clapper if you've used one). Sound is not an issue with my application. Since my initial checkout of the first unit I purchased, I will be ordering three more. I ran the unit in a loop triggering each relay for 500ms in rapid succession for an hour with no issues. One thing I personally noticed is that the screw in terminals were way better than I expected. The screws are nice and smooth and the teeth that grip your wire or terminal do so very well. I'm actually very happy considering the price.
M**0
Absolutely no instructions or app notes
Like the "Kootek" 2 channel relay board, this is a moderately complex board with absolutely no instructions or notes of any kind. The single question about the jumper, and answer, is far from enough to prevent accidental damage. In future, I will simply build these myself if needed, not wasting time with "Kootek". BTW it seems impossible to actually contact "Kootek" for help, other than the A'zon Querry system, which obviously does not help much.I have to add that the comments on A'zon here are so self-contradictory and unhelpful (i.e. "hooked it up and it worked great") does not help us understand HOW to 'hook it up' without blowing out the parts.When an item like this is sold by a vendor with absolutely NO guidance about its use, and a buyer mistakenly blows it out because of the lack of documentation, I believe the seller (Amazon or whoever) should be liable for replacement, or cash refund.
Trustpilot
2 months ago
1 month ago