- 5V 8-Channel Relay interface board, and each one needs 15-20mA Driver Current
- Equiped with high-current relay, AC250V 10A ; DC30V 10A
- Standard interface that can be controlled directly by microcontroller (Arduino , 8051, AVR, PIC, DSP, ARM, ARM, MSP430, TTL logic)
- Indication LED's for Relay output status
I asked a few questions and they sent full detail along with schematics and layout information.
I'm posting the additional detail they sent. The rest of the pin out information seemed pretty straightforward. Overall it is a neat, compact, durable design so far. We are using it in for HW design test purposes.
Power Supply: 5V DC / 400mA (relay all ON)
Input control signal voltage:
0V 0.5V Low stage (relay is ON)
2.5V -5V High state (relay is OFF).
Input control signal LOW state current:
2.5V: 0.1mA.
3.3V: 0.18mA.
5V: 0.35mA.
JD-VCC or VCC: Power supply input, 5V DC. (JD-VCC RELAY POWER VCC:SYSTEM VCC)
GND: Power supply ground and control signal ground.
CH_x: Control signal input, Low: relay ON, High: relay OFF.
COM / NO / NC: (C1=COM1, C2=COM2)
Control signal state low, the relay ON, COM NO disconnected, COM NC connected.
Control signal stage high, the relay OFF, COM NO connected, COM NC disconnected
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I must say it again AMAZON, this is not a toy! Why are these types of products always labeled as toys? It's really not much of a problem until you go to the review and see "How much fun is this toy? How would you rate this toy's educational value? How durable is this toy? How would you rate this toy overall?"The board is constructed pretty well and for the price I was surprised to find that every relay (I bought two boards) was working flawlessly. I love that there are two VCC connections one for the reference voltage to control the circuits, and one to actually switch the circuits. Because each relay takes 15-20mA to switch, this allows you to connect a separate power supply to the switching voltage and use the arduino to control the inputs. The arduino (at least the uno) will not output enough power on its own to physically switch the relays. By default there is a jumper connecting the two voltages, so you will need to pull that off and connect a separate supply. I had both boards connected and tested within 10 minutes. However, I am very familiar with this circuit as I constructed them myself last year. However, when I did it myself it took me a long time to solder it all and it cost more than simply buying these boards. The other thing I love about these boards is that the relay has 3 connections out where you can set up two separate circuits that alternate when the relay switches. When the relay is "off" (it's resting state) one circuit will be connected and when it is "on" the other circuit is connected. This means you can default your circuits either on or off. The relays I've used before didn't have that feature.
I only have two complaints. There was one loose solder connection on an output terminal that would cause the light on that relay to flicker. A quick touch-up with the soldering iron fixed it. The other is the lack of documentation, which I didn't really need because I had worked with this type of circuit before, but I was a little confused by the three outputs for a moment.
I will also say I wish that the inputs to the board had been female connections (same as the arduino) so that I could use my male-male jumpers, but that's just a personal preference so I wouldn't call it a complaint. Overall I am very happy with these boards.
Read Best Reviews of SainSmart 8-Channel 5V Relay Module for Arduino DSP AVR PIC ARM Here
I ordered this relay module to do some practical application learning for myself on how to make a raspberry pi control a relay module. The quality of the manufacturing on this board is very good. Up until now, I was working with a bread board and some relays from digikey which was a mess. This board fit right into my application and made everything nice and neat.Want SainSmart 8-Channel 5V Relay Module for Arduino DSP AVR PIC ARM Discount?
Experience: Software engineer, learning electronics with my Arduino. My dad is an EE talked me through all current measurements.SETUP:
Connect arduino powersupply 5v to VCC
Connect arduino Digital ground to ground
Connect arduino digital output to any IN1-IN8
You're in business!
CURRENT:
I connected my meter in series and found I was drawing 64mA across the Arduino 5v power supply and 1.9mA across the Arduino output pin.
I flipped it over and measured 7100ohms across the coil, meaning the coil is drawing 0.7mA at 5v.
These numbers honestly seem a little low to me e.g. I expected more like 19mA across the output, but 64mA across the power supply seems very reasonable with all eight relays drawing 400mA per the spec.
Note: Arduino max power supply voltage is 500mA on USB, so you're good there too.
PROS:
This won't blow up your Arduino.
I didn't realize this model had LEDs. I looked at the 4 relay model and the LEDs are bigger, but these are smaller and work great.
LED's in the circuit act as diodes. My dad told me when the field collapses on a DC coil it generates a negative voltage. If you don't have a diode in the way you could burn up your output transistor.
This has NC (Normal Closed) and NO (Normal Open) contacts on the high voltage side. So if you want your lights ON or OFF by default you can do that. It has a nice diagram on the board showing how the high voltage contacts are laid out.
Price
4 mounting holes on the board if you need to bolt it to something!
Lot's of fun you should buy one!
CONS:
N/A
OTHER:
The header PINs are really nice, but I only have male breadboard jumpers and need to buy some male-female jumpers from radio shack before I can hook this baby up to my xMas light setup!!
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