SainSmart 16-Channel 12V Relay Module For PIC ARM AVR DSP Arduino MSP430 TTL Logic

Customer Reviews

Good for RaspberryReview by Richard

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This board works well with the Rpi but requires a little thought to implement correctly.

First of all the VCC-JD jumper must be removed to isolate the coil voltage from the signal voltage.

The logic is backwards from what might be expected. When the Rpi GPIO or port expander pin is "off" (sinking voltage) the relay is energized.

The two relay version of this board is easily modified so that when a high is presented, the relay energizes. A trace cut and a couple of jumpers are all that are needed.

Other than that, no other considerations are needed.

There are some that say that another driver transistor is needed to interface this to the Rpi. This is NOT true. Having said that, there is the advantage that the logic is reversed (GPIO Hi=ON) when a transistor is added. One could add a hex inverter like a 74HC540 and do the same thing. The VCC-JD/VCC jumper must be re moved and +5 volts from a separate power supply be fed to VCC-JD. A wall-wart works nicely and maintains isolation.

I recommend that a I2C port expander such as the MPC23107 or MPC23008 be used with this relay board. An SPI bus port expander could also be used (MPC23S17 or MPC23S08) with the Rpi. Utilizing both I2C buses on the RPI, that means that a total of 256 relays can be connected to the Rpi. In addition another 256 relays can be connected via the SPI bus. for a grand total of 512 relays controlled by a single Rpi.













(Posted on 6/16/13)

opto-isolatorReview by Antonio

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What kind of opto-isolator have you used in this PCB? (Posted on 5/27/13)

Great Relay Review by Terri

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I just got the relay. After some test, it works great as expected. (Posted on 3/14/13)

Functional but a couple of surprisesReview by John

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Board works well. Would have liked to see better specs in the documentation. The IC's were specified on the schematic but the values of the resistors were not. I had to calculate the input current and the total load current for the +12v supply after I received the board. I also measured the values and confirmed my calculations.
Input current: 3.8 mA per input
Total current required for +12v with all relays closed: 510 mA measured (640 mA calculated worst case)
Happily surprised that total current draw was less than I thought.
One big drawback is that the design of the opto-isolation is really lame. The board has a separate 5v regulator that pretty much defeats the purpose of the opto-isolators. The bias network for the input opto's uses the non-isolated 5v supply that is derived from the +12v. If any transient hits the board, the spike can kick back into the driving circuit. I think that their idea was to make it easy to interface to the board, but I feel that they should have required the user to supply power for the input bias drivers. That way the driver circuit would have been truly isolated. (Posted on 2/8/13)

Great relay boardReview by Paul

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This is a great product at a great price. I have one in service switching broadcast transmitters every day. I am now ordering a second one for another broadcast transmitter site. (Posted on 7/23/12)

Great Relay!Review by Luke

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This relay module is of nice design, with the download documentation, I worked it out in no time. But it would be much better if it has the schematic included in the shipment. (Posted on 7/18/12)