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SainSmart 8-channel 12 V USB Relay Board Module Controller For Automation Robotics

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SainSmart 8-channel 12 V USB Relay Board Module Controller For Automation Robotics


Availability: In stock


This is USB controlled relay module with 8 relays SRD-12VDC-SL-C. You may use it for simple ON/OFF switching electrical devices - home lights, DC motors, solenodis and others. It may help you building projects like robotics and home automation. Each such board requires one USB port. The more USB ports you have the more Relay boards you may connect.




  • 8 SPDT relays SRD-12VDC-SL-C
  • Relay specification – 10A 250VAC/10A 125VAC/10A 30VDC /10A 28VDC
  • Power Supply - 12 VDC
  • Current consumption - 300 mA
  • FT245RL. Datasheet –(
  • Led for each relay output
  • Power Led
  • USb led
  • Size - 93mm / 70mm / 16mm
  • Windows software examples: VB6, BCB6, Java (netbeans), VB.NET 2010 Express, C++.NET 2010 Express
  • PCB parameters: FR4 / 1.5mm / two layers / metalized holes / HAL / white stamp / solder mask
  • Extra PCB openings for better voltage isolation
  • Doubled high current tracks



  • When the board is connected to the PC and the PC is restarted, the relays will be toggled several times. This is because of the structure of the FTDI chip.
  • The device must be supplied with 12 VDC or order to work.
  • There is no protection against reversed voltage! If the VCC(+12V) and GND are reversed the board will be damaged!
  • The board can not work without computer


Supply Characteristics:





Recommend voltage




Voltage limits

Including ripple



Nominal input current

Voltage 12VDC



Power dissipated

When all relays are ON




Against reverse polarity




Relay output:

Type     12V-T73-USB
Relay type     T73
Relay outputs count     8
Contact type     NO, NC
Current consumption 12VDC mA 30
Switching parameters
125 VAC / 28 VDC
250 VAC



Download Link

Customer Reviews

2 Item(s)

per page
Quite nice, but could be even betterReview by Sascha
(Posted on 3/27/14)

Seems to be quite well-built; looking forward to see how long it's gonna last in my test setup for doing power cycle tests of embedded devices. Use of standard components (FT245RL) makes it easy to control from Linux.

There a two drawbacks that could be addressed in future revisions or products:

1. Like hinted at in the description, the relays glitch during boot-up. This happens even with a USB power supply instead of the PC, so it's not a driver issue. Using an additional latch may help.

2. The board looks like it would fit a DIN rail case nicely, it even has the connectors placed appropriately. Unfortunately it barely does NOT fit: the two connector rows are a few millimeters too wide apart. Having USB and power supply on the sides would have been acceptable (though not perfect), but the 93mm are about the size of the case itself make it impossible to fit.

It's good enough for my own test setup, but because of these two issues I can't recommend it to my customers. Their test equipment is mounted on DIN rails and the relays may be wired in ways where glitches may cause short-circuits.

Great GreatReview by Ye
(Posted on 3/20/13)

The relay arrived in good condition and it's very well-built. I did some basic test on it, and so far no problem with it. I am searching some example code for it, but didn't have much luck. I contacted the support, and they gave me a link, where includes windows software examples. I really like this relay.

2 Item(s)

per page

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Prices and Rates

1.SainSmart provides two delivery methods from which to choose:
   (1)STANDARD SHIPPING(Free to USA, United Kindom, Canada, Australia, Germany, France, $5 to other countries)
   (2)EXPEDITED SHIPPING($12.50 to USA, $17.99 to other countries)



Import duties, taxes and charges are not included in the item price or shipping charges. Please find out as much as you can about import taxes in your own country before purchasing an item. In special cases, you may need to pay import duties on certain goods. We will endeavor to assist and cover in cases where duty is charged, if you are charged customs then please collect the package, pay any fees due and then contact us and we will reimburse you. For any assistant on this, you may kindly contact us. We promise to do our best for you.


Delivery & Tracking


Depending on your location and the type of goods you have purchased, will dispatch your items via 1 from 5 carriers. Items will be shipped from our main warehouse in China. If you prefer to have it shipped from other warehouse, please contact us via

Standard Shipping:

China Post is economic airmail reaching most part of the world, which generally takes about approximately 20 business days to arrive. And this will reduce the risk charging by local custom.
The delivery status of a package can be checked via the Internet at (for tracking numbers beginning with “RA”)

EUB is also known as E-packet, which is especially for delivery to USA. It takes about 10-12 days to arrive. The delivery status of a package can be checked via the Internet at (for tracking numbers beginning with “LN”)

Express Shipping:

DHL/UPS: We ship the item(s) by DHL / UPS from our warehouses in China. Your item(s) will normally be sent out within 1-2 business days and it takes approximately 3-5 business days to arrive depending on the destination.


Tracking website:

EMS: For some countries where UPS/DHL will not deliver, we will ship the item(s) via EMS, reaching you 8-15 days. Countries list for EMS shipping: Brazil, Russia, India, Turkey, Mexico, South Africa, Argentina, Saudi Arabia, Hungary, Romania, Israel, Philippines, Slovakia, Greece, South Korea.
The delivery status of a package can be checked via the Internet at (for tracking numbers beginning with “EE”)

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SainSmart 8-channel 12 V USB Relay Board Module Controller For Automation Robotics