I am trying to use a relay to power a RPi for the first time and just confused by how I should wire it. I am trying to control the relay with a ATtiny10 MCU (microcontroller) if that helps in explaining setup. My power supply input and both MCUs are 5V. Any help/guidance would be greatly appreciated.

Part # on Mouser: 769-DS1E-SL-DC5V

I am thrown off by the 2 positive ends in the datasheet circuit diagram.

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  • \$\begingroup\$ That's the two coils mentioned in the name. They both share one terminal. \$\endgroup\$
    – Hearth
    Dec 12, 2018 at 2:17
  • \$\begingroup\$ The response below explains functionality of Pins 1,3, and 6. @Hearth do you know how Pins 7,10, and 12 should be connected? \$\endgroup\$
    – SChand
    Dec 12, 2018 at 18:49
  • \$\begingroup\$ pins 7, 10, and 12 are the relay contacts. Pin 7 is the common contact, and will connect to either pin 10 or 12, depending on whether the relay is in the set or reset state. \$\endgroup\$ Dec 12, 2018 at 19:16
  • \$\begingroup\$ @PeterBennett so does that mean 7,10 and 12 are internal connections? I don't have to physically wire anything to them? \$\endgroup\$
    – SChand
    Dec 12, 2018 at 19:22
  • \$\begingroup\$ You wire whatever you want the relay to control to those terminals - they are the switch portion of the relay. \$\endgroup\$ Dec 12, 2018 at 19:29

1 Answer 1


This is a latching relay - it stays in either position without power. A "normal" (non-latching) relay requires that power is applied to hold the contacts in the "operated" position.

If you ground (connect to the negative side of the power supply) pin 3, and apply a short positive voltage pulse to pin one, the relay will move the contact to one position, and applying a short positive pule to pin 6 will move the contact to the other position. It is not immediately clear to me which coil will move the contacts to which position.

EXAMPLE: If you wanted to wire a Power Supply using this relay...

You would wire the positive supply voltage to pin 7, and the load positive terminal to pin 10 or 12. The negative side of the load will be connected to the negative side o fthe power supply. The relay contacts are used in a circuit the same way a switch would be used.

  • \$\begingroup\$ When you say "It is not immediately clear to me which coil will move the contacts to which position", do you mean you don't know which contacts make the relay Open or Closed? \$\endgroup\$
    – SChand
    Dec 12, 2018 at 18:46
  • \$\begingroup\$ Yes - it is not clear to me which coil will "set" the contacts, and which will "reset" them. If you have a relay, you can easily determine this with a suitable power supply and an ohmmeter. \$\endgroup\$ Dec 12, 2018 at 19:14
  • \$\begingroup\$ Using the Power Supply I would be measuring current right? Or do I measure Resistance (since you said Ohmmeter)? Never measured resistance to determine circuit functionality. I am assuming high resistance means closed and low resistance is open? \$\endgroup\$
    – SChand
    Dec 12, 2018 at 19:24
  • \$\begingroup\$ You would use the power supply to apply a voltage pulse to one coil, then use the ohmmeter to see whether pin 7 is connected to pin 10 or pin 12. When the contact is closed (making contact, able to pass current) the meter will read very close to zero Ohms. With the contact open (not able to pass current) the meter will read open circuit - same as if the leads are not contacting anything. \$\endgroup\$ Dec 12, 2018 at 19:29
  • \$\begingroup\$ Thank you for that explanation on using the Ohmmeter! \$\endgroup\$
    – SChand
    Dec 12, 2018 at 20:06

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