Need Help figuring this out


I am useing the Omron G6KU-2G-Y-DC5 Latching relay in a circuit wired as seen in the diagram (ignore the part number in the diagram)

The idea is simple. The Digi pin goes HIGH the Relay “sets”. Then when the Digipin goes LOW, the relay “re-sets”. This works great however, not for every relay.

I have 4 systems built with this configuration. on 2 of them the relays latch on and off every time. The other two, useing the same relays, the relay wants to “chatter” when SET (clicks on/off very fast). It doesn’t seem to want to latch in the ON position.

I changed the relays on one board and that worked. So I tend to think something isn’t right with the relays, but I just don’t understand why this is hapening.

You can’t drive this relay direct from a digital port you need a transistor.

You are overloading the output pins and damaging them that’s why you get the chatter. About 30mA is the maximum useful current draw.

Well I think you are not operating the relays properly. The fact that some of the relays work and some don’t seem to me to be a timing issue. There is a specification for relay set timing from their datasheet:

"3 ms max. (Approx. 1.4 ms - standard. Approx. 1.2 ms - latching)"

This means coil voltage must be applied for a certain amount of time. The fact that you are wiring the voltage source through the contacts means that the relay loses it’s coil voltage as soon as the contacts start to open and may not be long enough to latch the relay. Possibly if you wired a capacitor say 100-220 mfd from the top coil terminal (pin 10 in your drawing) to ground that might save enough charge source for more reliable operation?

Also a more reliable connection might be to use two digital output pins to drive the two coil terminals. A high and low or low and high would set or reset the coil respectively and after a 3 millisec delay you could then bring both output pins either both high or both low to remove coil current as the latching property will keep the relay in it’s last state.

Data sheet for your relay:$file/G6K_0609.pdf

I’ve used a similar single coil 5vdc relay in several projects with no problems, however I never applied switched +5vdc or ground return through the contacts for the coil operation, I think that is your problem.



From the datasheet the latching relay coil requires 5volts, 21.1 ma, 237 ohms. I have used a similar single coil latching relay driven directly from a digital output pin without problems.


Thanks Retro,

Actually a 10uf cap works perfactly. Larger values tend to reset the relay after a few millaseconds.

However, I don’t want to rely on this as a long term fix. So useing GM suggestion, I should be able to replace the relay with a MOSFET,
And use it as a switch, correct?

I have 2 relays now, one sends ground to an LED the other sends ground to a solenoid coil. I can drive the LED directly from the digipin so thats no roblem, but the other needs to provide about 650ma.