Hi we have a project to connect and cut off electrical outlet or lamp through Relay Currently when relay is not connected to a load, triggering relay from arduino doesn't have cause any problem. But when a load is connected while not immediate, arduino will hangs up after turning on relay. After h…

[image] wpsd2006: we already add some protection but to no avail. What kind of protection have used? See more about snubbers at WEB. Snubber A snubber is a device used to suppress ("snub") a phenomenon such as voltage transients in electrical systems, pressure transients in fluid…

Your 3v3 buck can't work without gnd. What's your ac load?

Yes we already add snubber in the relay and lc filter before buck converter

See this topic with identical problem [image] Powering Relay Board Issue - Losing MQTT Connection General Guidance Hi all, I've wired my setup according to the attached drawing. [image] However, I frequently lose my MQTT connection whenever a relay switches on or off. …

so in summary adding snubber and distancing all the cable that might emit EMI from arduino it should have solve the problem Our current snubber spec is R 100ohm and C 10nF

You are missing a couple of grounds.

Instead of a mechanical realy I might use a Solid State Relay. I would also use a seperate high quality power supply for the arduino.

[image] wpsd2006: Our current snubber spec is R 100ohm and C 10nF Disigning a snubber for a particular inductive load usually involves quite a bit of trial an error, especially if you know nothing about the load. 100 ohms and 100nf is a good starting point. The snubber board I cited in the ot…

From the looks of the setup, I'd say they're collaborating.

[image] anon85221860: From the looks of the setup I agree does look very similar.

Arduino hang when triggering relay with load

Projects General Guidance

jim-p July 21, 2025, 12:59pm 5

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Arduino hang when triggering relay with load

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