ESP32u and 4ch relay board

[joel gerardi]

I am trying to use a tasmotized ESP32u to control a relay board which has its own 110/5v transformer.  I also have a ds18b20 attached to the esp32.  If i use the 5v power supply on the relay board to power the esp32 via the 5v pin, the relay works but the ds18b20 does not.  It will come on and off meaning it display the temp in the gui sporadically. If i power the esp32u with a usb cable, the temperature displays perfectly but the relays dont work.

The ds18b20 is connected to GPIO16 and configured as such.

The relay board is 

https://www.amazon.com/dp/B077YLQ6DL?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_6

any thoughts?

[Philip Knowles]

Some ESP32 boards only give a 5V output on the pin and it can't be used as a supply, One of the reviews on Amazon says that the 5V drops as low as 2.5V when the relays are energised

---

From: sonof...@googlegroups.com <sonof...@googlegroups.com> on behalf of joel gerardi <joelg...@gmail.com>
Sent: 16 March 2025 14:53
To: TasmotaUsers <sonof...@googlegroups.com>
Subject: ESP32u and 4ch relay board

 

--
You received this message because you are subscribed to the Google Groups "TasmotaUsers" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sonoffusers...@googlegroups.com.
To view this discussion, visit https://groups.google.com/d/msgid/sonoffusers/ea237e14-8a53-4f2e-87fa-8cff2e6c7c6en%40googlegroups.com.

[Ron L]

One option is to use a couple of resistors and transistor (for each output/relay) along with the USB for power to the ESP32 so your temp probe works. Pic below shows Raspberry Pi but the resistor/transistor circuit still works on ESP device when needed.