Problem with SR04M-2

Other Hardware Sensors
1

I bought an ultrasonic distance transducer but I'm having issue using it.
The exact model is this one: https://it.aliexpress.com/item/1005006814323837.htm and it's called JSN-SR04T / AJ-SR04M

I'm using an ESP32 and EspHome.
I started with an LM7805 for power supply (down from 11.2V), esp has an external switching power supply.

The problem is that with default settings (trig with 20us) only 1 of 10 triggers are followed by a response.
Most of times when triggered the module remains silent.

Good trigger:

SDS00005
SDS00005800×480 74.8 KB

Bad trigger:

SDS00003
SDS00003800×480 73 KB

Trig chan was first connected directly but having problem I tried with a 2N7000 with a 10k Pull up to 5V to ensure a clean 5V signal instead of a 3.3V. No differences

Echo is read from ESP32 with a voltage divider 2k-1k

After many tests I increased the pulse for trigger to 80us increasing the good response to ~80%, or to 120us to have ~100%.

Is that something known? Also checking amazon or other revies I can see many people founding the same problem, is there a better solution than mine?

For next applications I also would know:

is 3.3V enough to trigger the board?

can I read the 5V from an ESP32 with a 10k input resistance? (1.7mA is not much)

Thanks

2

While some units do accept 3.3V logic, others are inconsistent or fail to trigger reliably.

You’re already using a 2N7000 with 10k pull-up to 5V, which is good. It ensures clean 5V levels for the TRIG pin — this is the best and safest method for mixed-voltage systems.

Keep using the MOSFET level-shifting circuit or a logic level shifter.

3

Yes, but also with a clean 5V trigger the board fails…