does it matter the polarity of the transducer pins on the hc-sro4? i have bought waterproof transducers but i cant get them working right.
The polarity shouldn't matter as they're essentially AC coupled anyway. What transducer are you using?
Not all transducers are tuned for 40kHz operation.
i bought these transducers
what i notice is if my hand is really close to the sensors sometimes i can get a reading that i know is correct but then it right back to garbage. im wandering if it may not be enough power to drive them? when my hand is more than a few inches away i cant get anything.
Update: if i leave it somewhere under a hard surface i consistently get a good reading then a bad reading
example of readings
-6850
56
-6846
56
-6848
56
-6824
56
-6844
56
-6806
56
-6770
56
looks like bypassing a resistor on the recv side transducer (not the ground pin" but the other pin of the transducer i traced it back to the nearest resistor and soldered over it and boom it works now
apeears this only works if i use the original recv transducer. what are my options at this point i have a feeling this uc is not enough power for these transducers?
really that's all you guys got. no breakout boards/ ideas
The microcontroller has very little to do with the sensitivity (assuming that's what you meant by "uc").
The Tx is usually driven by a MAX232 or similar, and the Rx is amplified by an op-amp.
If your transducers don't match the originals, you've got a problem on your hands.
TolpuddleSartre:
The microcontroller has very little to do with the sensitivity (assuming that's what you meant by "uc").
The Tx is usually driven by a MAX232 or similar, and the Rx is amplified by an op-amp.If your transducers don't match the originals, you've got a problem on your hands.
hmmm. well i must have done something wrong when i bought the transducers. could you perhaps point me to a set of waterproof transducers that might work with this hc sr04 board. or perhaps maybe a uc that supports dual transducers like the hc sr04? i think that maybe this uc dont have enough power or something on this board is not in specs for these transducers i bought. . im not sure i think maybe since these transducers are enclosed in a metal case that it may need more power to drive them. i know the are both 40khz sensors
so far im looking at these 2 sets of transducers,
or part number "US1440" from this website? https://www.futurlec.com/Ultrasonic_Sensors.shtml
There are more details about the HC SR04 schematic and modification over here
https://uglyduck.vajn.icu/ep/archive/2014/01/Making_a_better_HC_SR04_Echo_Locator.html
Instead of going through the trouble to make waterproof transducers work with HC SR04.
I just went for this other waterproof sensor one instead which has 2 transducers therefore less minimum distance and is sealed making it waterproof from all sides.