0
\$\begingroup\$

I took this guy from here - http://rlx.sk/en/accelerometer-gyro/3582-vibration-sensor-module-801s-er-sen801svs-.html and without noticing I have applied 3V3 instead of the advertised 5V to it. It also seemed to me it has worked fine. Can anyone tell me why it has still worked or if it makes any difference in this case ?

\$\endgroup\$
3
\$\begingroup\$

The module contains an extremely simple circuit:

enter image description here

The sensor is probably a mechanical one (metal ball or spring) so that works at almost any voltage. The opamp is an LM393 which works form 2 V supply and more.

So there's no reason why it would not work at 3.3 V.

Note however that I personally would not use this circuit as it has issues in its design. There's a reference circuit in the datasheet of the RZ801 which will work much better.

\$\endgroup\$
  • \$\begingroup\$ There is actually some analogueness in there. But this vastly enlightening document from the manufacturer uses a 9V input, so no risk in 5V at least. tme.eu/nl/Document/f057bde5b9f7ca0c86fbad8e5c5163e5/… \$\endgroup\$ – Asmyldof Jul 5 '17 at 8:22
  • \$\begingroup\$ @Asmyldof Do you mean that 4093 circuit is in the sensor module ? I don't think so, I think that it is simply a reference/example circuit and the actual sensor is just a loose/flexible spring used as a switch \$\endgroup\$ – Bimpelrekkie Jul 5 '17 at 8:36
  • 1
    \$\begingroup\$ Yet the page says there's an "analog out" and the Schematic also shows an "Aout" pin and why running through hoops with coupling capacitors or op-amps if the thing is a switching element? And if it were just a switch, what's the point to the trimming element? \$\endgroup\$ – Asmyldof Jul 5 '17 at 8:45
  • 1
    \$\begingroup\$ That opamp circuit is indeed questionable, I do not expect the sensitivity pot to work very well. Timing is also fishy with the cap at the output. It's a crappy circuit, that's for sure. I bet that the reference circuit from the RZ801S's datasheet works better. \$\endgroup\$ – Bimpelrekkie Jul 5 '17 at 9:02
  • 1
    \$\begingroup\$ @kellogs No not a guess, the circuit with the opamp simply does not make a lot of sense to me. The sensitivity setting for example seems to rely on the speed of the opamp which is a weird thing to do. Also the capacitor at the output, no sane circuit designer would do it like that. The 4093 circuit works much better, I've experimented with a similar circuit myself. \$\endgroup\$ – Bimpelrekkie Jul 6 '17 at 11:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.