Hello,
I need some help to create two sensors using LMV 721/722 OpAmp
One will be a light/dark activated switch for one led and the other a sound activated switch. Both must have sensitivity adjustment.
The light circuit I've manage to get it work only for the switch part (switching the In+ and In- of the op amp), the sensitivity one..no luck, as for the sound sensor nothing till now (the microphone is a capacitor one).
The supply will be a 3V Li battery.
Can any one please help me to solve these circuits?
Hi,
thank you for the reply.
The led is a 3mm
I increase the value of R4 to get more gain and remove C2...no success
"The divider R1/R2/R3 makes no sense" i don't know what do you mean by that...sorry, i don't want to be rude, but i am a new in electronics.
with this circuit I'm trying a camera remote shutter release and the case is small, but i think it will accommodate 2 3v Li batteries.
Any help or guidance will be appreciated
Thanks
"The divider R1/R2/R3 makes no sense" because there would normally be a voltage source at the top of R2. If the top of R1 is also connected to a voltage source, then it would seem to me that the diode U1 is backwards. (Incidentally, BPW34 has only two terminals, not three, in the data sheet that I find).
What do you thing about this one?
in order to simulate the circuit, the third pin of the photodiode represent the excitation source
PS How can i attach more pictures to this post?
the pictures are here
**broken link removed**
I want to build a camera shutter trigger with a light and sound sensor.
When the microphone detects a sound the shutter is on. I need to adjust the sensitivity to not have false triggers. To see the threshold that triggers my camera i need the led (actually there will be one more transistor -same base as first one - that closes the camera trigger circuit)
For the light sensor i need two modes:
1. Trigger at lighting or other flashes (sudden light increase)
2. To trigger when a beam of light that falls on the photo diode is interrupted (to get nice pictures of water drops).
This is what i want to achieve.
Instead of photo diode i an use a photo transistor, but it has slower response and I've read that for this type of application BPW will do a better job.
Hello,
I think I've made some progress here and i need your opinion
What I'm not able to do is to change the circuits sensitivity so i need some advices.
One more thing, do you think it is possible to increase the time of led (D1,D2) being lit without using a 555? If yes, how can i do it?