Fun with a phototransistor
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- เผยแพร่เมื่อ 29 ม.ค. 2018
- On the bench today I tinker with a phototransistor circuit. I connect it to the oscilloscope and audio amplifier to see and hear the output. Let's see if an ordinary transistor is sensitive to light.
- วิทยาศาสตร์และเทคโนโลยี
What a great video. So informative, many thanks.
Very cool experiments, was working on an application and this has helped a lot. Thanks
Awesome latch with the transistor!!
Cool experiments. Thanks for sharing.
Wow! That’s sooo cool!
Great video! Thanks!
Outstanding!
Good lord, John, that's an old package. (sheepishly) I still have some old Archer packs in my kit. Almost makes me want to dig out the old Lafayette stereo and work on that. (Now there's a name from the past! ;) )
Keep the vids coming.
Great video
Hi John. That was totally awe some,,
Yeah I always found it really interesting that any PN junction device can be used as a photodetector. This will work with LEDs or regular PN junction diodes. It's easiest to use a diode with a glass package like a zener or a 1N4148 signal diode. I can get almost 2v and maybe 25microamps out of a white LED as a photocell.
This effect works in reverse, as well. If you run enough current through a diode or a photocell or even a solar cell, it'll emit light. Though the light emitted is in the infrared, but you can see this infrared easily enough with a digital camera. Any digital camera will pick up infrared light without any modifications to it. You can test this yourself by pointing a TV remote at your phone's camera and you can see the LED flickering when you press a button. It's really neat!
Could you control the gain reduction on the base of the phototransistor by, say, a 2.2K (fixed) + 5M (pot), to allow low/high gain as needed? Also, might be interesting if a jig was made with white LED (powered by DC) directly aligned at the phototransistor (with circuit as used), whereupon you try passing smoke/water vapor/?? or even the heat rising from a candle between them, to play with sensing "optical transmissivity"
That’s really cool
wow sir!!!that's amazing,LiFi technology
The small breadboard is cool
thats pretty cool, wonder if that would work with a laser diode from an old cd rom drive, could you get better range ect..
Nice touch playing Beethoven's Ninth! :-)
ats89117 banger
Great demonstration. A couple of things: first, perhaps it was not apparent during filming, but at 6:41, the LED bulb does appear to cast a flickering light, just barely visible at the top. Also, what are the two music tracks you used, out of curiosity? Thanks!
How did you calculated the resistor value to reduce the sensitivity?
do you have the schematic or list of components?
Hello; what I like to build is a sound pickup for a film projector,how to build a circuit that goes into a pre-amp,the light source is a exciter bulb
I'm guessing it's a 60Hz frequency from the AC powering the light.
Every Electron in my body cells miss Radio Shack ! I have surplus electronic parts about 40 years old and test equipment that still works like new.
This one is very "Forrest Mims".
Is it possible of we make it reverse? For example once the phototransistor detect a dim light the led will light on. Because phototherapy lamp which is use for jaundice baby using photototransistor to detect a decreasing of light produced then a warning LED will light up.... so does anyone know how it can be happen?
i was trying to do isolated current control on the +ve side with an n-mosfet, connecting the gate to a pull up resistor of 6.8k to 9v and collector of a pc817 to pull down the gate voltage ground. the led of the opto is being driven by an opamp (via a 330ohm) connected in diff amp config to a separate power source.
but it's not working properly, when it's in action it's pulling down a lot, then doing sort of proper control to some range. i am thinking, this is because the opto interface is not as responsive. any suggestions please ?
Check rate of change at output of opamp and isolator through rate of change across the sensing device. Do this test separate from the circuit or the effects of feedback may mislead you. Once the circuit is working properly through its detection range, interface it with the mosfet gate. You may need to tinker with the gate circuit to get it regulating properly.
separate test, ok. i think i will need another opto. ok, will check it separately.
I'm surprised how small the die is in the T03 transistor, that's like what I'd expect from a counterfeit part.
It is out of an old TV from the 70's. Probably part of the voltage regulator and wasn't a high current device.
build a light box and put led in various locations in the box and maybe use a variable resistor to adjust light
send music to your to-3 transistor.
Would an incandescent lamp on a direct DC source flicker, like and old flashlight. It makes sense that a lamp on an AC source would flicker at 60Hz or 50Hz in Europe.
Mike oliver It would flicker at a 100 or 120 Hz.
Incandescent blubs give light because of heat. The wire can't cool in 10 ms, so I doubt you'll get any flicker from incandescent bulbs.
Oh yes you can. See th-cam.com/video/E_2ZNXC4zEI/w-d-xo.html
What about a little modulated laser. So that you could send the music from far away. (100meters ?)
Yes you can certainly do that.
reminds me of an episode of "Burn Notice", where michael bounces a laser off the large window of a room where people are speaking, uses the reflected beam to hear what they are saying. (so basically the reverse of what you're suggesting)
Maybe test with high power led's?
Or LASER diode.
Just what I was thinking. I think that is a vid in modifying a laser pointer to audio modulate and point it at the photodiode from a distance.
btw, I want to know sir on Tv remote control is that LED or phototransistor?
On the remote is a IR (infrared) LED, on the tv a phototransistor with a coating that only lets through IR light.
Has anybody ever told you you sound just like Owen Wilson?
19th viewer but 1st liker.
Lol
Re. Radio Shack... well at least their online shop is still open. For what their pathetic stock is worth.
I went to the RS site and looked up "locations near me" and it returns "authorized dealers" and some come up as pharmacies and other non related businesses. I'll have to go to one and see what the hell is really going on. There is no "real" RS store within a 100 miles of me now. I thought several hundred were to remain in business.
First