Thanks!! That's better!! But they're listed as infrared. I wonder how much infrared is emitted from the neon bulb?Don't use NTE parts if you don't need to. They are always overpriced.
View attachment 280114
I edited my post after you read it. It would be helpful if you told us what amplitude and pulse width you're dealing with.Thanks!! That's better!!
My post #9 shows the dirt simple schematic I'm using. Too simple to work that is. I tried an Uno thinking it would be more real-time than the Raspberry Pi / Node Red application I started with.By the way, there are several models of Arduino as well as clones. Which model are you using? It may make a difference.
Plus, I reviewed all of your posts and I don’t see a schematic of how you’re wiring your phototransistors. That would be useful. Include your connection to the Arduino. Just draw one on paper and take a clear photo. Then attach it here.
Also, you’ve been asked to post your Arduino sketch. Please use code tags and paste your code into a post. Ask if you don’t know how to use code tags.
You have been given lots of suggestions to a problem which you haven’t described in sufficient detail. A good answer needs to know this information.
Ok, but the schematic in post #9 won’t work necessarily with an Uno. The thresholds for an Uno are 0 up to 0.2 x Vcc = low. (My post #9 shows the dirt simple schematic I'm using. Too simple to work that is. I tried an Uno thinking it would be more real-time than the Raspberry Pi / Node Red application I started with.
I need a channel check. I thought the thread starter was using a Rasbery Pi but now reading post #1 I do see mention of an Arduino. Now I see what I missed.Ok, but the schematic in post #9 won’t work necessarily with an Uno. The thresholds for an Uno are 0 up to 0.2 x Vcc = low. (0.5V with 5V VCC). Vcc down to 0.7 x Vcc = high (3.5V and above for 5V VCC)
Well alrighty, the Uno would be 5 volt logic. The Pi would be 3.3 volt logic. So yes, with an Uno the logic in post #9 won't work unless the V+ is changed to 5.0 volts.I tried an Uno thinking it would be more real-time than the Raspberry Pi / Node Red application I started with.
I’d measure the voltage between ground and the (Uno) GPIO pin output (and NOT connected to the Uno) while the photo transistor was dark and lit. Let us know what they are…Yes the supply voltage to the phototransistor was changed to 5 volts on the Uno and 3.3 on the RPi.
Thanks! I'll build this circuit hopefully this weekend and report back.As suggested this might be a voltage threshold level issue. Here is an AGC(Automatic Gain Control) that uses a Photo transistor in reverse bias mode. In reverse bias mode, the PN juction looks like a capacitor to the rest of the circuit that discharges (leaks) proportionally to the amount of light exposed to the PN junction. Another benefit using the Photo transistor in this mode is that you minimize the Miller effect because you don't have the gain of the transistor contributing to amplifying the input parasitic capacitance which could dampen (filter) very quick voltage spikes.
Reference: (Miller effect
https://circuitcellar.com/resources/quickbits/miller-effect/
View attachment 280267
Before you do, please make the voltage measurements I suggested. If they aren’t what they should be, a pulse stretcher won’t work and you’d have wasted your time.Thanks! I'll build this circuit hopefully this weekend and report back.
is there a way to calculate the voltage output given this data? I think it’d be just as easy to measure the output directly. I still think the voltage is not high enough to be read as a high by the Arduino and has nothing to do with the pulse width.Here is the spectral response of the Vishay phototransistor shown in post #21.
View attachment 280591
Orange covers about 600, so the transistor's response will be down to about 40% compared to the peak.
That would be my guess and neon lamps are not quite the picture of brilliance.is there a way to calculate the voltage output given this data? I think it’d be just as easy to measure the output directly. I still think the voltage is not high enough to be read as a high by the Arduino and has nothing to do with the pulse width.
In that case, another transistor could be used to provide a high enough level for the Arduino.
I don't know Dick. My take was the fence pulse were 6 KV and the detector circuit was similar to what I posted in post #8. My guess was the thread starter was using a photo transistor to detect the illumination from a neon bulb. I based my logic on that. Now I don't know what to think with think being the operative word.Looking back at the first post in this thread, we are leaning over backwards to detect a 600 volt pule from an electric fence. I would seem much more efficient to sense a 1kv to 6 kv pulse than to try an note the glow of a neon lamp. I think we are on the wrong track.
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