The Jfet amplifier will pickup every radio station, TV station, police radio, ambulance radio and every other radio signal in town.

The 3-transistors circuit has useless resistors and is missing important resistors. It needs an extremely low current input of almost 2V.

 

The Jfet amplifier will pickup every radio station, TV station, police radio, ambulance radio and every other radio signal in town.
The 3-transistors circuit has useless resistors and is missing important resistors. It needs an extremely low current input of almost 2V.

Hmmm, yes i remember something ... Thank you.
Thank you for the circuit correction also ! That was my friend circuit that you corrected. He is younger than me, but old school.
So it's a radio receiver in a word.

 

So it's a radio receiver in a word.

No. A radio receiver has LC tuned circuits so it picks up only the radio signal you want. Your Jfet or three emitter-follower transistors have no tuning so they pick up everything all at the same time. They even pick up 50Hz or 60Hz electrical mains hum.

You talked about a "proximity detector". Usually it detects the infrared heat from a person near it.

 

And finally today I received my 2 types: 2N7000 and 2N7002 Field effect transistors.
From 31 08 2020 to 07 10 2020. 1 month, this time it came surprisingly fast ! Probably covid is beating on the drums of mass media too loud these days. Usually it takes more than 2months and a record of 8 months 1 time. This is an exception from the rule of lazyness. Im happy it came fast, but im shocked in the same time.
It passed a little time from when I interrupted this discuttion, but here is the summary:
@sghioto give me the new models of field effect transistors , I bought them both types To-92 and SOT-23 (because i never try it with a smd before).
He also give me a circuit to build.
https://www.instructables.com/Proximity-Sensor-with-2N7000-mosfet/#:~:text=FET Proximity Sensor,relay, power transistor or mosfet
The whole thing is for my old circuit with the light beam interruption, and now i will upgrade it with this FET. Also the LM3914 will benefit from it (the 10 leds driver). The interruption will be made when the last led from the led driver will be activated.
So, this is the summary.
I will update the progress from now on, here. I will also make it as much as possible to update the opamp discussion, since we made some very nice progress in there. But that discussion was while waiting for this one to be able to continue.
I will work on both in the same time as much as i can.
Thank you so far !

 

From 31 08 2020 to 07 10 2020. 1 month, this time it came surprisingly fast !

Does this mean you ordered them from China? I'd be very cautious buying individual components from any source in China unless it was a reputable distributor. I've done it, but you have to be aware of the fact that they could be counterfeits; and not even what you thought you were buying.

A few years ago, a member bought what he thought were temperature sensors in T0-92 packages from someone on eBay. They didn't work and turned out to be transistors. Some counterfeiters only care about package type. I've seen pictures where they pull devices from boards and sort them by package. They even do this for surface mount capacitors that cost half a cent each. When you live in an area where you can get by on a few dollars a day, even pennies count.

 

To avoid confusion, you should call them MOSFETs. There are dozens of types of FETs, but not all have an insulated gate.
MOSFETs are static sensitive devices and most discrete devices don't have any ESD protection. In the past year or so, I've damaged 3 2N7000. None died outright, but all exhibited high leakage after being damaged. That's indicative of junction damage.

- Mosfet then. I was thinking they are FET's , being MORE sensitive to the hand movements, very subtle fields. We call them here [transistors with an effect of a field], to be quite word for word. But is a large misunderstanding and people call them either FET or mosfet or the long name, they are all in the same hole together. How do you call such very sensitive MOSFET's, that are susceptible to any radio frequencies as mister audioguru mentioned ,and when in this specific circuit with the hand movement? More sensitive MOSFET's? I dont know. But that I was thinking before.
- The only problem I know for sure they have, is not expose them to any electromagnetic fields, because they will die. Like I have a very old transformer soldering gun, with a copper loop that get hot in 2 seconds after I press the contact button. That emit this EMF that i was told in very old days to be careful. So when dealing with them must only use soldering iron.
I think they are also sensitive to electrostatic voltage. So I must discharge my hands, on a piece of metal before handling them. I think. Or washing my hands, that will get rid of electrostatics, but wait to dry on air or wind (blowing on my hands).
- The master of all the earth, the mighty ebay, and yes from China, since its the most cheap. I know, im attracted too much for the cheappies. I had some bad deals with them, not sending at all the packages, or very late, or my postage is with grabby hands, who knows. But in a large majority of cases i received pretty good products and im happy. Like in 90% of the cases. I fight a lot with them, reminding them they are out of the time limit...its a bit of hell with them. But is ok, if i know how to pick them. I kind of have a 3'rd eye now for ebay deals, from so many years of fighting with them. Its an adventure. But they are cheap so that beats everything else. No question. I understand what you say, being risky. I hope i dont speak too soon now before testing them and discovering some weirdness. We'll see soon enough.
Thank you for jumping here with the discussion.
Ill update with this circuit when is done, very soon.

 

- The only problem I know for sure they have, is not expose them to any electromagnetic fields, because they will die. Like I have a very old transformer soldering gun, with a copper loop that get hot in 2 seconds after I press the contact button. That emit this EMF that i was told in very old days to be careful. So when dealing with them must only use soldering iron.
I think they are also sensitive to electrostatic voltage. So I must discharge my hands, on a piece of metal before handling them. I think. Or washing my hands, that will get rid of electrostatics, but wait to dry on air or wind (blowing on my hands).

No.
All electronics are susceptible to damage from ESD (eletrostatic discharge), some more sensitive than others.

FETs and MOSFETs used to be shipped with fine wire wrapped around all leads. Today they are shipped in antistatic foam or containers.

Touching piece of metal or washing your hands is not going to prevent ESD. You must have ESD-safe workstation, mat, and wristband.

The old transformer soldering gun is not going to destroy a MOSFET. What is more important is that all soldering tools be grounded. Your typical handheld solder sucker is more likely to cause more harm than you would expect.

The only problem I know for sure they have, is not expose them to any electromagnetic fields, because they will die.

That is next to impossible. Just where you are you are being bombarded with lots of EM fields and ionizing radiation, AC mains, cell phones, TV, radio signals, gamma radiation from inside your own body and the chair you are sitting on, and cosmic radiation from outer space.

 

The gate of a Mosfet is insulated with a layer of Metal Oxide. It is damaged by 20V or more. Because it is insulated then static electricity can damage it.
A Jfet has its gate as a PN junction.
Do not call then both FETs because they are very different.

 

Mosfet then. I was thinking they are FET's , being MORE sensitive to the hand movements, very subtle fields. We call them here [transistors with an effect of a field], to be quite word for word. But is a large misunderstanding and people call them either FET or mosfet or the long name, they are all in the same hole together.

A MOSFET (notice all caps because it's an acronym) is a field effect transistor. It just happens to have an insulated gate which differentiates it from a device such as a JFET that has a PN junction on it's gate.

The master of all the earth, the mighty ebay, and yes from China, since its the most cheap.

Cheap on eBay usually means counterfeit these days. That wasn't the case 10-15 years ago, but counterfeit parts are a big problem on eBay, Amazon, Ali Express, Banggood, etc. There are few semiconductors that I'll buy from any of those sources.

 

No.
All electronics are susceptible to damage from ESD (eletrostatic discharge), some more sensitive than others.

This is a new information for me. I was not informed about this aspect. So... even a (passive) resistor or a track wire are sensitive to ESD? That is very interesting ! I should probably get into more details about how strong and ESD can get and prevention or cleaning measures.I never thought serious of this. I mean, I am aware of the active components fragile gates, or junctions or electron/holes barriers those are easy to get damaged, especially when working. But a solid block of resistance or capacitance? Its definitely interesting to think about it.

A Jfet has its gate as a PN junction.

I see. I call it FET, but is the same as saying is a jfet. But never a mosFET. Hmmm... -1 grammar point for me. Yah, nice explanation too, I like it ! I know i dont look like knowing much, but i do know much, read much and have an interested attention to a lot of things and details. Is that i didnt exercize them as i do with you here. Im inexperienced. Very interesting points.
Im also thinking right now... because of your clarification, how many depositions are there? Like you said, the pn jonction, then oxide on semiconductor deposition.... anything else? Im not sure there are more than this, or maybe very little deviations but in general lines are on the same branches ? Im also tired and i cant think at the moment on anything else. Brain freeze at this point.

Cheap on eBay usually means counterfeit these days. That wasn't the case 10-15 years ago, but counterfeit parts are a big problem on eBay, Amazon, Ali Express, Banggood, etc. There are few semiconductors that I'll buy from any of those sources.

Its interesting... you are all keep telling me about ebay products being fake, but for me all are working fine,for a very long time, years and years, and i really have no complaints in this part. Then the issue is probably somewhere else perhaps? Hmmm.... It puts you to think. If you can believe me what im saying is truth, then is something very mischievous in play from china to america maybe. For me , an european, is not the same as for american. At least i get some troubles but, i never got rocks painted black or other type of component instead of the original components. I probably got sometime a "fake" one as you put it, but it was very quickly demistified as a mistake and the seller send me the right thing after that. (took me other 2months but its another story) Its also interesting the ebay headquarters: https://www.ebayinc.com/company/contact-us/ the first square mention they are from USA and not at all from china as I originally thought they be. And I got over this information 2-3 months ago too. All this time I was sure they are from china. It is weird indeed if you got false things. Or some people are over-reacting maybe, and it spreads, who knows... It may look to me personally like there are diferent markets for diferent continents, for americans works some markets but the rest dont, for the europeans or asians some markets and others dont. It [appear] its a global market movement, but it might be as I say it, different for each region on the globe. I hope im not stupid. :] All here are VERY subjective impressions, not at all to throw the cat on anything.
//
- On another plan, I just tested the new sensitive MOSFET, smd 2n7002 and TO-92 2n7000 with the circuit from the video and it is working excelent from the first try on both on them and with the same response on both, at least i dont see any difference from the precarious experiment im doing, but it is a valid one so it counts and im happy so far. The thing right now that i must take care is the sphere of influence to make it fit as i please.
The next step is to add lm3914 led driver to this circuit.... it will look glorious, i tell you.

 

Its interesting... you are all keep telling me about ebay products being fake

That's because it's a big problem. If you're just learning circuits, the last thing you need is defective or counterfeit components. If you choose to buy components from disreputable sources, you need to contend with parts of unknown origin and quality.

Some who buy "cheap" parts know that they need to do 100% testing, but few of us will have the resources to do comprehensive testing. If you value your time, you'll buy parts from reputable places. For years now, I've bought most of my components from Jameco and Newark. Both companies certify the authenticity of the parts they sell. You won't get that assurance from anyone on eBay, Ali Express, or the like.

 

Very little update but i thought it is nice.
Smd next to TO-92. The smd mounting, to be able to use it on breadboard. Both are working fine.

 

2 customizations I want to be able to make.
If im asking too much, tell me and ill concentrate to other more important aspects of this project.
This part is important but not that critical so you can resolve it for me (if its easy), or leave it (if its too hard).
As always, thank you until here.

 

The smd mounting, to be able to use it on breadboard.

I made up some SC-89 to DIP adapters using scrap copper clad and a Dremel tool and decided the commercial ones were more convenient.

The SOT-23 adapters cost about $0.05 each and the leads cost about $0.10 each in low quantity (when you can find them).

I have some surface mount 555 timers I want to use, so I bought some SOP16 adapters for $0.07 each. I have no issues with buying these adapters from Ali Express.

The soldering on the homemade adapters isn't very good. I needed some P MOSFETs in a hurry and all I have are surface mount. I used wire solder and reflowed it. I used solder paste for the SOT-23 devices.

 

These days, many treat all semiconductors as being static sensitive, but I don't worry much about bipolar semiconductors. I've had transistors and TTL logic stored in plastic drawers for decades and they'll probably stay that way until I want to do something with them.

I have no concerns about this TTL device inserted in styrofoam and in a plastic bag. That's how it was packaged by the manufacturer or distributor:

 

These days I thought at what i want. Its the hardest thing sometimes to figure it out.
I had a floating idea, like a white cloud. Now is down on paper.
For full resolution: https://www.deviantart.com/q12a/art/Q20201010-Light-Switch-Design-857811350
Next is the wiring, im working now on them(wires) and is... something. :] oh boy.
Ill use layers of connection boards most probably; sandwiched.

 

The problem is ... that i have to integrate the sensing circuit and the sensing wire.
What I present so far (my original thought) was only the led driver circuit.
I might add this back plate, and around it add the sensing wire (or behind it).
Maybe you have some interesting design ideas, that I didn't think of. That's why i post my progress here.
Another problem is the power source and probably the ldr circuit also(with a laser head instead of a led head), but those can sit on the top box over the door.
And I also plan a remote control (the simplest possible, probably with a led or IR led and a ldr) and its receiver. All these must take some space in my top box probably. But is not show yet here. Not its time.
The top box space is not a problem, it can be as large as it wants it.
The led driver circuit is having too many wires so it must be build directly on the white wings thing (version 1)... or version 2, wires from outside. (im just thinking out loud).
My original idea was to have those white wings like a thin sticker, and the circuit to be invisible, on a separate box most probably because is taking thickness and my sticker should be paper thin (+ the smd leds thickness on it). And to drag all those wires there... its a mess. And also the large sensing wire, that I didn't envision its position or shape, but only the wings with leds on them. Actually was the leds first then the wings just follow the led's shape, and became white background in shape of wings. That's the whole truth. I swear. The large oval wire around was not in my plan at all. Its kind of BIG now. I wanted it small and cute and "where the hell do I switch the light from?" but now is big and screaming "here I am". Its ok.... now that i fight with the problem and i find a solution. Im writing it here, in the hope you may have diferent ideas, youve definetly seen more than me. Its ok in the end, i already paved the road, what i say is im open to other ideas. I have a very crazy one, to carve the wall and borrow under it everything... and leave only the original wings outside. Heh... crazy, yes?
For now something is done, that is more important.
Draw on top of my stuff, i dont mind, any idea you may have and think it will be cool is very welcomed.



full rezolution here, these are very big images 4000x6000px, and you should zoom in to be able to see the details
https://www.deviantart.com/q12a/art/Q20201012-Light-Switch-Design-V2-857903750
https://www.deviantart.com/q12a/art/Q20201012-Light-Switch-Design-857903673

 

Here is the progress: Crazy progress and i hope you like it.
I worked for it for 6 weeks , very slow and frustrating, but im glad im finish it.
Ill have to make the art pages ...ugghhh... another pain in the back.
im only bragging with it right now...nothing really to ask.
Feel free to comment or ask me anything you think is suspicious.

And thank you for all your help so far !

 

Feel free to comment or ask me anything you think is suspicious.

Nice! What does the sensor circuit look like?

Have you considered etching a board instead of wiring point to point? I always use sockets for IC's to make it easier to replace them if they fail. They don't fail very often, but it would be tedious to have to remove and restore connections to the pins. I've only replaced one IC in the past 20 years (in a broken curve tracer).

EDIT: A nit. Most of us pronounce it L-E-D because it's an acronym. We also spell it with all caps for the same reason. I used to work with someone who pronounced HP's Unix operating system (HP-UX) as H pux. No one at HP called it that. They spelled it out: H-P-U-X.

 

- Someone from this forum give me a video link to this sensing circuit. I looked back in all my posting and i could not find it anymore. Too many things were discussed. I just lost track of it. I will search further and when i will find the video i will re-post it here. This is on a piece o paper i keep it on my table. There is 1Gohm resistor there, in the Gate of the 2N7000, that must be made from a matching wood stick, with 2 wires as pins in the margins of it. Is working wonderfully so far. The antena is 15cm in the original, but mine is less because testing. But it will be 15cm or more soon after making the "case" for it.
Sorry for the low rez but the writing is small and my camera is garbage for close ups.

edited here: I find the video:

- I will try to apply your correction about spelling L-E-D in the future and not as a single word as i get used to.

- My original plan was to make this "wings with leds" as [Flat] as I could. Its an entire story to this thing.... But I could not, I failed. But even if i failed, it is good as it is , since it is working. And is in some degree flat enough. That is why i can not permit to insert IC sockets. And I risk, with my IC already mounted as it is,to not be able to change it, i know. But is the best formula I could think of. My strongest fight i had was with the long wires. And for them i spent like 3 weeks... probably, or more. I failed a ton with them. I wanted them as thin as i could have them and played with 0.12mm on diverse mediums. The problem is they are undulating/springing and is impossible for me to keep them straight. I spent a ton of time to make them straight. I failed every time. But i lean some other tricks on the way. Then i decided to jump back to the thicker wire of 0.25mm that is more stable and is keeping its shape after i bent it. What i did here is prototyping. Also i did it because as you can observe already, i am working on a cardboard surface and not a textolite/Fiberglass surface. It is cheaper (for me) and is an old trick i learned a long time ago. I did so many things with this formula and it worked fine every time. No strange interference or anything weird. Is as good as the rest of the normal boards as long as i keep it clear of wet surfaces. And usually I do. I know is riscky but is also cheaper, and cheap beats everything else. In the END, if i really-really want it, I will make it "official", on textolite/fiberglass with copper laminated on it. I think the short name is PCB. But that is very expensive for my budget that is not renewable. Everything that i do, i think of it as prototype and not a final board.
I am glad that you like it. I like it too, especially after so many failings. In reality, is more nicer than in video. It is like an alien piece of tech. hehehehe.