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1:14 AM
tbf even 10years ago a sot23 was quite wasteful for a diode
now a sot23-5/6 that I agree with, especially with the likes of wson
 
@JonRB why were sot23 single diodes even a thing to begin with?
 
:)
I blame Zetex
 
@JonRB :P how come? were they the first to do that?
 
chucking out tonnes of good bjt
dunno if they were the 1st
only good thing about sot23 diode is IF you got the pinout wrong you can rotate it freely and it will fitr
 
 
12 hours later…
JRE
12:54 PM
@Shalvenay I don't know about single diodes in SOT23, but I used to see a lot of dual diodes like this:
Pin 1 to ground, pin 2 to circuit supply voltage, pin 3 to a digital IO pin. The idea being to protect the circuit from overvoltage or negative voltages on the IO pins.
Most ICs have such diodes built in. The external ones can handle more current, so supposedly protect the ones in the ICs from damage.
 
 
3 hours later…
3:30 PM
Hi, I have a question: can someone recommend me an NPN/PNP transistor with collector-emitter breakdown voltage equal about 200÷300 V and a transition frequency equal about 100÷300 MHz? (like those RF ones, but with higher voltage rating) I searched around the web, but I couldn't find anything like that. Do they even exist? If not, then what are people using for example in a powerful AM transmitter (like 0.1 ÷1 kW)? Electron tubes presumably?
 
4:15 PM
(I want to increase the output voltage of my function generator, I was reading and testing some ideas, but had no success, also I don't want to pay ~100$ for an op amp that will be able to do that, so I am searching for a way to do this using discrete components, line in AN-272, but I am worried, that transistors, due to parasitic capacitances, transition frequencies, won't be able to work as expected in the MHz region (a couple MHz, maybe 1X MHz at most), this is just a proof of concept)
 
JRE
@KamilWitek What are you intending to do with the amplified output? Maybe there's a way to do the ultimate task without having to do complicated, expensive stuff.
 
Back then I wanted to simply increase the output voltage of my function generator, because it would be useful sometimes, but now my father wants to try some "electrotherapy", like ÷50V, XXX kHz. I am a bit sceptical of this, but now I think, that he won't give up and he will ask me every day about this... I thought of using a class AB current amplifier at the output of my function amplifier, and then feed this signal into a ferrite core transformer, to boost the voltage.
Then I could use the fig 6, AN-272 for low frequencies and this for the higher ones, but with an off-the-shelf transformer it's not working as intended, the output power is very limited, I will have to do some reading and probing on this to understand why...
TS250 waveform amplifier looks promising, but sadly I couldn't find any schematics to understand how they managed to do it.
My function generator has an output impedance of 50R (current amplifier also), so I think that making the primary of the transformer 50R (roughly, it's resistance, no inductance included), then max power would be transmitted from amplifier to the transformer, and then I could adjust the secondary resistance (turns!) to match my required voltage, but this is just a wild guess, I'm still learning.
 
JRE
4:34 PM
@KamilWitek I'm not going any where near "electrotherapy."
 
It's exactly called "Rife Machine", the variant without a plasma lamp as antenna. It looks safe... If it was not, then people wouldn't buy it...
Even if it won't help, then an upgrade for my function generator would be welcoming :)
 
JRE
@KamilWitek People do a lot of things that aren't safe.
 
That's completely true, I haven't realized it; Thanks, it makes you think about the world we live in...
 
JRE
Rife machines are most often associated with cancer. I do hope your father isn't skimping on standard cancer treatments and hoping to be cured by the hocus pocus of "alternative medicine" treatments.
 
No, it's not cancer, it's Lyme borreliosis; Do you think, that these so called "Rife machines" are a hoax?
 
JRE
4:48 PM
Rife machines are junk. The link above goes to the US national institute of health, and has nothing good to say about Rife machines.
This is a test of a typical Rife machine. Also has nothing good to say about the machines.
 
@JRE I saw a historical electrotherapy room at a museum... can confirm that people do stupid stuff without evidence.
 
Yes, but they don't help, so he is searching something unconventional.
(My father thinks, that Rife machine works because back then Rife cured a lot of people and the US presumably destroyed his machine because they wanted to "heal" people with drugs that don't work so you would pay for nothing. So because they destroyed it, he thinks that it MUST've worked. I was sceptical about this and now I am even more sceptical, I will definitely read those articles, thanks)
(Sorry for typing for so long; English is not my native language and I still have some problems with it.)
 
There's plenty of money to be made in the medical machines department as well
 
That's true, it's exactly what I told him, but he still thinks, that it MUST work...
 
JRE
@KamilWitek Lyme disease sometimes leaves a person with aches and other problems, even after the bacteria itself has been destroyed in the person's body. The disease itself is gone, but the body has taken damage that can't be fixed.
 
5:02 PM
If I (in the medical community) made a device that could cure XYZ, and nothing else would work, I could charge whatever I want
 
JRE
That's why you want to have Lyme disease treated as soon as possible after you contract it. You have to cure the bacteria before it can cause damage.
 
Look at the cost of a thermometer for a doctor's office
 
As I said before, I am going to read those articles and talk to him, to me it just looks like a scam, and You guys have the same opinion. Thank You very much for help :) . Later I am planning to wait for an offer and buy maybe a destroyed power function generator and look what is inside, because it won't leave my mind.
 
@KamilWitek Look for old service manuals of function generators - Old ones will often have transistor schematics
 
OK, back then even some normal manuals contained schematics, but now even some service manuals don't have them, just a note to replace the board with a brand-new one...
 

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