My kid wants to buy my this t-shirt:

​

Thing is, I myself don't even know what it is! I see a transformer on the left, with an inductor connected to its center tap, then a halfwave rectifier... and on the right, a biased bipolar transistor with its gate decopuled by a cap... but what is the darn thing supposed to do? Or is it just useless gibberish?

 

Hello,

The circuit shows a FM discriminator:
http://www.radio-electronics.com/in...reception/ratio-fm-detector-discriminator.php

Bertus

 

My kid wants to buy my this t-shirt:

And does the kid know what it means?

Ah, @bertus has solved it.

 

And does the kid know what it means?

Ah, @bertus has solved it.

No, he doesn't... but it looks funny... Anyway, now that I know what it does, I wished I knew how it works! ... but analog electronics has always been my Achilles heel...

 

No, he doesn't... but it looks funny... Anyway, now that I know what it does, I wished I knew how it works! ... but analog electronics has always been my Achilles heel...

Kid these days.

 

Hello,

Read the attached PDF.

Bertus

 

Hello,

Read the attached PDF.

Bertus

Nice! ... will definitely read it, later on. Thanks!

 

​

Enough said! ​

 

The important part is in the next paragraph: When the signal is at the tuned center frequency, the outputs are equal and opposite. Only when the frequency shifts does the circuit produce an output. Sounds like a Phase Locked Loop, doesn't it? Or an automatic tuner which would tend to lock on the strongest signal when the tuning knob is near a good station you want to receive.

Point is, there is more than one use for a circuit that ignores a certain frequency and outputs an error signal related to any other input frequency.

 

Only when the frequency shifts does the circuit produce an output

Very, very interesting. Thank you. I'm guessing that's the whole point of FM, right? Discriminating (filtering) information based on changes in frequency?

 

Very, very interesting. Thank you. I'm guessing that's the whole point of FM, right? Discriminating (filtering) information based on changes in frequency?

That is the very definition of FM.

 

Hello,

I found an other PDF.
On page 3-13 the discriminator is described in more detail.

Bertus

 

@cmartinez

Here is the FM Ratio discriminator/detector portion of a navy manual titled Electronic Circuits. It discusses the Application, Characteristics, Circuit Analysis, and Failure Analysis of the vacuum tube and transistor/solid state circuits.

The transistor amplifier in your example is a simple phase splitting amplifier used to drive a push-pull amplifier circuits.

Enjoy the read.

 

Hello,

The circuit shows a FM discriminator:
http://www.radio-electronics.com/in...reception/ratio-fm-detector-discriminator.php

Bertus

None of the product reviewers on Amazon.com were able to come up with "FM discriminator" in the past 3-years this product was available and you have an answer in less than 15 minutes! Engineer Of The Month award to you, Sir.

The bickering whether or not it is a complete/useful circuit on Amazon.com is kind of funny.

https://www.amazon.com/ComputerGear-What-Circuit-Science-T-shirt/dp/B001BZ49R8

 

My kid wants to buy my this t-shirt:

​

​

Why is your kid buying stuff this week? Wasn't his pile of Christmas presents big enough?

 

​

Why is your kid buying stuff this week? Wasn't his pile of Christmas presents big enough?

We buy some gifts through Amazon U.S. sometimes, and then later pick them up while on our routine shopping trips to McAllen or Brownsville, TX.
Living close to the border has its perks, you get the best of both worlds. ... but sometimes also the worst

 

So basically, if you're in on the joke, the shirt says the wearer is discriminating? In an approved way, like in choosing a mate?

Or is the wearer against discrimination in a "bad" way, like using skin color as a hiring criterion?

Seems like a long way to go to make an ambiguous statement.

 

So basically, if you're in on the joke, the shirt says the wearer is discriminating? In an approved way, like in choosing a mate?

Or is the wearer against discrimination in a "bad" way, like using skin color as a hiring criterion?

Seems like a long way to go to make an ambiguous statement.

... and to think that one of my new year's resolutions is to make my life simpler ...

 

... and to think that one of my new year's resolutions is to make my life simpler ...

Well, I suppose the viewers of the shirt won't know either, so who cares?

 

A visit to the dictionary is in order. Your employer discriminates between a group of applicants to determine the best for the job. How they discriminate can be cause for a lawsuit.

You can ask the applicant anything that directly relates to the job description. That shirt would be a perfect question to ask of an electronic engineer. One could ask the prospective employee to draw the input and the two outputs. There was a time when circuit identification was on tests. Of course, there were block diagrams and schematics used extensively as well. Today, there is a severe lack of documentation, so the repairers go right for the "normal" failure components. Some can check all the electrolytics in a device with a hand held ESR meter faster than they could retrieve a schematic ...

from: www.m-w.com
Definition of discriminator

1. : one that discriminates; especially : a circuit that can be adjusted to accept or reject signals of different characteristics (as amplitude or frequency)
   
   First known use: 1828

Definition of discriminate
discriminated
discriminating

transitive verb

1. 1a : to mark or perceive the distinguishing or peculiar features ofb : distinguish, differentiate <discriminate hundreds of colors>
   
   
2. 2: to distinguish by discerning or exposing differences; especially : to distinguish from another like object

intransitive verb

1. 1a : to make a distinction <discriminate among historical sources>b : to use good judgment
   
   
2. 2: to make a difference in treatment or favor on a basis other than individual merit <discriminate in favor of your friends> <discriminate against a certain nationality>

First known use: 1628

Everyone discriminates.