Designing circuits at the most basic level

I will try to add basic circuit designs to this blog.

It will be like a design diary where I will try to explain my methods of designing transistor circuits.

First a little background of my experiance with electronics.

I started out in the 1980's with an interest in learning how to program a TI computer in basic. This was so much fun that I soon wanted to know how computers worked on the inside as well.

So I began to read all the basic electronics books I could get. Then I bought those electronic kits from "radio shack" and would experiment and take lots of notes as I was lerning how to design circuits.

By the late 80's I was building all kinds of electronic gatgets from transistors.

I never took an interest in integrated circuits, because I wanted to learn how to design circuits like the ones in those boxes.

So I would buy the integrated circuit manuals, and look at the schematics, and try to design my own circuits using transistors available in discrete form.

I soon realized that integrated circuit schematics don't work so well with discrete transistors.

So I designed my own logic gates using discrete components, and began making them into my own Integrated circuit boards.

Then I combined them to make digital functions.

From that I bought (on sale) lots of bread board sockets, and electronic components, and began designing coumputer functions, using all transistors.

One of my biggest projects was a "character generator with a ram" for the ram I used SCR's and drive circuitry to store the data.

Made plenty of MS flip flops coupled to become modulo counters, for the scanning process for each row and column of a display I made from led segments.

That project took about 8 power supplies I had to build, and the whole thiong was on a shelf in my room that was around 2ft. wide by 4ft. long approx.

Then I took 2 home study courses (basic electronics) and (electronic circuit design) from NRI.
And 1 course from CIE.

When I took the basic course from NRI. it comes with course equipment for doing the labs. I got 2 oscilloscopes 25MHZ. from the 2 courses I took. as well as design labs and multimeters and freq. counter. Which is part of the tuition cost.

My background is as a hobbyist only, because I am not in the electronics profession.


So now I will start posting some of my design projects.



I am experimenting with a CE amp.

I am testing to see how changing the RE will cause a change in Vout. in according to Av=RC/RE.

first I built the circuit shown.
Then I checked for proper voltages at Vc,VE,VB.
Hooked osciloscope probe to input and another probe to VC. checked for sine wave amplitude and Av. also checked for any distortion.

Everything is good. Now replace RE with a res. sub box. and began to increase this new RE, value, as RE increased Vout. decreased, sine wave amplitude decreased but kept good lineararity (NO distortion).

So conclusion by varying higher the RE value will cause NO distortion on output waveform and will decrease amplitude of output wave form approx. according to RC/RE = Av.
CE amp.JPG

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