Pick a chip, any chip. Data Sheet build for a beginner.

[opensourcefan]

I want to dive deeper into data sheets. I'm thinking of building a circuit from a data sheet using its typical use case for whatever it happens to be.

Question: Other than a triple 5, can anyone suggest the perfect component for a circuit build from a decently written data sheet?

I may even take it as far as PCB design just for experience.

I've done it already with a 555 so would like to approach it fresh and dumb.

[srb1954]

You could try building a power supply based on the classic LM723 voltage regulator.

Building and testing a design based on this chip will expose you to a variety of techniques that are frequently required in analog circuit design:

• Voltage references
• Negative feedback loops
• Feedback loop stability and transient response
• Circuit element power dissipation and heatsinking
• Component tolerancing
• Circuit verification and measurement techniques

[Siwastaja]

Another classic which is kinda fun:
https://www.ti.com/lit/ds/symlink/lm3914.pdf

[Swake]

Analog?
- Try a 723 and build a good power supply. Yes these are old but at least as mythic as the 555, and you'll learn a lot from those implementations.
- Experiment with common cheap operational amplifiers such as the 741.
- LM3914 and LM3915 and build led bar-graph meter. as sound level indicator or battery level indicator.
- XR2206 as function generator, but I think these are not manufactured anymore.

Digital?
- Choose an 8 pin atmel µC and build a blinking light on a breadboard. Sounds silly and too simple, but you'll need a power supply and have to be able to program that thing. Make it blink at the rate of something you measure (temperature, light level,...)
- Build a rs485 interface and have 2 computers/controllers talk over that serial interface.
- 4066 and switch between audio signals.
- TLC5940 16-Channel LED Driver.

Alternatively, search for the electronics magazines of the late 1990's or 2000's. There are plenty PDF's online. A I'm sure you'll find some interesting projects that you can dissect on component level. Circuit Cellar; Elektor; Nuts and Volts mag; everyday practical electronics; ...

[Smokey]

If you are looking for a full circuit, with component values and everything, you probably want to find the schematic associated with a dev board made by the manufacturer.  Datasheets often have a stripped back version of the typical circuit, and often don't give values for all the components. 

[Kleinstein]

AFAIK the XR2206 got a new life as a Chinese copy, though with some problems. Not as good as the original, but it seems to be available again as some relatively cheap kits.

Much of experimenting does not need a PCB. For simple learning experiments a bread board may be more practical.
If you want something more digital, some counters (e.g. 4060 or 4017) with LEDs could be OK for a simple test.

For analog some operational amplifiers can be a good idea - no need for a special type.
A simple square / triangle generator wuild with 2 OP-amps is reasonable easy. Similar a Wien bridge sine generator can be reasonable for the start.

[Infraviolet]

MCP4251 digitally (SPI) controllable potentiometer? You can write an SPI control library for use with a microcontroller at the same time as designing a circuit (such as a digitally frequency changeable 555 oscillator) to use it in.

[opensourcefan]

Thanks for all the suggestions! I do like the LM723 idea. I can extend my experience from that into a diy LTZ based voltage reference maybe.

It is important for me to work from the datasheet as that's the whole point for this exercise, as far as it will take me anyway.

[barshatriplee]

Try LM386 OPAMP.
https://www.jameco.com/Jameco/Products/ProdDS/839826.pdf
You can follow the application circuits given in the datasheet to build audio amplifiers. You can vary their gains too.

[opensourcefan]

I think I'm going to combine the 723 with a 317 to add complexity and fun. That'll be two datasheets to decipher.

[Doctorandus_P]

How good is your opamp knowledge?

The basics of opamps are pretty simple, but they all have limitations and getting to know them and how to deal with them is an important part of learning electronic design. The old LM741 is not a good opamp, but it's still an excellent choice for doing some measurements and verifying them with the datasheet. You can also add some other opamps in the mix (such as the also very old TL071 (with offset compensation) or TL072 (Dual).

A fun circuit is to just use them as a buffer and put an electrolytic capacitor on the input. Then charge the capacitor with some voltage, disconnect it and see how quickly the voltage starts drifting.

[ppTRN]

I would go for a ADC + DAC combo. Fun to build, simple enough (using ADC0808 & DAC0808) and kinda interactive letting you change the input voltage

[Smokey]

How good is your opamp knowledge?

The basics of opamps are pretty simple, but they all have limitations and getting to know them and how to deal with them is an important part of learning electronic design. The old LM741 is not a good opamp, but it's still an excellent choice for doing some measurements and verifying them with the datasheet. You can also add some other opamps in the mix (such as the also very old TL071 (with offset compensation) or TL072 (Dual).

A fun circuit is to just use them as a buffer and put an electrolytic capacitor on the input. Then charge the capacitor with some voltage, disconnect it and see how quickly the voltage starts drifting.

I feel like opamps is the biggest mine field out of all the typical parts in a design.  There are so many actual consequential deviations from the "ideal opamp".  I'm not even sure how you would go about getting a good intuition without having to spend the bench time figuring out why your circuit isn't working over and over. 
Just taking RRIO opamps, and the fact that they call them rail to rail when that's not actually possible...
https://www.eevblog.com/forum/projects/how-rail-to-rail-are-we-really-talking-here/
Input common mode diodes restricting your voltage range, but only on some opamps....
Input offset and thermal drift...
Not enough bandwidth... or way too much bandwidth...
I'm glad I started out when split supplies were more common.  Single supply opamps have a whole other set of traps.

[Terry Bites]

The LTZ ref requires some careful circuit and pcb design to get the stated performance- It can be tricky to get this right, not for the beginner I'd say.
There's a lot you can do with (CD)4046 cmos PLL: FM demodulator, programable frequency standard, tone detector and more.

[Doctorandus_P]

I feel like opamps is the biggest mine field out of all the typical parts in a design. 

Yes, and this makes them an excellent choice for studying datasheets

But in general, it makes more sense to turn it all around.
First find a project that has your interest and that you actually want to build, and then gather, read and understand datasheets of IC's that are (candidates for) that project.