Electronics > Beginners

Advanced Beginner interested in learning more especially abt analog synthesizers

(1/3) > >>

slick8086:
Hi,

So I say I'm an "advanced" beginner because I've been doing really basic electronics for a long time.  I know what most components are like resistors, capacitors, diodes, transistors, LEDs etc.  I've made a bunch of electronic projects before.  I can solder well.  I have and can use a multimeter.  I've even designed and had made a simple PCB. https://oshpark.com/shared_projects/Riu5kmba.  I can "read" a schematic, but my understanding of it is very limited.  Like if it was a sentence I could sound out all the words phonetically, but I wouldn't understand what some of the words meant and I'd only have a vague understanding of what the whole sentence meant without some help.  I can assembly pretty complicated kits, and get them working properly, but it is more like painting by numbers. 

Things I know that I don't know.  I know there is a thing/concept called and RC circuit, but I don't know how to employ it.  I know there are things called op amps, but I don't know how to use them.  There is more that I'm not thinking of right now for sure.   

Obviously I don't know, what I don't know.  Where do I go from here?  I know that I need to deepen my understanding of the basic things I already know but I'm easily not finding the resources online to learn? 

My goal is to someday be able to design and implement an analog synthesizer on my own.  I've been looking at schematics for VCOs, VCAs, ADSRs, and so on, but unfortunately they all go right over my head.  Like I could probably breadboard some of them and get them to work, but I wouldn't know why they were working, and if they schematic had an error, I wouldn't know.   I couldn't adapt a schematic that works on +15v -15v to work on +12v -12V instead.

What is my next step?  Are the resources available online or do I have to sign up for EE classes at a real school?

Advice is much appreciated.

rstofer:

--- Quote from: slick8086 on March 10, 2019, 11:53:06 pm ---Things I know that I don't know.  I know there is a thing/concept called and RC circuit, but I don't know how to employ it.  I know there are things called op amps, but I don't know how to use them.  There is more that I'm not thinking of right now for sure.   

--- End quote ---

A series RC circuit can be either a low pass filter or high pass filter depending on configuration (whether the signal goes in the resistor or the capacitor).

https://www.electronics-tutorials.ws/filter/filter_2.html
https://www.electronics-tutorials.ws/filter/filter_3.html

When we talk about a 'low pass' filter we mean that at high frequencies, the signal is attenuated.  We pass low frequencies, we attenuate high frequencies.

Op amps are a separate course!
Google for 'w2aew op amp' to find 3 excellent videos
Google for 'eevblog op amp' to find 3 more excellent videos

Op amps are important building blocks for all kinds of analog circuits, particularly audio circuits (mixing boards, synthesizers, etc).  They can be used to create all kinds of active filters (low pass, band pass, high pass) as well as adding signals.  I don't do audio so I'm not real clear on how synthesizers work.  Google might help...

https://noisehackerspace.com/amazing-op-amp-powerful-synth-diy/
 
https://www.electronics-tutorials.ws/filter/filter_5.html
https://www.electronics-tutorials.ws/filter/filter_6.html

You really need to know op amps.  There is a great book "Op Amps For Everyone" that might be helpful:
http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf
But only after understanding the w2aew and eevblog videos above.

In fact, you are going to need to understand Ohm's Law, Kirchhoff's Laws (particularly the current law) and a wee bit of matrix algebra (just a tiny bit, no big deal).  Or some other way to solve simultaneous equations.  Low level stuff...

Oh, and you can use op amp integrators to build up analog computers.  An integrator is a low pass filter (of sorts).

3db:
I agree with the great advice given by RSTOFER.
You should also check out the late Ray Wilson's Youtube channel  https://www.youtube.com/channel/UCp6OK4J97aPWccFpUgKj_Mg
His website is well worth a visit and you can buy his book which will help you understand more about synths.

3DB

rstofer:

--- Quote from: slick8086 on March 10, 2019, 11:53:06 pm ---Obviously I don't know, what I don't know.  Where do I go from here?  I know that I need to deepen my understanding of the basic things I already know but I'm easily not finding the resources online to learn? 

--- End quote ---
Khan Academy Electrical Engineering program
https://www.khanacademy.org/science/electrical-engineering

Digilent Real Analog class
https://learn.digilentinc.com/classroom/realanalog/

There are literally thousands of tutorial sites on Google.  You need to refine your search and look for specific topics.

You will need some math.  Maybe you already have plenty but, if not, Khan Academy is a good place to start.

--- Quote ---My goal is to someday be able to design and implement an analog synthesizer on my own.  I've been looking at schematics for VCOs, VCAs, ADSRs, and so on, but unfortunately they all go right over my head.  Like I could probably breadboard some of them and get them to work, but I wouldn't know why they were working, and if they schematic had an error, I wouldn't know.   I couldn't adapt a schematic that works on +15v -15v to work on +12v -12V instead.

--- End quote ---
Due to op amp design, it might very well be impossible to make it work.  The signal may have a high enough voltage swing to drive the +-12V op amp to saturation whereas the +-15V design had enough headroom.  This is a datasheet issue!

You will also want to convert dual rail designs (like +-15V) to single rail (+5V?) designs.  The book I recommended above can help with that.  It should be obvious that signal swings will be more limited.

Rail-to-rail op amps try to minimize the issue of not being able to swing the input or output signals close to the rails.  But read the datasheet!  Some can go to the + rail but not the - rail, some are rail-to-rail on input but not output, and so on.

--- Quote ---What is my next step?  Are the resources available online or do I have to sign up for EE classes at a real school?

Advice is much appreciated.

--- End quote ---

Buy some op amps and play with them on a breadboard.  I would suggest starting with +-15V amps (see videos for op amp selection) and moving to single supply op amps later on.

The LM358 is as good as any.  Note that it can only get to about 1.5V from the + rail but apparently it can get all the way to the - rail.

This clipping phenomenon is described in w2aew's videos.  He shows it on a scope.

Got a scope?  Got a dual output supply?  Signal generator?  If you really want to do this thing and you don't have enough equipment, please consider the Digilent Analog Discovery 2 and the associated parts kit.  It will allow you to track the Real Analog course.  The AD2 has a dual output supply (low voltage, +-5V), dual channel oscilloscope, dual channel signal generator, 16 bit digital IO and logic analyzer.  None of which begins to show you the tools in the Waveforms software.  You want to see how an RC low pass filter REALLY works?  Fine, use the Network tool.  It will give you attenuation and phase shift versus frequency in a beautiful Bode' Plot.

If I were just starting out and wanted to LEARN electronics, the AD2 would be my first tool.  It is truly a lab in a backpack (with a laptop) and totally capable of replacing a bunch of test gear.  Read the instructions carefully, there are voltage limitations.  Don't even think about using it on some kind of high voltage switching power supply.

https://store.digilentinc.com/analog-discovery-2-100msps-usb-oscilloscope-logic-analyzer-and-variable-power-supply/

I bought the Jameco 20626 Dual Output Supply the other day.  I haven't assembled it yet but I'll get around to it sooner or later.  I had planned to use it as +-15V for an analog computer I built some time back.

https://www.jameco.com and search for 20626  The link is too ugly to post.

rstofer:
You didn't say what equipment you had and, of course, I jumped in with the Analog Discovery 2.  It is remarkable how many people think this is a toy!  In terms of accuracy, the scope on the AD2 uses a 14 bit ADC.  My Rigol DS1054Z, and many much more expensive scopes) uses an 8 bit ADC.  Yes, the frequency is limited but includes all of the range of interest for audio and most digital circuits.

The Pro bundle plus the analog parts kit is the way to go
https://store.digilentinc.com/analog-discovery-2-pro-bundle/

Add the analog parts kit for $55
https://store.digilentinc.com/analog-parts-kit-by-analog-devices-companion-parts-kit-for-the-analog-discovery/

You're looking at $354 which is a TON of money, until you compare it to an equivalent set of individual pieces of test equipment.  In any event, education has never been free!  Dave did a video on the Analog Discovery



It is for the original version, replaced by the AD2...

You can download the Waveforms software and play with the tools even without a device.  Just use the Demo device and explore all the features.

I know, I sound like an evangelist, but I really believe that the AD2 is ideal for learning electronics.  Everything you need is in one place.  You can, of course, omit the Pro Bundle and the analog parts, the AD2 is $279 by itself.  You can buy your own chips and add the BNC adapter board later on.  The advantage to the full package is that it matches the Real Analog course.

ETA:  The video shows a very old version of the software.  Download and play with the newest version:
https://reference.digilentinc.com/reference/software/waveforms/waveforms-3/start

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod