Tutorial on Digital to Analog Converters (DAC) and Example Using the MCP4728 Part 1

[@samacumen]

Good content with superb clarity. Cleared a lot of concepts for me. I was pondering over it for days, and here we are done in 28 min :)

[@UpcycleElectronics]

Cool run through. I'm really interested in this subject right now as a simple hobbyist. This may be a little long for a YT comment but hopefully you'll bare with me. I got one of the cheap Chinese "linear" power supply kits based on an ATmega8 and 8 bit R2R. After getting halfway through putting it in an enclosure, I decided to look and see if I could find the original project as most Chinese kits tend to be based on OSHW projects. That lead me to the tuxgraphics (probable) origins of the kit. I also read a couple of threads on the EEVBlog forum describing the naive simplicity of the tuxgraphics design. I was about ready to toss everything at this point. It's kinda irritating when people jump on YT and create content about stuff like these kits and fail to do their research about the origins of the product and fail to do the most basic functionality testing. I came across a few people that claimed this kit was at least marginally useful, and got it. At $12 it's no big deal, but lesson learned. ...anyways, I went ahead and built the dumb thing. I figured I could still make use of a few aspects of the project even if I must toss out the kit entirely. I'm thinking about creating the video I wish I had come across showing why this kit is bad....I just have to figure out how to correctly characterize a R2R DAC. I know Alan (W2AEW) has an upload about R2R's hopefully I can pick up some pointers from your next upload and from Alan. This power supply kit apparently uses the m8's ADC and the R2R to set the output. It also has a transistor based amplification stage, and a wire wound ceramic resistor as a shunt for current limiting. I took some pictures of the 2 bare boards and will probably do I full KiCAD schematic along with showing a line by line retrace of the boards. (BTW - I'm not monetized/don't plan to change that/this is not self promotion - it's actual ignorant curiosity) The subject of the kit got me wondering how such a design can be improved. Apparently the design uses PWM and oversampling to extend the resolution of the DAC on the 3 LSBs. I'm curious if a simple op amp buffer would improve the setup by shifting the feedback corrections to an analogue control loop. This subject also has me interested in the practicality of using DACs in op amp feedback networks for precision DC applications. In a hobbyist type of application, why can't we just calibrate a DAC in the μC, maybe even with some form of temperature compensation? I also wondered about using 2x lower resolution DACs in a circuit for an integrated output. Something similar to a typical course and fine adjustment setting on a traditional linear power supply. I'm sure my questions reveal my naivety here, but I'm genuinely interested and trying to learn more about the real world applications of DACs and how to characterize them. You've probably already established, if not recorded, all of the content you intend on making for this subject. I'm not asking you to make anything specifically about this, or for me. You don't even need to answer my aforementioned questions. This is just intended as an example of the kinds of questions a dumb hobbyist without an academic background on the subject may have, and a practical product specific issue representative of the type of "trap for young players" one might encounter. Regardless, thank you for another save the reference level upload. -Jake

[@ForceTronics]

Hey Jake, this is a really long comment. But it is better than the some of the comments I get that just use one sentence and say how do I design X (where X requires lots of questions and hours of work). Those types of questions I just don't answer so I do appreciate the detail you included. I stay fairly busy 7 days a week so I don't have the time to research the exact kit you are referring to but here are some top of the mind comments: --> kits that don't work are frustrating but working through the issue is a great way to learn --> It sounds like this kit has you build a DAC from the discrete component, are you using the kit just to learn about DACs (which is great) or do you have a need for a DAC in a project? If the latter is true then just go with an off the shelf DAC IC (like the MCP47xx family) and learn how to use it. --> You mention something about PWM and oversampling, which I didn't follow. I do have a video on how to create a DAC using a PWM signal. It is only for applications that don't need a high accuracy DAC. Here is the link: kzbin.info/www/bejne/d5y2nmSNbd2Xgbs -->You mention op amps and not sure what your level of experience with op amps are but they can be tricky if you are making an assumption on a spec or capability. There is many times I have bought op amps for a particular application but they didn't work and I had to turn to a senior engineer to help me understand the knowledge gap so make sure you understand all the specs for an op amp before you plan it in your design (plenty of material on the web on op amp specs) Good luck

[@aliens1192]

Thank you very much for the very nice lecture (:D)!

[@pekkagronfors7304]

Great content.

[@reginaldmorton2162]

great vid

[@chengyangliu7608]

Is MCP4728 able to generate different waves with different voltage and frequency simultaneously？

[@dexbani7938]

Cool

[@reginaldmorton2162]

Could you please explain the chord electronics Dave DAC?

[@ForceTronics]

I am not to familiar with that product line, but after a quick search it looks like it takes a stream of digital music and coverts it to a high quality analog signal to drive speakers

[@ThiefKingBakuraX]

Its DAX!