Scullcom Hobby Electronics #53 - DC Voltage Calibrator Part 1

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Scullcom Hobby Electronics #53 - DC Voltage Calibrator Part 1

Рет қаралды 35,544

Күн бұрын

In this project we will design and build a DC Voltage Calibrator, providing a voltage range from 0 to 10 volts in 1 milli volt steps. The user interface will be a TFT display with touchscreen.
Below are links to version 1 of the software for the Arduino Nano. Also a zip file which contains the schematic, PCB artwork (Version 2) and component layout:
www.scullcom.co...
www.scullcom.co...
Parts List link below:
www.scullcom.co...
Below is a link to my KiCad files for this project:
www.scullcom.co...

Пікірлер: 283

@vernonbosshard9317 Жыл бұрын

I think your projects are the better ones to build, they seem to be very accurate and well designed. I had no idea all this stuff was available, I graduated tech school in 2000 and kind of dropped out of the scene for a while. No I wasn't in prison, worse, I lived with my ex. AKA wicked witch of the west

@isidoromaich7226 6 жыл бұрын

It great to have you again doing videos... I think you gave us some time to finish the past projects :)

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. Its nice to get back to electronics and a new project. I need to get back in to the swing of things again. Regards, Louis

@paulcollins664 6 жыл бұрын

I'm skipping a couple of past projects for the moment to get to this one, I'm having to build a much more compact workshop, where I'm building almost all home made equipment,because I enjoy the building, I've wanted one of these for sometime, thank you Louis you certainly have your finger on the pulse,I love these projects featuring TFT, screens, and the fact your using normal size parts, the nano and tft are quickly becoming the hobbyists and radio amateurs friend. 73 Paul M0BSW

@scullcomhobbyelectronics1702 6 жыл бұрын

Hi Paul, Looks like you are going to be busy. This is the first time I have done a project using a TFT touchscreen so it is also a learning process for me to. All the best, regards Louis

@paulcollins664 6 жыл бұрын

~Hello Louis, I like to keep the grey matter busy,, plus I'm learning something everyday,TFT & Oled are very interesting devices although Oled screens of a decent usable size, are still a bit expensive in my view.

@tonysfun 5 жыл бұрын

We all miss you! Hope you'll get more time for your hobby! God luck and wish you lots of health and no more problems!

@IanScottJohnston 6 жыл бұрын

Love the calibrator project, I can see this one being built by lots of folks. Well done.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Ian. Its not quite up to the standard of your unit but it may prove adequate for the hobbyist. All the best Louis

@jameshauser1507 6 жыл бұрын

WOW Louis, that was a long recess from Scullcom School of Electronics. But, family does come first. I think I can speak for all that we missed you so much. Yes we missed the projects and the videos---but the real truth is we missed YOU. It is so good to see you again. We love you buddy. Have a Merry Christmas and a Happy New Year. I am not sure how you come up with these ideas for projects but I like your way of thinking. Take care Louis. God bless you.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks James. Very nice of you to say. Have a great Christmas :-) Regards, Louis

@recolaq 6 жыл бұрын

Thanks again for another awesome opportunity to learn electronics. Opposed to all the other channels trying to explain how the components work, your channel shows what you can with it. This triggers me to dive deeper in to the nitty gritty of electronics. Thanks again

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your comments. Glad to hear you find it helpful. Regards, Louis

@timothysvec8568 6 жыл бұрын

Sir, your voice was just made for explanation of projects. Thank you for explaining things, in a way that I totally understand.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Timothy for you nice comment. Regards, Louis

@Moonbrony 6 жыл бұрын

Glad to see you back again. Great little unit, worth the wait for this one.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks nice to be back. Regards Louis

@williamna5800 6 жыл бұрын

Welcome back! Great to see you're back in the saddle, and new projects coming along. This just made my day!

@scullcomhobbyelectronics1702 6 жыл бұрын

Hi William, Glad to hear it :-). Nice to be back. Regards, Louis

@basildouglas855 5 жыл бұрын

An exceptionally well presented project. Bundles of information and zero guess work required. Brilliant!

@kaumohlamonyane272 6 жыл бұрын

Amazing engineer, amazing indeed👌

@scullcomhobbyelectronics1702 6 жыл бұрын

Thank you :)

@tonybell1597 6 жыл бұрын

Welcome back! Nice project!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Tony. Regards Louis

@TheKetsa 6 жыл бұрын

Good to see you back. Thanks for the great projects !

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for you kind comment. Regards, Louis

@berniken6511 6 жыл бұрын

Hi Louis, very nice project and good to see you back. its obvious to see the work that has gone into the project..............thank you.................................................Berni

@scullcomhobbyelectronics1702 6 жыл бұрын

Hi Berni, Thought I would try something different. First project with a touchscreen. We learn as we progress :) Regards, Louis

@qsptecnologia 6 жыл бұрын

It's great to see you again. I will follow this other project. Thanks a lot to share your acknowledge

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your comment. Regards, Louis

@techtalkmike4968 6 жыл бұрын

Good to see back in the lab Louis. This will be an outstanding project to build from start to finish. Thank you.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Mike. Hope to get Part 2 filmed soon. Regards, Louis

@guilldea 2 жыл бұрын

Amazing, this is exactly what I used looking for to expand my electronics knoweledge, a thoroughly explained design process and process

@Gooberslot 6 жыл бұрын

Woohoo! A Scullcom video in my subscriptions? Christmas has come early. Glad to see you haven't abandoned making videos.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. Have a good Christmas. Regards, Louis

@Yuehanlad 6 жыл бұрын

glad to here you call it an electronics workshop, I don't get why so many people on youtube call it a Lab

@frandavies944 6 жыл бұрын

Great return project! Looking forward to Part 2, including how to calibrate the calibrator and exploring future options.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. I will be working on Part 2 in the next days. Regards, Louis

@esnam6557 6 жыл бұрын

Very nice project. Thanks you very much for sharing all the details with us. Looking forward for part 2.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your comment. Regards, Louis

@PeterRidge 6 жыл бұрын

Good to have you back with new vids, Louis. Looking forward to the next part.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Peter. Regards, Louis

@mrtom64 6 жыл бұрын

Excellent! Your projects just keep getting better. Thank-you for the time and effort you put into your videos, it must be heart-breaking to have to eventually wipe off those white-board diagrams....they are very much appreciated.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Tom, Yes it is a shame when I have to wipe off some of my drawings. But I hope they help with the explanations :) Regards, Louis

@markj3851 3 жыл бұрын

Louis- We love your videos and hope you are well. Looking forward to some future updates and wish you the very best!

@EdwinFairchild 3 жыл бұрын

this gentleman is a genius

@craxd1 Жыл бұрын

When calibrating a source, I was taught about using the first digit and decimal in lower digit numbered meters to gain a digit at the end. For example, when setting a 10 volt standard, you would adjust it to 9.9999 on a 4 1/2 digit DMM, so the digits shift between 9.9999 and 10.000, which will get you closer to a reading of a 5 1/2 digit DMM at 9.99999. This would apply to a 5 1/2 to 6 1/2 digit DMM as well, and even a 7 1/2 digit. Essentially, you're fishing for that last unseen nine and splitting hairs.

@tommyh4049 6 жыл бұрын

Thank goodness you have this info posted I have been racking my brain for days trying to build schematic for same project. Biggest difference in mine is substituting adc to 22bit mcp3551 which may be overkill but fun to think of resolution in 6 digit ranges.

@scullcomhobbyelectronics1702 6 жыл бұрын

Hi Tommy, Glad to hear you found it helpful. You mentioned the MCP3551 which is an ADC, but for this project you would need to use a DAC. Regards, Louis

@tommyh4049 6 жыл бұрын

Scullcom Hobby Electronics my mistake, I'm trying to build more of a self calibrating type bench multimeter/power supply to clear up any confusion. It's a rabbit hole for sure. It seems that your circuit would make it easy to make an add-on board to make this work especially since you have 2 voltage references to compare against and extra unused pins. I will try to get some simulation data when I get a chance to try this. Thanks.

@scullcomhobbyelectronics1702 6 жыл бұрын

OK I understand now. All the best with your project. Regards, Louis

@rolanddietrich5776 6 жыл бұрын

great to have you back

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Roland, nice to be back. Regards, Louis

@MaddMart 6 жыл бұрын

Glad you're back with another great little project. Something to get my teeth into over the Christmas holidays :-)

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for the comment. Hope to get Part 2 of this project done before Christmas. Regards, Louis

@valakatz3967 3 жыл бұрын

Nice to see you back, great project and thank you.

@SpeccyMan 6 жыл бұрын

Nice to see yet another great project. I'll take quality over quantity with your videos every time, Louis.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Nick. I do spend a fare amount of time in preparing for my projects so it can take longer than doing reviews. I also spend time on editing my videos down to a maximum of about 45 minutes which also takes longer, especially deciding what to leave in and what to take out. Anyway just hope I get the balance right. Regards, Louis.

@craigs5212 6 жыл бұрын

Nice project, board looks really great. One thing to consider is the ~30 ohm Drain-Source ON resistance of the DG303, it's a little high to use in the output circuit without upset to the calibration for differing load conditions without feedback compensation. One also has to watch the switch's leakage current as well. The switches are most likely ok in in the gain stage however I didn't check the gain sensitivity for the ON resistance vs the 25K internal op-amp resistors. Consider running the entire DAC/Op-amp chain for a fixed 10V output then use the analog switch to make a .5X ref voltage for the DAC for the low voltage range. Any switch error can be calibrated out with an adjustment resistor on the the reference and the reference .5 divider. Thanks for the video, I need to make one of these some day.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Graig for your comments. With regards the 30 ohm on resistance of the analog switch at the output. This should only be an issue once you start drawing say the higher or maximum current of this unit at about 30mA. But if the unit is used for checking the calibration of test equipment than I think it should not cause any real problems. That said, we could improve the accuracy at the higher currents by replacing the DG303B (U6) with a MAX4622 (but twice as costly) which has an ON resistance of only 3 ohm, but I would also have to alter the print layout on the PCB to match the changes in IC pin connections (maybe an option for another version of this project). Another option could be to use the existing analog output switch to control a small reed relay. Your second point is also interesting but the current DAC (MCP4922) I am using has a maximum supply voltage is only 5.5V. Regards, Louis

@GADELHAS82 6 жыл бұрын

The return of the master

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks :-)

@TheFunkman 5 жыл бұрын

I sure hope to see more great videos soon Louis. Hope you are well.

@engineeringadventures1229 6 жыл бұрын

Great work man! I respect the time and effort you put in minute details like detailed schematic drawn on white board. I loved it all. I am also working on a similar project and would like to show you once completed. Thanks a lot, keep it up.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your comments, much appreciated. Regards, Louis

@psilin9473 6 жыл бұрын

Very glad you’re back. Another great learning project! Good explaination also. Thumbs up!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thank you :-)

@renelefebvre53 6 жыл бұрын

Great work and very good description . Bravo à vous monsieur !

@scullcomhobbyelectronics1702 6 жыл бұрын

Thank Rene, much appreciated. Regards, Louis

@wolfgangschweiger9557 6 жыл бұрын

At the moment, I'm working hard on your DCLoad project and some modifications of mine. And now, you push the next out - I'm on hurry, on christmas time I don't leave the lab...;-) Nice and many thx!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Wolfgang. Looks like you are going to be busy over Christmas :-) Regards, Louis

@wolfgangschweiger9557 6 жыл бұрын

Ohhh yeah!

@no1spod 6 жыл бұрын

Glad to see you back! thanks for another great project.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Simon.

@cccyberfamilydk 6 жыл бұрын

Nice to have you back. And as usual a great video.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Christian. Regards, Louis

@looxylook825 6 жыл бұрын

Thank you verry much for all the effort put in your projects and videos. Learn a lot every time.

@looxylook825 6 жыл бұрын

Just one idea, in terms of signal to noise ratio - isn' it better to do the higher gain in the first stage (2x 1x instead of 1x 2x) ?

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks this may be an option which could be done in software. I will have a look at noise in Part 2 of this project. Regards, Louis

@klcbsoft 6 жыл бұрын

Most excellent presentation of a great project, especially the schematics - jawdroppingly awesome. Thanks for sharing your knowledge.

@scullcomhobbyelectronics1702 6 жыл бұрын

Glad you enjoyed it. Regards, Louis

@MrOrangeman18 6 жыл бұрын

Can’t wait for part 2 of this. Keep up the good work 👍🏼

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@shaggygangst 6 жыл бұрын

it's great to have you again doing videos. i was very excited when i saw the notification from youtube

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. Managed to get back in my electronics work shed. Regards, Louis

@electro3976 6 жыл бұрын

As always extremely educational and expertly explained, wonderful stuff. Keep them coming.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@electro3976 6 жыл бұрын

Sharing your expert knowledge and encouraging the hobby engineer is wonderful. Without doubt the most educational and matter of fact electronics design engineer on here.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your kind comment, much appreciated. Regards, Louis

@kgsalvage6306 3 жыл бұрын

Very nice project. I like the touch screen with the audrino. I haven't got into using them. I have just been sticking to repairs. Might have to build some projects and utilize a touch screen interface. I liked your electronic load also. 👍

@tubeDude48 2 жыл бұрын

Very nice project.

@alx_256 6 жыл бұрын

Very nice video. In Part 2 it would be interesting to see what happens at the switching borders (4.000V / 4.001V and 8.000V / 8.001V ). It might turn out that 4.000V will measure more than 4.001V.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Alex for your comment. I will have a closer look at those crossover points and try and remember to show it in Part 3. Regards, Louis

@bostedtap8399 6 жыл бұрын

Excellent project and presentation.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@RobB_VK6ES 6 жыл бұрын

Welcome back with another outstanding presentation and explanation Louis. What is the bottleneck with display refresh? the SPI bus or the AT Mega 328? Perhaps one of the STM 32 F1 "Blue Pill" kind of sort of Arduino compatible boards might be faster. Dirt cheap on Ebay

@scullcomhobbyelectronics1702 6 жыл бұрын

Hi Rob, Thanks, The problem is the screen refresh rate for the TFT. I am currently using the Adafruit library which may not be the fastest. I believe someone may have modified this library for a faster screen refresh rate, so I will have a look for it. I have tried in the software to only write to the TFT if something changes, this helps. Hopefully this is something that we can improve as the project progresses. Regards, Louis

@ernestb.2377 Жыл бұрын

Interesting watch. Quick to part 2 as during the video I was curious what the overall accuracy and stability would be...

@brucefox6580 6 жыл бұрын

Hi Louis, Thank you once again for a great project. Bruce.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Bruce.

@jix177 6 жыл бұрын

Nice project, great to see you back.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@iuri.castro 6 жыл бұрын

Its nice to see you're back!

@scullcomhobbyelectronics1702 6 жыл бұрын

Nice to be back doing electronics. Cheers, Louis

@TheDefpom 6 жыл бұрын

Very nice project, you could use the 2nd dac to trim the op amp divider voltage to give smaller than mV steps.... I think you could take it down to uV levels. I did a video of my repairs to a Fluke 343A DC calibrator on my channel earlier in the year, and am in the process of a video series repairing a Fluke 5200A AC calibrator, some might find it interesting.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your comments. I am some upgrades planned for later. Thanks for the tip on your Fluke 343A DC calibrator. Regards, Louis

@MarcoFranceschini1971 4 жыл бұрын

Amazing design Louis...

@tsmupdatertsm7633 6 жыл бұрын

24:44 I think you did a lot of work to draw this diagramm. Great Job!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. Yes it did take me some time to draw. Regards, Louis

@kostasb8883 6 жыл бұрын

I love your videos. Learn a lot every time. Thank you!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Kostas.

@electronic7979 6 жыл бұрын

Excellent project

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@RonaldWijermars-rohmega 6 жыл бұрын

Fantastic video once again. Your videos really help to make circuit design more accessible for beginners like me. I did notice that your tft refresh rate is very low. Have you considered trying the STM32F103C8T6 boards? The difference in speed is quite big, there is a comparison video between the stm32 and the arduino nano using a ILI9341 display, it really is night and day. Not to mention they can be bought for as little as $1.72 and have some other upgraded features as well.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Ronald for your comment. Thanks for bringing my attention to the STM32 board. I have not used this type of board yet but it looks very interesting and as you say the cost is very low. There must be a way of adding that type of board to the Arduino IDE software which would make life easy when programming. Regards, Louis

@MauroSedrani 6 жыл бұрын

Welcome back! Great work!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Mauro, Nice to be back in my electronics workshop working on a new project. Regards, Louis

@FantaBH 6 жыл бұрын

Great video , well done explained . Thank you for your effort in making this project.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks, Your welcome. Regards, Louis

@akhurash 6 жыл бұрын

Awesome project. You have great projects and such good details!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. Regards, Louis

@jlegen 6 жыл бұрын

thanks for sharing this great project! perhaps just a tiny simplification - if the touch controller is a xpt2046, no level shifting is needed at least for the touch connections. the xpt is rated for 2.7-5v according to data sheet...

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. Yes the TFT uses does use the XPT2046 touch screen controller. Thanks for the information. Regards, Louis

@ufohunter3688 6 жыл бұрын

Another superb project by the master... One must be able to adjust the 4096 volt-ref with a meter like yours. Otherwise, it might not have the accuracy of 1mV, but it will surely have 1mV resolution. That'd reason alone to send it off for calibration, if you don't have the means to calibrate to 1mV. Figure-1 on page 3 of the DG303B shows how clever the switch is! I wonder how much noise these other ICs introduce into the static generated voltage by the voltage reference IC? Would one be able to connect a 1:1 push-pull audio amp to use as an output driver for a programmable power supply capable of 1Amp output?

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for the comments. I will look at some easy ways for the hobbyist to calibrate this unit in Part 2. I will also be looking at overall performance and noise. We could use some of the techniques I use in this project with a programmable power supply, may be another project later. Regards, Louis

@ufohunter3688 6 жыл бұрын

The circuit is flexible and accurate enough to have both in one! With the right output driver that won't load the ref part, but could deliver 0-12V at 1Amp. Maybe a JFET OP amp as a voltage follower + a current driver. Or even use the second DAC. One thing though, what will happen in a case of a sweep say from 2V to 10V? Since it switches between 2 ranges, will it not cut power (brake before make) for a few uS, where the interruption is small enough that the inline caps would pickup the slack?

@scullcomhobbyelectronics1702 6 жыл бұрын

Interesting idea. The break before make should not cause any issues as the time involved is only 50 nano seconds.

@rjordans 6 жыл бұрын

You could add an LT3080 to drive larger loads, up to 1.1A and the voltage can be set by applying the right output voltage level directly to the control pin

@Jackdantte 6 жыл бұрын

Fresh content , nice video .... Thanks for that pasion you are the man

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@ivolol Жыл бұрын

The MAX6(2/3)41 are actually a trade-off. The temperature coefficient isn't long term, reference drift is. the MAX63NN has roughly half the typical temperature coefficient - 0.5ppm, of the MAX62NN's - 1ppm typical. However the MAX62NN lists its long term drift spec at only 20ppm/1000 hours, beating the '63 at 30ppm/1000hours; I believe this is where their numbering scheme comes from but I could be wrong. So it's basically a trade off if you want the tightest short-term tempco, or the lowest possible long-term drift.

@anjayv8347 6 жыл бұрын

can't wait for the second part ! great video ! i learned a lot , thank you !

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Anjay. Hope to start work on part 2 soon. Regards, Louis

@mikaras 6 жыл бұрын

Nice project.. I'm really impressed with the whiteboard schematics, It must have taken a bit of effort? :-)

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Mikael. Regards, Louis

@Inspironator 6 жыл бұрын

Awesome project! I am curious to understand if instead of using the first Op Amp as a X1 and the second as an X2 in the case of the 4V output range provides a more stable output than if you have the gain switched the other way around, X2 for the first Op Amp and the second as X1. I say this because any noise introduced by the first, however little, is amplified by the second Op Amp. Verification only requires a minor software change. I wouldn't provide this comment if we weren't interested in a precision and stable output. Meanwhile, I'm curious as to how to employ the second DAC... :)) Great work, Cheers!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your comments. With regards the 2x first and 1x next for the 4V to 8V range, I did try that originally in my testing with the software but found for some reason it worked better the other way - I will have a further look at that. In part 2 of this project I will be looking at its performance including noise and take on board what you say. I have a number of ideas for the second DAC but have not finalised that yet, hence the reason why I have provided the extra socket connection options on the schematic and PCB. Regards, Louis

@Inspironator 6 жыл бұрын

Louis, it may be due to an impedance mismatch into the first stage. Thanks!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks, have to take a further look at it.

@jerkovicbrate 6 жыл бұрын

Thanks for free knowledge.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Miloš.

@vernonbosshard9317 Жыл бұрын

What do you use a DC voltage calibrator for? BTW like the fact you give the component list, PCB etch and everything right here, one stop, no need for a gerber file reader and all that stuff. I used to etch things like circuit boards and other things using ferric chloride at a company. EPA regs made it difficult to stay in business.

@samuellourenco1050 6 жыл бұрын

Nicely drawn schematic!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@irawarnaca8133 6 жыл бұрын

Great video! You did an amazing job on everything, thank you.

@scullcomhobbyelectronics1702 6 жыл бұрын

Glad you enjoyed. Regards, Louis

@BeetleJuice1980 6 жыл бұрын

always happy to have you back with amazing projects !! sorry about the stupid question , but how can an arduino nano handle over 5volts?

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks. The Arduino does not handle over 5V it only operates from 5V or 3.3V supply. We use the software code programmed in the Arduino to do the calculations and output a digital representation of that information on the SPI bus to feed both the TFT display and the 12 Bit DAC. It is the DAC that generates the actual voltage output in our case up to 4.096V and it is the other two OP Amps (their gain controlled by the Arduino and the CMOS anaolg switch IC) which use a higher supply voltage of ±15V to generate an output voltage up to 10V. Regards, Louis

@aleneme 6 жыл бұрын

Thank you sir for your time and the great video.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Alexandre.

@etienneguyot9069 4 жыл бұрын

Hello Louis. Coming late to your nice project... I've a simple question: am I the only one to notice that the schematic around the switched OPamp doesn't fully reflect the bloc diagram? According to your long explanation about the choice of the multiplication factor 1x 2x 4x, these are cascaded by selecting x1 or x2 on both stages. But the schematic shows that the second switch actually select the output of the first OPA (x1 or x2) or the output of the fixed x2 gain of the second... Is there any advantage to do so instead of replicating the 1x, x2 gain selection of the first OPA to the second OPA?

@karlD1963 5 жыл бұрын

Given you can only multiply by 2 or 4, how do you get, say, 9.7V?

@leonerduk 6 жыл бұрын

One very easy thing you can do is link both DAC channels with, say, a 1000:1 divider on one of them giving it the ability to "nudge" the output a little way. Between them they then act as a coarse/fine adjustment pair, greatly increasing the set resolution and possibly allowing you a digit or two more on your setting, if you calibrate it well enough

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Paul for the comment. I did have in mind something similar but I am also looking at some other uses for the second DAC. I will try and cover it in Part 2 of this project. Regards, Louis

@Flip-Flop-Rio 6 жыл бұрын

Great project, my friend! As always your channel is 10. I always follow your videos! I already gave my like! Michel Rio de Janeiro - Brazil

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Michel, Glad you enjoy. Regards, Louis

@subigirlawd_7307 6 жыл бұрын

This is so awesome ❤ Thank you so much for making this educational video...

@scullcomhobbyelectronics1702 6 жыл бұрын

Thank you. Regards, Louis

@konicekj1 6 жыл бұрын

thank you for another great educative video

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Jaroslav much appreciated. Regards, Louis

@jcddcjjcdnz 6 жыл бұрын

Wonderful presentation.Thanks.

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks John.

@manelsoria2403 6 жыл бұрын

Well done !!! Congratulations and thanks !!!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Manel.

@stoptheirlies 10 ай бұрын

So if there are two DAC's in the package and they each have a seperate voltage ref input and each have an output, why didn't you put the 4.096 ref on one and the 1.2 volt ref on the other and just switch the output ? instead of all that switching?

@stoptheirlies 10 ай бұрын

So you have minus 15 from the charge pump feeding a minus 15 volt regulator? so how can it regulate with no voltage to work with? you need about 3 volts across it for it to regulate

@cmuller1441 6 жыл бұрын

Nice to see new videos. I would power the dcdc from 18v to avoid polluting the 15v with some switching noise. Also do the 2x first and the 1x next for 4V to 8v. Also why stopping at 4V? Why don't you go to 4.095v before the x2?

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks for your comment. Yes I agree about feeding the negative DC to DC converter IC direct to the 18V input supply. I did hint at that in my video and will have a look at that in part 2. With regards the 2x first and 1x next for the 4V to 8V range, I did try that originally in my testing with the software but found for some reason it worked better the other way - I will have a further look at that. Regards, Louis

@qzorn4440 2 жыл бұрын

wow, what would be cool is to place the 6.5 digit multimeter and the calibrator both in the same instrument enclosure 🤔 like the Ronan X86 with 2 input & 2 output leads 🤩thanks 💒

@freda5344 6 жыл бұрын

what a great project. lots of expensive components tho. Just thinking if you get a single more expensive component - DAC, say 18bit, and less precise other components, analog switches already introduce a problem anyway. Then use software to calibrate away the errors. Major drawback, you need access to something to calibrate against, $$

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Fred. Yes agree some of the parts are a little costly. In Part 3, I may make some changes to help with calibration. Regards, Louis

@sanosanbaby 5 жыл бұрын

Awesome as usual!

@MarcoFranceschini1971 6 жыл бұрын

Very very very brilliant...

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Marco.

@TrickyNekro 6 жыл бұрын

Great video! Thank you very much! I would have gone with some things different but that would be more for effect :-P For example, I would have gone with a flyback for example for the -/+15V rails, can be implemented with something as easy to get as MC34063 maybe another more modern IC but still with trafo, it can take a wider input range, make it easy for battery conversion. Would have gone also probably for another implementation to get also negative voltages, cause why not. Could also have gone with a MOSFET reverse input protection and combine it with a soft power button. Still, the idea is pretty cool! Thanks for that!

@scullcomhobbyelectronics1702 6 жыл бұрын

Hi, Thanks for your comments. It is interesting you mentioned the MC34063 as I am using that IC on a new Function Generator project I am currently working on as my next You Tube video project. Regards, Louis

@samchan5251 6 жыл бұрын

In the design spec you said you want 1mV step. But (if I understand correctly) in the 8-10V range, your resolution will reduced to 4mV because of the x4 gain form INA105. For example if I set the output to be 9.001V, arduino will tell the DAC to output 9.001/4 = 2.25025V will is not possible for a 12bit DAC. If I really want 1mV resolution, should I use 16/24bit DAC instead?

@scullcomhobbyelectronics1702 6 жыл бұрын

The resolution of the 12 Bit DAC can only go down to 1mV in the current design and so in the example you gave of 9.001V which is then divided by 4, the output from the DAC will be only good to 3 decimal places so it will output 2.250V, the INA105's will then multiply that by a gain of 4 giving an output of 9.000V. If you want more resolution from the DAC then a 16 Bit DAC would be a good option but the cost of a suitable 16 DAC would increase 5 times or more. A 16 Bit DAC would increase the resolution to a few uV. I will be looking at some update options in part 2 of this project to increase the resolution/accuracy. Regards, Louis

@MeiklesAndDimes 6 жыл бұрын

Great video!

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks Brandon.

@Graham1904 4 жыл бұрын

Surely the 7912 is a negative 12Vdc regulator not a negative 15Vdc one?

@pradipkhare 6 жыл бұрын

Hi Louis, Thank for the video and good work. Please keep it up as it is very educational with well explanation and right description too. However, I think you may eliminate using the gain switches by using the internal gain of 2 by the DAC itself, by using the 5V VREF and setting the INA105 with the gain of x2. It means, if the user inputs a maximum reference voltage of 10 to set, then it can be divided by 2 inside the Nano to drive DAC to generate 5V output on A and then configuring precision Diff OpAmp to gain of 2 (gounding the pin2) to get the output of 10V max. What do you suggest please? Regards, Pradip

@scullcomhobbyelectronics1702 6 жыл бұрын

Hi Pradip, Thanks for your comments. I did look at the x2 internal gain of the DAC ouput amplifier but that has a number of limitations. Since the maximum supply voltage for the DAC is only around 5 volts, that limits the maximum output voltage anyway to about that level. So it will only be of use if you were to use a lower voltage reference. Which would be an option. Another point is the internal OP amp of the DAC with x2 is not as accurate as an INA105 set to a gain of 2, so you may get more errors. Having said that, your idea is of interest if you did use a 2.048V reference as each step of the DAC will give exactly 0.5mV and so improve the overall resolution. Its worth giving it a try. Thanks, Louis

@Atteluxy 6 жыл бұрын

Really good Explanation with those Drawings! please keep your good work up;)

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks.

@samhsavdr9647 6 жыл бұрын

Great master again perfect job

@scullcomhobbyelectronics1702 6 жыл бұрын

Thanks ;-)

@ToltecMerc 6 жыл бұрын

Why does your Fluke meter continue to give readings after you remove the probe from the circuit? Is this a peak hold feature? It's weird because the value keeps changing after you remove your probes.

@scullcomhobbyelectronics1702 6 жыл бұрын

This is due to the fact that the Fluke 8842A has an input impedance of around 10 GigOhm on voltage ranges below 20 volt. When it auto-ranges above 20 volts then the input impedance of the meter drops to about 10 MegOhm (similar to a standard multimeter) and then you don't see this effect. The residual voltage you see remaining on the display is what is held by circuit capacitance. You can zero the reading if you wish by simply shorting the test leads, if the test leads are simply left floating then the reading will take a long time to drop to zero and that the changing reading you see on the display is the effect of that. This is one of the effects of having a multimeter with a very high input impedance. But I am sure you will understand the benefits of having a very high impedance at lower voltage readings. If you look at 40:03 of my video you will see at that point I short the meter leads together. Regards, Louis