Variable Bench power supply (Dave design based) - Page 1
Forum section: electronics / general

author: MilanM
author_rank: Contributor
timestamp: April 28, 2016, 02:05:15 pm
content: Hello GuysNew member here!I am glad that i am part of the EEWblog community now.Well i follow the EEVblog youtube channel for a last 2 or 3 years or soand i have visited the forum but only as guest.I am one of those engineers who do their daily job and who dont care sharing the designs on web, but now i decide to change that.The reason why i have decide to do a design and build this variable bench power supply (Dave based on LT3080) is only for fun purpose and because i wanted to know exactly how my bench supply work what performance it have bla bla bla...Well for schematic and for PCB design i am usually using DipTrace software, and it is like that since i first try itOk enough of that in general part now lets see some technical side of power supply.I used a mixture of all 3 versions Dave has publish and make my own which suit my needs.In base i used the Atmega2560 processor because it have enough pins to drive all of the things i wanted.I keep the INA219 and MAX4080F for current measurements.I found INA219 as a superb easy to use chip for precise current measurements and i keep MAX4080F as a current-sense amplifier.As a op amp i have used LT1491 its not cheap part but i have use it because i have quite a lot of spare (from the old projects)Its a quite good op amp with good characteristics do a goole search for datashet.What i found interesting is a usage of some sort of TFT display instead of some 2x16 or 4x20 characters display, the reason for that is because i wanted to print some more data out, like shunt voltage drop (INA219 support that) (MAX4080 through ADC MCP3208) In general i want to print on display quite a few more parameters instead of only voltage, current and current limit.For that purpose i choice this one from banggoodhttp://www.banggood.com/3_2-Inch-320-X-480-TFT-LCD-Display-Module-Support-Arduino-Mega2560-p-963574.htmlMy pre regulator part is quite a poor one, i simply pick one of the shell parts available and i have used LM2596S-ADJ, i put simple 20 turn pot there to adjust the voltage and that was about it. I am planing to use some better one and to attach some digital pot in order to controll the pre regulator output voltage so it is software controlled and always slightly above regulator voltage (pre regulator and regulator are not same thing!)I used MCP4922 12 bit dac to set the voltage and MCP3208 8 channel ADC 12bit to do ADC measurements i guess there is no need for explanation on those 2.I do a design last weekend and schematic is not cleared up and it is not checked, before some PCB manufacturing i like to do clear up, for now it is as it is, i guess there are no errors in design but there is a chance that i miss something (for example on MCP4922 i left a SHDN pin unconnected cause i still didnt decide how i will controll the dac output through software or hardware). So please dont print those PCB-s yet, my goal is to make a good open source open hardware project so we can work on it together.On software side i didnt do much, that is something what i am start working on from the moment i order PCB-sFor now i will attach a schematic PDF file, schematic and PCB source files and 3D view of PCB quite a few pictures.If i post this topic on wrong section of the forum i am sorry didnt go through forum complitely yetLets start a discussion!RegardsMilan

author: ebclr
author_rank: Super Contributor
timestamp: May 28, 2016, 02:47:48 pm
content: If you really wanna do a nice thing replace the processor with a Psoc, they will have everything you need , Ad Da Display interface ,even the op amps.http://www.cypress.com/documentation/development-kitsboards/cy8ckit-059-psoc-5lp-prototyping-kit-onboard-programmer-and

author: Back2Volts
author_rank: Unknown
timestamp: July 11, 2016, 08:42:43 pm
content: Quote from: ebclr on May 28, 2016, 02:47:48 pmThat is an interesting idea. ADC, DAC, Opamps, comparators and microprocessor are there. Do you think it could control a TFT display ?Edit: I just put about an hour browsing the Tech. Ref. Manual for the PSoC 5LP. Seems to be a very sophisticated device. Looking at the display driver section I quickly realize that I have absolutely no clue about the LCD display technology.