audioguru Posted December 12, 2013 Report Share Posted December 12, 2013 My problem is that there is no more ICs to find anywhere at reasonable price tag, neither MC or TLE variant. They were like 1$/piece but now i cant to find them anywhere. I live in EU and shipping from USA is insane so im kind of stuck!The MC34071 in the through-hole package is not made anymore. Some distributors still have some left.The TLE2141CP is available at the two largest American semiconductor distributors for $1.58 and $1.81 each and they have hundreds in stock.Go to www.farnell.com and click on the flag of your country. They are a large international electronics parts distributor (Element 14?). Quote Link to comment Share on other sites More sharing options...
red_81 Posted December 12, 2013 Report Share Posted December 12, 2013 Unfortunately, my country (Croatia) is a fresh part of EU so most online shops doesn't have "my flag" yet... Maybe some will do shopping in USA and offer me private deal. Tnx anyway Quote Link to comment Share on other sites More sharing options...
Guest picotrain Posted December 13, 2013 Report Share Posted December 13, 2013 Hi all,I am beginning to amass the parts for this project. I am going by the version found here as I believe it is the most recent, pls correct me if am wrong - http://www.electronics-lab.com/forum/index.php?topic=19066.msg1010703Regarding the 16000uF 63V Capacitor, the main one I can find seems to be for Denon audio equipment http://www.ebay.com/itm/1PCS-12000UF-63V-NCC-For-DENON-AUDDIO-Capacitor-/221184028851?pt=LH_DefaultDomain_0&hash=item337f9870b3Is this correct? I found others on ebay that matched the specs. Would the Denon audio capacitor be problematic?Thanks in advance :) Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 13, 2013 Report Share Posted December 13, 2013 12,000uF/63V was a standard one in Canada when I wrote the parts list. 16,000uF/63V will also be fine. Quote Link to comment Share on other sites More sharing options...
Guest picotrain Posted December 13, 2013 Report Share Posted December 13, 2013 Sorry, that was a typo, I meant 12000uF :-[ Quote Link to comment Share on other sites More sharing options...
redwire Posted December 14, 2013 Author Report Share Posted December 14, 2013 gizmo322, try http://www.electronics-lab.com/projects/mcu/008/index.html. There is an AVR version out there http://www.electronics-lab.com/projects/test/007/. I'm working on a version that uses an Adafruit 32u4 breakout board and uses a usb cable to program, eliminating any expensive programing tools. While the breakout board is more expensive than the bare chip, programing is much simpler. Quote Link to comment Share on other sites More sharing options...
Guest dragansparky Posted December 15, 2013 Report Share Posted December 15, 2013 i want to made this supply but i want to know can i use with symmetrical mode with two boards end i want to know how to change power etc 0 to 40v 0 to 5 amp Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 15, 2013 Report Share Posted December 15, 2013 i want to made this supply but i want to know can i use with symmetrical mode with two boards end i want to know how to change power etc 0 to 40v 0 to 5 ampI don't know what you mean by "symmetrical mode". Is it one is a positive supply and a second one is a negative supply? Then build two completely separate supplies and connect the + output of one to ground so its ground connection becomes a negative output.The circuit will need a complete re-design for 40V at 5A output. If the output is shorted or is a low voltage at 5A then the output transistors will dissipate 250W which is A LOT of heat. Quote Link to comment Share on other sites More sharing options...
Guest dragansparky Posted December 15, 2013 Report Share Posted December 15, 2013 i want like a dual +40-0-40 then i have 80 volt Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 15, 2013 Report Share Posted December 15, 2013 i want like a dual +40-0-40 then i have 80 voltThis project gives 30V, not 40V. There is a 5A version.If you make two 0V-30V at 5A projects then you will have up to +30V and up to -30V at 5A. A total of 60V maximum.If you accidently short one supply to the other supply then it will probably blow up. Quote Link to comment Share on other sites More sharing options...
Guest dragansparky Posted December 15, 2013 Report Share Posted December 15, 2013 ok i will use standard schematic with 2x24vac transformer. and i want to made two similar boards. can i short boards together - on first board to + on second board then probably i will have 60v. +30-0--30 can i use like that (sorry for my bad english) Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 15, 2013 Report Share Posted December 15, 2013 ok i will use standard schematic with 2x24vac transformer. and i want to made two similar boards. can i short boards together - on first board to + on second board then probably i will have 60v. +30-0--30 can i use like thatThe schematic and parts list on the project page has errors and does not work properly. The transformer is supposed to be 28V or 30V at 4.3A (118VA), for 3ADC output, not a 24V transformer. Then the opamps must be higher voltage ones, the TLE2141. The driver transistor is changed and there are two output transistors with emitter resistors. Other parts are also changed. The revised schematic and revised parts list are in this thread.There is a 5A parts list available.You can make two projects each with their own transformer and connect them in series to get 60V maximum at 3A. But if the output of one gets shorted to the other then they will probably blow up. Quote Link to comment Share on other sites More sharing options...
Guest dragansparky Posted December 15, 2013 Report Share Posted December 15, 2013 thanks audioguru you help me a lot i found chematic with the changes with two 2n3055 transistor Quote Link to comment Share on other sites More sharing options...
Guest picotrain Posted December 16, 2013 Report Share Posted December 16, 2013 We seem to have lost the extensive discussion on this power supply topic. I attached what I believe is the latest version. NOTE the parts list included in the attached zip file is REV 5 dated 12/13/13 and covers the next 125 pages of this tread. In the image of the populated PCB in the Rev 5 zip file from the updated 1st post in this thread, there appears to be a wirewound with heatsink resistor mounted on the TO-3 heatsink. Seeing as the 10W resistor is mounted on the PCB (and using a 0.27Ω instead of 0.47Ω with 5V6 Zener missing?), I can only assume that the resistor is the 0.33Ω on the emitter of each 2N3055.Would that then mean the 2W rating (according to the parts list) of the 0.33Ω is a typo? 2W seems a bit (lot?) small.I am considering having the Rev 5 PCB made by OSH Park, who have a order minimum of 3 boards. According to their site, 3 of these boards cost $63.30 (+ shipping I would assume).Would anyone be interested in splitting an order 3 ways? Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 17, 2013 Report Share Posted December 17, 2013 In the image of the populated PCB in the Rev 5 zip file from the updated 1st post in this thread, there appears to be a wirewound with heatsink resistor mounted on the TO-3 heatsink. Seeing as the 10W resistor is mounted on the PCB (and using a 0.27Ω instead of 0.47Ω with 5V6 Zener missing?), I can only assume that the resistor is the 0.33Ω on the emitter of each 2N3055.Would that then mean the 2W rating (according to the parts list) of the 0.33Ω is a typo? 2W seems a bit (lot?) small.The photo shows Redwire's 5A version of this project. The 0.27 ohm/10W resistor on the pcb is R7 which is 0.47 ohms/10W on the 3A version. 5A x 0.27 ohms= 1.35V. 3A x 0.47 ohms= 1.41V which is almost the same.5A squared x 0.27 ohms= 6.75W. 3A squared x 0.47 ohms= 4.23W which would make a 5W resistor extremely hot so a 10W resistor is used.The missing heatsink in the photo is for the bridge rectifier module in the upper left corner.I do not know why the 5.6V zener diode is missing from the pcb in the photo.With each of the two output transistors conducting 1.5A then each 0.33 ohm emitter resistor dissipates 1.5A squared x 0.33 ohms= 0.74W which would make a 1W resistor extremely hot so a 2W resistor is used. The 5A version uses three output transistors, each with a 0.33 ohm emitter resistor then each conducts 1.67A so again the resistor is 2W. Quote Link to comment Share on other sites More sharing options...
Guest picotrain Posted December 17, 2013 Report Share Posted December 17, 2013 Thank you Audioguru!Could you advise a part number for the inline bridge rectifier for a 3A version? Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 17, 2013 Report Share Posted December 17, 2013 Thank you Audioguru!Could you advise a part number for the inline bridge rectifier for a 3A version?I simply look in the catalog of the parts distributor I buy parts at (I use Digikey or Newark).I don't know which country you are in and I don't know which manufacturers are available in your country. Quote Link to comment Share on other sites More sharing options...
redwire Posted December 18, 2013 Author Report Share Posted December 18, 2013 picotrain , The actual board layout has not changed since I posted the pictures in the first post. One or two part values have changed. I had several boards made if you would like to purchase one/two. I suspect it would significantly cheaper than getting 3 boards made. Send me a PM if you are interested. You have noticed that there is a missing 5.6 Zener. The reason is that about the time I developed the boards, Audioguru suggested using 2 diodes in series instead of the 5.6 Zener diode. Consequently, I prepared to board to use either 2 diodes in series or a 5.6V Zener. I noticed that the 0.47 Ohm resistor got quite warm and I wanted 5A capability so I used a 0.27 ohm resistor and it works fine. The trimmer allow me to set the max output for the transformer being used. I used a RS2005M bridge rectifier from Mouser. I had not installed the heat sink when I tested it and took pictures but I found a nice one out of an old computer power supply. I ran it with 3A without a heat sink and while it got very hot it didn't fail. Note that the ideal placement would be against the case. If you decided to do this, then simply run the 4 wires from the bridge rectifier to the board. Quote Link to comment Share on other sites More sharing options...
redwire Posted December 18, 2013 Author Report Share Posted December 18, 2013 Some accessories I'm working on. The displayOn issue when building the display is programming the chip. I'm building a board with smd components that uses the 32u4 breakout board from Adafruit. It can be programmed with a usb connector and does not need a special programmer. While simply buying a microcontroller is significantly cheaper, if someone does not want dive too deep into things this is an alternative.The lcd display can be mounted vertically or horizontally. Oh, the first line on the LCD displays the voltage. The chip senses when nothing is connected and displays the "connect wire" notice. It has outputs for a small fan, that can be set to turn on at a certain temperature or current setting. There are numerous "spares" that allows the board to be used for other purposes (operating a servo, leds, or other sensors). Quote Link to comment Share on other sites More sharing options...
tubefans007 Posted December 22, 2013 Report Share Posted December 22, 2013 Schematic Diagram Quote Link to comment Share on other sites More sharing options...
tubefans007 Posted December 22, 2013 Report Share Posted December 22, 2013 PCB layout Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 23, 2013 Report Share Posted December 23, 2013 picotrain, this design is underdeveloped. It only works for a simple, solitude variable power supply.No.This is my improved design. It works very well.Recently we found out that the MC34071 opamps are no longer available in through-hole packages so the Texas Instruments TLE2141 opamps should be used instead. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted December 24, 2013 Report Share Posted December 24, 2013 The error amplifier opamp is two transistors away from the output. Low gain and high input current means low beta. So this isn't the best voltage regulator. Quote Link to comment Share on other sites More sharing options...
audioguru Posted December 24, 2013 Report Share Posted December 24, 2013 The error amplifier opamp is two transistors away from the output. Low gain and high input current means low beta. So this isn't the best voltage regulator.What are you talking about, Kevin?With an output current of 3A from the project, the driver transistor is an emitter-follower with a voltage gain of 0.9. The two output transistors have a voltage gain of about 0.85 which is reduced to 0.8 by their emitter resistors. Then their total voltage gain is 0.72 times.These transistors are inside the negative feedback loop of the error opamp.The TLE2141 opamp has a typical voltage gain of 450,000 so the total voltage gain is 0.72 x 450,000= 324,000 which is divided by the closed loop gain of 2.7 so the total is 324,000/2.7= 120,000 times.Then if the output voltage tries to drop 1V it will actually drop only 1V/120,000= 8.3uV which is almost nothing.But we know that circuit wiring has some resistance that will increase the voltage drop a little.You talked about beta:1) The typical beta of the output transistors at 3A maximum load (1.5A for each transistor) is 80 so the collector current of the driver transistor is 3A/80= 37.5mA.2) The typical beta for the BD139 driver transistor at 37.5mA is 135 so the output current of the error opamp is only 37.5mA/135= 0.3mA.The error opamp works perfectly with an output current up to 20mA so here it works perfectly. Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted December 24, 2013 Report Share Posted December 24, 2013 The opamp having a very high voltage gain should regulate it's output at the voltage set by the offset RV1. The 0.85 gain of the negative feedback loop transistors combined with R12 is where the loss in load regulation is. However, the voltage response is quick. Quote Link to comment Share on other sites More sharing options...
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