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0-30V Stabilized Power Supply


redwire
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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?).
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Guest picotrain

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.msg1010703

Regarding 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=item337f9870b3
Is this correct?
I found others on ebay that matched the specs. Would the Denon audio capacitor be problematic?

Thanks in advance :)

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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.

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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

I 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.
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Guest dragansparky

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)

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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

The 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.
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Guest picotrain

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?
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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.
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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. 

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Some accessories I'm working on.  The display

On 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).

post-34537-14279144579585_thumb.jpg

post-34537-14279144582006_thumb.jpg

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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.
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