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Author Topic: 0-30V Stabilized Power Supply  (Read 330962 times)
PETROS1308
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« Reply #1428 on: January 20, 2013, 05:30:43 AM »

I have a tranformer 28Vac/5A.. It's ok to use it for the last version of power supply 0-30v 0-3A???
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mendimano
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« Reply #1429 on: January 20, 2013, 05:44:33 AM »

It is perfect for that.
 Grin
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darthtony
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« Reply #1430 on: January 21, 2013, 01:01:10 PM »

Hi, i am a beginner in electronics, and i decided tobuild this power supply. Unfortunately, i built the original design(here: http://www.electronics-lab.com/projects/power/001/index.html)(i didnt check out this topic). It seemed to work fine , but while i was testing it before finishing the enclosure, it started to have problems. Anyway, after a couple of burnt transistors, now i have a contsant(non-adjustable) output of 30V, howver the current limiting seems to work just fine. If i disconnect the middle wire from the voltage adjustment pot, the output will "float" around 1-4V, howver if i touch it to either of the other wires that go to the pot, it will shoot up to 30V again. Any ideas of what  could be wrong?Are the corrections that i have seen necessary?(it really took me alot of time to make the pcb(twice, beacause once i printed it upside down) and to make it work, so i really dont want to start over again. thanks in advance

I should note that it is not exacltly the original design: i am using a larger bridge rectifier, a 10,000uf cap, a second R7 i parallel with the first one, and 2x2n3772 in order to get 5-6A that my transformer(24VAC secondary) can supply.Howver right now i am testing it with only 1 2n3055.
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ram2010mech
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« Reply #1431 on: January 28, 2013, 01:56:00 AM »

Hi Friends,

I have bought all the components in the list except one, I could not get the capacitor C1 = 12000uF/63V in the market . Can any one please suggest the alternate for this or please help me to get this component.

Thanks
Ram
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thenr.
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« Reply #1432 on: January 28, 2013, 05:00:03 AM »

I've bought mine on eBay, but it's 10000uf not 12000uf... good price, fast ship.

http://www.ebay.com/itm/2PCS-AUDIO-Electrolytic-Capacitor-30-41mm-10000UF-63V-63V-10000UF-/251121225080?pt=LH_DefaultDomain_0&hash=item3a77fdcd78


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audioguru
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« Reply #1433 on: January 28, 2013, 08:37:14 AM »

12000uF is a common value in The West. Use 10000uF or 15000uF instead.
Use a 10000uF parallel with a 1000uF, 2200uF, 3300uF or 4700uF.

Most of us do not buy electronic parts in a "market", instead we go to an electronics parts distributor store or buy them online where they have millions of values for everything. 
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ram2010mech
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« Reply #1434 on: January 31, 2013, 06:31:11 AM »

Thanks guys....
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Question
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« Reply #1435 on: February 04, 2013, 10:41:58 AM »

To everyone who made it: does this power supply worth making it?  Huh
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redwire
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« Reply #1436 on: February 04, 2013, 09:40:55 PM »

Yes,   Some of the benefits:

1.   Develop skills in making pcbs, and using software such as Eagle.
2.   Learn troubleshooting
3.  Utilizing a design (as revised) that is probably the best available
4.  Ability to ensure quality parts are used
5.  Satisfaction and pride in successfuly completing a project
6.   Develop skills in understanding programming AVR chips (LCD Display project)
7.   leveraging these skills to build other project using servos, lcd displays, flashing lights, etc   http://www.youtube.com/watch?v=ryhK9xIUcrQ 
      (sorry about the poor film quality)

If price and time are your primary concerns then buying one a commercial unit would be your best option.
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Question
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« Reply #1437 on: February 08, 2013, 02:02:39 PM »

Hey, I have a few questions (about the schematic, posted in the first post of this topic):

1) There is diode D10 (1N4148) written in the parts list, but it isn't in the schematic. So I do not need it at all (it is just a mistake in the parts list)?

Also, I don't know where C10 came for, but in original nor remade version schematics the is no C10 at all.

2) Do I need to use a silicone isolator for 2N3055 transistors of TO3 package type:

http://www.spiratronics.com/images/newimlib/mica_to3_mounti.JPG
http://www.rcl.lt/img_prod/IIZT3.jpg

I do not understand the purpose of this isolator. Is it a must? Or these transistors can be screwed to cooler with screws (using thermo paste, of course) without making any isolation between aluminium cooler and a case of transistor?

3) About the power supply: for example I will use digital ampermeter module. When will the chosen value of current limit will be seen? Only when a load will be connected to the power supply? If yes, then current limit value changing with linear potentiometer will be not available to see when no load is connected? Thank you.
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audioguru
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« Reply #1438 on: February 08, 2013, 04:46:39 PM »

Hey, I have a few questions (about the schematic, posted in the first post of this topic):

1) There is diode D10 (1N4148) written in the parts list, but it isn't in the schematic. So I do not need it at all (it is just a mistake in the parts list)?
I started modifying this project. My latest schematic and parts list do not have D10 that I deleted from the original defective version.

Quote
Also, I don't know where C10 came for, but in original nor remade version schematics the is no C10 at all.[
I added C10 to filter the supply for U3 when I added the 10V zener diode. It is shown on my latest schematic but it is not called D10 and is not called anything. It is on my parts list.
The 10V zenewr diode is not called anything on my schematic but is called D12 on my parts list.

Quote
2) Do I need to use a silicone isolator for 2N3055 transistors of TO3 package type?
The output transistors have their collectors connected together and their metal case is the collector. If no insulators are used then the entire heatsink should be insulated from the chassis. With insulators for the transistors then the heatsink can be connected to 0V.

Quote
3) About the power supply: for example I will use digital ampermeter module. When will the chosen value of current limit will be seen? Only when a load will be connected to the power supply? If yes, then current limit value changing with linear potentiometer will be not available to see when no load is connected?
The amp-meter will reduce the voltage regulation a little.
The project has current regulation, not simple current limiting. Current regulation reduces the output voltage (and lights the red LED) so that the current cannot increase when it occurs. Make a scale of current for the current-setting pot. Minimum is a few mA, halfway is 1.50A and maximum is 3.0A.
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« Reply #1439 on: February 08, 2013, 05:08:22 PM »

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The output transistors have their collectors connected together and their metal case is the collector. If no insulators are used then the entire heatsink should be insulated from the chassis. With insulators for the transistors then the heatsink can be connected to 0V.
Why they should be connected to 0V?
And more, do those 0.33 Ohm 2W resistors (thay are connected to power transistor emitters) must be with heatsinks? http://www.arcolresistors.com/wp-content/uploads/2011/07/5034-18-arcol-330x220.jpg

or can be used simple ceramic ones: http://speakerbug.com.au/shop/images/WireWound_47ohm_small.jpg
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audioguru
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« Reply #1440 on: February 08, 2013, 06:28:03 PM »

Why should the heatsink be connected to 0V?
When metal parts are connected to 0V then they provide shielding from interference to the circuit.

Quote
And more, do those 0.33 Ohm 2W resistors (thay are connected to power transistor emitters) must be with heatsinks? or can be used simple ceramic ones?
The maximum load for the project is 3A. Then each 0.33 ohm resistor has 1.5A (plus some small base current).
The power in each resistor is (1.5A squared) x 0.33 ohms= 0.74W so an ordinary 2W resistor or a 5W ceramic resistor can be used.
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« Reply #1441 on: February 17, 2013, 10:55:35 AM »

Hello, I almost finished the experimental board of the latest version 3A power supply. As the transformer I have a transformer from the old times Bulgarian 0-30V, 0-5A power supply named "ТЕС-14". I do not know real ratings of secondary voltages and their amps, but there are written diameters of windings. As I found, there is one secondary winding with about 26,7 - 27 VAC without any load, it's wire diameter is 1,74mm. This transformer is big and very heavy, so later, if everything will work, I will probably find another, but I have a question, can I use this one for the primary experiments of the power supply, like testing, diagnose troubleshooting...?

I have attached photos of the board, there is no 12000uF capacitor connected to this time, I will do it later. Can you give some important notes, comments and warnings about the board. For example, which wires must be thick, how about 12000uF capacitor isolation... Which parts of the circuit aren't safe to touch accidently? Thank you.
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