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Posted March 14, 2012
Or a multiturn pot.
Posted May 18, 2010
I'll change the 3 TLE2141, the BD139 and the 3 2N3055 for new ones (and put R17 the original value 33R). I want this PSU to work better than my old (fixed) version (3A).I don't like the way the PSU (Redwire 5A) is working now... the old (fixed) version I build is working better than this one... :-\I hope with the changes it will work better than my old PSU... :'(And after I change the components
Posted May 13, 2010
And the PSU don't reach zero volts... Can I make any modifications in R10 or in RV1 to make the 0V adjust reach zero?
Ok, I know. I don't change the opamps. It's the same TLE2141. What about the R17 increase changes? It's ok?When I calibrate the LCD meter it's show the correct current load of the same 120mm PC fan (0,23A), but when the calibration finish the meter shows 0,13A only. :'(
I can't remember which version you are making.my latest version works only with MC34071 or TLE2141 opamps and will not work with 741 or OPA445 opamps.I build the redwire 5A version with TLE2141 opamps.Yes.There are many plastic films. Mylar is another one.I don't change the capacitor because I don't find a 10uF in polyester or mylar type.Yes.To the led go off in the current pot set to minimum and the voltage pot set to minimum or maximum I have to increase the R17 to 150R.I think your current meter is not calibrated correctly.I calibrate the meter folow the instructions in the autor site. http://www.elfly.pl/multimetr/multimetr_en.htm
Posted May 12, 2010
For now I only have 6 OPA445 opamps... No more TLE2141 :'(. (Samples from TI)The film capacitor you are talking are polyester film type?If I increase R17 value I will solve the led on problem in the current pot set to minimum?And the current LCD meter shows less current than the multimeter shows when I power 1 120mm PC Fan 12V 0,33A (The multimeter shows constant 0,23A and the LCD meter shows 0,14A.The R7 is two 0,47R 10W in paralel (0,235R = 0,24R?).
Hi AudioGuru, R17 is 33 ohms and is connected at the lowest voltage pin of the current-setting pot. But I measure the voltages enter -C1 point (0V) and pin 3 of U3 (wiper connection in current POT): 8,3mV (current pot set to minimum and led on); 12mV (current pot set to led off). When the led is off the output is 21,4mV (zero adjust trimpot set to minimum).In this test I used only 2 2N3055, to have access to the PCB and make the measurements.
Posted May 11, 2010
I use the TLE2141 too. I'll measure the voltage in input of U3. The schematics I have is the november/09 version.I put the parts in the part list.The meters are oscilating I think is because the input voltage for the LCD meter are above 35V, the limit for the 12V regulator. I put a 22R resistor in series and it don't oscilate more.I have the previous version of the PSU (3A) and it adjust the zero and the current pot in the minimum don't light the led.
And the voltage and current in the LCD meter are oscilating... :( :-\ ???
I have problems with my PSU (Redwire 5A version). I used 3 2N3055, two 0,47R 10W (it's the only I got) for R7, two 10.000uF caps for C1.The voltage pot works good, but the current pot in the minimum setting, without load, lights the led.And the zero volt regulation trimpot don't adjust to zero.Can anyone help me?Regards.
Posted May 6, 2010
Hehehe, I had the same pot problem... :) usually I put the wiper in the center in the PCB, but I build the PSU and it don't work, then I change the pots wiper position and it's seemingly looks ok now... I'll test a little bit more... :) Thanks notedly to AudioGuru and Redwire for the support.Thanks to all who comment in my previous posts: hero999, erivanst, and others.I'll post some pictures soon.
Posted April 6, 2010
AudioGuru, I'm building the 5A version. therefore is the reason I want to put 3 or up to 4x 2N3055.The measurements of Hfe of the four 2N3055 with the results of 159-180 Hfe where got under 2,5mA of current in the Hfe test. Under 1,5A of course the Hfe will be lower. But I don't know to make this conversion to have the results for the Hfe (159-180 Hfe - 2,5mA) under 1,5A.I attached the SC Analyser 2005 project for information only.
Hi AudioGuru, I see the datasheet values for the transistores. With the "SC Analyser 2005", a Elektor Project, I read the Hfe of my 4 2N3055 and they are in the range of 159-180 Hfe under 2,5mA current test. It's right? Can you guide me to the right results to know if the redwire circuit will support 4x2N3055?Thanks for your support too.Erivanst, do you find the Atmega8 smd version for the LCD Multimeter?
Posted April 2, 2010
Ok, so we can safety have a max 5A continuous current draw output (6A intermitent)? Still I can use 4 2N3055 (5-6A output)?
So how much is the max output Amps with the components i told? Without damage the BD139 or U2? Still i can use 4x2N3055? I have to regulate the max current safety to how much amps? Regards Audioguru. please guide me to get the best of the PSU with the parts I have.
Posted April 1, 2010
I plan to use 4x2N3055 with 0R33 5W emitter resistor each, A 10A diode bridge, 2x10.000uF for C1, a 30V (2x16AWG) secundary for transformer, a fan and 2x0R47 10W for R7. I'm waiting only for the TLE2141 samples from Texas Instruments. I think I'll get about 8-10A output? The transformer come from a old PC AC stabilizer. I dismount and rebuild it for the PSU purposes. I'll build the PSU in the case of the same PC AC stabilizer I got the transformer. I'm planning the panel.Wat do you think about it Audioguru? Give me a light. ;D regards.
Posted March 23, 2010
Hi AudioGuru, this fine adjustment for corrent is correct?
Posted March 10, 2010
Hi Erivan!It's the meter proposed in the main page of the project, but in DIP version. http://www.electronics-lab.com/projects/power/001/index.html (someone change the link)Check the page of the author of the LCD meter:http://www.elfly.pl/multimetr/multimetr_en_DIP.htm
Posted March 9, 2010
For the original PSU I build can I make the Ivan proposal's (2nd 2N3055, bigger capacitor and 27 V for the opamps) and increase the resistor W's? I don't want to make another PCB for this PSU. And how can I effectively know the real PSU output or the Transformer output? How can I make this test? With a car light bulb, a shower resistence, resistors or other method? Any Tips?Thank you.
Hi AudioGuru, it's because the iginal PSU is already assembled and working, with this limitations, off course... And I want to make it more reliable.I'll build the 5A RedWire version too, I already make the PCB for it and i'm waiting for the parts...The transformer I use in the original version have a secundary of 26V at about 3-3.5A. In this PSU I don't need the 30V in the output, ok? So I can use this transformer... In really In this PSU I need less than 30V! If it is the case I can rebuild the secondary, but In this PSU I think i'nst the case because I need less than 30V as I said before...I Hope you can understand me... and help me! ;)I am at your disposal.
So, Audioguru I understand that have more to modify in the original project. I only want to save my original project, make the mods to make it more confiable... I'll make the mods sugested from Ivan and change the watts of some resistors too with your guidance ;D off course, hehehe. The 2N2219 in my project ahs a heatsink appropriate for this package, and I want to put a fan in the PSU, the LCD meter module has a control for a fan with a mosfet, it power the fan when the load is heavy duty, I think... ;).Can you describe, please, the all parts I have to modify? resistors watts, etc...Here the pictures of my original project and the LCD module... After I post inside pictures of it ok?
I am also a little confused with some connections points in the RedWire PCB...connection point 4B, 4B1, 4, 4A...etc. Can redwire give some help? ???
Posted March 8, 2010