tag:blogger.com,1999:blog-4191887753331304313.post2725172175068402988..comments2023-08-20T10:54:33.570+03:00Comments on DIYfan: Adjustable Lab Power Supply - take two :)Христоhttp://www.blogger.com/profile/14002909704834630953noreply@blogger.comBlogger389125tag:blogger.com,1999:blog-4191887753331304313.post-39525267799962453332023-02-19T18:16:49.376+02:002023-02-19T18:16:49.376+02:00Hi, awesome post first of wall. I like that fact t...Hi, awesome post first of wall. I like that fact the everyone is involved in a way 😊. So I have a big problem and can't seem to figure out what tha cause might be. I want to build a dual channel PSU using your v4 design. I have ordered online some nice PCBs based on your design and soldered most components. The transformer has 2 independent secondaries: 30V, 2.6A. voltage controll seem to work finw mostly but the current limitation LED is always on. I can't see to find the cause and have replaced many of the SMD parts as well as OPAMP (TL072) due to probably high current consumption. Please give me some tips where to check. Forgot to mention that reference voltage is 9.7V and negative voltage -3.1V.Robert Rosuhttps://www.blogger.com/profile/00966624852015033156noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-52809012466470569072021-01-28T12:36:11.594+02:002021-01-28T12:36:11.594+02:00Hello Христо.
I made version 3 of your power suppl...Hello Христо.<br />I made version 3 of your power supply.<br />It seems to work fine but output voltage goes only to 23.5V<br />I have 35V on C1, 33V after IC3, -3V after IC4. And 9.6V on Z2 , Z3 zeners. <br />Rotating potentiometer P4 does not affect. <br />When i rotate P4 voltave on IC1B pin 5 goes from 0 to 9.6 in the same time on the pin 6 voltage goes only to 8V then remain unchangable.<br />I know that opamp must keeps voltages on inputs equals, i studied theory but in practice i can't understand how to fix this.<br /><br />I hope you are visiting this blog ...<br /><br />Anonymoushttps://www.blogger.com/profile/13048171423621944359noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-11941502735051163322020-12-23T12:23:24.596+02:002020-12-23T12:23:24.596+02:00Hello
Христо!
I am a newbie in electronics and I ...Hello <br />Христо!<br />I am a newbie in electronics and I want to make a good power supply for myself. I want to make the version 3 of your circuit. Please help me out as to changes I need to make in the circuit to have a 0-20volt 0-2A power supply. I have a transformer which is 24Vac 3A. I could not understand what is the function of Z4 in the circuit.<br />Thank you!Deepak Royhttps://www.blogger.com/profile/18286332172974343911noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-7541366118388774342020-12-22T19:19:55.973+02:002020-12-22T19:19:55.973+02:00hello Христо!
i am a newbie in electronics. i want...hello Христо!<br />i am a newbie in electronics. i want to make the version 3 P.S. i have a transformer of only 24V ac @ 3A. what changes i need to make in order to obtain the perfect regulation? by the way 0-20V @ 2A is enough for me. Thank you!Deepak Royhttps://www.blogger.com/profile/18286332172974343911noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-32224852755649312982020-07-03T16:03:18.649+03:002020-07-03T16:03:18.649+03:00And for the second question. You can use 1 transfo...And for the second question. You can use 1 transformer but with 2 separate secondary windings, connected to two identical boards of the power supply. The two channels should be separate all the way (including separate grounds) and you can connect only their outputs to form a dual rail power supply.Христоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-45984015211896226452020-07-03T15:17:15.289+03:002020-07-03T15:17:15.289+03:00The current schematic is not suitable for what you...The current schematic is not suitable for what you want. There are two solutions: <br />1. Add a voltmeter across pin 3 of IC1A and GND and maybe with some clever voltage divider the reading of the voltage will be correlated to the current limit setting. <br />2. Add a scale around the current limit potentiometer and via measurement mark the appropriate values. This will not be very accurate, but will give you a rough idea what is the current limit at the moment. Христоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-23114613942824097182020-07-03T14:58:31.610+03:002020-07-03T14:58:31.610+03:00This PSU looks almost exactly like what I am looki...This PSU looks almost exactly like what I am looking to build. However, I would like to be able to have visual indicators for both the actual voltage and current draw as well as the values that have been set. For instance, if the current limit is set to 2A, but the load only draws 1A, I want to see 1A on one meter while at same time being able to see that the limit is 2A. Likewise for the voltage when running in current limit mode. This is useful to be able to adjust the set values.<br /><br />Do you have an idea of how to achieve this?<br /><br />Another question: Ideally, I would like to build a large unit with at least 2 channels, based on two copies of this schematic. What would that mean for the input transformer? Do I need two copies, or can I use a single transformer with multiple windings? The two channels need to be isolated to allow for -12V, 0V, 12V for instance.Kallehttps://www.blogger.com/profile/06647765137115788469noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-20844936809191086282020-04-22T11:20:40.311+03:002020-04-22T11:20:40.311+03:00thank you for you're ansver about if I use onl...thank you for you're ansver about if I use only 20VAC ... I did test it and it works perfect. If I would ever meet you in person I would buy you a beer for succha great schematic you have shared with the rest of the world.Unknownhttps://www.blogger.com/profile/10071188650101328940noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-89312601974116767492020-04-05T03:16:10.785+03:002020-04-05T03:16:10.785+03:00I don't know, maybe it will work, but the max ...I don't know, maybe it will work, but the max output voltage obviously would be lower - probably 20-22 Vdc. The best way is to re-calculate the values of some of the resistors: R10 and R21 for the voltage regulator, R4 and R5 for the correct current trough the zeners. R2 and C2 for the negative rail. And R12, R11 for correcting the gain of IC1B.<br />In fact you can remove the voltage regulator IC3 entirely because the voltage will be lower enough to supply the opamps directly.Христоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-24299230329827859692020-04-04T21:04:01.876+03:002020-04-04T21:04:01.876+03:00Great job you did with this schematic. What would ...Great job you did with this schematic. What would happen if I would have only 20V of AC from my transformer?Unknownhttps://www.blogger.com/profile/10071188650101328940noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-90713885092263890942020-04-04T20:20:55.586+03:002020-04-04T20:20:55.586+03:00Great work you did with this schematic. I was wond...Great work you did with this schematic. I was wondering what would I have to change if I have only 20V AC from my transformer?Unknownhttps://www.blogger.com/profile/10071188650101328940noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-78886068164844304102020-03-24T01:27:02.571+02:002020-03-24T01:27:02.571+02:00Maybe the heatsink is not large enough. You can ad...Maybe the heatsink is not large enough. You can add a fan to cool even more. Make sure to apply thermal paste between transistor and heatsink. Also possible reason for high failure rate can be fake transistors - they usually have smaller crystals and lower power and current ratings.Христоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-20052626706704503302020-03-23T22:22:15.082+02:002020-03-23T22:22:15.082+02:00Hi. I built power supply version 2 and this works...Hi. I built power supply version 2 and this works fine but this PSU likes to burn output transistors.<br />I do not know how much of them i burned. Schematics works good with up to 2 amperes but when i connect bigger load such as automobile lamp to try maximum current the lamp burned out with one of the 2n3055 when stressed. What can i adjust in this schematic to stop burning transistors ?<br />Anonymoushttps://www.blogger.com/profile/13048171423621944359noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-42419591332793349752020-02-19T20:56:29.828+02:002020-02-19T20:56:29.828+02:00Hi. I do not know how you can get this schematic w...Hi. I do not know how you can get this schematic work. On the third pin of LM337 i have only 5V and on the output of LM337 i have 1.5V with opamp installed. When opamp is removed then output is -3V. I have changed R2 to 90ohm and C2 to 100uF it does not give any more current the voltage if dropped if opamp is placed back. Anyone can help ?Anonymoushttps://www.blogger.com/profile/13048171423621944359noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-32921525685104412522019-12-26T14:16:38.772+02:002019-12-26T14:16:38.772+02:00*three solutions :)*three solutions :)Христоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-25685296493786764352019-12-26T14:15:15.388+02:002019-12-26T14:15:15.388+02:00The minimum current depend (in part) on the input ...The minimum current depend (in part) on the input offset voltage of the IC1A. There are two solutions:<br />1. You can try to change the opamp.<br />2. You can connect the lower side of P3 via resistor to the negative rail (-3V) to compensate the input offset voltage. The resistor should be about 28-30k (if my calculations are correct). I haven't tried this solution, so be careful.<br />3. You can use two separate single opamp TL081 instead of one double opamp TL082. The TL081 have two pins dedicated to offset null adjustment. in this PDF (page 13, figure 20) is shown how to connect these: http://www.ti.com/lit/ds/symlink/tl082.pdfХристоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-36676099560729322912019-12-26T05:08:40.728+02:002019-12-26T05:08:40.728+02:00Is it possible to get the current limit down to 2 ...Is it possible to get the current limit down to 2 MA? So far, 15 MA is the best that i could do.<br />Thanks for your projects!ElectronicsGeekhttps://www.blogger.com/profile/09432718050277152674noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-55269444840305520392019-12-25T13:28:52.661+02:002019-12-25T13:28:52.661+02:00No, it's different than short circuit protecti...No, it's different than short circuit protection. It's current limiting - you can adjust the maximum current allowable from 10-20mA to 3A. If you short circuit the output and the current is set to 3A, the output transistor(s) will have to dissipate 120+ W power and will probably fail. <br />Short circuit protection usually do not limit the current until it's high enough and then it limits it to a safe level.Христоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-23686655002346396412019-12-24T20:41:40.109+02:002019-12-24T20:41:40.109+02:00This power supply is automatic short circuit prote...This power supply is automatic short circuit protected when the positive and negative are joined at the output?<br /><br />Questo alimentatore e protetto contro i cortocircuiti quando si congiungono il positivo con il negativo in uscita?<br /><br /><br /> Elektronikhttps://www.blogger.com/profile/10113145140629915650noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-19249343228554692312019-04-15T18:29:38.481+03:002019-04-15T18:29:38.481+03:00Can you send me, please?Can you send me, please?Elissonhttps://www.blogger.com/profile/17373380248597928656noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-67532696861655876242019-04-15T18:19:33.039+03:002019-04-15T18:19:33.039+03:00Hi friend you have this project for 0-15v 0-3A ple...Hi friend you have this project for 0-15v 0-3A please thank youElissonhttps://www.blogger.com/profile/17373380248597928656noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-21491871890895677702019-03-08T14:30:26.358+02:002019-03-08T14:30:26.358+02:00I don't understand exactly what you mean.
Cons...I don't understand exactly what you mean.<br />Constant current mode is in a way overload protection - the current can't go over the set limit. Against overheating you can add a simple thermal switch (normally closed) like these: https://www.ebay.com/itm/5Pcs-Temperature-Switch-Control-Sensor-Thermal-Thermostat-35-160-Degrees-KSD301-/163307099368<br />Mount it on the heatsink and connect it between one side of the secondary winding of the transformer and the bridge rectifier - if temperature go higher than selected the switch will go off and will cut of the power to the board. These switches are rated 10A, so you shouldn't have any problems.Христоhttps://www.blogger.com/profile/14002909704834630953noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-75721003891069785222019-03-04T23:01:50.403+02:002019-03-04T23:01:50.403+02:00Regard.
Can you add protection from the overload,...Regard. <br />Can you add protection from the overload, if I wish please request more load protection schemesAftonhttps://www.blogger.com/profile/06954857046284282894noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-73112568531182888362018-12-28T08:45:20.458+02:002018-12-28T08:45:20.458+02:00Please help me with the calculation part of this s...Please help me with the calculation part of this schematic.Arkapravahttps://www.blogger.com/profile/04662174296094675267noreply@blogger.comtag:blogger.com,1999:blog-4191887753331304313.post-50345458695996265872018-12-09T13:14:38.128+02:002018-12-09T13:14:38.128+02:00please i await your response. thanksplease i await your response. thanksAnonymoushttps://www.blogger.com/profile/05609019673818559761noreply@blogger.com