benuron Posted September 22, 2009 Report Share Posted September 22, 2009 Can I use a atx power supply to power the op amps of the opl3 module?It will create some kind of noise in audio signal? ???It was the -12/+12v or the -5/+5v... Quote Link to comment Share on other sites More sharing options...
nILS Posted September 23, 2009 Report Share Posted September 23, 2009 If the few mA that the opamps pull are above the minimum current draw of your atx power supply, then technically yes. Most PC power supplies will introduce a lot of noise audible though. Quote Link to comment Share on other sites More sharing options...
Shuriken Posted September 23, 2009 Report Share Posted September 23, 2009 A PC PSU is unstabilized. What you really want is a stabilized design. I have build a psu according to the following the following design: http://www.circuitsonline.net/schakelingen/30/voedingen/78xx-voeding.htmlThe PCB setup: http://www.uploadarchief.net/files/download/co%2078xx%20voeding%202008.pdfYou can use the design for both the +5V and the -12 and +12 Volt. Or you can combine the -12 and +12 in one design like: http://www.reconnsworld.com/power/multipowersupply.gif Quote Link to comment Share on other sites More sharing options...
benuron Posted October 1, 2009 Author Report Share Posted October 1, 2009 Thnaks for the reply's ;)I will use Center Tap Transformer method http://www.midibox.org/dokuwiki/doku.php?id=bipolar_12v_psuI have some doubts in what transformer should I buy...This one is 15-0-15v 0.3Ahttp://www.leiritronica.com/electronica/product_info.php?cPath=7_8&products_id=41297This is 15-0-15v 1Ahttp://www.leiritronica.com/electronica/product_info.php?cPath=7_8&products_id=41299Or a toroidal transformer of 80 VA 2 x 24 V / 2 x 1,67 Ahttp://www.aquarionet.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=9838&category_id=139&option=com_virtuemart&Itemid=71Which one is the best to power the opl3 module and maybe later the AOUT module? :) Quote Link to comment Share on other sites More sharing options...
boops Posted October 2, 2009 Report Share Posted October 2, 2009 hi i 've used a 30VA 2 x15 works fine...regards Quote Link to comment Share on other sites More sharing options...
Janis1279 Posted October 2, 2009 Report Share Posted October 2, 2009 I have some doubts in what transformer should I buy...This one is 15-0-15v 0.3Ahttp://www.leiritronica.com/electronica/product_info.php?cPath=7_8&products_id=41297Which one is the best to power the opl3 module and maybe later the AOUT module? :)To power the opl3 module and maybe later the AOUT module(-es), is enough with this 15-0-15v 0.3A transformer.But to power the Core module from the another transformer with a little lower secondary voltage ~ 7,5 to 10 volts . Quote Link to comment Share on other sites More sharing options...
benuron Posted October 2, 2009 Author Report Share Posted October 2, 2009 To power the opl3 module and maybe later the AOUT module(-es), is enough with this 15-0-15v 0.3A transformer.But to power the Core module from the another transformer with a little lower secondary voltage ~ 7,5 to 10 volts .Thanks! I will use that 15-0-15v transformer.To power the core module I already have an 9v wall wart supply. :)But...I have more questions!sorry :PI do the math and the capacitor size is 1410uF so I will use a 2200uF, right?Any rectifier will do the job?Do I have to had precautions in which I should pick?What fuse to pick?Fast/slow blow?current? Quote Link to comment Share on other sites More sharing options...
Janis1279 Posted October 3, 2009 Report Share Posted October 3, 2009 But...I have more questions!sorry :PI do the math and the capacitor size is 1410uF so I will use a 2200uF, right?Any rectifier will do the job?Do I have to had precautions in which I should pick?What fuse to pick?Fast/slow blow?current?http://www.midibox.org/forum/index.php?PHPSESSID=8672ceb6daaa67070d21551f269466ce&topic=6735.0http://www.midibox.org/forum/index.php/topic,13044.msg111261.html#msg111261 Quote Link to comment Share on other sites More sharing options...
fussylizard Posted October 3, 2009 Report Share Posted October 3, 2009 See also: http://www.midibox.org/dokuwiki/doku.php?id=northernlightx Quote Link to comment Share on other sites More sharing options...
boops Posted October 4, 2009 Report Share Posted October 4, 2009 hi,of course a another 9v transfo for the 5v of the core..the 30VA 2 x15 works fine for the -12v ;+12v... i 've build with a classic shematic,regards Quote Link to comment Share on other sites More sharing options...
benuron Posted December 18, 2009 Author Report Share Posted December 18, 2009 Ok! I've finished the core and opl3 module, moving to the constrution of the psu. I've more questions... :unsure: On the NorthernLightX schematic after the rectifier, the voltage increase but in the wiki page about bipolar supply's it says that the voltage drops. Anyone can explain? How much is the power consumption of a full midibox FM? :) Quote Link to comment Share on other sites More sharing options...
Janis1279 Posted December 18, 2009 Report Share Posted December 18, 2009 I've more questions... On the NorthernLightX schematic after the rectifier, the voltage increase but in the wiki page about bipolar supply's it says that the voltage drops. Anyone can explain? http://www.answers.c...e_rectification : ... The average and root-mean-square output voltages of an ideal full wave rectifier can be calculated as: ; Where: Vdc,Vav - the average or DC output voltage, Vp - the peak value of half wave, Vrms - the root-mean-square value of output voltage. π = ~ 3.14159 e = ~ 2.71828 Peak loss An aspect of most rectification is a loss from the peak input voltage to the peak output voltage, caused by the built-in voltage drop across the diodes (around 0.7 V for ordinary silicon p-n-junction diodes and 0.3 V for Schottky diodes). Half-wave rectification and full-wave rectification using two separate secondaries will have a peak voltage loss of one diode drop. Bridge rectification will have a loss of two diode drops. This may represent significant power loss in very low voltage supplies. In addition, the diodes will not conduct below this voltage, so the circuit is only passing current through for a portion of each half-cycle, causing short segments of zero voltage to appear between each "hump". ... Regards, Janis Quote Link to comment Share on other sites More sharing options...
benuron Posted December 19, 2009 Author Report Share Posted December 19, 2009 So there is a voltage drop... Sit a bit confused! â– Theory of operation â– The big resistors will dissipate an amount of Volts equal to the amount of Ohm they're rated for, at a current of 1 Ampere. If the current is less than 1A they will dissipate less, but the regulators will be stressed less too, so this is exactly what is wanted. The power out of the mains can be plus or minus 10% of the specification (115V or 230V). Let's assume it is -10%, as it is in my house. So, instead of the 12V the trafo delivers at 230V, it in fact delivers 10,8V (12V - 10%). When rectified and filtered, the voltage becomes 10,8V * 1,41 = about 15,23V. this is perfect for the 7812 and 7912, so far so good. Where that 10,8v * 1,41 comes from? Quote Link to comment Share on other sites More sharing options...
benuron Posted December 19, 2009 Author Report Share Posted December 19, 2009 Found a site with the answer http://www.kpsec.freeuk.com/powersup.htm#smoothing If I use a 12v transformer... The main voltage in my house is 240v so the voltage in the secundary side of transformer would be 12,52v, after the full wave rectifier 11,12v (1,4v loss) and after the smoothing 15,57v good for the 12v regulators, right? Quote Link to comment Share on other sites More sharing options...
Janis1279 Posted December 19, 2009 Report Share Posted December 19, 2009 Found a site with the answer http://www.kpsec.fre...p.htm#smoothing If I use a 12v transformer... The main voltage in my house is 240v so the voltage in the secundary side of transformer would be 12,52v, after the full wave rectifier 11,12v (1,4v loss) and after the smoothing 15,57v good for the 12v regulators, right? I could be wrong. But your secondary DC voltage calculations refers to the power supply with not any load at the output! If you have possibilities to make this similar rectifier + the linear regulator model and to make some simple experiments with loads up to 100 mA, (I think, it's enough for the first time Midibox FM bi-polar power supply), it will give more details for your information. Regards, Janis Quote Link to comment Share on other sites More sharing options...
benuron Posted December 20, 2009 Author Report Share Posted December 20, 2009 I could be wrong. But your secondary DC voltage calculations refers to the power supply with not any load at the output! If you have possibilities to make this similar rectifier + the linear regulator model and to make some simple experiments with loads up to 100 mA, (I think, it's enough for the first time Midibox FM bi-polar power supply), it will give more details for your information. Regards, Janis Yes, my calculations are without load. I made an order of one transformer with 30va and 2x12v, when it arrives I will experiment. And here are some pictures with the core running the midimon app and the opl3 module :) Quote Link to comment Share on other sites More sharing options...
benuron Posted May 4, 2010 Author Report Share Posted May 4, 2010 Finally I can hear some sound from mbfm! :frantics: Bipolar psu and opl3 module The "family" Some more queestions...in my bipolar psu it gives me +12.04v and -11.94v, is that a problem? :ermm: Quote Link to comment Share on other sites More sharing options...
nILS Posted May 4, 2010 Report Share Posted May 4, 2010 Nope, that's well within spec ;) Quote Link to comment Share on other sites More sharing options...
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