kpete Posted January 16, 2014 Report Share Posted January 16, 2014 Hi all, I built a LPC MidiBox core and wanted to power it from a +12v source. Problem being that the LM7805 dissipates so much power, it gets very hot, even with a heat sink. I was wondering if anyone has tried using a 811-2196-5-ND switching regulator as a substitute. At 90% efficiency it should run fairly cool, even at its 1.5amp output current limit. Here is a Link to the PDF. It costs $4.30 USD for 1 from DigiKey. I was also wondering if it might have problems with the switching noise getting into some of the analog circuits and create audible noise. I don't have this problem since my project is just digital in nature. But it might be a problem for others. Pete Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted January 17, 2014 Report Share Posted January 17, 2014 Hola Pete, those 780X switcher replacements are very usable imho - especially if they only power digital circuitry. But many have used it for analog stuff - if the switching frequency is high enough (> audible range) and you filtered with a few caps and maybe an inductor for scenarios, where there are sudden current changes (not necessary in many applications). Here is another unit, that i´ve used personally and that works great: http://uk.farnell.com/tracopower/tsr-1-2450/converter-dc-dc-5v-1a-sip/dp/1696320 Many greets, Peter (with the same pre and surname as i was told by SmashTv ;-)) Quote Link to comment Share on other sites More sharing options...
mono Posted January 17, 2014 Report Share Posted January 17, 2014 hi kpete, i was just reading this: is there any reason to use 12volts ? im using the LM1085 (http://uk.rs-online.com/web/p/low-dropout-voltage-regulators/5339404/) together with this heatsink: http://uk.farnell.com/aavid-thermalloy/tv1500/heat-sink-to-220-218-14-c-w/dp/179934 theres also an lf33 for the 3.3volts without heatsink. it works fine from a 6volt power-supply and it gives you up to 3amps @ 5volts! it gets warm, but never hot. i dont know about your dc-dc-converter, but for the price of that you can get the 2 voltage-regulators and the heatsink. also theres no problem with switching noise! regards, mOnO Quote Link to comment Share on other sites More sharing options...
kpete Posted January 17, 2014 Author Report Share Posted January 17, 2014 The low dropout part is great but I don't have 6v to work with. The organ has a great 12v supply and I can also see where I might want to use it in other projects with even higher voltages, that if I change the 22000uf 15v capacitor to a higher voltage value. I'm not to worried about spending $4 more for a part that solves the heat issue using 12v or higher. I guess my question was also thinking about reliability. Maybe I will just buy 3-5 of these units and see how they work. I read that some people have problems when using them around RF transceiver (wireless) applications which I don't have around the equipment. Guess I will find out when I do further testing. Too bad I don't have a spectrum analyzer and antenna for testing. Quote Link to comment Share on other sites More sharing options...
Duggle Posted January 18, 2014 Report Share Posted January 18, 2014 Hi kpete, have you searched ebay? There are very many DC DC circuit boards for just a few bucks (in some cases including postage). One suggestion is to use such a switch mode regulator to provide your 5V on the core (simply replace the 7805 with the switch mode PCB) and leave the 3.3V regulator as is (it won't get hot with a 5V input). I've done this works fine, cool as can be. Quote Link to comment Share on other sites More sharing options...
kpete Posted January 20, 2014 Author Report Share Posted January 20, 2014 (edited) I see what you mean Duggle. There is even one for 99 cents. From the picture it doesn't seem to use an inductor which worries me a bit. I see other units which have inductors at 10 units for $12.08 which looks great. Should work fine by adding 3 wires from the LM7805 mounting holes to the new step down regulator module. Edited January 20, 2014 by kpete Quote Link to comment Share on other sites More sharing options...
Duggle Posted January 20, 2014 Report Share Posted January 20, 2014 Should work fine by adding 3 wires from the LM7805 mounting holes to the new step down regulator module. Yes, this will work. Alternatively, feed a 5V input to the core (from the regulator) and leave the 7805 in place, it doesn't hurt to leave it there. Quote Link to comment Share on other sites More sharing options...
civi Posted May 26, 2014 Report Share Posted May 26, 2014 (edited) I have to agree with @Duggle. A simple DCDC can simple erase this problem of using basic voltage regulators since DC-DC convertors are very cheap and have very few losses because they can be made efficient because of the volume for circuitry available to them. Anyways, if you still have to get 5V from 12V using a voltage regulator, I’d suggest getting an LF series IC because of their power efficiency. A small driver circuit might be required but well, everything has its pros and cons. pcb design Edited September 5, 2014 by civi Quote Link to comment Share on other sites More sharing options...
Duggle Posted May 26, 2014 Report Share Posted May 26, 2014 What "LF series IC" are you talking about? Quote Link to comment Share on other sites More sharing options...
Walter18 Posted September 18, 2014 Report Share Posted September 18, 2014 Hi! I would like to share this great online resource for anyone seeking a voltage-regulator: http://www.directindustry.com/industrial-manufacturer/voltage-regulator-62756.html Quote Link to comment Share on other sites More sharing options...
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