Looks like the price of the L4940 has gone up... its now ~$1.57 at 10 each from Avnet...
On Sat, Jul 19, 2014 at 2:26 PM, Tom Lafleur <[email protected]> wrote: > I have been using ST-Micro L4940 LDO (.7v drop) 1.5A, TO220 voltage > regulators on my board... Much better that the 7805, runs cooler that the > 7805's and at Avnet Express, its a bit under $1 each... > > I have also found that Avnet Express is alway cheaper that Mouser, Jamco > or Digikey for most parts.... > > > On Sat, Jul 19, 2014 at 9:47 AM, Gary Kaufman <[email protected]> wrote: > >> Josh - >> >> There's a tiny 1A switch mode voltage regulator on Ebay (Item >> 261355553215) and directly on the seller's site: >> >> http://www.elabpeers.com/40v-to-5v-voltage-regulator-lm7805.html >> >> Looks like it might be a perfect fix for the problem here. I suspect the >> problem isn't the 1A rating, but rather the thermal limitations of the >> TO-220. >> >> I've ordered two and can report back once I receive them. I offered the >> seller $9.50 each / quantity 2 with the ebay "Make an offer" and it was >> quickly accepted. >> >> - Gary >> >> >> On 7/19/2014 11:49 AM, John Monahan wrote: >> >> Just want to mention, people may want to consider using the 1.5A To-220 >> regulators rather than the old 1A 7805’s. For example a L7805CV (Jameco >> #924633). Indeed I seem to remember Mouser had 3A 5V’s in a TO-220 package. >> >> There are a lot of chips for one 7805 on that board. On a V2 version >> Josh, you might want to consider a 3A LM232K, I know they are a real pain >> to get, take up much more room, but they do run much cooler. >> Alternatively put two To-220’s on the board. It’s probably just me, but I >> don’t like hot boards. Over time the fiberglass starts to deform/change >> color… minimally put a mica washer between the heat sink and board. Also >> use heat sink paste. >> >> >> >> John >> >> >> >> >> >> *From:* [email protected] [mailto:[email protected] >> <[email protected]>] *On Behalf Of *Crusty OMO >> *Sent:* Saturday, July 19, 2014 5:34 AM >> *To:* [email protected] >> *Subject:* RE: [N8VEM-S100:4637] 8080 CPU - Heat is ON - Wet Finger Test >> >> >> >> Hi Guys, >> >> Because the 7805 can get hot, I want to just issue a safety warning for >> everyone. >> >> Hopefully, most of you already know this, but just in case, it's always a >> good idea to remind and inform the new comers. >> >> When powering a board for the first time, be ready to check the voltages >> and monitor the heat of the regulator(s). >> Cut power off at the sign of any trouble. >> >> When monitoring the heat of the regulator by finger, always use a wet >> finger. Doesn't sound right near electricity, but hopefully you have a >> properly grounded power supply and chassis. The wet finger will prevent >> severe burns if the temperature is over 100c. When it's over 100c, a quick >> light tap on the surface with a wet finger will give a quick sizzle. It's >> like testing the temperature on your clothes iron. The best way is to use >> an infrared surface thermometer, but I only got one of those a few months >> ago. Up to now, I've always used the wet finger without incident. >> >> Regards, >> Josh Bensadon >> >> -- >> You received this message because you are subscribed to the Google Groups >> "N8VEM-S100" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> -- >> You received this message because you are subscribed to the Google Groups >> "N8VEM-S100" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "N8VEM-S100" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > > ~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~ > > Tom Lafleur > (858) 759-9692 > -- ~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~ Tom Lafleur (858) 759-9692 -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
