Gary, Yours is a very good idea (and I bought a few of those regs for my own use) but I fear there is a chance we cannot use them on this board: Josh mentioned using an 1A v.reg on the board, but from the photo he posted on a previous thread about the 8080A card I see he used an L7805CV, which does 1.5A. I wonder if the filled card goes above the 1A barrier... If not the switching regulator can really be the definitive (and backward compatible with IMSAI cabinet) solution to the problem.
Fabio On Saturday, July 19, 2014, 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] > <javascript:_e(%7B%7D,'cvml','[email protected]');> [ > mailto:[email protected] > <javascript:_e(%7B%7D,'cvml','[email protected]');>] *On Behalf > Of *Crusty OMO > *Sent:* Saturday, July 19, 2014 5:34 AM > *To:* [email protected] > <javascript:_e(%7B%7D,'cvml','[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] > <javascript:_e(%7B%7D,'cvml','n8vem-s100%[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] > <javascript:_e(%7B%7D,'cvml','n8vem-s100%[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] > <javascript:_e(%7B%7D,'cvml','n8vem-s100%[email protected]');> > . > For more options, visit https://groups.google.com/d/optout. > -- Dott. Fabio Battaglia Blog - http://mercatopo.blogspot.com -- 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.
