Or, how about putting old linear technology behind us, and embracing the LM2576T-ADJ switching buck regulator? You can buy this puppy ready-made for about $14: <http://tinyurl.com/yhma5h5>
Just change the 8200 ohm resistor to fix the output voltage. The LM2576T-ADJ is rated at 3 amperes. 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Ed Yoho Sent: Friday, February 26, 2010 5:12 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Micor UHF Repeater Base 9.6 vdc currentrequirement? DCFluX wrote: > In that case Just a straight 7809 or 7810 also would not require > isolating the tab and can be mounted straight to the metal chassis. > >> If it were me, I'd just use a 9 or 10 volt three terminal regulator >> (7809 or 7810) and skip the whole LM-317 or diodes in the ground leg >> deal. It only serves to make the circuitry more involved , harder to >> mount, and for NO advantage whatsoever. >> >> Kevin Custer >> > Folks might consider using an LM2940-9 or LM2940-10 (or another LDO regulator) instead of the 7809 / 7810 as the dropout voltage is much lower (0.5V on the 2940 versus 2V on the 78xx typical). This would allow regulation to continue down to an input of 10.5 (-10) or 9.5 (-9) volts. The 7810 will lose regulation at around 12V and the 7809 at around 11V input. Not overly important if the system is being powered from a regulated supply, but if via batteries.............. Ed Yoho W6YJ
