Questions about these 5V regulators seem to be coming up all the time. My thinking is, if the ampage is less than about 0.8 Amps/board I use the TO-220 1A LM7805's (e.g. Jameco #902071, ~$0.45) and a small heat sink. More typically I use the 7805CV's. They are 1.5Amps and cost the same (#924633). It the total ampage is around 1 Amp, personally I prefer the LM309K's (#23499, $5 each) and a larger heat sink. For greater than about 1Amp I use the LM323K's (or the difficult to find 78H05's) both rated at 3 Amps and the same price. I find the diamond shaped heat sinks (#189835) fit best on most boards. The is no beating the TO-3 for heat dissipation and simplicity. You can run your box with a lower 8 Volt line and use the lower drop-out regulators (and have less heat e.g. the LM2940ET-5.0's (1Amp, $1.40). There are cheap 5 Volt TO-3's on eBay etc. However I would always test them under load (a light bulb) for a few hours first. If you are into efficiency as Bob suggested you need to go to a switching regulator. In the past I have had a KISS approach to V regulators on boards, but with Bob's prodding I have just started using these. Here is a picture of an upcoming 80386 V2 board allows you to use either the TO-3 or switching regulator. Will see how it works out. BTW while I have you and unrelated. The VGA boards just came in, will test in the next few days and report. I will also be announcing a updated/improved SMB V3! Stay tuned... John -----Original Message----- From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Don Caprio Sent: Wednesday, March 11, 2015 10:53 AM To: n8vem...@googlegroups.com Subject: [N8VEM-S100:6514] 7805 Package choices Hey brains I have a question. I'm designing a 5V circuit. Considering the 78L05 (TO-92) and 7805 (TO-220). The L05 is rated at 100ma while the 05 comes in 1a and 1.5 versions. Is there anything in between? 100ma is not quite enough while the 7805 is overkill. Space is a concern so I like the TO-92 package. If I'm reading the datasheet right for a 7 segment display it draws 25-30ma for each segment? Thats a current draw of 250ma if all segments are lit. Therefore I may have to use the 7805/C or change my design to use dual state LED (17-22ma) instead of the 7 segment LED. -- Don Caprio ilv...@gmail.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 n8vem-s100+...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
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