Power supplies

mosc · Posted: Mon Feb 11, 2008 11:17 am Post subject: Power supplies

Most CMOS logic will work well on 5 Volt DC supplies. Before starting to build a Lunetta, it's a good idea to start with a good 5V DC supply.

This topic is for people to post designs for such supplies, or places where they can be obtained, etc.

CMOS logic uses very low power, so it is possible to use batteries. Standard AAA, AA, D, and C cells are about 1.5 V. So 3 or 4 in series makes a usable supply and your Lunetta becomes portable.

Please post power supply designs here, as well as questions and comments.

Clack · Posted: Mon Feb 11, 2008 1:44 pm Post subject:

I just based this off the lm317 datasheet and other sources I could find cos its quick to lay out - and i know how to do it! Very Happy

.

Based on the LM317 - PSU2 version is probably better - all resistors in ohms not Kohms

6.5-20v dc needed

PSU.GIF

Description:

Filesize:

6.32 KB

Viewed:

516 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

PSU2.GIF

Description:

Filesize:

8.28 KB

Viewed:

505 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

blue hell · Posted: Mon Feb 11, 2008 2:05 pm Post subject:

I'd not use the adjustable one ... even bad old TTL is happy from 4.75 to 5.25 V , so it's not too critical.

Clack · Posted: Mon Feb 11, 2008 2:20 pm Post subject:

oh right ok.. cool. Bit over the top then! to be honest they dont really need schematics there is barely any parts - I guess a little PCB/Stripboard layout is all that is needed

williamsharkey · Joined: Jul 31, 2005 Posts: 61 Location: usa

<- newbie

Why regulate voltage when one can combine household batteries in series and parallel to obtain ~5 volts.

Is this for people who: don't want to use batteries and have a dc power supply in the range of 6.5 to 20 volts?

Clack · Posted: Tue Feb 12, 2008 9:10 am Post subject:

Yeah, it works with most dc wall warts ( you find them everywhere theese days - it will work with most ) - its especially usefull if you want some LED's. too many of them an it will not take long to drain battery power. Batteries wont need regulators

Im not a great fan of batteries when you use them in your bedroom - it seems a waste - although im sure you could say using mains is a waste too.

As blue hell said though - using this regulator is probably a bit over the top - i'll leave it up anyway. but a lm7805 is probably better - they are easy to find sometimes in electronic junk too.

blue hell · Posted: Tue Feb 12, 2008 10:04 am Post subject:

Clack · Posted: Tue Feb 12, 2008 12:02 pm Post subject:

oh right, heh - I just put that on because 680R is the nearest value I can get

williamsharkey · Joined: Jul 31, 2005 Posts: 61 Location: usa

Why is C2 drawn differently than C1, do they represent different types of capacitors?

Perhaps the order of connection of the leads matters in C1?

23isgood · Posted: Tue Feb 19, 2008 3:23 pm Post subject:

Why not just build one of these new power supplies from MFOS? I hate wall warts but this is pretty easy to build.

http://www.musicfromouterspace.com/analogsynth/WALLWARTSUPPLY/WALLWARTSUPPLY.php

danielwarner · Joined: Dec 18, 2006 Posts: 65 Location: Sacramento

williamsharkey · Joined: Jul 31, 2005 Posts: 61 Location: usa

danielwarner · Joined: Dec 18, 2006 Posts: 65 Location: Sacramento

In this instance, the cap comes after the voltage regulator, after the voltage has been regulated down to +5V. You'll be fine with a 10V cap.

danielwarner · Joined: Dec 18, 2006 Posts: 65 Location: Sacramento

For future reference:

If you have two 10V caps, you can put them in series and they will behave like one 20V cap at HALF the farad rating

Two 10V 20uF caps in series would give you a 20V 10uF cap