the best power regulator

[John Gutmann]

what is the best power regulator for 5 volts to use with TTL? I know there are some good ones in the TO-220 package but idk what ones. any ideas? links?

[Matt Krass]

Regulating down from what? You might want to check out Maxim ICs (www.maxim-ic.com) level shifters, nice stuff and they'll usually give you free samples.

[Mike Betts]

Originally Posted by sparksandtabs

what is the best power regulator for 5 volts to use with TTL? I know there are some good ones in the TO-220 package but idk what ones. any ideas? links?

Without more information as to exactly what your specifications are, the 7805 is the industry standard for TTL applications.

The 7805 is made by many manufacturers. Here is National's implementation.

Mike

[Hutch]

Ugh, sorry about the Puzzler post... Definitely left logged in and I didn't notice.

Anyhow, I'd say the best solution would be the regulator but if you don't have one, another (possibly cheaper) solution could be made with appropriately rated zener diodes.

EDIT: Found some decent diagrams and an explanation of how to do things the zener diode way, as well as how to do it with regulators (just keep hitting next slide):

http://www.mines.edu/Academic/course...t11/sld005.htm

[John Gutmann]

down from 12 volts

[John Gutmann]

so if i used a 12 volt in put and get +5volts as an output then what do i use as ground?

[BrianBSL]

Originally Posted by sparksandtabs

so if i used a 12 volt in put and get +5volts as an output then what do i use as ground?

On a 7805, and most regulators, the grounds are tied togeather. on a TO-220 package, the metal tab is usually internally connected to the ground as well (so make sure you don't short anything out on it).

[Hutch]

Yep voltage is all relative, so it's output 5 volts relative to the wire the chip's ground is attached to.

[John Gutmann]

so i use the output ground as the input ground, and i have seen schematics of 7805's that hav non-polarized capacitors between the leads and i was wondering if those are neccessary, if they are what size should I use? and if not should i use somthing else

[Hutch]

They aren't completely necessary, but they will prevent current spikes. When logic gates change states, they draw a lot of current (relatively), and the capacitors across the leads will keep the the current drawn from spiking as much.

[ConKbot of Doom]

Yes, the caps are necessary. The stabilize the regulator and keep it from oscillating. Larger caps however, will help out with current spikes. Larger caps in addition to the small ones, not instead of.

[Hutch]

Hmmm I didn't recall them being necessary. But I at least am 99% sure that you can have the large ones instead of small ones since, after all, parallel capacitors are like one bigger capacitor (hooray for narrow, worthless AP physics knowledge ).