Re: CMOS Super Keyer II -- battery/regulator


From: Stephen M. Shearer, 695-7719 (
Date: Mon Jan 23 1995 - 16:57:46 EST

> Hi Stephen!
> I built the CMOS Superkeyer about a year ago and have been really
> happy with it.
> When I built it I added a very low current 5-volt regulator made by
> Maxim and used an alkaline 9V battery. It has been running for over
> a year now. I used the 9V battery because it is smaller than the
> three AA cells.
> I don't believe a nicad is necessary, as the current drain is very
> low in fact, that a power switch is not needed!
> For a speaker, I used a small surplus speaker used in laptop
> computers. Unfortunately, the type of speaker I am using does not
> have much volume. I also have a earphone jack so I usually connect
> up a larger external speaker to the jack.
> Have fun!
> 73s..... :-)
> Charles
>Charles Furnweger NEC Electronics, Inc. Mountain View, CA
>Voice: 415 965-6433 FAX: 415 965-6374

        I like the idea of the MAXIM regulator, but I wasn't quite sure where to fine one,
(han't had the time to "hunt") until I got my latest copy of EE Product News(tm) and MAXIM
has a full page add... They have a new(?) one just for 9v (5.5 to 11.5v) to 3, 3.3 or 5volt
useage. Number MAX639, MAX640 and MAX653. I am not sure which number goes with which
voltage. (what regulator did you use???) For other readers, Digi-Key carries the chip (8
pin dip or surface mount). I need to find a current copy of the catalog to see how much
$$$'s (it may be new enough not to show in the catalog). Anyway, I sent a FAX
(408-737-7194) to MAXIM for information and their "power supply design guide". BTW, also
from EE Product News, Micro Linear Corp. has a dc-dc converter that will convert 1v to 3,
3.3, or 5v. So, if you want to run on a single AA battery....

Since the keyer can operate at 3 to 5.5 volts, does anyone have any reason why I souldn't
run at the lower voltage (to get the most out of the 9v battery) MAXIM info says it will
"squeeze the last drop of energy from a 9v battery", squeezein to 3.3v sounds better then
5.0??? I was going to use a 4.5v battery (about the same size as the 9v) a #523 at ~$5.00.
I like the 9v/reg better as the regulator also has a low battery output, maybe I can drive a
led on the front panel?

I have found time to put the keyer together, now it's make it fit into the small case I
found. I plan on making my own switch(s) for the push buttons as I want lever switchs in
the front panel along with the mini speed pot. I found small lever switches, but they will
tip over the case when "pushed"... Digi-Key also has small speakers, I'll try before I
drill mounting holes... I may also "play" with driving an led to "see" the function
response(s) for the switches and a earphone/speaker jack to bypass the led. (anyone have
thoughts???) My case is (outside) 3.918 x 0.972 x 1.77deep... inside I only have 3.213 wide
by 0.827 high... not a lot of space (note I am working in 0.001 of an inch - overkill, as
0.01 would do...)

73, Steve WB3LGC

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