cyamamot@kilroy.jpl.nasa.gov (Cliff Yamamoto) (10/23/90)
(I'm cross-posting this to pc.hardware for those tinkerers over there)
I've been an avid reader of Sci.electronics since my college days and it
has always been so helpful. The wealth of information is staggering and
I'd just thought I'd submit this simple one evening project for those
interested. It's really too simple to be considered a significant project
but I felt it was useful enough to make one myself half a year ago.
For those who have played with Compaq computers, you'll note that they
use interesting floppy drives whose in-use LED changes color depending on
the density of the floppy. I thought this was pretty useful since I'm in
such a rush, I rarely pay attention to the floppy label and rely on the
LED color to determine the capacity. I liked this feature so much on my
Compaq at work, I wanted to add it to my 386 at home. So here's an ASCII
schematic of what I made:
+5 VDC
| 1/6 1/6
|\ LS04 |\ LS04
Reduced Write (pin 2) >-------| >o----+-----| >o-----+
|/ | |/ | NOTE: red and
| V V green LEDs are
Gnd - Red - Green actually a
____________ | | single bicolor
Drive in Use >----/\/\/------+--------------+ LED.
220 ohm
Red = Lo Density Green = Hi Density
Figure 1 - New In Use LED circuit
Notes: - Reduced Write (pin 2) is low when low density (360K/720K)
- Reduced Write (pin 2) is high when high density (1.2M/1.44M)
- Reduced Write is located on pin 2 of the 34 pin edge connector
- Drive in Use on most floppy drives is active low and is connected
DIRECTLY to the cathode of the original In-Use LED (see Fig. 2)
- Power for +5 VDC can be obtained from pin 4 of the power connector
- Ground can be obtained from pin 3 of the power connector
- Most (if not *ALL*) bi-color LEDs have a common cathode
- Tie all unused inverter inputs to +5 VDC or Gnd (ground)
- You may not need the 220 ohm resistor if your floppy drive already
has one ON THE CATHODE side. Most drives however are configured as:
Red
220 ohm LED ____________
+5 VDC >----/\/\/---->|------> Drive in Use (often NAND gate output)
Figure 2 - Circuit often found on most floppy drives
I took a LS04 and snipped all the pins off leaving just the stubs on the
sides of the chip. Soldered some long wire-wrap wire to it then wrapped
the chip in some duct tape. Small enough to tuck somewhere on the floppy
drive itself.
Most of the parts can be found in your junk box or at Radio Shack. I don't
know if they carry a bi-color LED though. I was lucky since I had just
bought a Toshiba 1.2Mb floppy drive from SoftWarehouse (a fairly large
computer store chain around the USA). This Toshiba had a bi-color LED
built-in! But it was only there so the user could pick the LED color
with a jumper.... permanently! A few cuts with an Xacto, some patch work
to the circuit and that was it.
I probably went overboard on the details, but what I appreciate about
Sci.electronics are the folks here who don't assume everyone is an
electronics wizard. We all had to start at the bottom sometime and I
hope this little project will encourage other beginners to get their feet
wet.
Cheers!
Cliff Yamamoto
-------------------------------------------------------------------------------
USnail: Clifford K. Yamamoto - KA6JRG | Email: cyamamot@kilroy.jpl.nasa.gov
Jet Propelled La-bore-atore-ee | cyamamot@grissom.jpl.nasa.gov
4800 Oak Grove Drive | cky@hydra.jpl.nasa.gov
M/S 238-737, Section 333 | cyamamot@devvax.jpl.nasa.gov
Pasadena, Calif. 91109 | cyamamot@jato.jpl.nasa.gov
---------------------------------------+---------------------------------------
MaBell: (818) 354-1242 - off. (818) 354-6042 - alt. (818) 354-6426 - lab.schriste@uceng.UC.EDU (Steven V. Christensen) (10/24/90)
cyamamot@kilroy.jpl.nasa.gov (Cliff Yamamoto) writes: >... I >hope this little project will encourage other beginners to get their feet >wet. >Cheers! >Cliff Yamamoto Great little project!! We need more projects of that type in sci.electronics! Steven -- Steven V. Christensen U.C. College of Eng. schriste@uceng.uc.edu For the adventurous: svc@elf0.uucp
halbert@grenada.UUCP (Halbert Stone) (10/26/90)
Yes this is great! I have just begun to reawaken my desire to tinker; I used to about 18 years ago... boy things have changed... I would like to see more **Simple Projects** and please don't assume I know much about the particular parts you might think of as generic... The basic concepts are still unchanged but the parts used these days are very different (In the old days bread boarding with a couple of transistors was exciting.) I was not able to continue doing that sort of thing until recently so I'm a bit lost. I would like to start using my XT clone in projects which would monitor and respond to changes; to learn about data acquisition and hardware control. I saw a recent posting about building a transmitter like the garage door opener. That sort of thing could be controlled via the computer to transmit various codes which would be specific signals to activate a variety of things without wires! Gee where do I start...? I'll continue to read here and learn... Thanks, Hal Stone
mlord@bwdls58.bnr.ca (Mark Lord) (10/29/90)
In article <1990Oct23.162706.10585@elroy.jpl.nasa.gov< cyamamot@kilroy.jpl.nasa.gov (Cliff Yamamoto) writes: < <For those who have played with Compaq computers, you'll note that they <use interesting floppy drives whose in-use LED changes color depending on <the density of the floppy. I thought this was pretty useful since I'm in <such a rush, I rarely pay attention to the floppy label and rely on the <LED color to determine the capacity. I liked this feature so much on my <Compaq at work, I wanted to add it to my 386 at home. So here's an ASCII <schematic of what I made: < +5 VDC < | 1/6 1/6 < |\ LS04 |\ LS04 <Reduced Write (pin 2) >-------| >o----+-----| >o-----+ < |/ | |/ | NOTE: red and < | V V green LEDs are < Gnd - Red - Green actually a < ____________ | | single bicolor < Drive in Use >----/\/\/------+--------------+ LED. < 220 ohm < Red = Lo Density Green = Hi Density Well, Radio Shack (here) only sells the two-lead type of bicolor LEDs. With these, the direction of current flow determines the LED color. Any gurus out there who'd be willing to post an equally quick&clean circuit for performing the same function with this two-lead type of LED ? Thanks! -- ___Mark S. Lord__________________________________________ | ..uunet!bnrgate!mlord%bmerh724 | Climb Free Or Die (NH) | | MLORD@BNR.CA Ottawa, Ontario | Personal views only. | |________________________________|________________________|
mlord@bwdls58.bnr.ca (Mark Lord) (10/29/90)
In article <4748@bwdls58.UUCP> I wrote: > >Well, Radio Shack (here) only sells the two-lead type of bicolor LEDs. >With these, the direction of current flow determines the LED color. > >Any gurus out there who'd be willing to post an equally quick&clean >circuit for performing the same function with this two-lead type of LED ? As a starter, I propose the following circuit, using a quad NOR gate package: |\ Reduced Write -+-------------| \o------+ -|-- +---| / | \ / | |/ LED \/ | | o | |\ R220 +--------|---| \o------+ ____________ | | / Drive In Use -----------+---|/ The invertor from ReducedWrite to the bottom NOR gate is simply one of the spare NOR gates from the package, with the other input tied to ground (resistor?). -- ___Mark S. Lord__________________________________________ | ..uunet!bnrgate!mlord%bmerh724 | Climb Free Or Die (NH) | | MLORD@BNR.CA Ottawa, Ontario | Personal views only. | |________________________________|________________________|
wolfgang@wsrcc.uucp (Wolfgang S. Rupprecht) (10/30/90)
>Well, Radio Shack (here) only sells the two-lead type of bicolor LEDs. >With these, the direction of current flow determines the LED color. >Any gurus out there who'd be willing to post an equally quick&clean >circuit for performing the same function with this two-lead type of LED ? Yea. I'll bite. The simplest solution is if you have a spare 1488 rs-232 driver. +12v 1488 | |\ Red-Green ---------| >------/\/\/\/\--------(LED)-----+ |/ 1k 1/4w | | V gnd -12v This will drive the led with about +/- ~8 ma. Change the resistor to 470 ohms to increase this to 16ma if you want and your led likes this much current. -wolfgang -- Wolfgang Rupprecht uunet!wsrcc!wolfgang (or) wsrcc!wolfgang@uunet.uu.net Snail Mail Address: Box 6524, Alexandria, VA 22306-0524