[Laser] Re: daytime receiver
Stewart Nelson
sn at scgroup.com
Thu Oct 14 02:57:31 EDT 2004
> is that website mirrored anywhere? qsl.net blocks
> several isp's from viewing their webpages (im on AOL)
> so i cant see anything
>
Tim,
Learn to use a proxy server, or get a real ISP.
Jim Moss text, copied from his site at
http://www.qsl.net/wb9ajz/laser/data/cheepo.txt
is below:
--Stewart, KK7KA
---------------------------------------------------------------------
Cheepo Laser "CW" Transceiver
by WB9AJZ/6 Jim Moss jmoss at berlioz.nsc.com
revised 5/5/97 added 1K resistor to ground from 150K feedback.
Parts can all be found at Radio Shack. Feel free to substitue better parts
or redesign at will. There is no ownership, or responsibility for this
design associated with me. Use at your own risk! But have fun! Use care
when operating lasers, as they can cause eye damage. More on this another
time. Just don't look into the beam for now.
Receiver
--------
Parts:
TL082 opamp, rs# 276-1715
LM386 audio amp
photo transistor rs#276-145a
1K Ohm Resistor
10Mohm Resistor
150Kohm Resistor
3 .01uF capacitors
10k pot
2 10uF caps
50 uF cap
2 battery clips
2 9v batteries
2 9v battery connectors
1 earplug speaker
1 1/8" sub min jack
double perf board with copper, break in half
Forgive the "TEXTUAL" drawing: I'm sure you can improve on this
mediocre design.
+9v
|
\ 1/2 TL082 1/2 TL082 LM386
/ 10M
\ .01uF 3|\ 1 .01uF 5|\ 7 .01uF 10K pot
/-----||------|+\--+----||------|+\---+-||-----\ |\ 50uF
|/ ---|-/ | ---|-/ | / 3| \ 5 +
~~| | 2|/ | | 6|/ | \<----|+ \-----||--center
|\ |_______| | 150k | / |--|- /1 10uF of
v \/\/\/\/ \ | 2| /----||--| jack
| Note: TL082 power is\ | | |/8 + |
-9v pin8 to +9v / -9v -9v \_________|
pin4 to -9v \ 1K
/ Note: LM386 pin 6 to 0v
| pin 4 to -9v
gnd 10uF cap from
6 (+) to 4
OK thats the Receiver. Should take about an hour to build.
To test it, just turn on a light and listen to the buzz.
You can adjust sensitivity by changing out the 10M resistor with a smaller one.
ie. 1M or 100k or 10k. The pot can adjust volume (somewhat). The 386 is
strong enough to drive a small speaker (like computer type).
Transmitter
-----------
Parts
laser pointer (any will do, but look for one you can route a wire pigtail out
of without destroying it! Then you can still use it for work!
I am trying to standardize here on 670nM, but you can choose.
this only becomes important when you start using bandpass
filters. I run a 4mW one.. you can use 1-5mW. Fry's here
in CA has sales with their cheepest at 29.99+tax. beam looks
OK, but a bit broad.
LM555 astable osc
NPN xsistor (your choice of #)
4.7k resistor
10k resistor
15k resistor
10k pot
8.2k resistor (you can change this)
.068uF cap
2 1/8" jacks
2 1/8" plugs (1 for keyer, 1 for laser)
1 9v battery connector
1 9v battery
2 9v battery clips (1 for laser, 1 for battery)
1/2 (the leftover half) PC perf board (about 2"x2")
Goal is to build a on/off controllable 800Hz oscillator to key the laser.
You can adjust .068 cap and resistors as you like.
10k pot 4.7k
\/\/\/--\/\/\/-- .068uF
T | ----------------+----||---
| | 15k | | |
\-----+9v +/\/\/+ n/c to pin GND
| | | | 2
---------------------------
| 8 7 6 5 |
| LM555 |
| |
| 1 2 3 4 |
---------------------------
| | | |
GND to pin | +-----------------On/Off Key to +9v
6b | \
| / 8.2k /------Keys laser
| \ |
| | | (optional)
| GND +-\/\/\/\-- +9v
| / 10k
| 1.5k |/
\--/\/\/\/\---| NPN of choice
|\
V
GND
Inside the laser you will find the switch that turns it on and off.
Identify the ground and voltage sides with a VOM. Connect ground of laser
to ground of cct. Connect hot side of switch to "keys laser".
Use your keyer or hand key or switch to key the "ON/OFF KEY". One side
goes ot this pin the other to +9v. If you need to, you can add a
transistor cct to buffer to your keyer. Mine works fine.
Mount the 2 9v battery holders one on top, one on bottom of the cct board.
you can put the battery in one and the laser in the other.
To test: point laser to ceiling. Move it back and forth quickly while
holding the key down. You will see dashed lines instead of a solid line.
You can even "see" the duty cycle! This was discovered by my daughter!
- - - - -
TOGETHER?
You can put the 2 pieces in a case, but... beware the rx picks up the
555 oscillation. Best to encase the RX in an alum case OR since we are
cheap, aluminum foil (with a wire to the cct board ground). Be sure to
leave a hole for the phototransistor.
AIMING?
Handheld is almost useless. A camera tripod is good. For practice go
to your local car parts store and look for DOT-90 reflectors. They have
sticky backs and you can get a great return on them (about $4). Or head to
the junk yard for reflectors off cars (thunderbirds have GIANT ones in the
rear lenses (a few years ago).
Bore sites seem very good. I mounted a 1/8" ID tube to my laser. I site
thru it. Works good in daylite, but problems at nite, unless there is a
light source at your target.
Lots more to be written on this subject... LATER!
CLOSING
DO IT! I need contacts in JUNE from UC Santa Cruz, CM87xx!
Jim
WB9AJZ/6 Sunnyvale, CA CM87xi
jmoss at berlioz.nsc.com
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