[Laser] 5 mw laser transceiver kit

Tue Sep 21 17:27:24 EDT 2010

briefcase / Altoids tin
4 Amp/hr gel-cell / 2 AA batteries

Not even remotely the same....

----- Original Message ----- 
From: "Chris L" <vocalion1928 at hotmail.com>
To: <laser at mailman.qth.net>
Sent: Tuesday, September 21, 2010 4:56 PM
Subject: Re: [Laser] 5 mw laser transceiver kit

>
> Our latest Fresnel/LED optical transceivers fold down to the size of a
> briefcase, flat. With Luxeons thay can be powered off a single 4 Amp/hr
> gel-cell. The optical units have a carry handle to a allow them to be
> carried to mountain tops on foot. Where's the problem? --- Chris VK3AML.
>
>> From: laser at codeadam.com
>> To: laser at mailman.qth.net
>> Date: Tue, 21 Sep 2010 11:54:36 -0400
>> Subject: Re: [Laser] 5 mw laser transceiver kit
>>
>> In reading backwards to the original post that started all of this, it
>> appears to me that original intent of this project, "5 mw laser
>> transceiver
>> kit" was a small device that could fit in ones pocket, run off a couple
>> of
>> self contained small batteries such as AA or AAA (or even a 9 volt
>> battery)
>> and be able to demonstrate short range (couple of miles to a few tens of
>> miles) optical freespace communications.
>>
>> I don't think anyone can argue that LEDs and fresnel lens are the way to
>> go
>> when it comes to ultimate DX but something of that magnitude and size
>> hardly
>> meets the goals of this project.
>>
>> If I knew nothing about this and saw a demonstration at a public meeting
>> (such as a hamfest) where two people were talking over a light beam using
>> equipment that was easily set up and when done could be slipped into my
>> pocket I would be a lot more impressed than seeing a table full of large
>> lens and batteries that needed to be hauled in a car or truck.  This in
>> no
>> way is meant to take away from the larger setup.  It's simply not the
>> right
>> tool for the topic being discussed.
>>
>> Now if the topic of this was "Ultimate DX freespace laser setup" then in
>> my
>> humble opinion the LED / fresnel setup would be the way to go.
>>
>> Of course in keeping with the original idea, "5 mw laser transceiver kit"
>> there is absolutely no reason why one must use a laser.  It could be
>> built
>> using an LED or array of LEDS for the transmitter.  (Before the days of
>> LEDS
>> and lasers people used to modulate light bulbs!)   However, I think the
>> laser is really the way to go for a small setup like this especially when
>> it
>> comes to public demonstrations and attacting new people to the hobby.
>> The
>> laser has self contained optics which are more than ample for this
>> project
>> and over the distances it is intended to be used scintillation is almost
>> a
>> non issue.  Many of us got our start using equipment such as this.  Some
>> achieved their goal and went no further.  However, for others this simple
>> setup wetted their appetite and eventually led to the "Ultimate DX
>> freespace
>> laser setup".
>>
>> I hope the concept of the "5 mw laser transceiver kit" does not stray so
>> far
>> from it's original intent that many will loose interest before it even
>> gets
>> started!!!  This topic has broken down into comparing apples and oranges.
>> For many the "5 mw laser transceiver kit" is all the freespace optical
>> communcation system they will ever need.  For those that need something a
>> bit more, there will always be room for improvement later on and they
>> will
>> always have the "5 mw laser transceiver kit" as a reference to measure
>> just
>> how much better their "Ultimate DX freespace laser setup" is...
>>
>> Just my .02 1/2 cents worth...
>>
>> =====
>>
>> ----- Original Message ----- 
>> From: "Tim Toast" <toasty256 at yahoo.com>
>> To: <laser at mailman.qth.net>
>> Sent: Monday, September 20, 2010 9:18 AM
>> Subject: [Laser] 5 mw laser transceiver kit
>>
>>
>> > Hi All
>> >
>> > It's great to see someone has put a kit together. That is sure to
>> > spark some interest in optical coms. In the interest of a little
>> > fun competition, it would be nice to have a simple kit for laser
>> > com's too. One obvious advantage (or not so obvious) for laser
>> > over LED, is size and power consumption. A simple laser transceiver
>> > could be made very small and portable, even pocket-sized and
>> > battery powered. Under 90 ma. for most 5 mw diodes.
>> >
>> > It would help if everyone could start with the same size, easy to
>> > obtain, enclosure. One that comes to mind is the old "Tuna Tin 2"
>> > kits. You could actually use a tuna can (Tuna Tin THZ or
>> > Tetrazzini?) but someone suggested to me to use one of those
>> > "Altoids" candy tins. They have an easy access door and complete
>> > sheilding, plus plenty of room for a circuit board and batteries
>> > inside. These are the large 5" x 3" x 1" inch size boxes. They
>> > also come in a couple smaller sizes and even round ones, all with
>> > resealable metal lids or doors.
>> >
>> > I was looking at some amplifier circuits today and saw this high
>> > gain hearing-aid design that uses 3 transistors and one battery
>> > (1.5v). If you switch the microphone with a photo detector front
>> > end, you have a high-gain receiver plus part of the transmitter
>> > too. A laser transceiver could be made very small and energy
>> > efficient using a low voltage like 3 volts (2 cells). A 3, 6 or
>> > 9 volt design for the small light-weight battery sizes. With a
>> > dual 555 timer chip, you can have a simple high quality PWM AM
>> > for the laser and a tone generator for MCW or alignment. The
>> > goals being low cost, light wieght, easy to put together etc..
>> >
>> > Relatively cheap optics that work well:
>> > If you are willing to take apart some junk equipment you can find
>> > lots of optical goodies. The old VHS Camcorders can supply most of
>> > the optical parts. An old DVD player will get you a 5 milliwat red
>> > laser diode (these are often dual wavelength visible/IR diodes with
>> > three pins, or four pins if it has a monitor diode) and some small
>> > lenses to use. These even have one lens you can use to collimate
>> > the laser fairly well (the laser pickup "output" lens is a 5mm or
>> > 6mm f0.9 or faster type) or it can adapt the beam for use with a
>> > larger lens. The main large glass lens on the camcorder is usually
>> > a 25 to 50mm f1.0 type when used by itself. It can work for either
>> > transmitter or receiver. Some of the older ones have a fine
>> > adjustment twist focus.
>> > For short range use, it might be nice to be able to defocus the
>> > transmitter and receiver some - up to 10 degrees or more maybe -
>> > these twist focusing lenses would be great for that.
>> > Inside the camera zoom lens are a few smaller glass lenses in both
>> > positive and negative types plus a special "eyepeice" type assembly
>> > - similar to a 15 - 20mm Kellner telescope eyepiece. This could
>> > make a nice finder when paired with a larger objective lens and a
>> > cross-hair. The video viewfinder eyepiece is also adjustable and
>> > could be used for either one or a finder. It is usually a 20mm F1
>> > or F2 plano convex plastic lens.
>> > The performance won't be excellent obviously with these small
>> > lenses but should work for the shorter ranges ok. (under 50 miles
>> > or so?? :) you can always break out the big optics for better
>> > performance.
>> >
>> >
>> > tim toast
>> >
>> >
>> >
>> >
>> >
>> >
>> >
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