[Laser] 5 mw laser transceiver kit

Tue Sep 21 16:56:15 EDT 2010

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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