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Hi Everyone:
I was just given 3 solar cells by a friend.
These are the kind that can be purchased
at Radio Shack. Each one delivers 6 volts
at 50 mA maximum. I have already testedHi Everyone:
I was just given 3 solar cells by a friend.
These are the kind that can be purchased
at Radio Shack. Each one delivers 6 volts
at 50 mA maximum. I have already tested
them and they actually delivered 6.5 volts,
roughly, when the sun was low on the horizon,
in the late autumn afternoon, here in Connecticut.I do intend to run an FM transmitter from these.
The package will have a 49 MHz receiver (for now)
which will be
connected to the transmitter. This will relay
audio from my station.I am searching through my junk box for some
old FM Part 15 walkie talkies that operate on
49.83 MHz. I have 3 of them. I have found
one, now all I need to do is find another one.The station audio will be fed directly into the
circuitry of one 49 MHz unit.The solar power repeater package will then
receive the signal and repeat it on the FM band.I may need some more solar cells and some other
parts to isolate the cells from each other.Because of my eyesight limitations, and the fact
that complicated projects are difficult for me,
no attempt will be made to charge any batteries
on this unit (for now). It will just run when
the sun is visible to supply the energy.Because of life’s limitations, my Part 15 station has
always been the kind for experimentation. I wish
I could broadcast real programming to a real
audience. Although I do have ideas for real
broadcasting, it’s not in the cards right now.But I have always wanted to try to make a solar
powered repeater in the 88 – 108 range.Assuming I find that other 49 MHz unit, it will
be happening soon.If you guys have any comments, please let me
know.Best Wishes
Bruce, MICRO1690/1700P.S. I do intend to put the unit in a
very high spot.
Total posts : 45366Hi MICRO1700
Will the audio originate in the computer?
How will it get to the SENDING unit at 49mHz?
Will the SENDING unit be indoors or outdoors?
What structure will the sending unit be mounted on?
How far away will be the RECEIVING unit at 49mHz?
What structure will the RECEIVING unit and FM transmitter be mounted on?
Total posts : 45366The initial tests will just be in my house to get it
working. There are 5 FM channels in the 49 MHz
band. I would like to operate between two channels
if possible. So, instead of 49.86 or 49.875 – I would
(hopefully, eventually) modify the units to be on 49.8675 (if my math is
correct.) This will be independent of any other
AM or FM transmissions from my station. My station audio
chain will feed the 49 MHz transmitter the same way it feeds
any of my other transmitters. The 49 MHz
transmitter will be upstairs in my house for now.The solar powered 49 MHz receiving unit and the FM transmitter
will be in a little box with solar panels on the side facing the
sun and have transmitting and receiving antennas. The idea is
that is could be put anywhere. I want to put it high up in a
neighbor’s tree, about 800 feet from my house.Because my programming is old jazz, big band, and old radio
shows, fidelity (or lack thereof), will not be a big deal.I have to go – but I will tell you more when I can.
Best Wishes
Bruce, MICRO1690/1700
Total posts : 45366you know,
I modified an RC planes controller to send out audio.
It actually did not sound bad.
Total posts : 45366Thank you Mr. Crow for the idea about the
RC plane controller. That’s a good idea.One of the solar cells powers my C. Crane
transmitter when held right under a 40 watt
light bulb. So this is a start.Best Wishes
Bruce, MICRO1690/1700
Total posts : 45366Your testing with solar and the 49mHz is interesting.
This is the 75th Anniversary of Major Edwin Armstrong’s first FM transmission on 42.8mHz from Alpine, New Jersey.
The original FM band, before television got it moved, was somewhere in the 40 to 50mHz region.
So, MICRO1700, how about dedicating your experiments to the inventor of Frequency Modulation and let’s all solar collect with out-loud readings from The Book of Part 15.
Total posts : 45366One thing you might want to watch out for – the transmitted signal on the FM band could get into the 49Mhz receiver and cause issues. I’m assuming that the walkie talkies are fairly inexpensive, so their front ends could easily be overloaded with the (relatively) strong signal from the FM transmitter.
When I run my Rangemaster, the signal can get into my amateur radio receiver (especially on 40 meters), which is a lot more sophistocated that that 49Mhz walkie talkie. And the antenna’s are separated by at least 25 feet, with some fairly expensive low loss cable running from the amateur receiver to the antenna.
Total posts : 45366To Artisan Radio:
You are absolutely right. The FM BCB transmitter
might swamp the 49 MHz receiver.Well, I guess we’ll see what happens. My intent is
to have this be an inexpensive project for now –
and the 49 MHz radios are just sitting around my
house somewhere – except for the one I have found.
It’s in a safe place now. So I only have to find one
of the other ones. Anyway, thanks for the input,
I appreciate it.And to Carl:
I am about 100 miles from Alpine, New Jersey. I actually
did try to hear the 42.8 MHz transmissions in West Hartford,
Connecticut. I went to a famous place, as far as radio
and television is concerned. I went to Selden Hill, in West
Hartford. I’m sure you have read about the early VHF
experiments in the late 1930s that took place there.Early experimenters were able to receive some of the first
television transmissions from New York City at Selden Hill
in the late 1930s.Also, some of the same people built a gigantic radio controlled
glider and launched it down Selden Hill. The glider’s receiver
used vacuum tubes and received around 60 Mhz, if I’m not
mistaken.The old FM band went from 42 to 50 Mhz, I believe. I was
not able to hear the Alpine transmission on 42.8, but I’m
glad I tried. I understand the originator of the 75th
anniversary FM transmission from Alpine had reconstructed
(or built from scratch) a replica of a famous 250 watt RCA
42.8 MHz FM transmitter. It used the wonderful Phasitron vacuum tube.
The transmitting antenna used for the anniversary tribute in Alpine was on the same
tower that Major Edwin Armstrong had constructed there for
the Yankee Network. It is a tower
that cannot be missed, because it has 3 gigantic cross pieces
on it.I could ramble on about this subject for hours.
Thanks to both Artisan Radio and Carl.
Best Wishes,
Bruce, MICRO1690/1700
Total posts : 45366A little off topic but with regard to the Armstrong Commemerative Broadcast, I have a recording of the program broadcast a few years ago.
The broadcast was simulcast on the original frequency with a special authorization license and the web. My recording was off the web.
The program was quite long so I broke it into a few files to keep the files smaller.
I’m sure it was probably copyrighted so no one would want a copy to air (wink-wink-nod-nod).
Total posts : 45366Hi MRAM! Armstrong is a personal hero of mine, too.
I’m sure you and a lot of other people on this board
have seen the incredible documentary, “Empire Of The Air.”It’s a real shame that Armstrong did not live to see
FM radio really flourish!Best Wishes
Bruce, MICRO1690/1700P.S. My brother is a broadcast historian and
heard that broadcast from five years ago.
I believe it was also broadcast from WFUV, 90.7,
Fortham (Sp?) University, New York.
Total posts : 45366Upon reading the comments about the commemorative broadcast I checked archive.org and found the 70th Anniversary program available as “community audio.”
http://www.archive.org/details/armstrong-commemorative-broadcast
Total posts : 45366Thanks for that, Carl.
That’s good to know.
Bruce, MICRO1690/1700
Total posts : 45366I found the second 49 MHz walkie talkie. I wired
my station audio processor output directly into the
circuit board of the first 49 MHz unit and shorted out
the transmit switch so it would always stay in transmit
mode.Then I wired directly into the board of the second 49 MHz
unit that will be used as the receiver.I turned my audio board and audio processor, and put a record
on the turntable. Then I was running audio into the
49 MHz transmitter. Then I brought audio out of the
49 MHz receiving unit and fed it to my C Crane transmitter,
which has been modified for mono and is transmitting on
88.3 MHz.Listening to the FM radio on 88.3 – well – it sounded pretty good.
The fidelity was acceptable.
(In other words, the music had highs and lows, it
didn’t sound like a telephone.) Both 49 MHz units and the
C Crane are running on batteries right now.Right now there are no antennas on the 49 MHz transmitter
or receiver. The units are about 15 feet apart and there
is no noise, just a little hum because the 49 MHz units are
not in shielded boxes.I bought some diodes to isolate the solar cells because they
will be in parallel with each other. Running the C Crane will
be no problem in sunlight (I think) as I was able to run it under
a light bulb (well, almost touching the bulb). Although I haven’t
measured the current the C Crane needs, I don’t think it is much.I need a few more solar cells to power the 49 MHz receiver.
Right now my local Radio Shack
doesn’t have any, but I will get more when they are in stock.
Again – the solar cells that were given to me are the same as
the ones obtainable at Radio Shack. Each one is 6 volts at
50 mA.So I have almost all of the pieces for a remote 49 MHz receiver
and Part 15 FM repeater that will run off of sunlight. No attempts
will be made to charge batteries at this point of the experiment.And as mentioned before, I want to get onto a 49 MHz link frequency that is
in between the baby monitor channels.So far so good.
Best Wishes
Bruce, MICRO1690/1700
Total posts : 45366Would you get better sound outcomes with the audio processing after the receive walkie? That way you could re-curve the audio after the audio had gone through the STL…
kewl work, all the way around
Total posts : 45366If your 49mHz system doesn’t have pre-emphasis you might consider adding it to the transmitter and de-emphasizing either in the receiver or after the receiver.
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