Solar Power Update

Hello Bruce MICRO1700 and I'm going to join the crowd following youe experiment.

With each report please provide a sun report including

Time of day
Location of sun overhead
Clear or cloudy
voltage reading at each time

That will help us form a view of what is happening.

Hello Bruce MICRO1700 and I'm going to join the crowd following youe experiment.

With each report please provide a sun report including

Time of day
Location of sun overhead
Clear or cloudy
voltage reading at each time

That will help us form a view of what is happening.

Hi Carl!

Well, the time of day I did this test was
between 11:30 AM and 12:45 PM
Eastern Standard Time (here in Connecticut.

The sun was in the southern part of the sky
at an azimuth of about 70 degrees.

The sky was a beautiful blue, but it was
occupied by maybe 30 percent clouds.

I do not have any voltage readings, yet -
and current would be very interesting, too.
I'll have to get some meters hooked up so
I can look at current delivered and current
consumed.

I can tell you this. A solar cell will deliver some
voltage from an overcast sky, but there must
be virtually no current available. I could
not power the C Crane under those conditions.

The weather has been cloudy here for days.
This was the first chance I had to try to power
the transmitter directly from sunlight. As long
as there is enough sun to cast shadows, the
hookup works.

I wanted to try to power the STL receiver,
but the sunlight is gone now.

I've got to get some meters in line for the
next test. (Whenever the sun comes back.)

As with all my projects, this is going to take
a fair amount of time.

But it is really fun.

Best Wishes,
Bruce, MICRO1690/1700

Hi Carl!

Well, the time of day I did this test was
between 11:30 AM and 12:45 PM
Eastern Standard Time (here in Connecticut.

The sun was in the southern part of the sky
at an azimuth of about 70 degrees.

The sky was a beautiful blue, but it was
occupied by maybe 30 percent clouds.

I do not have any voltage readings, yet -
and current would be very interesting, too.
I'll have to get some meters hooked up so
I can look at current delivered and current
consumed.

I can tell you this. A solar cell will deliver some
voltage from an overcast sky, but there must
be virtually no current available. I could
not power the C Crane under those conditions.

The weather has been cloudy here for days.
This was the first chance I had to try to power
the transmitter directly from sunlight. As long
as there is enough sun to cast shadows, the
hookup works.

I wanted to try to power the STL receiver,
but the sunlight is gone now.

I've got to get some meters in line for the
next test. (Whenever the sun comes back.)

As with all my projects, this is going to take
a fair amount of time.

But it is really fun.

Best Wishes,
Bruce, MICRO1690/1700

After having a successful try at running
the C Crane FM transmitter just by sunlight
and nothing else, I went to step two.

Step two was (and still is) to run the 49 MHz STL
receiver just by the sun. Hook the two units
together and you have a solar powered
repeater, as I mentioned in the other thread.

Step three will be to change the STL to the
900 MHz band.

Step four will be to work on a recharge scheme
that is self sustaining.

Step two has failed so far. (Oh, and hi to
Carl, all my sun and sunlight data was just
about the same as the first experiment.)

I have four solar cells each supplying
6 volts at 50 mA. I put two cells in series
for 12 volts at 50 mA. I did the same with
the other two cells. The I paralleled both
pairs to theoretically provide 12 volts at
100 mA.

There is one slight problem here. The 49 MHz
receiver wants 9 volts. As far as I can tell
it draws 25 mA at that voltage. I hooked it up
to the solar cells that are delivering 12 volts.
My reasoning was that the 49 MHz receiver would
work fine at 12 volts but nothing happened.

I know the receiver was not damaged, because
after that try I put it back on a 9 volt battery
and it was fine. Perhaps at 12 volts, instead of
9, the current demand for the STL receiver is
more than the solar cells can provide.

So that's where things are now.

Best wishes,
Bruce, MICRO1690/1700

After having a successful try at running
the C Crane FM transmitter just by sunlight
and nothing else, I went to step two.

Step two was (and still is) to run the 49 MHz STL
receiver just by the sun. Hook the two units
together and you have a solar powered
repeater, as I mentioned in the other thread.

Step three will be to change the STL to the
900 MHz band.

Step four will be to work on a recharge scheme
that is self sustaining.

Step two has failed so far. (Oh, and hi to
Carl, all my sun and sunlight data was just
about the same as the first experiment.)

I have four solar cells each supplying
6 volts at 50 mA. I put two cells in series
for 12 volts at 50 mA. I did the same with
the other two cells. The I paralleled both
pairs to theoretically provide 12 volts at
100 mA.

There is one slight problem here. The 49 MHz
receiver wants 9 volts. As far as I can tell
it draws 25 mA at that voltage. I hooked it up
to the solar cells that are delivering 12 volts.
My reasoning was that the 49 MHz receiver would
work fine at 12 volts but nothing happened.

I know the receiver was not damaged, because
after that try I put it back on a 9 volt battery
and it was fine. Perhaps at 12 volts, instead of
9, the current demand for the STL receiver is
more than the solar cells can provide.

So that's where things are now.

Best wishes,
Bruce, MICRO1690/1700

Hey Bruce Micro1700 good laboratory going on over there.

I'm glad the question of changing voltage came up, because that's a branch of electronics I've always meant to explore.

I have (in deep-storage) a Ramko Audio Board whose power supply is (from memory) a 12-Volt DC bus that feeds a string of little black devices, each of which changes from 12-V to particular other voltages, like 6-Volts, 24-Volts, and I think up to four or five total different voltage busses. Maybe later I'll dig out the schematic.

My guess is that someone will know what those little voltage changers are called.

Hey Bruce Micro1700 good laboratory going on over there.

I'm glad the question of changing voltage came up, because that's a branch of electronics I've always meant to explore.

I have (in deep-storage) a Ramko Audio Board whose power supply is (from memory) a 12-Volt DC bus that feeds a string of little black devices, each of which changes from 12-V to particular other voltages, like 6-Volts, 24-Volts, and I think up to four or five total different voltage busses. Maybe later I'll dig out the schematic.

My guess is that someone will know what those little voltage changers are called.

Hi Carl! Are you maybe talking about DC to DC
converters?

I suppose in this particular case in going from 12
volts to 9 (which is what I need to do), I can just
make do with a voltage divider, or something
similar to that. Or maybe use Ohm's law and just
put a resistor into the voltage line.

Best Wishes,
Bruce, MICRO1690/1700

Hi Carl! Are you maybe talking about DC to DC
converters?

I suppose in this particular case in going from 12
volts to 9 (which is what I need to do), I can just
make do with a voltage divider, or something
similar to that. Or maybe use Ohm's law and just
put a resistor into the voltage line.

Best Wishes,
Bruce, MICRO1690/1700

I'm going to put a resistor in series with the
STL receiver B plus lead and try things again
when the sun comes back out. I calculated
the R value. Hopefully, with the needed drop
in supply voltage (as mentioned above) the
receiver will consume less energy and operate
from the sun.

In the next test I'm going to have a bunch
of meters in the line so I can see what happens.

I suppose a wintertime sun produces less useful energy
than a summertime sun.

Looks like it's going to be cloudy the next few days.

I'll have another report as soon as I can.

Maybe, somewhere out there, a reader of this board
might also try this experiment sometime.

Best Wishes
Bruce, MICRO1690/1700

I'm going to put a resistor in series with the
STL receiver B plus lead and try things again
when the sun comes back out. I calculated
the R value. Hopefully, with the needed drop
in supply voltage (as mentioned above) the
receiver will consume less energy and operate
from the sun.

In the next test I'm going to have a bunch
of meters in the line so I can see what happens.

I suppose a wintertime sun produces less useful energy
than a summertime sun.

Looks like it's going to be cloudy the next few days.

I'll have another report as soon as I can.

Maybe, somewhere out there, a reader of this board
might also try this experiment sometime.

Best Wishes
Bruce, MICRO1690/1700

(snip)"Hopefully, with the needed drop in supply voltage (as mentioned above) the receiver will consume less energy and operate from the sun."

Of course, it depends on the current draw, but a 9v dc battery doesn't have much available either so maybe it will work.

I get the feeling you're trying hard to do this with just parts on hand, but FYI you can get a selectable voltage unit from rat shack designed for 12v dc input from a cigarette lighter socket.

ASIDE: Personally, I've never observed anyone lighting a cigarette from an auto lighter in 10 years ... maybe it's time to come up with a better interior 12v connector for trucks, cars, boats, etc. Whaddaya think? 😉

For my own pet project, I've started considering designs for a combo solar/wind turbine generator. But even with that, I could still run out of adequate power and have to go to backup, so does anyone have a detector circuit I can use for automatic power supply switching?

(snip)"Hopefully, with the needed drop in supply voltage (as mentioned above) the receiver will consume less energy and operate from the sun."

Of course, it depends on the current draw, but a 9v dc battery doesn't have much available either so maybe it will work.

I get the feeling you're trying hard to do this with just parts on hand, but FYI you can get a selectable voltage unit from rat shack designed for 12v dc input from a cigarette lighter socket.

ASIDE: Personally, I've never observed anyone lighting a cigarette from an auto lighter in 10 years ... maybe it's time to come up with a better interior 12v connector for trucks, cars, boats, etc. Whaddaya think? 😉

For my own pet project, I've started considering designs for a combo solar/wind turbine generator. But even with that, I could still run out of adequate power and have to go to backup, so does anyone have a detector circuit I can use for automatic power supply switching?