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Re: Solar Mesh node power experiment
#Meshtastic
I took the Meshtastic node down off of the tower's 10' spot and brought into the shack for a checkup.
My main concern was if anything got hot enough to melt anything.?
None, nada.
Because it offers a view of the final wiring and mounting I took a few pictures with and without the insulating cover.
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Next will be to button it back up and get on the tower, this time at the 20' level.
I'm relatively confident I won't need to climb back up twice. ?
73
Mike N0QBH |
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Re: Solar Mesh node power experiment
#Meshtastic
3rd Day Update
To coin a military term Bravo Zulu - doing great!
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We had a fair part day charging Friday 12/20.
Almost no sun Saturday until about 2 pm.
Sunday is sunny (aptly named :).
As the chart shows, it was able to warm up and charge the 3 Ah battery in almost all conditions.
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Now we can think about deploying year round mesh nodes in good locations without electricity available.
73
Mike N0QBH
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Awhile ago I ordered a cable assembly from Digirig for the Baofeng UV5R model handheld radios.
The cable is prewired for the Digirig and comes with a second programming cable that uses the Digirig's serial capabilities allowing a program like Chirp to read and write the radio's program memory.
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My reason was to see if the inexpensive $35 Baofeng radio will work with VARA FM and Winlink for nearby stations accessing the W0AYE-10 gateway.
The results?
Yes and no.
I have two of these radios, one a few years old and the other purchased in the past year.? Both UV5R model.
The old one works VARA FM like a dream and seems to be a rival to the Yaesu FT-60 I've been using.
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The new UV5R with identical settings, on the other hand, is unable to complete a connection with the gateway.
It's transmit to receive turnaround time is way too slow for VARA causing the incoming data to be missed.
Searching the Internet showed this to be a very common issue with the Baofengs and VARA FM.
What remains unclear is if the problem is model change related or variations within same models.
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If you have one and want to find out, I can probably test it before you spend $35 on a cable set.
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For folks planning to use handheld radios, invest in a gain antenna around 2' long. Night and day difference in signals.
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73
Mike N0QBH
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Re: Solar Mesh node power experiment
#Meshtastic
I wired the heater circuitry into the node's solar charging harness and mounted the thermal sensor on the long narrow side of the battery.
Both the sensor and heater pcb are held in place tight with a small tie wrap around the battery. Not the one shown.
Then I wrapped this assembly in two layers of thin foam for insulation. The battery assembly sits atop a 1/4" foam pad to further insulate it from the case.
I also updated the node's firmware to the latest stable release while I had it in the shack.
The white connectors shown attach to the RAK 4631 mesh node circuit pcb.
Bottom to solar jack and battery's to the battery jack.
I'll get pictures next time it's in the shack.
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Then I put the node back on the tower to wait for a sunny, freezing day.
Today (12/20) was a perfect test with temps in the single digits and bright sun part of the day.
The battery was down to about 60% from a stretch of cloudy days.
The simple circuit warms the battery as long as the temperature sensor is open (<32F), else all the current goes to charge the battery.
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Meshtastic has some nice built in metrics for visualizing it's power status over time.
In it you can plainly see when the battery is being warmed (low half of the "square wave") and charging when the voltage is higher.
It also gives a good idea of the duty cycle which tells me the heating is gentle.
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While this is only day one of testing, the results are very promising as a solution to the LiPo battery cold weather problem in solar powered remote nodes.
The first two hours were bright sun then filtered through clouds the rest of the day.?
Interestingly, it was still charging, tho not as fast.
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73
Mike N0QBH
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Iss SSTV event
#SSTV
Now is the time to download Yoniq MMSSTV, for your PC, or Robot 36 for your smart phone if you interested in capturing pictures from the International Space Station!
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Re: Solar Mesh node power experiment
#Meshtastic
PCB with parts soldered on and wired for testing the actual circuit.
The main concern is how hot at full output (1.25W).
Tie wrapped to the battery and un-insulated brought the battery temperature up about 20 deg F above surroundings.
The pcb alone with only air to cool it rises to about 140 deg F after 10 minutes.?
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The switch mimics the function of the thermal switch.?
In operation the thermal switch opens when the battery temp drops below 32 deg F.
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Switch closed (on) MOSFET gate is high - no current - no heat.
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Switch open (off) and the MOSFET gate goes low - turned on. Almost 1/4 Watt.
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Next is to install the heater in the solar powered node and see how the idea fares in the real world...
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73
Mike? N0QBH
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The SSTV experiment over the .03 repeater was mostly a bust Sunday evening.
The repeater was dropping out mid transmission on a 90 second picture.?
A simplex test showed no issues, so it's unclear why. Timeout timer?
Maybe we'll try it with the new UHF repeater, mostly to compare results.
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73
Mike N0QBH
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Nothing fancy. It's for folks want an opportunity to try out their SSTV skills.
To listen in, just a audio cable between the 2m radio's speaker jack and a computer sound card mic in should do it to listen in while running any of the SSTV programs.
I'll send a few pictures and if some of the others are set to transmit they can share some too.
Just a lot of fun making weird noises turn in to pictures.
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73
Mike N0QBH
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I'm gauging interest in having an impromptu SSTV net after the W0SW net on Sunday evening to exchange a few pictures.
I'd like to host the net on the 147.03 repeater to let more folks tune in and copy the signals S-9.
We used to do it 30 years ago without issue.
Slow scan FM is no different than voice communications from the repeater's standpoint.
However, I thought it would be a good idea to get some club member input first.
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Leon KF0OUA and myself have done some SSTV simplex on 146.550 and it works well between us because we have fairly tall antennae.
Doing over the repeater just lets more folks get good copy.
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Opinions? Questions? Answers? :)
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73
Mike N0QBH
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Re: Solar Mesh node power experiment
#Meshtastic
Solar Mesh node update.
The thermal switch has worked exactly as expected opening at freezing thus isolating the solar panel from the charge circuit and the battery.
This is done to prevent damaging the LiPo battery.? Charging when the cell is below freezing is a no-no.
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So far, the longest "off" period was almost a week before the weather warmed and the sun recharged the 3.7 volt 3 Ah LiPo battery.
Fortunately, the node is lightly used and very frugal with it's Watts, so it stayed on with some power to spare (30%).
The next goal is to use the solar electricity to heat the battery up, allowing it to charge when the sun is shining on those below freezing days.
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After some trial and mostly error, I believe I have a circuit simple enough for others to make.
The idea is to sense when the thermal switch has opened isolating the solar panel from the charging circuit.
This, in turn, shunts the solar panel current through a 20 ohm resistor at 5 volts generating 1.25 Watts of heat.
The resistor is a larger surface mount variety laying on a double sided copper clad circuit board which becomes a heat sink.
Some short wires soldered to both sides transfer the heat to the pcb bottom and the battery.
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By using a P channel MOSFET I was able to do it all with one device, an IFR9530 3 legged TO-220.
It's gate senses the volts on the thermal switch out, turning on hard when the switch turns off and vice versa.
The 100k pull down resistor insures the MOSFET gate goes low while a blocking diode built in the node's solar charge circuit prevents any back flow from the battery.
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Here's the yet to be populated circuit board as it would sit next to the thermal switch atop the battery.
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Here's a crude schematic of my idea.
It worked FB on a breadboard so I'm taking the next step.
Once the resistors show up I'll be able to finish building and install it.
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Here's where the completed heater circuit will be spliced in and mounted on the battery.
I'll lay a toothpick between the sensor and the heater to keep it from warming the sensor directly.
The battery lays on a foam pad to insulate it from the case.
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Next installment will have the heater installed and running.
Then test to fail.
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73
Mike N0QBH
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ARRL 10m Contest
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Re: Winlink county specific weather report
I found a reason for the clipped emails
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If your group has public archives, the domain information is automatically stripped from the online message archive. This is to keep spammers and bots from mining your public messages for valid email addresses. The exception is any post with the groups.io domain, in which case it is retained. If absolutely necessary, try posting it like this:? myemail(at)domain(dot)net [or something to that effect]. I've found that most human beings are sharp enough to figure out what that really means, while (hopefully) the bots might struggle with it a little bit. |
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Today's installment is on the Digirig USB sound card interface.
It's very popular due to it's large cable assortment for various radio models including the Baofeng handhelds.
The first link is the Digirig's setup page for folks like me who like to read instructions slowly and digest them.
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The second link is to one of YouTube University's instructional videos from Dennis, K0TX.
In this video he goes over connecting the Digirig to the computer and radio.
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?In this video which is very similar, the radio is a Baofeng handheld.??
If you decide to go this route be sure to look into a better antenna or a coax adapter to use your outdoor 2m antenna.
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73
Mike N0QBH
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N0QBH Mike Berg
WD0HXV Tony LaPatka
W0AYE Ben Wussow