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by mosespi
Sat Oct 20, 2018 12:50 am
Forum: General discussion
Topic: Rechargeable, portable power alternatives to Lipo and Lithium Ion Batteries
Replies: 3
Views: 443

Re: Rechargeable, portable power alternatives to Lipo and Lithium Ion Batteries

Rechargeable AA NiMH batteries will work fine (or C or D cells). If you don't mind a slow charge rate, trickle charging them is easy and works. Hook up 6 or 8 cells in series and use a DC-DC buck converter. This is essentially the basis for a UPS I make. For most all battery types you will have to i...
by mosespi
Thu Oct 18, 2018 4:49 am
Forum: General discussion
Topic: A2 app performance class SD cards
Replies: 11
Views: 4286

Re: A2 app performance class SD cards

While doing some testing of add-on boards on a half dozen RPIs a few months ago... I noticed one was booting noticeably quicker. Turns out I had unknowingly purchased an A1 class card. Good stuff.

Regards,
-Moses
by mosespi
Thu Oct 11, 2018 8:57 pm
Forum: Advanced users
Topic: Brief voltage drop on UPS like system. would a capacitor fix it?
Replies: 53
Views: 6706

Re: Brief voltage drop on UPS like system. would a capacitor fix it?

Hi mosespi, thank you for the info! A sudden thought struck me, do you think it would be possible to replace the resistor with say, a 200k trimpot or rheostat? I'd like to test what value works best once I manage to get it working again, but dislike the idea of repeatedly soldering and desoldering ...
by mosespi
Tue Oct 09, 2018 5:21 am
Forum: Other projects
Topic: 'StayAlive' battery.
Replies: 9
Views: 1297

Re: 'StayAlive' battery.

Would something like this do http://www.allspectrum.com/mopower/ You would need to sort power surges, voltage differences and check if the Pi does not draw power when off (hate to find it flat Monday going to work) but it may be a start point. That is my design linked above. It has an automotive gr...
by mosespi
Sat Oct 06, 2018 7:43 am
Forum: Advanced users
Topic: Brief voltage drop on UPS like system. would a capacitor fix it?
Replies: 53
Views: 6706

Re: Brief voltage drop on UPS like system. would a capacitor fix it?

Anyway, while I wait for it to arrive, I was wondering if anyone had any concerns or advice regarding using the oscilloscope. Yes! Do remember that for most bench type scopes the ground connector (outer barrel) on your BNC probe is actually GROUND, like from the building! Trying to measure voltages...
by mosespi
Tue Oct 02, 2018 7:59 pm
Forum: General discussion
Topic: Cigar plug adapter for PI power
Replies: 2
Views: 315

Re: Cigar plug adapter for PI power

Check this out: http://www.allspectrum.com/mopower/ My design. It has a wide input voltage range (up to 30VDC) and an automotive grade TVS (transient voltage suppressor). You don't need to use the UPS functions if not needed.. but it is capable of turning the Pi on and off based on input voltage, am...
by mosespi
Wed Sep 19, 2018 10:13 pm
Forum: General discussion
Topic: Industrial Environment Life Expectancy of Raspberry Pi 3 Model B and Raspberry 0 W Module.
Replies: 6
Views: 9187

Re: Industrial Environment Life Expectancy of Raspberry Pi 3 Model B and Raspberry 0 W Module.

Drying out of electrolytic capacitors gives you a defined lifetime for most modern electronics. I don't believe any of the RPI models have any (although your power supply may), so we go on to the lifetimes of all the other components, it's mostly passives and semiconductors. Modern passive parts and...
by mosespi
Thu Aug 30, 2018 6:35 pm
Forum: General discussion
Topic: Wireless/wifi voltage monitor/battery monitor/ADC that works with Pi?
Replies: 6
Views: 2889

Re: Wireless/wifi voltage monitor/battery monitor/ADC that works with Pi?

I have a UPS that you can use that will do this. It has input voltage and battery ADCs. There are an 4 additional ADC too. If you hook it up to the car it will read the bus voltage on it's input ADC. http://www.allspectrum.com/mopower/ The UPS also has the ability to power up the Pi on a timer.. so ...
by mosespi
Thu Aug 30, 2018 6:18 pm
Forum: General discussion
Topic: Thermal printer + cash drawer with Raspberry Pi 3 b+?
Replies: 4
Views: 1106

Re: Thermal printer + cash drawer with Raspberry Pi 3 b+?

Some experience from the past.. might be outdated info, so do your own research. Cash drawers we looked at were mainly serial controlled and came in two flavors, dumb and smart. Dumb ones would open the drawer on receipt of ANY serial command. Smart ones you could 'talk' to, mainly to figure out if ...
by mosespi
Tue Aug 14, 2018 12:02 am
Forum: Advanced users
Topic: Fan Power Source
Replies: 2
Views: 359

Re: Fan Power Source

You can also power it from the USB-A connectors. Bonus in that on some RPIs it's protected at 1.2A (total for all ports) and you may be able to turn it on and off from software.

Regards,
-Moses
by mosespi
Sat Aug 11, 2018 7:52 pm
Forum: General discussion
Topic: Raspberry Pi and 3G
Replies: 8
Views: 1290

Re: Raspberry Pi and 3G

Lots of inexpensive (less then $100) USB cell modems around, not the most reliable for unattended/sever use, but they work. I usually write scripts that power cycle the USB power on the Pi to reset these types of modems, it helps bring them back up most of the time. Better reliability exists at a pr...
by mosespi
Sun Aug 05, 2018 7:01 pm
Forum: General discussion
Topic: Pi 3 at 80 Celsius with no load (dead?)
Replies: 12
Views: 1106

Re: Pi 3 at 80 Celsius with no load (dead?)

Preliminary CPU/SOC damage test.. power up your Pi with the SD card REMOVED. If the CPU/SOC is uncomfortably hot to the touch, it's damaged.

Regards,
-Moses
by mosespi
Thu Aug 02, 2018 9:42 pm
Forum: Automation, sensing and robotics
Topic: Battery powered Pi car is having power issues.
Replies: 13
Views: 1375

Re: Battery powered Pi car is having power issues.

He seems to be running a 5/6v motor with 12v as well. The draw will be much greater and likely bad for the motors. These motors might be fine running direct off his 4AA pack (which is what the toy that it came from used?) and that might be the root of his problem all this time. Devnull1232, swap the...
by mosespi
Wed Aug 01, 2018 5:59 am
Forum: HATs and other add-ons
Topic: Looking for a converter for 230V > 12V and 12V > 5V
Replies: 4
Views: 846

Re: Looking for a converter for 230V > 12V and 12V > 5V

Another option would be to use a 19v laptop power adapter. Plug it in were convenient AC is available, then you can run a single pair of low voltage wire (outdoors too) to your weather station. Buck convert the 19v down to 12v, 5v or whatever else you need. Laptop adapters are fairly cheap and plent...
by mosespi
Wed Aug 01, 2018 5:31 am
Forum: Automation, sensing and robotics
Topic: Battery powered Pi car is having power issues.
Replies: 13
Views: 1375

Re: Battery powered Pi car is having power issues.

What Heydt said. Most AA NiMH cells start dropping off fast after about 2A or so. If you have a fast multi-meter, you may be able to see the momentary voltage drop on the pack when under heavy load. Some options to consider.. - Upgrade to C cells, they are capable of providing higher current. - Swit...
by mosespi
Mon Jul 30, 2018 5:58 pm
Forum: HATs and other add-ons
Topic: ETA for Official POE Hat for 3B+
Replies: 66
Views: 13466

Re: ETA for Official POE Hat for 3B+

Thanks for the reply. I'll check into that. So you're saying that this option would require neither a PoE hat nor a switch? I love DIY. Most pi people do. As long as someone has done the steps before I can usually cobble together pieces If you are referring to the passive POE option, yes, a POE hat...
by mosespi
Thu Jul 26, 2018 9:40 pm
Forum: General discussion
Topic: UL and Flammability rating for Raspberry Pi 3B+ [solved]
Replies: 20
Views: 1785

Re: UL and Flammability rating for Raspberry Pi 3B+ [solved]

Here is another posting with some more information: viewtopic.php?t=215444
by mosespi
Thu Jul 26, 2018 8:25 pm
Forum: HATs and other add-ons
Topic: ETA for Official POE Hat for 3B+
Replies: 66
Views: 13466

Re: ETA for Official POE Hat for 3B+

I can imagine how ladders on ice wouldn't' work too well. Depending on your experience or tolerance for DIY.. another option might be passive POE injectors.. like this one: http://www.allspectrum.com/store/power-over-ethernet-passive-poe-injector-splitter-kit-p-9169.html Inject 12v or so into the ne...
by mosespi
Wed Jul 25, 2018 12:09 am
Forum: Advanced users
Topic: Using batteries with multiple boost converters
Replies: 6
Views: 842

Re: Using batteries with multiple boost converters

As long as your boost converter and battery are all within their specifications I would not anticipate any problems when NOT charging. It's another matter when the battery is charging. Charging lithium batteries is a bit of a delicate process, and introducing a load to the battery that the charger w...
by mosespi
Fri Jul 20, 2018 6:47 pm
Forum: Advanced users
Topic: [RESOLVED] Verifying transmission complete on Tx/Rx
Replies: 4
Views: 705

Re: Verifying transmission complete on Tx/Rx

If you control both sides, add some sort of checksum and verify the data received is intact before acting upon it.

Regards,
-Moses
by mosespi
Wed Jul 18, 2018 8:44 pm
Forum: Advanced users
Topic: Brief voltage drop on UPS like system. would a capacitor fix it?
Replies: 53
Views: 6706

Re: Brief voltage drop on UPS like system. would a capacitor fix it?

I think those are 0402 or 0603 resistors.. about the smallest most people can work with. It's mostly done under magnification. At that size removing them is easy; a big glob of solder on your iron, enough to where it covers both leads, will usually pull them right off the board. Putting them back is...
by mosespi
Wed Jul 18, 2018 8:02 pm
Forum: General discussion
Topic: GPS recommendations
Replies: 5
Views: 772

Re: GPS recommendations

The easy way for the Pi is to buy a USB GPS 'puck' like this one.. http://www.allspectrum.com/store/gps-navigation-module-vk-162-mouse-usb-ublox-p-9136.html I've used that particular one with good results. There are plenty of others available, especially with just a plain serial interface sold for u...
by mosespi
Wed Jul 18, 2018 7:44 pm
Forum: General discussion
Topic: RPi (Zero) in extreme temperatures experiences
Replies: 7
Views: 1093

Re: RPi (Zero) in extreme temperatures experiences

Several summers ago I had a Pi 2 (I think) set up for some power supply/UPS tests inside of a car. It was continuously running for approx 3 or 4 months, right through the hottest parts of summer. We would get heat waves lasting many days of 44C+ temperatures. I can take a guess that the interior tem...
by mosespi
Wed Jul 18, 2018 7:18 pm
Forum: HATs and other add-ons
Topic: Can I switch one Pi off/on with another?
Replies: 13
Views: 1469

Re: Can I switch one Pi off/on with another?

Here is the watchdog feature on a UPS of my design.

http://www.allspectrum.com/mopower-hw2/#WATCHDOG

It will automatically cut and reapply 5v power to the Pi if the watchdog timer expires. It's a full blown UPS, so you have that too if power fails.

Regards,
-Moses
by mosespi
Wed Jul 18, 2018 6:50 pm
Forum: Advanced users
Topic: Brief voltage drop on UPS like system. would a capacitor fix it?
Replies: 53
Views: 6706

Re: Brief voltage drop on UPS like system. would a capacitor fix it?

I don't see anything in the datasheet that gives a low limit on the charge current. That chart is under typical characteristics and as Paul mentioned in this second point.. they must stop the graph somewhere right? I would try anything between 0.25 to 1A for testing purposes.

Regards
-Moses

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