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by JohnsUPS
Sun Mar 10, 2019 9:13 pm
Forum: Beginners
Topic: Choosing a device for analog
Replies: 7
Views: 427

Re: Choosing a device for analog

Here are a couple of additional suggestions for obtaining pulses: Affix a magnet or two to the rotating part (wheel and front sprocket), and locate hall effect sensors so that they switch when the magnet travels by it. Count the pulses of each, and do the math in software. Affix an optical pickup so...
by JohnsUPS
Sun Mar 10, 2019 8:54 pm
Forum: General discussion
Topic: Pi 3 gets too hot
Replies: 33
Views: 1942

Re: Pi 3 gets too hot

If the Pi is abnormally heating up without an SD card installed, you should consider it toast and replace it. The problem is most likely down deep within an IC on the board (most likely the uproc). Finishing your project but having the Pi live in the refrigerator is a poor solution. Attempting to re...
by JohnsUPS
Fri Mar 01, 2019 12:51 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Programming 16 mA load on GPIO
Replies: 4
Views: 298

Re: Programming 16 mA load on GPIO

Your load determines the amount of current that needs to be supplied. Because you had stated the load will be ~2ma, you should be safe. However, be careful that the current requirements of your load don't occasionally spike above the 16ma limit, or you risk damaging the Pi. It may handle it (or not)...
by JohnsUPS
Fri Mar 01, 2019 12:24 pm
Forum: General discussion
Topic: Operating 24/7
Replies: 15
Views: 1752

Re: Operating 24/7

In leiu of an SD card, I prefer to run an SSD. So far, so good. No problems with power outages, although the environment is UPS and generator backed. The Pi has been up 24x7 for months now - not as long as some others on this thread, but you get the idea - very stable and reliable if set up properly...
by JohnsUPS
Thu Feb 28, 2019 12:32 pm
Forum: General discussion
Topic: Best way to power 4 x Raspberry Pi
Replies: 31
Views: 1546

Re: Best way to power 4 x Raspberry Pi

If I were to power a cluster of Pis, I'd just get a power supply like the one that you listed (5VDC @ 10A). To keep things simple and reliable, I'd then get 5 micro USB cables, cut the other end off, strip the wires, connect them in parallel then connect them to the power supply and be done with it....
by JohnsUPS
Wed Feb 27, 2019 11:51 am
Forum: General discussion
Topic: High Wattage Remote Relay
Replies: 12
Views: 885

Re: High Wattage Remote Relay

I'm trying to build a remote relay that can support >1500W AC. So long as you're not switching an inductive load, and a heater isn't, then look at a contactor. A contactor is basically a relay on steriods. Looks like you're only switching about 12.5A (@120V), or a bit over 6A (@240V), but you want ...
by JohnsUPS
Mon Feb 25, 2019 4:07 am
Forum: Advanced users
Topic: Advice on project components...
Replies: 14
Views: 1137

Re: Advice on project components...

Ok, I see the issue. Using the setup in the YouTube video I linked to supplies the coil side of the relays with 5V from the PSU - but he's basically getting lucky that the LED/input side is working as they are being triggered by the GPIOs at 3.3V - but really should be getting at least 4V to be rel...
by JohnsUPS
Thu Feb 21, 2019 11:00 pm
Forum: Troubleshooting
Topic: Error: dhcpcd[429]: enXXX: hardware address XX:XX:XX:XX:0f:15 claims 192.168.0.3
Replies: 3
Views: 373

Re: Error: dhcpcd[429]: enXXX: hardware address XX:XX:XX:XX:0f:15 claims 192.168.0.3

Yes, this sounds like a duplicate IP address situation on your network. A simple test to perform before deciding on a static address to use is to ping your desired address to see if there is a reply. If so, then it is in use. You should be able to log into your home router to see what the DHCP scope...
by JohnsUPS
Thu Feb 21, 2019 12:21 pm
Forum: Automation, sensing and robotics
Topic: Ultrasonic sensor and voltage division
Replies: 19
Views: 1414

Re: Ultrasonic sensor and voltage division

Another way to look at the situation of voltage division is to consider a potentiometer. The construction is that of a resistive element with a sliding tap. Using a 10k pot for an example, set the pot halfway, and you have, in effect, a circuit with two 5k resistors in series with the tap at your ha...
by JohnsUPS
Wed Feb 20, 2019 3:51 am
Forum: Beginners
Topic: Different GPIO Pins?
Replies: 16
Views: 1325

Re: Different GPIO Pins?

Yes, resistor dividers are cheaper, and is the best solution to knock down a higher voltage swing input to something safe for the Pi. However, when using a GPIO as an output to drive something else, 3.3V may not be enough, not to mention the rather weak current sourcing ability. 3.3V is well within ...
by JohnsUPS
Mon Feb 18, 2019 11:57 am
Forum: Automation, sensing and robotics
Topic: High reliability, high accuracy temperature/humidity sensor
Replies: 11
Views: 1661

Re: High reliability, high accuracy temperature/humidity sensor

I have also found the DS18B20's reliable. I'm also using the OWFS file system and a DS2482 (for driving long distance and to protect the Pi) for reading the sensors, and it works great. No overhead problems. For short runs I'd probably use a GPIO pin (buffered, of course). The DHT sensor data sheet...
by JohnsUPS
Sun Feb 17, 2019 3:17 am
Forum: Automation, sensing and robotics
Topic: High reliability, high accuracy temperature/humidity sensor
Replies: 11
Views: 1661

Re: High reliability, high accuracy temperature/humidity sensor

I have also found the DS18B20's reliable. I'm also using the OWFS file system and a DS2482 (for driving long distance and to protect the Pi) for reading the sensors, and it works great. No overhead problems. For short runs I'd probably use a GPIO pin (buffered, of course). The DHT sensor data sheets...
by JohnsUPS
Wed Feb 13, 2019 12:19 am
Forum: Automation, sensing and robotics
Topic: High reliability, high accuracy temperature/humidity sensor
Replies: 11
Views: 1661

Re: High reliability, high accuracy temperature/humidity sensor

So long as the temperature range you wish to measure is between -55 degC to +125 degC, I would recommend the Dallas 1-wire temperature sensors. They're accurate (as long as they're sourced from a reputable dealer/not fakes) and have a programmable resolution. The data conversion time is approximatel...
by JohnsUPS
Wed Feb 06, 2019 12:50 pm
Forum: Beginners
Topic: Battery pack
Replies: 5
Views: 522

Re: Battery pack

by davidcoton » Wed Feb 06, 2019 4:58 am It can be worse than that. It might bethat the capacity is quoted at the battery voltage (3V7) because that gives a higher number (specmanship). To get meaningful figures, multiply capacity (Ah) by the relevant voltage and work in Wh. That means the battery ...
by JohnsUPS
Wed Feb 06, 2019 2:59 am
Forum: Beginners
Topic: Battery pack
Replies: 5
Views: 522

Re: Battery pack

I have a 6600 mha lipo battery pack. Would it be safe to plug this into my rpi 3b+? Without knowing the output voltage of your battery pack, the question can't be directly answered. The output voltage is the important specification here, not so much so the current sourcing capability of the pack. T...
by JohnsUPS
Wed Feb 06, 2019 2:40 am
Forum: Beginners
Topic: Multi output power source options
Replies: 5
Views: 288

Re: Multi output power source options

Given the price point, I would be a bit concerned about how well regulated the supply was and whether the output voltage would drop under moderate loads. I could find no claims/specs for regulation in the ad.
I agree.
by JohnsUPS
Tue Feb 05, 2019 3:49 am
Forum: Beginners
Topic: Multi output power source options
Replies: 5
Views: 288

Re: Multi output power source options

If I were going to make what you are describing, I'd first figure what the theoretical maximum current requirement would be (16 Pi zeroes is going to be a lot different than 16 Pi 3's). Your supply may have to be able to deliver some real current, so caution is in order. My main point: In any event,...
by JohnsUPS
Sun Feb 03, 2019 6:47 pm
Forum: Beginners
Topic: Different GPIO Pins?
Replies: 16
Views: 1325

Re: Different GPIO Pins?

Sat Feb 02, 2019 5:45 pm Don't forget rule #101, when using GPIO's, putting 5V on a GPIO means immediate destruction of your RPI :!: :!: :!: :!: RPI's do not tolerate 5V (or even 4V) on their GPIO pins! Voltage level translators are your friends.......they are much cheaper than a Pi of any flavor. ...
by JohnsUPS
Sun Feb 03, 2019 6:40 pm
Forum: Beginners
Topic: Power a raspberry pi zero w with POE
Replies: 8
Views: 5716

Re: Power a raspberry pi zero w with POE

W. H. Heydt wrote: ↑ Sat Feb 02, 2019 9:45 pm klricks wrote: ↑ Sat Feb 02, 2019 7:33 am JohnsUPS wrote: ↑ Fri Feb 01, 2019 8:55 pm .... No need to split out the wiring, as the device is POE capable, ... I didn't mean that this is something extra the user has to do. The split out is done internally ...
by JohnsUPS
Sat Feb 02, 2019 3:07 am
Forum: Beginners
Topic: Different GPIO Pins?
Replies: 16
Views: 1325

Re: Different GPIO Pins?

I totally agree with the notion of putting the Pi in a case. Good advice there. It is what I do during development. Tabletops, benches or whatever can have things that may get under the Pi and then it "mysteriously" stops working (that is unless the magic smoke gets out). As far as becoming acquaint...
by JohnsUPS
Sat Feb 02, 2019 2:55 am
Forum: Beginners
Topic: Power a raspberry pi zero w with POE
Replies: 8
Views: 5716

Re: Power a raspberry pi zero w with POE

MathMXC wrote: ↑ Fri Feb 01, 2019 2:04 pm I recently got a raspberry pi zero w and I also bought one of these https://www.neweggbusiness.com/product/ ... 002c-00010. I was wondering if I could power a raspberry pi zero w over POE through one of these adapters? Please let me know if this is possible...
by JohnsUPS
Tue Jan 29, 2019 3:27 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Using RASClock and an Adafruit ADS1115 Simultaneously
Replies: 8
Views: 751

Re: Using RASClock and an Adafruit ADS1115 Simultaneously

Did you verify that the RASclock and the ADS1115 are at different I2C addresses?
by JohnsUPS
Tue Jan 29, 2019 3:05 am
Forum: Automation, sensing and robotics
Topic: Buying quality components?
Replies: 6
Views: 612

Re: Buying quality components?

I can comment on the Dallas 1 wire temperature sensors if you're planning on using them - DON'T get them from China. :oops: They're much less expensive, but probably fakes. They do work (spit out data), but the calibration of the ones I bought were way off. I purchased some from two different vendor...
by JohnsUPS
Sun Jan 27, 2019 12:26 am
Forum: General discussion
Topic: Power Supply - Radio Interference
Replies: 38
Views: 2097

Re: Power Supply - Radio Interference

For this reason there is no connection between anything on the output side and anything on the input side. The output floats. Get a multi-meter and verify that for yourself. My post never stated anything about the output side. All references to ground were in context to be that of the input side. T...
by JohnsUPS
Sat Jan 26, 2019 2:44 am
Forum: General discussion
Topic: Power Supply - Radio Interference
Replies: 38
Views: 2097

Re: Power Supply - Radio Interference

Sorry to be blunt but that shows a complete lack of understanding. The official PSU has no ground connection. There are only 2 contacts on the casing to mate with the interchangeable mains pins. Therefore a ground loop is impossible. I respectfully disagree. The official power supply may not have a...

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