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by PiGraham
Tue Oct 17, 2017 6:31 am
Forum: General discussion
Topic: Remote email printing
Replies: 5
Views: 129

Re: Remote email printing

They have a POS system, touch screen front counter, touch screen in prep area for call in with POS receipt printer in prep area (doesn't have a problem with flour). I think you're thinking another touch display over the prep area. Would require me to start an entirely new business. The current POS ...
by PiGraham
Mon Oct 16, 2017 2:45 pm
Forum: General discussion
Topic: Remote email printing
Replies: 5
Views: 129

Re: Remote email printing

Paper seems like a bad idea. Can't you go paperless? Can't you display orders on a screen that can indicate which are open, which fulfilled, prep time, collected etc? Some non-touch gesture sensors could allow hygienic review and updating. If the ordering site collected mobile numbers you could even...
by PiGraham
Mon Oct 16, 2017 9:09 am
Forum: Python
Topic: pi3d - merge shapes of two different colors
Replies: 3
Views: 93

Re: pi3d - merge shapes of two different colors

I don't much about Pi3D but maybe you can apply a texture to the merged shape to colour it. Alternatively keep the parts as separate meshes with their own colours. There is an AddChild function. Would that allow you to add the ball as a child of a stick so that you can move both as a unit? The Tiger...
by PiGraham
Fri Oct 13, 2017 8:16 am
Forum: General discussion
Topic: Why do new forum members not come back?
Replies: 30
Views: 1464

Re: Why do new forum members not come back?

Maybe they read the answers but there is no feedback from OP. Last Active time in profile may show this but s/he can read the answer without login. It would certainly be disappointing if replies were never even read but I think the "no feedback from OP" is the issue. Why is there no feedback from t...
by PiGraham
Thu Oct 12, 2017 9:27 pm
Forum: Python
Topic: Comparing two images using PIL
Replies: 13
Views: 389

Re: Comparing two images using PIL

I'm trying to compare two images and get a number value. What comparison do you want to make? Comparing histograms can be a good technique for similar images. It is relatively unaffected by scale or rotation and quick to compute, but it ignores details and what the image actually contains as object...
by PiGraham
Thu Oct 12, 2017 3:34 pm
Forum: Troubleshooting
Topic: Stuttering Servos / Intermittent Servo
Replies: 5
Views: 133

Re: Stuttering Servos / Intermittent Servo

powered with a 9V battery Is your servo rated for 9V? If it's designed for 4.8V it may have died from over voltage. It seems specs vary a lot. It may be rated to 10V and be fine, or not. Do you have any way to test that it still works? Going to higher voltages can destroy servos, so testing the upp...
by PiGraham
Mon Oct 09, 2017 9:25 am
Forum: Beginners
Topic: Conecting dual sd cards
Replies: 5
Views: 192

Re: Conecting dual sd cards

USB reader is the easy option but you can connect SD card on SPI bus.
https://ralimtek.com/Raspberry_Pi_Secondary_SD_Card/
by PiGraham
Mon Oct 02, 2017 6:48 pm
Forum: Automation, sensing and robotics
Topic: connecting multiple magnetic switches
Replies: 10
Views: 447

Re: connecting multiple magnetic switches

How far apart are these doors and windows? Running long wires to 3.3v logic inputs could lead to false alarms due to electrical interference.
by PiGraham
Mon Oct 02, 2017 4:32 pm
Forum: General discussion
Topic: Cycling Sensors for Cycling Computer
Replies: 12
Views: 613

Re: Cycling Sensors for Cycling Computer

What Model would be best for a cycling computer, because from what ive looked at the Raspberry Pi Model 3 satisfies what I need for the cycling computer? Model 3 is OK. Pi Zero uses less power which gives longer life on batteries. Any model Pi will have limited life on battery compared to a typical...
by PiGraham
Sun Oct 01, 2017 3:51 pm
Forum: Beginners
Topic: 3W 850nm leds working voltage?
Replies: 29
Views: 879

Re: 3W 850nm leds working voltage?

I have a different opinion. I think all four of the nuts and bolts that connect the two LED board to the camera board are ground. Each board has one other external connection - the terminal with the cross-head screw. Those two terminals should be wired together and to a positive supply voltage. Wha...
by PiGraham
Sat Sep 30, 2017 3:55 pm
Forum: General discussion
Topic: Alumininium heatsinks with thermally insulating adhesive.
Replies: 7
Views: 1959

Re: Alumininium heatsinks with thermally insulating adhesive.

Certainly thermally conductive adhesive tape is a more sensible choice, but tape (0.076mm thick) isn't going to be a thermally impenetrable barrier. Simple tests - does the heatsink get hot? does fitting the heat sink make a difference to CPU temperature?
by PiGraham
Fri Sep 29, 2017 9:54 am
Forum: Automation, sensing and robotics
Topic: Sound triangulation
Replies: 12
Views: 1265

Re: Sound triangulation

if the sensors are closer together than the distance to the noise maker - the incoming waves are parallel and the delta in arrival time subtends an angle (arcsin spacing/delta t ? something like that) (Only one pair needed for bearing). That is probably not the case here: I have three microphone mo...
by PiGraham
Fri Sep 29, 2017 8:08 am
Forum: General discussion
Topic: Help: Looking for someone to advise on pi schools space gravity project
Replies: 21
Views: 873

Re: Help: Looking for someone to advise on pi schools space gravity project

When you say you can stop the motor by lightly rubbing against it do you mean just the motor on it's own, against the motor shaft? Or do you mean whatever the motor is attached to? It should be hard to stop a NEMA17 stepper shaft by hand, but it might be quite easy to stop a 1m diameter wheel attach...
by PiGraham
Fri Sep 29, 2017 7:35 am
Forum: General discussion
Topic: Help: Looking for someone to advise on pi schools space gravity project
Replies: 21
Views: 873

Re: Help: Looking for someone to advise on pi schools space gravity project

Yes it is about control, although I guess that's just an issue of code (not that it is a small one :oops: ) but the issue I was getting when I tried was the substantial stepper with the L298 board I'm not getting the torque, you can lightly rub against it and stop it. I wonder if this was that I ha...
by PiGraham
Thu Sep 28, 2017 9:47 pm
Forum: General discussion
Topic: Help: Looking for someone to advise on pi schools space gravity project
Replies: 21
Views: 873

Re: Help: Looking for someone to advise on pi schools space gravity project

I think discussion of what the project actually does is entirely on-topic and potentially helpful. If there was a very clear requirement given we could just work to that, but we know next to nothing about the project and what might be involved. Unspecified control of unspecified motors to move somet...
by PiGraham
Thu Sep 28, 2017 7:19 pm
Forum: General discussion
Topic: Help: Looking for someone to advise on pi schools space gravity project
Replies: 21
Views: 873

Re: Help: Looking for someone to advise on pi schools space gravity project

My simple question then is what do you mean by "replicate reduced gravity"? How do you do that? Please don't think I'm making you out to me some kind of anti-gravity device nut head. I'm genuinely interested. That is a good question. One that immediately came to my mind. I gave it a little thought....
by PiGraham
Thu Sep 28, 2017 9:11 am
Forum: Automation, sensing and robotics
Topic: Looking for motion tracking sensor/ sensitivity sensor
Replies: 8
Views: 339

Re: Looking for motion tracking sensor/ sensitivity sensor

Hi. Excellent!!!!! so sorry I did not know how to explain it that well =\ for what Im looking for haha.... but what you suggested should be what im looking for. there is also another sensor that im searching for. It like what they use in the movie, that you can stick on people face ( like a little ...
by PiGraham
Wed Sep 27, 2017 10:57 am
Forum: Automation, sensing and robotics
Topic: Looking for motion tracking sensor/ sensitivity sensor
Replies: 8
Views: 339

Re: Looking for motion tracking sensor/ sensitivity sensor

Do you want to track the position of people in an area, or do you want a touch sensor that measures where a finger touches and how it moves over the sensor? It seems you want to stick a touch sensor to an arm and read the motion of a finger that touches that sensor. Is that right? If so you may be a...
by PiGraham
Wed Sep 27, 2017 8:48 am
Forum: General discussion
Topic: Power RPi zero W with 3.7v lithuim battery
Replies: 15
Views: 575

Re: Power RPi zero W with 3.7v lithuim battery

OutoftheBOTS wrote:
Wed Sep 27, 2017 8:46 am
As I said on earlier post I will put a tiny DW01a on the power supply it has a transistor the switches off the power if it gets too low see http://cxem.net/master/files/97_DW01A-DS-11_EN.pdf
Cool
by PiGraham
Wed Sep 27, 2017 7:41 am
Forum: General discussion
Topic: Power RPi zero W with 3.7v lithuim battery
Replies: 15
Views: 575

Re: Power RPi zero W with 3.7v lithuim battery

I am more concerned about size. The concern with Li-Ion and Li-Po batteries is the fire risk. Over discharge can lead to crystal growth in the call that causes overheating during charging and can result in fire. You may know that Samsung had problems with Galaxy Note7 LiPo batteries catching fire a...
by PiGraham
Tue Sep 26, 2017 4:13 pm
Forum: General discussion
Topic: Power RPi zero W with 3.7v lithuim battery
Replies: 15
Views: 575

Re: Power RPi zero W with 3.7v lithuim battery

The RPi will shut down before the battery can be over discharged so over discharge won't be a problem. You need to do more than shutdown the Pi. You need to disconnect the battery. A Pi in shutdown draws current and will over-discharge the battery. If you connect a battery to a Pi Zero's 5V pins on...
by PiGraham
Tue Sep 26, 2017 4:07 pm
Forum: General discussion
Topic: Incompatible Video Signal
Replies: 5
Views: 217

Re: Incompatible Video Signal

And if composite is your TV PAL, NTSC or other?
by PiGraham
Tue Sep 26, 2017 10:04 am
Forum: General discussion
Topic: Power RPi zero W with 3.7v lithuim battery
Replies: 15
Views: 575

Re: Power RPi zero W with 3.7v lithuim battery

It is important not to over discharge LiPo batteries (they can catch fire when recharged if they have been over discharged). The LiPo Shim looks like a good option Automatic shutdown at 3.0V to protect your battery The Adafruit product mentioned by Pimoroni would be a good all-in-one https://shop.pi...
by PiGraham
Tue Sep 26, 2017 8:12 am
Forum: General discussion
Topic: Power RPi zero W with 3.7v lithuim battery
Replies: 15
Views: 575

Re: Power RPi zero W with 3.7v lithuim battery

Pi models with switchmode regulators will work at lower voltage but they won't work down to the minimum voltage of a LiPo. That means you won't get the full capacity of the battery. The Pi will stop working before the battery is exhausted. This blog suggests 3.4v is viable. Don't try battry direct t...
by PiGraham
Tue Sep 26, 2017 6:17 am
Forum: Automation, sensing and robotics
Topic: Track and Field timing system
Replies: 9
Views: 562

Re: Track and Field timing system

I don't know your budget but to recognize the athlete(s) you can use RFID bracelet with a good RFID antenna. The RFID readers start with antennas that can read maximum 3cm to antennas that can read 20 meters so you can find a good solution for your specific scenario.. 20m RFID? Would that have the ...

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