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by PiGraham
Mon Jul 16, 2018 7:55 pm
Forum: General discussion
Topic: IVPort Dual camera multiplexer
Replies: 17
Views: 2505

Re: IVPort Dual camera multiplexer

Dear all, I need camera multiplexing IV Board to switch between my cameras. how long it takes to switch the camera? Suppose processing of images are performed in less than 5ms and there is no need to save images on disk, is it possible to capture image frames at 90 fps? Best Regars Bear in mind tha...
by PiGraham
Mon Jul 16, 2018 7:45 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

According to https://toshiba.semicon-storage.com/ap-en/product/linear/transistor-array/detail.ULN2003APG.html the datasheet for that particular part number ... Fixed that for you. It's noteworthy that Toshiba is EOLing that part, and recommending TBD62003. That uses a FET instead of a darlington, s...
by PiGraham
Mon Jul 16, 2018 7:32 pm
Forum: General discussion
Topic: Controlling 100 LEDs?
Replies: 6
Views: 167

Re: Controlling 100 LEDs?

Good advice, Just out of curiosity what's the max number of pins I can extend to even with additional products? There isn't really an answer to that. It depends how fast you need to upfdate states and how far signals have to travel. In general the further you need to go the slower and the more disc...
by PiGraham
Mon Jul 16, 2018 1:41 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

Soo we're probably stuck again. We got the ULN2003APG and followed this diagram https://imgur.com/a/cXkL5Wq on youtube except we didn't use the headers. Unfortunately the switch works on LEDS but not on our solenoid(We tested solenoids again because it was hard to find 12v batteries for the relays)...
by PiGraham
Mon Jul 16, 2018 1:33 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

Do you have any resistors in sries? The diagram shows LEDs with current limiting resistors, as needed for LEDs, but you don't want to add resistance to the solenoid circuit. What voltage do you measure at the ULN pin when the switch is on? What voltage do you measure at the battery +ve terminal when...
by PiGraham
Mon Jul 16, 2018 10:59 am
Forum: Beginners
Topic: camera preview on 3.5" hdmi lcd
Replies: 1
Views: 24

Re: camera preview on 3.5" hdmi lcd

Yes, of course. The camera preview naturally goes to the system default display which will be the HDMI display if there is one. You can get the raspistill / raspivid preview to display on other small TFT screens that connect by SPI bus if you run fbtft to provide a frame buffer and fbcp to automatic...
by PiGraham
Sun Jul 15, 2018 3:25 pm
Forum: Add-ons
Topic: Relay' connected to Rpi Zero W - causes it to freeze
Replies: 28
Views: 498

Re: Relay' connected to Rpi Zero W - causes it to freeze

1. I use common relays that operate at 5VDC, and triggered by gpio 3.3V. I do not think that labeling it as "Arduino" or "Raspberry Pi" does not make any technical difference. The technical difference has been explained several times but I'll to make it plain. Arduino gpio operates at 5V (Note ther...
by PiGraham
Sat Jul 14, 2018 8:06 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: ADC for analog video (possible?)
Replies: 26
Views: 580

Re: ADC for analog video (possible?)

Z80 Refugee wrote:
Fri Jul 13, 2018 9:41 pm
6by9 wrote:
Fri Jul 13, 2018 11:00 am
The Pi has hardware acceleration for H264 or MJPEG video encoding.
I think you mean video decoding.
It does both. If you use raspivid to record a video it uses H264 hardware encoder to compress it.
by PiGraham
Sat Jul 14, 2018 8:03 am
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

It's very unlikely that we can find a neodymium magnet to use as a core here so we'll probably stick with the lollipop core and just compensate by using a bigger voltage battery to power the solenoids. Just a quick question about the transistors since we've decided to use them. Given that the PI ca...
by PiGraham
Fri Jul 13, 2018 6:07 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

How about using miniature neodymium magnets as the cores? Now you've confused even me! according to earlier posts, the coil (300 turns round a non-ferrous (?) lollipop stick) pulls a pin (probably iron) down So using a magnet for the core would just hold the pin permanently down. I'd use a steel sc...
by PiGraham
Fri Jul 13, 2018 6:03 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

How about using miniature neodymium magnets as the cores? Now you've confused even me! according to earlier posts, the coil (300 turns round a non-ferrous (?) lollipop stick) pulls a pin (probably iron) down So using a magnet for the core would just hold the pin permanently down. I'd use a steel sc...
by PiGraham
Fri Jul 13, 2018 4:29 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

0.5 seconds to go up and 0.5 seconds to go down would be ideal. The biggest goal we're trying to achieve for this is to make it as compact as possible. Have you made some really tiny solenoids? How big are they? Right now they're half an inch long and only have 300 turns so they're pretty thin as w...
by PiGraham
Fri Jul 13, 2018 9:21 am
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

Z80 Refugee wrote:
Fri Jul 13, 2018 9:18 am

I already said that.

Relax. We agree.
by PiGraham
Fri Jul 13, 2018 9:15 am
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

dibolero wrote:
Fri Jul 13, 2018 2:22 am
0.5 seconds to go up and 0.5 seconds to go down would be ideal. The biggest goal we're trying to achieve for this is to make it as compact as possible.
Have you made some really tiny solenoids? How big are they?
by PiGraham
Fri Jul 13, 2018 9:13 am
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

I think you are mistaken there. Take another look at the Fritzing diagram. The button is shown with a black wire to the blue rail of the breadboard and that rail is shown connected to GND on the Pi header. The other side of the switch has a blue wire going to the gpio input and a pullup resistor. I...
by PiGraham
Fri Jul 13, 2018 7:48 am
Forum: General discussion
Topic: Need help with camera not supported in camera libraries
Replies: 6
Views: 190

Re: Need help with camera not supported in camera libraries

This is not feasible. The camera is Firewire and Pi doesn't have a Firewire interface. The driver / API for the camera only supports Windows.
Use a different camera or use a WIndows x86 SBC that has Firewire.
by PiGraham
Thu Jul 12, 2018 6:11 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

With an engineer's wet finger, I would say they need to actuate in about 0.1 seconds to reasonably impress. If it took a second to move up or down, it wouldn't look right. That's more what I expected. It would feel almost instant at that. It's a rather critical parameter for choosing the actuator.
by PiGraham
Thu Jul 12, 2018 6:09 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

They are connecting 5V to one side of the solenoid coils and the switch pull-up. That's not correct. Read what I had to say about it (immediately above your post). I think you are mistaken there. Take another look at the Fritzing diagram. The button is shown with a black wire to the blue rail of th...
by PiGraham
Thu Jul 12, 2018 2:57 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

dibolero wrote:
Thu Jul 12, 2018 2:06 pm

Ideally they could go up and down in one second.
That's much slower than I expected. I should think linear steppers would be a good option for a smaller device. I would guess they might move 3mm in 250ms, but that is only a guess.
by PiGraham
Thu Jul 12, 2018 2:03 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

How fast do the pins need to move? I sonder if you could use miniature linear stepper motors. example on eBay Advantage of a screw is it will not give under finger pressure and takes no power to hold position. Possible disadvantage is might be too slow to move. There are lots of variants larger or s...
by PiGraham
Thu Jul 12, 2018 12:52 pm
Forum: Add-ons
Topic: Relay' connected to Rpi Zero W - causes it to freeze
Replies: 28
Views: 498

Re: Relay' connected to Rpi Zero W - causes it to freeze

As suggested - I tried to power the relay ( instead of pi's 5V ), with external power supply: Relay was powered correctly ( green led was ON )- but switching was not done ( voltage difference of 3.8 between trigger GPIO connected on relay to GND on relay ). You should never get >3.3 Volts on a gpio...
by PiGraham
Thu Jul 12, 2018 10:09 am
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

What is the motivation for making your own solenoids? As a learning experience that's a good thing to do but you can buy them for £1 each and they probably work better. https://www.ebay.co.uk/itm/DC-4-5V-40g-3mm-Open-Frame-Actuator-Push-Pull-Solenoid-Electromagnet-ZBUK/142800577556?hash=item213f93e414
by PiGraham
Thu Jul 12, 2018 10:06 am
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

Just to clarify, was this system wrongly designed? https://www.hackster.io/hitherejoe/braillebox-braille-news-reader-e86060 This is a braille project on hackster, he used 100ohm resistors with 5v solenoids and this was basically our starting point and basis of what we did with our project. I am afr...
by PiGraham
Wed Jul 11, 2018 7:27 pm
Forum: Automation, sensing and robotics
Topic: Controlling homemade solenoids using Rpi Z W
Replies: 51
Views: 766

Re: Controlling homemade solenoids using Rpi Z W

So we took a stupid risk and tried connecting the homemade solenoid to the pi without a resistor and surprisingly it didn't do anything. The 3 volt battery was able to move the pin so isn't the 3.3v gpio pin supposed to be enough? You shouldn't connect inductive loads to logic circuits, including d...
by PiGraham
Wed Jul 11, 2018 3:36 pm
Forum: Add-ons
Topic: Relay' connected to Rpi Zero W - causes it to freeze
Replies: 28
Views: 498

Re: Relay' connected to Rpi Zero W - causes it to freeze

Hi, Motor is powered from wall (220VAC), 4 wires : 0, GND, Ph-UP, Ph-DOWN. . relay switch power to UP wire, or Down wire ( 2 different relays ). my biggest confusion is what is the connection between switching power to the motor, can FREEZE the RPI. a) i'll try later on to connect Relay to external...

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