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tlfong01
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Cat Home DIY Q&A - Solenoid How To

Fri Jan 11, 2019 7:31 am

Cat Home DIY - Solenoid pulling door

I am in the middle of making a Rpi controlled cat food dispenser. So far I have learnt how to use Rpi to control a solenoid [1] .

Now I need to design some mechanical flap thing to attach to a plastic box of dry cat food, so that Rpi can ask the solenoid to pull a hinge connected flap (or door, or window like thing) so the food falls to a bowl.

I also thought about a sliding door etc, but not sure what is the best way to go.

As shown in the attached picture, I have mechanical things like pull and push springs, hinges, and it is handy for me to go to the corner metal work shop or TaoBao to buy other cheap things. I am a cheap hobbyist, my motto is "As cheap as possible, but not cheaper."

I don't have any 3D printer. I have basic metal work tools, like hack saw, file, drill etc to process 2/3/4mm thick plastic sheets. I also have thin aluminium angles 1/2 inch to one and half inch. I prefer light aluminium work to heavy mild steel work.

All brainstorming design ideas welcome.

[1] My solenoid experiments
viewtopic.php?f=91&t=230325&start=25#p1413958

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pcmanbob
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Re: Cat Food Dispenser - How to open the box to let the food fall

Fri Jan 11, 2019 11:49 am

Why not try a simple web search ?

There are a number of pet feeder examples on the web which might give you ideas and not all of them use 3d printing.

https://www.google.com/search?client=fi ... cat+feeder
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Re: Cat Food Dispenser - How to open the box to let the food fall

Fri Jan 11, 2019 1:16 pm

pcmanbob wrote:
Fri Jan 11, 2019 11:49 am
Why not try a simple web search ?
There are a number of pet feeder examples on the web which might give you ideas and not all of them use 3d printing.
https://www.google.com/search?client=fi ... cat+feeder

Ah, actually I have been web searching in the past 6 months and could not find one that suits all my requirements. One of my requirements is to use a 1N solenoid to open the 'door' of the cat food box.

I want to use a solenoid because this cat feeder is a companion project of the cat door, which is also using a solenoid perhaps 5N strong. I will be asking for help on the cat door project perhaps a couple of days later.

I have no experience in using a solenoid, so I would like to do some sort of problem based learning. It is only today, that I learnt the difference between push and pull type solenoid. So my question is a bit misleading. I should have said that I only know how to use pull solenoid, but push solenoid might be better. That is why I used the word 'brainstorming' when asking for help.

...

I am learning very very slowly, it took me two months to learn how to use Lua to write a GPIO blink LED program but found it useless for my HX711 weight sensor. I also spent a couple of months learning how to use I2C MCP23017 to control temperature sensor DHT11, but also failed, because Rpi I2C speed is limited to 100kHz. I did spend a couple of months learning how 5/12/24V relay works, and decided to DIY my own, ...

Sorry for typo errors and unstructured paragraphs. Perhaps I should tidy up and condensed to a short paragraph to introduce my hobbyist project. I actually tailored my project specs to Cornell U's EE year projects, perhaps more later, ...


So if you find me any Rpi projects using solenoid, for cat feeder or else, I would appreciate it. Many thanks.

Update 2019jan11hkt2236

Below are the Cornell U student projects that I am learning from.

Cornell University ECE5725 Spring 2017 Raspberry Based Projects
http://skovira.ece.cornell.edu/ece5725- ... -projects/

Cooking Robot Food Dispenser
https://courses.ece.cornell.edu/ece5990 ... sions.html

RPi Plant Watering Robot
https://courses.ece.cornell.edu/ece5990 ... index.html
Last edited by tlfong01 on Fri Jan 11, 2019 2:40 pm, edited 4 times in total.
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pcmanbob
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Fri Jan 11, 2019 1:55 pm

Controlling a solenoid is basically the same as controlling an LED using the pi gpio.

The only difference is the voltage and the much higher current drawn by the solenoid compared to the LED.

So you need some interface between the pi gpio and the solenoid, the simplest would be to use one of the relay boards/hats made for the pi and then use one of the relays to switch the power on/off to the solenoid.

You could also build your own interface circuit using suitably rated transistors.

As for an example from the raspberry pi blog https://www.raspberrypi.org/blog/drops- ... and-bread/
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Fri Jan 11, 2019 2:23 pm

pcmanbob wrote:
Fri Jan 11, 2019 1:55 pm
Controlling a solenoid is basically the same as controlling an LED using the pi gpio.
The only difference is the voltage and the much higher current drawn by the solenoid compared to the LED.
So you need some interface between the pi gpio and the solenoid, the simplest would be to use one of the relay boards/hats made for the pi and then use one of the relays to switch the power on/off to the solenoid.
You could also build your own interface circuit using suitably rated transistors.
As for an example from the raspberry pi blog https://www.raspberrypi.org/blog/drops- ... and-bread/

Rpi Using Relay to Control Solenoid

Ah, you are completely right, using Rpi and a relay to control solenoid is very simple. My simple python program is the one below. You may also like to look at my solenoid experiments.

Rpi3B+ program to control ZYE1 Version 2019jan10
viewtopic.php?f=91&t=230325&p=1414971#p1414433

And as I said, I am very slow in learning things - it took me one week to learn the basic things about the solenoid and finally wrote the program. :)
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Re: Cat Food Dispenser - How to open the box to let the food fall

Sat Jan 12, 2019 4:09 am

pcmanbob wrote:
Fri Jan 11, 2019 11:49 am
Why not try a simple web search ?
There are a number of pet feeder examples on the web which might give you ideas and not all of them use 3d printing.
https://www.google.com/search?client=fi ... cat+feeder

3D Printer vs Basic Metalwork (Aluminium/Acrylic) Hand Tools

Well, actually the main reason I prefer hand tools rather than 3D printers is that [cheap] 3D printers cannot print aluminium and acrylic, not to mention they are ridiculously slow.

By the way, I found more toys like spring balance and pulleys for the ”Solenoid Pulling Cat Food Container Door/Window/Opening Design“. Crowd innovative brainstorming ideas still always welcome.

...
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Re: Cat Food Dispenser - How to open the box to let the food fall

Sat Jan 12, 2019 7:58 am

tlfong01 wrote:
Sat Jan 12, 2019 4:09 am
3D Printer vs Basic Metalwork (Aluminium/Acrylic) Hand Tools
Well, actually the main reason I prefer hand tools rather than 3D printers is that 3D printers cannot print aluminium and acrylic, not to mention they are ridiculously slow.

3D Printed Rotating Usher Design

But I am not that out of 3D printing. For the following rotating cereal usher, I would get a print to order, from a local maker club, the Maker Bay.

Homemade Dog Feeder with Arduino UNO - eriksuch 2015 19,927 views
https://www.youtube.com/watch?v=TcqbZ_y5WI0

And as almost always, Arduino guys are smarter in hardware DIY design than Rpi guys! :mrgreen:

Hong Kong Maker Bay
https://www.makerbay.org/

MakerBay is a Hong Kong-based maker group with locations in Central and Tsuen Wan with space, tools [Laser cutter, CNC miller, 3D printers!] and community focused on using innovation for social and environmental impact.

Technology is a part of human nature | Cesar Jung-Harada | TEDxShanghai
https://www.youtube.com/watch?time_cont ... zE5VPTg6Us

...
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Re: Cat Food Dispenser - How to open the box to let the food fall

Sat Jan 12, 2019 9:33 am

tlfong01 wrote:
Sat Jan 12, 2019 7:58 am
...

Cat Food Dispenser Design Notes

/ to continue, ...

...
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Re: Cat Food Dispenser - How to open the box to let the food fall

Sun Jan 13, 2019 9:30 am

tlfong01 wrote:
Sat Jan 12, 2019 9:33 am
Cat Food Dispenser Design Notes

Weekend Aluminium Cutting Work

Aluminium angle dimension = 0.8mm x 12.5mm x 25.3mm (0.03" x 0.5" x 1")

Bon Qui Qui - I will cut you - 62,967 views
https://www.youtube.com/watch?v=sS2q6xIDRUc

...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Mon Jan 14, 2019 4:37 am

pcmanbob wrote:
Fri Jan 11, 2019 1:55 pm
Controlling a solenoid is basically the same as controlling an LED using the pi gpio.
The only difference is the voltage and the much higher current drawn by the solenoid compared to the LED.
So you need some interface between the pi gpio and the solenoid, the simplest would be to use one of the relay boards/hats made for the pi and then use one of the relays to switch the power on/off to the solenoid.
You could also build your own interface circuit using suitably rated transistors.
As for an example from the raspberry pi blog https://www.raspberrypi.org/blog/drops- ... and-bread/

Using TIP120 to control solenoid

So I have used the KY019 relay to control the solenoid and all is well. But when I googled more arduino tutorials on solenoid (not than many Rpi tutorials around), I found many guys use the TPI120 NPN transistor instead of a relay.

I have never heard of TIP120, though I did play with power MOSFET (forgot the part number update - IRF540N) long time ago. So I googled the datasheet and found it good.

TIP120 is single channel, not like the ULN2003 used in the piano project your referred. But I only need one channel, so TIP120 should be a good choice. So I am going to order some TIP120 to replace the bulky KY019 relay.

Many thanks for your tip.


TIP120 NPN Plastic Medium-Power Complementary Silicon Transistors
https://www.onsemi.com/pub/Collateral/TIP120-D.PDF

Update 2019jan14hkt1334

I visited Mike Cook's blogsite and found his blog post very good. I also wish what William H. Bell wishes, a Rpi project page, saving everybody's time searching but found most of them are Arduino related! :(

Solenoid-Controlled Glockenspiel - Mike Cook
http://www.thebox.myzen.co.uk/Raspberry ... Board.html

William H. Bell says: 22nd Jun 2012 at 3:21 pm
https://www.raspberrypi.org/blog/drops- ... and-bread/

Are projects like this one going to be collected together into a set of links or pages for schools? While it is good to see on the blog, in the longer term a project page would be a better reference.

Update 2019jan14hkt2028

Now I remember I used the power MOSFET IRF540N. I need to check if it is as good as TIP120. If yes, then I might try IRF540N.

...
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Re: Cat Food Dispenser - How to open the box to let the food fall

Mon Jan 14, 2019 6:09 am

tlfong01 wrote:
Sun Jan 13, 2019 9:30 am
tlfong01 wrote:
Sat Jan 12, 2019 9:33 am
Cat Food Dispenser Design Notes
Weekend Aluminium Cutting Work
Aluminium angle dimension = 0.8mm x 12.5mm x 25.3mm (0.03" x 0.5" x 1")

Gilbow G56 Snip

I have been using the 'cutter' to cut thin aluminium sheets for some years. I found it very good, but I always wondered why it is made in Shiffield, not in another great country. So I googled, and found the following.

Gilbow G56 Straight Jewellers Snip £23
https://www.tooled-up.com/gilbow-g56-st ... prod/4506/

The IRWIN Gilbow G56 is a straight blade cutting snip which has been designed for use on precious metals.

The long handle/short blade ratio gives the user more control when cutting.

Irwin Gilbow snips and shears have a great cutting capability which this is much greater than the strength of the user and will provide a good, clean, easy cut edge to any workpiece.

The original Gilbow G56 jewellers tinsnips were first designed many years ago [and manufactured in Sheffield], and have dominated the sheet metal cutting industry to such an extent that today, snips and shears are referred to as 'Gilbows'.

* Type: Jewellers Tinsnip
* Size: 180mm (7in)


Snips - Wikipedia
https://en.wikipedia.org/wiki/Snips
...
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Re: Cat Food Dispenser - How to open the box to let the food fall

Mon Jan 14, 2019 7:32 am

tlfong01 wrote:
Mon Jan 14, 2019 6:09 am
Cat Food Dispenser Design Notes


Solenoid opening/closing cat food container window manual testing notes
...
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Re: Cat Food Dispenser - How to open the box to let the food fall

Mon Jan 14, 2019 1:40 pm

tlfong01 wrote:
Mon Jan 14, 2019 7:32 am
tlfong01 wrote:
Mon Jan 14, 2019 6:09 am
Cat Food Dispenser Design Notes

Solenoid opening/closing cat food container window manual testing notes


Cat Food Box Design Notes

Now that the manual simulated test of solenoid pulling hinged window of cat food box looks more or less OK, I am going to test it out on the real 3L acrylic box. The window to let the food fall is 6 x 14cm. So I will think about how to use the solenoid, (or stepping motor, or servo) to open this window.
...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Tue Jan 15, 2019 6:20 am

tlfong01 wrote:
Mon Jan 14, 2019 4:37 am
I have used the KY019 relay to control the solenoid and all is well. But when I googled more arduino tutorials on solenoid (not than many Rpi tutorials around), I found many guys use the TPI120 NPN transistor instead of a relay.
I have never heard of TIP120, though I did play with power MOSFET IRF540N long time ago. So I googled the datasheet and found it good.

Rpi GPIO driving IRF540N Power MOSFET

I googled and found that IRF540's gate source threshold is up to 4V. Rpi GPIO is only about 3V. So I need a gate driver. Because I already used TSX0104 to shift Rpi GPIO signals from 3V3 to 5V0. So I can just use it. To make very sure, I am looking at the signal waveforms, NE555, DSG (Digital Signal Generator), Rpi GPTO 3V3, and Rpi GPIO 5V0 (shifted by TSX0104)

All looks good.
...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Tue Jan 15, 2019 7:53 am

tlfong01 wrote:
Tue Jan 15, 2019 6:20 am
I googled and found that IRF540's gate source threshold is up to 4V. Rpi GPIO is only about 3V. So I need a gate driver. Because I already used TSX0104 to shift Rpi GPIO signals from 3V3 to 5V0. So I can just use it. To make very sure, I am looking at the signal waveforms, NE555, DSG (Digital Signal Generator), Rpi GPTO 3V3, and Rpi GPIO 5V0 (shifted by TSX0104)

Rpi GPIO driving IRF540N

Now I am reading the datasheet. It appears that if gate source voltage is 4.5V, drain source current can go up to 20A, enough for my little solenoid which needs much less than 2A.
...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Tue Jan 15, 2019 3:04 pm

tlfong01 wrote:
Tue Jan 15, 2019 7:53 am
Rpi GPIO driving IRF540N

IRF540 blinking LED test OK

youtube IRF540 blinking LED
https://youtu.be/SAR_2v_SOFg
...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 4:26 am

tlfong01 wrote:
Tue Jan 15, 2019 3:04 pm
tlfong01 wrote:
Tue Jan 15, 2019 7:53 am
Rpi GPIO driving IRF540N
IRF540 blinking LED test OK
youtube IRF540 blinking LED
https://youtu.be/SAR_2v_SOFg
...

Solenoid Postmortem

Now that the NE555 IRF540 combination can drive the LED, next step is to try driving the 12V Solenoid. And as soon as I connected the little solenoid, a scary thing happened, ...

All the indicator LEDs of both the Rpi system and the ZYE1 solenoid test jig went out immediately, without any white smoke coming out first.

The Rpi3B+ and ZYE1 were using two independent 200VAC to 12VDC PSUs. So my first guess is that the solenoid Back EMF has reset both PSUs through the AC200 mains wires.

I disconnected everything and hardware switched off and on both PSUs. Only the Rpi PSI goes on, the ZYE1 PSU is dead, :(

...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 4:57 am

tlfong01 wrote:
Wed Jan 16, 2019 4:26 am

Back EMF killed PSU Postmortem

I found the dead PSU has no power green LED. I tried a new PSU and found everything OK. So the verdict is that the Back EMF killed my PSU!
...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 6:05 am

tlfong01 wrote:
Wed Jan 16, 2019 4:57 am
So the verdict is that the Back EMF killed my PSU![/i][/color]

Rpi toggles ZYE1 at 0.5Hz

/ to continue, ...

Rpi toggles ZYE1 at 0.5Hz
(youtube) https://youtu.be/pmLlhG_-6BU
...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 7:05 am

tlfong01 wrote:
Wed Jan 16, 2019 6:05 am
tlfong01 wrote:
Wed Jan 16, 2019 4:57 am
So the verdict is that the Back EMF killed my PSU![/i][/color]
Rpi toggles ZYE1 at 0.5Hz
/ to continue, ...
Rpi toggles ZYE1 at 0.5Hz
(youtube) https://youtu.be/pmLlhG_-6BU
...

PSU Postmortem

I found the fuse of the dead PSU has not blown. So it might be Back EMF damaged some over voltage protection circuit.

Over Voltage Protection - Sun Power
https://www.sunpower-uk.com/glossary/wh ... rotection/

Enclosed PSU - MeanWell
https://www.meanwell.com/
https://www.meanwell.com/productSeries.aspx#tag-6-16
https://www.meanwell.com/webapp/product ... prod=RS-15
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 9:38 am

tlfong01 wrote:
Wed Jan 16, 2019 7:05 am

Second PSU 12V 2.1A for Testing Bigger Solenoids

Now I am assembling a bigger PSU for testing bigger solenoids.

All cables are nylon cable tied for strain relief, to avoid carelessly pulling cable too hard, causing poor contact, intermittent circuit breaking, introducing back EMF, killing my Rpi.

I am worrying that the back EMF thing might cause unpredictable trouble. So I am placing aside the first version of the solenoid evaluation board and also the Rpi.

I will only use this new version of 12V 2A PSU for testing, and only using NE555 signals.

Rpi will not be used unless I have tested using NE555 and am pretty sure that no back EMF would kill the NE555 or PSU.

...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 12:39 pm

tlfong01 wrote:
Wed Jan 16, 2019 9:38 am

Heavy Duty PSU (5~32VDC, 8~12A) for Multiple Big Solenoids

Now I have assembled this big guy, both adjustable voltage and adjustable constant/short circuit current.

Heavy Duty PSU Adj Volt and Amp 5V to 32V, 8~12A - ¥60
https://detail.tmall.com/item.htm?id=56 ... 3ad40BQdf0

...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 12:53 pm

tlfong01 wrote:
Wed Jan 16, 2019 12:39 pm

IRF540N Power MOSFET No Solenoid Load Test

Last time I let the IRF540N to switch the solenoid and found the 12VPSU fried. Now I have retested every devices and found that everything works well.

In other words, it was only the 12V PSU killed by the back EMF, the 12V to 5V PSU is not damaged. Also the Rpi PSU was auto reset, but found OK after hardware power on reset.

...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 1:07 pm

KY019 Relay to drive small and big solenoids

Last time' test using IRF540N power MOSFET killed my 12V PSU. I have lost confidence on it. So I will go back using relay which I have been found reliable.

I am thinking of starting with the simplest relay KY019. I will test both a small 0.8N and a big 20N solenoid.

...
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Re: Cat Feeder DIY - How to use solenoid to control cat food flowing out of box down to bowl

Wed Jan 16, 2019 1:21 pm

tlfong01 wrote:
Wed Jan 16, 2019 1:07 pm
I am thinking of starting with the simplest relay KY019, ...

KY019 5V Relay Specification

RE: RELAY MODULE KY-019 5V Postby tlfong01 » 2018-Jun-02 Sat 10:10 pm
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