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by jadel
Wed Mar 06, 2019 10:22 am
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

tlfong01 wrote:
Wed Mar 06, 2019 12:58 am

Big Picture and Long Description Please! :mrgreen:
My question is more about a general possibility. Could I control let's say five electromagnets using one relay board and one power supply?
(while supplying each magnet with about 12V)
by jadel
Tue Mar 05, 2019 4:58 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

tlfong01 wrote:
Tue Mar 05, 2019 3:09 pm


which the one? :mrgreen:
by jadel
Tue Mar 05, 2019 2:42 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

tlfong01 wrote:
Tue Mar 05, 2019 2:32 pm

All magnets can share the same power supply, if total power is not exceeded.
Would the circuits be similar to the one for a single magnet or would I have to make big adjustments?
by jadel
Tue Mar 05, 2019 2:29 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Thanks for the help everyone got it working.
Just curious if I wanna have more than one magnet does each need it's own power supply or could I use the same one for more than one magnet.
by jadel
Mon Mar 04, 2019 10:59 am
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Just confirming before I miss anything up, this circuit should work with the relay connected at the NO end and the middle. Correct? Note: I couldn't find a relay board on the circuit making website, so I am using a single relay which will be part of a relay board. The relay board will be connected t...
by jadel
Sun Mar 03, 2019 5:18 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Two reasons: The GPIO drives a 3.3V signal, and the relay needs 5V The relay needs more current than the 10 to 15mA a GPIO can deliver So the transistor is used as a current amplifier, and 5V switch. Currently I am powering the relay board with a separate 12 V power supply. Wouldn't this be enough ...
by jadel
Sun Mar 03, 2019 4:36 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

pcmanbob wrote:
Sun Mar 03, 2019 3:58 pm

In reference to
Capture2.PNG
This diagram
Capture2.PNG (112.12 KiB) Viewed 1651 times
And this
tlfong01 wrote:
So there are at least three circuits you can choose.

(1) Small NPN BJT such as 2N2222 and 5V relay (Note 1),

by jadel
Sun Mar 03, 2019 3:42 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Also just for my own understanding, can someone please explain the need for the transistor.
Thanks
by jadel
Sun Mar 03, 2019 3:41 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

1. I am 90% sure that you don't need any flyback diodes for the relays, because the relays are driven by ULN2803 octal darlingtons with built in flyback diodes. Just checking you mean I don't need it across the relay not the whole circuit, right? 2. The schematic date is dated 2011. There is 80% ch...
by jadel
Sun Mar 03, 2019 10:20 am
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

If you don't have the link, you can show me a picture of you module, or skim the following posts and tell me which relay looks like yours. https://www.amazon.co.uk/gp/product/B07568JFNV/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 I only wanted to clarify that it was a board because I'm unsure ...
by jadel
Sat Mar 02, 2019 10:08 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Note - if you have already bought a 12V relay, you can use it, getting the same 12V power for electromagnet. This question might seem silly but I'm a bit confused by the phrasing. Does this mean I don't have to use an external power supply and just connecting the solenoid to the board will supply i...
by jadel
Sat Mar 02, 2019 10:05 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

the relay also needs a flyback diode. I forgot to mention I don't have a single relay. I'm using a "relay module driver board module with optocoupler", so I am using female to female pins to connect between the pi and the pins on the board. How would I add a flyback diode between them? Does that me...
by jadel
Sat Mar 02, 2019 12:18 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

So would this type of circuit work for it. https://forum.allaboutcircuits.com/proxy.php?image=http%3A%2F%2Fimg4.hostingpics.net%2Fpics%2F483312transistorrelaysolenoidvalveflyback.png&hash=ecb29a13ff8e50f6fb20e7c79773d9f3 Also from this circuit would I have to use both the GPIO pins and the relay or...
by jadel
Fri Mar 01, 2019 7:29 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

It is a 10SQ045, here's the data sheet: http://www.senocn.com/data/PDF/10SQ030-10SQ100.pdf Looks good to me. However, many people often disagree with me, in particular mahjongg and rpdom. So watch this space. Its certainly useable, just probably a bit overkill, but who cares. So would this type of ...
by jadel
Wed Feb 27, 2019 7:32 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Using a diode that can carry the full current of the coil seems to be preferable to using a small one and hoping. Using a diode that can switch fast enough to take the spike would be preferable to frying everything. We don't know what jadel's "10A, 45V diode" is, It is a 10SQ045, here's the data sh...
by jadel
Wed Feb 27, 2019 1:23 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Using a diode that can carry the full current of the coil seems to be preferable to using a small one and hoping. Using a diode that can switch fast enough to take the spike would be preferable to frying everything. So does that mean the ones I have wouldn't work, or would they be safe enough to ke...
by jadel
Wed Feb 27, 2019 11:08 am
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Re: Connecting electromagnet to pi

Note, to keep the dissipation on the FET low, you need the FET to either be completely closed (no voltage between gate and source) or open (a large voltage between gate and source), that is why two transistors are used to drive the gate voltage, also with this circuit the FET is off when you turn o...
by jadel
Tue Feb 26, 2019 2:50 pm
Forum: Automation, sensing and robotics
Topic: Connecting electromagnet to pi
Replies: 94
Views: 7401

Connecting electromagnet to pi

I want to control an electromagnet that I built with my rpi. I built the magnet myself and want to run 12V into it, it has 2 ohm resistance so the current will be 6 A. I have a 12V relay board that I connected to the pi. I also have a 10A, 45V diode that I will be using for flyback. My main issue is...

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