Electrical Engineering

abinjacob

7:47 AM

hello

Tom you are here too.

Can i get a help regarding running dc motor?

anyone here

here is a link to a post asking how to run dc motor using pwm

0

Q: How to get 6V DC motor running using PWM through STM board

simulate this circuit – Schematic created using CircuitLab I have taken help from previous posts to redraw the circuit, but the 6v motor is not driving at all. However, instead of connecting PD12 pin, if I connect 5v pin from STM board , motor rotates good without PWM. MOSFET Gate is conne...

the first image is added after taking suggestions and adding 3v is my thought in first image

anyone any idea, please help

PlasmaHH

8:17 AM

Dang, i feel like someone stole me an hour...

Zeta.Investigator

12:28 PM

What is with this "Bracket Challenge"?

pages.electronicdesign.com/bracket-challenge-2017

What is the measure of voting? If I understood right, there is no real actual project-based competition and the whole thing is based on fanatic popularity??

Marla

@Zeta.Investigator . . . I just read the page you posted, and the link to all the rules. Definitely sounds like a popularity contest.

Zeta.Investigator

@Marla Then those poor colleges ain't got a slim chance... I can already predict the final is between MIT and Stanford

Marla

Quoting the only criteria mentioned : "The top U.S. based universities have been selected according to a criteria set by our editorial staff"

But that is just for creating the original pool of universities.

Followed by : "The goal is to highlight universities that are highly active in a number of engineering communities (design competitions, hackathons, robotics, research, incubators)."

Zeta.Investigator

12:46 PM

@Marla But I think the winner of each round should be chosen based on some real engineering contest measure not a football fanboy-ism vote!-vote!...

Marla

It is their contest, and they can do it any way they choose. Others can make up contests to their own desires.

Zeta.Investigator

@Marla sure :D

Marla

I am surprised they convinced so many reputable vendors to donate prize.

Zeta.Investigator

@Marla It is a positive-feedback loop! The more famous and rich colleges which already have (I guess) all kind of flashy ANSYS licences will win again!

Marla

The prize I have always wanted is a spectrum analyzer with bandwidth from DC to White Light.

Zeta.Investigator

12:53 PM

@Marla You're RF-engineer, am I right? Quick question (as I read you like "quick" ones :D), how difficult is it to design a satellite receiver like commercial ones, using off-the-shelf parts and ICs?

Marla

@Zeta.Investigator First, I didn't say I liked the phrase "quick question". I meant that I was amused that people thought there was such a thing here as a "quick answer".

RF also deals with distributed components that are not visible (stray capacitance, etc).

Making layout difficult and requiring several iterations of PCB that require intuitive thinking and keen observation of geometries of components and layout.

(not magic, but not caculable either)

And the test equipment for troubleshooting isn't inexpensive.

Zeta.Investigator

@Marla Thanks. Doesn't the digital receiver's main board have to do more with non-RF circuitry and DSPs? Suppose the signal has came from dish and LNBs and such...I mean, the rest of the system still has to do with RF?

Marla

I do not have relevant experience with modern satellite receiving systems. I do use SDRplay for RF spectrum analyzer. And finally, I consider anything above DC to be RF :) . . . :)

en.wikipedia.org/wiki/Extremely_low_frequency . .. . Like for communicating with submarines .

Zeta.Investigator

1:12 PM

@Marla OK. What books do you suggest for RF field? I have a simple Walkie-Talkie toy and I'm simultaneously amazed by it and I don't know how it works! :'(

I did a little search in the net and it came up to Bowick's RF circuit design and 2 books from Hayward....

Marla

@Zeta.Investigator I don't have a book that I would recommend. Look for what textbooks are being used by colleges and universities. That way you will have common reference with your contemporaries to discuss.

Zeta.Investigator

@Marla Ok..Thank you for your time

Marla

welcome

@Zeta.Investigator . . I just viewed Bowick's book on Amazon. The reviews for the book seem to be very good.

Zeta.Investigator

@Marla Yeah I've also read them...But I was looking for a more n00b-like solution... If you want a python book, robotics book or embedded systems book, there are tons of DIYs and evil geniuses around...but looks like when it comes to RF, people just don't come near it! lol

Marla

@Zeta.Investigator View this. Not knowing your level of education, it might help. : ti.com/lit/ml/slap127/slap127.pdf

Zeta.Investigator

1:25 PM

@Marla I've skimmed over it yesterday. It is a nice presentation. Thank you...

abinjacob

2:01 PM

hello

Marla

2:29 PM

@abinjacob hello. and a good morning here

abinjacob

@Marla its good evening here :)

i am confused regarding rotating a dc motor using pwm singal

i mean signal

Marla

ok, go on

abinjacob

i have written a post in electrical stack, asking about the solution, here is the link

0

Q: How to get 6V DC motor running using PWM through STM board

simulate this circuit – Schematic created using CircuitLab I have taken help from previous posts to redraw the circuit, but the 6v motor is not driving at all. However, instead of connecting PD12 pin, if I connect 5v pin from STM board , motor rotates good without PWM. MOSFET Gate is conne...

microcontroller power-supply mosfet dc-motor stm32f4

the first image is edited after taking help from experts, although connecting 3v directly is my thought, is it a good idea

dc motor did not start even after making changes like adding resistors, as advised by experts

Marla

Where do you want to connect 3v to ?

abinjacob

i do not want to , i have just shown in first image

one advisor suggested, that gate to source voltage is not high enough to make mosfet on

Marla

2:39 PM

True, your IRFZ44N has a minimum requirement of 4 volts to turn on. 3v or 3.3v will not turn the FET on

abinjacob

what should be done?

Marla

What frequency will you use for your PWM ?

the 10 kHz mentioned in your question is the PWM frequency ?

abinjacob

yes, i have used the same frequency, also tried with 20kHz

Marla

Find a logic level converter to convert 3 volts to 5 volts. Use the 5 volts to drive your FET. ( you mentioned that your STM board has a 5 volt supply)

Changing frequency will not help

abinjacob

so can i connect 5v to mosfet

Marla

2:51 PM

you can drive the gate to source with 5 volts, yes. The maximum gate source voltage for your mosfet is 20 volts

abinjacob

how should i connect 5v pin from stm board into mosfet

after 1k owm resistor, before it or before the joint between 1k and 10k

?

please don't get angry with so many questions

Marla

Do not connect 5 volts directly to the mosfet gate.

abinjacob

how should it be then?

Marla

Obtain (purchase or build) a logic level translator. This is an additional circuit that converts your logic level 3v PWM to logic level 5v PWM.

abinjacob

can you help me with that, how to make it

and is the pwm signal from stm board of 3v level?

Marla

3:00 PM

I do not know if logic level from STM is 3 volts. Commenters on your question said it was 3 volts. You can measure the voltage with your voltmeter

If you don't have a voltmeter, then I can not help you

abinjacob

ok, then how to make the logic level convertor,

and why should 5v not be connected directly to mosfet

Marla

If you connect 5 volts supply directly to your MOSFET, what do you think the MOSFET will do ?

connected to the MOSFET gate ?

Do you happen to have a NPN transistor ?

abinjacob

ok i got it

yes the mosfet irfz44N, i guess N stands for NPN

Marla

no, the N doesn't stand for NPN.

NPN transistor is a bipolar transistor.

abinjacob

n-channel?

Marla

3:05 PM

your MOSFET is N-channel, yes

Have you determined whether your logic outputs are 3 volt or 5 volt ?

abinjacob

is IRFZ44N MOSFET, good for the porpose?

i mean purpose

no, i will tell, i do not have the equipment, but i will tell quick

Marla

If your STM board puts out 5 volts for a logic 1, and 0 volts for a logic 0, then your MOSFET is ok for the circuit. . .

If your STM board puts out 3 volts or 3.3 volts for logic 1, then your MOSFET is NOT good for the circuit.

abinjacob

definitely it is not 5v, otherwise it would have run.

i had connected 5v instead of PWM signal, and the motor was working great

but i am not getting the exact value of voltage level from pin

i found some clue from internet, that logic level is 3.3v

but datsheet said, 2v to 4v gate to source voltage

@Marla are you there?

Marla

4:02 PM

@abinjacob. . 2 to 4 volts range. So if your particular device is the 4 volt one, then the most wouldn't turn on

Mosfet *

abinjacob

which mosfet should be used then

Marla

Search for mosfet with the high range of 3 volts or less

abinjacob

i searched

found some with 0.4 v gate-source threshold voltage-0.4v

vishay.com/docs/71692/71692.pdf

onsemi.com/pub/Collateral/NTJS3157N-D.PDF

is it good to go with

Zeta.Investigator

4:30 PM

Folks here are more experienced than me, but you should look for a "logic level MOSFET". And for building a 3.3 to 5 logic level converter circuit, take a look at the philips (NXP) application note for using I2C with 5 volts... APPLICATION NOTE
Bi-directional level shifter for
I²C-bus and other systems.
AN97055

www.nxp.com/documents/application_note/AN10441.pdf

abinjacob

@Zeta.Investigator Sir, doed that means I need to use I2C protocol?

i mean does

Zeta.Investigator

4:52 PM

@abinjacob No, you asked for a level shifter circuit and I think that application note which provides a 2 transistor solution for doing so, does what you want. You should ask from others too.

Also I think you should put a resistor in series with MCU and gate of MOSFET

And a diode from drain to source for protecting against back emf

abinjacob

@Zeta.Investigator yes, resistor and diode is added, first image of schematic should be considered

0

Q: How to get 6V DC motor running using PWM through STM board

First image is edit of image 2. simulate this circuit – Schematic created using CircuitLab I have taken help from previous posts to redraw the circuit, but the 6v motor is not driving at all. However, instead of connecting PD12 pin, if I connect 5v pin from STM board , motor rotates good ...

microcontroller power-supply mosfet dc-motor stm32f4

i think replacing single mosfet will be easier than using two transistors, if it works as required.

are the mosfets good to go with for the purpose?

if changing mosfet won't work, then two transistor scheme will be followed

abinjacob

5:16 PM

for now Good night, see you soon @Zeta.Investigator @Marla

Zeta.Investigator

5:47 PM

@abinjacob Good night

Nick Alexeev

8:07 PM

I have a board where 200 components are SMT and a few are THT. Some of the SMT components are on the bottom side (solder side) of the board. The PCB assembly house may want to wave solder the THT components and use a pallet to mask the SMT components at the bottom. How much clearance for the pallet should I leave between the THT pins and the SMT components?