Go to advanced search

by boyoh
Sun Feb 16, 2020 5:12 pm
Forum: Beginners
Topic: The energy consumed by a raspberry card
Replies: 10
Views: 307

Re: The energy consumed by a raspberry card

Ohm's Law concerns voltage, current and resistance. It is irrelevant if one has values for voltage and current and wishes to calculate power ("wattage"). from BoyOh The watt (symbol: W) is a unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per seco...
by boyoh
Sun Feb 16, 2020 11:13 am
Forum: Beginners
Topic: The energy consumed by a raspberry card
Replies: 10
Views: 307

Re: The energy consumed by a raspberry card

First is to check the voltage and the current , then using Ohms Law to give you the Wattage. Ohm's Law concerns voltage, current and resistance. It is irrelevant if one has values for voltage and current and wishes to calculate power ("wattage"). from BoyOh The watt (symbol: W) is a unit of power. ...
by boyoh
Sat Feb 15, 2020 11:37 pm
Forum: Beginners
Topic: The energy consumed by a raspberry card
Replies: 10
Views: 307

Re: The energy consumed by a raspberry card

First is to check the voltage and the current , then using Ohms Law to give you the Wattage. You do the tests on / load and off/ load . For testing on load use a high wattage high specs resistor . Make Shure the resistor you use will not take the current beyond the Pi full load Then the rest is up t...
by boyoh
Sat Feb 15, 2020 7:12 pm
Forum: Beginners
Topic: Switching from Arduino to RPi, what parts to buy
Replies: 5
Views: 178

Re: Switching from Arduino to RPi, what parts to buy

You are given the option of setting the GPIO I/P To a impedance level that the processor can respond to. In its high impedance state floating, It will not, sink or source a working level signal. This being a logic level 0 low or 1 high, So you must set it to a working impedance level by setting the ...
by boyoh
Thu Feb 13, 2020 11:36 pm
Forum: Beginners
Topic: Wiring inductive sensors in series
Replies: 38
Views: 688

Re: Wiring inductive sensors in series

You can't put optos in series. Not very many anyway as I explained in my first post. Or any optos at all in this case. Good points Peter. IIRC there was an upper limit to the resistance though. A huge improvement over that first diagram TecHnoGuy. We are definitely headed in the right direction. I ...
by boyoh
Thu Feb 13, 2020 11:35 pm
Forum: Beginners
Topic: Wiring inductive sensors in series
Replies: 38
Views: 688

Re: Wiring inductive sensors in series

You can't put optos in series. Not very many anyway as I explained in my first post. Or any optos at all in this case. Good points Peter. IIRC there was an upper limit to the resistance though. A huge improvement over that first diagram TecHnoGuy. We are definitely headed in the right direction. I ...
by boyoh
Thu Feb 13, 2020 4:34 pm
Forum: Beginners
Topic: Wiring inductive sensors in series
Replies: 38
Views: 688

Re: Wiring inductive sensors in series

My advice is stick to your first circuit and use the opto Isolaters transistors in Series Using 5v instead of 3.3v through the opto transistor chain.. Use a Opto Isolator from the last opto isolator in the chain as a voltage leveler 3.3v to the GPIO IN / PUT. No need for Potential Dividers This mean...
by boyoh
Tue Feb 11, 2020 11:24 pm
Forum: Beginners
Topic: Wiring inductive sensors in series
Replies: 38
Views: 688

Re: Wiring inductive sensors in series

Thanks for the reply. I hadn't heard of opto-isolators before so never would have thought of it. Just to check that I have understood correctly I have made a circuit diagram where the symbols labelled IC are the opto-isolators. Pi_Senssor-Circuit_1.png (Edit: And also I assumed resistors would be n...
by boyoh
Tue Feb 11, 2020 9:09 pm
Forum: Beginners
Topic: Wiring inductive sensors in series
Replies: 38
Views: 688

Re: Wiring inductive sensors in series

Thanks for the reply. I hadn't heard of opto-isolators before so never would have thought of it. Just to check that I have understood correctly I have made a circuit diagram where the symbols labelled IC are the opto-isolators. Pi_Senssor-Circuit_1.png (Edit: And also I assumed resistors would be n...
by boyoh
Tue Feb 11, 2020 8:17 pm
Forum: Beginners
Topic: interfacing multiple components with Raspberry pi
Replies: 3
Views: 82

Re: interfacing multiple components with Raspberry pi

how to interface an ultrasonic sensor, moisture sensor and gsm module with Raspberry-pi 3 B+ and how to write the program? From BoyOh Do you understand basic Electronics ? Do you understand how the Raspberry Pi In /Put & Out/Put's work The Raspberry Pi is NOT PLUG & PLAY You have some research to d...
by boyoh
Fri Feb 07, 2020 11:55 am
Forum: Beginners
Topic: Fitting a fan without using GPIO?
Replies: 20
Views: 407

Re: Fitting a fan without using GPIO?

Pi Board.jpg
Pi Board.jpg (60.13 KiB) Viewed 83 times

You could use this board for building your projects on , I fitted 4 slotted Opto Isolators for voltage leveling
and projects control .All built on Vero Board .Good project for learner

Regards BoyOh
by boyoh
Thu Feb 06, 2020 9:32 pm
Forum: Beginners
Topic: Fitting a fan without using GPIO?
Replies: 20
Views: 407

Re: Fitting a fan without using GPIO?

You could fit the Fan in the Pi box , and having it temperature controlled just using the 3.3v rail and 5volt for the fan , Using a NTC Thermistor switching a transistor to switch the fan on and off , The thermistor is Temperature controlled resistor If you do use a Thermistor use a preset in series...
by boyoh
Tue Feb 04, 2020 3:57 pm
Forum: Beginners
Topic: Powering a RPi 3B+ through GPIO vs USB
Replies: 14
Views: 354

Re: Powering a RPi 3B+ through GPIO vs USB

The Pi is not designed to be used as a power house. If you want to run power hungry projects ,you must use buffer stages , and let the Pi control them with low power signals The USB connection is the one to use . Using GPIO to feed the power to the Pi is asking for problems ,and also bypassing the s...
by boyoh
Sun Feb 02, 2020 10:23 am
Forum: Beginners
Topic: Using different sensors wiring
Replies: 11
Views: 479

Re: Using different sensors wiring

These are examples of how to use both a potential divider circuit and an opto isolator to connect the sensor to your pi. I would consider the opto isolator circuit the better option especially if you are going to be using a sensor voltage nearer the 36V maximum. https://i.imgur.com/Ww07eGK.jpg You ...
by boyoh
Sat Feb 01, 2020 8:42 pm
Forum: Beginners
Topic: Raspberry Pi control Relay with momentary switch
Replies: 27
Views: 1534

Re: Raspberry Pi control Relay with momentary switch

You've got more patience than me, drawing diagrams that way! As long as the resistors are high enough (10K) the diodes should be unnecessary. There are still two minor issues for the OP to iron out: 1. If the Pi fails with the GPIO high, the lights will be held on. 2. If the Pi fails with no 3V3 su...
by boyoh
Sat Feb 01, 2020 1:34 pm
Forum: Beginners
Topic: Raspberry Pi control Relay with momentary switch
Replies: 27
Views: 1534

Re: Raspberry Pi control Relay with momentary switch

You'll need to find a way to turn it off again! (Probably needs a push to break button). And avoid shorting the Pi output when you get Pi and switch driving same thyristor (needs one resistor). A faulty Pi could force the lights permanently on. From BoyOh Check the circuit you will see the N/C = No...
by boyoh
Fri Jan 31, 2020 4:23 pm
Forum: Beginners
Topic: Raspberry Pi control Relay with momentary switch
Replies: 27
Views: 1534

Re: Raspberry Pi control Relay with momentary switch

You'll need to find a way to turn it off again! (Probably needs a push to break button). And avoid shorting the Pi output when you get Pi and switch driving same thyristor (needs one resistor). A faulty Pi could force the lights permanently on. From BoyOh Check the circuit you will see the N/C = No...
by boyoh
Thu Jan 30, 2020 4:21 pm
Forum: Beginners
Topic: Raspberry Pi control Relay with momentary switch
Replies: 27
Views: 1534

Re: Raspberry Pi control Relay with momentary switch

I am looking for is simple latch relay circuit. For example PI send a pulse it will latch the relay and if doesn't PI fail. The momentary switch push will send the same pulse the relay will latch. The low voltage relay will control another high voltage for the lights. This could be don using a Thyr...
by boyoh
Wed Jan 29, 2020 11:33 pm
Forum: Beginners
Topic: Raspberry Pi control Relay with momentary switch
Replies: 27
Views: 1534

Re: Raspberry Pi control Relay with momentary switch

Anybody has any suggestions? One main point is you must have a emergency y lighting system installed, Not in the pi controlled system The system must be Fail To Safe at no time must you take for granted that the system is ELECTRILY DEAD If the system fails it must be attended to by some one WHO kno...
by boyoh
Fri Jan 24, 2020 9:30 pm
Forum: Python
Topic: PIR motion detection code
Replies: 13
Views: 377

Re: PIR motion detection code

You are given the option of setting the GPIO In/ Put impedance ( resistance ) level that the processor can respond too In its high impedance state Floating, it will not sink or source a working level signal this being a logic level 0 low or 1 high, So you MUST set it to a working impedance ( resista...
by boyoh
Wed Jan 22, 2020 11:51 am
Forum: Beginners
Topic: Question regarding minimum power required?
Replies: 16
Views: 534

Re: Question regarding minimum power required?

Point to remember is

The strength of a current (amps) is directly proportional to a pressure ( volts) between two points.

But is inversely proportional to its Resistance (ohms )

Regards BoyOh
by boyoh
Mon Jan 20, 2020 4:58 pm
Forum: Off topic discussion
Topic: For mahjongg Moderator , On his remark on my post
Replies: 22
Views: 1357

Re: For mahjongg Moderator , On his remark on my post

I got a report from some user that your post was "unreadable", asking to warn you that your post was "unreadable". When I checked your post I understood what was meant by "unreadable", as it was a jumble of text with linefeeds at all the wrong places. I could have "repaired" the text, but frankly i...
by boyoh
Mon Jan 20, 2020 12:58 pm
Forum: Off topic discussion
Topic: For mahjongg Moderator , On his remark on my post
Replies: 22
Views: 1357

For mahjongg Moderator , On his remark on my post

This post is to mahjongg " Moderator" concerning his remark to my Post on the print spacing. I thought you was a bit blunt , saying the post was Unreadable, yes I should have spaced it better I hope the post contents was not wrong or misleading, as this could give the impression to some reading the ...
by boyoh
Sun Jan 19, 2020 5:54 pm
Forum: Beginners
Topic: Input protection with resistors
Replies: 18
Views: 606

Re: Input protection with resistors

You are given the option of setting the GPIO I/P To a impedance level that the processor can Respond to. In its high impedance state floating It will not sink or source a working level signal This being a logic level 0 low or 1 high, So you MUST set it to a working impedance level by Setting the in...
by boyoh
Sun Jan 19, 2020 10:19 am
Forum: Beginners
Topic: Input protection with resistors
Replies: 18
Views: 606

Re: Input protection with resistors

You are given the option of setting the GPIO I/P To a impedance level that the processor can Respond to. In its high impedance state floating It will not sink or source a working level signal This being a logic level 0 low or 1 high, So you MUST set it to a working impedance level by Setting the int...

Go to advanced search