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by boyoh
Thu Jul 09, 2020 7:02 pm
Forum: Beginners
Topic: GPIO - high side switching an LED
Replies: 3
Views: 85

Re: GPIO - high side switching an LED

I might be wrong with this , but it might be like a Darlington Pair configuration. So it might be very sensitive

To lower the sensitivity try a 4k7 resistor from base to ground. Or try other value resistors ( Not to low )

Regards Boyoh
by boyoh
Thu Jul 09, 2020 4:35 pm
Forum: Beginners
Topic: LED help
Replies: 15
Views: 325

Re: LED help

Using LEDs is a part of the learning curve of learning basic Electronics , If you can't master this , don't go any
further untill you understand this

Regards BoyOh

This might help you
led  circuit.jpg
led circuit.jpg (91.29 KiB) Viewed 56 times
by boyoh
Tue Jul 07, 2020 8:37 am
Forum: Beginners
Topic: Over-Voltage and Over-Current protection circuit
Replies: 8
Views: 280

Re: Over-Voltage and Over-Current protection circuit

Don't make it obvious that that you are a very Wealthy man with a lot to steal . The cost of the system you want to install will cost more than you want to protect Place a singe saying NO Money Or Valuables kept on Site All the information you want to know , you will get from a Security Specialist F...
by boyoh
Fri Jul 03, 2020 11:00 am
Forum: Beginners
Topic: Electronics questions
Replies: 7
Views: 419

Re: Electronics questions

This might seem a bizarre Idea for a potential divider for this project , This might give more stable operation than moving the slider back and fore , The Idea is using a Photoresistor and a resistor as the potential divider Use a filament bulb and the slider in series with a dc volts to suit the bu...
by boyoh
Sun Jun 28, 2020 10:59 am
Forum: Beginners
Topic: Adding 12V PC Fan to Raspi 4B
Replies: 10
Views: 349

Re: Adding 12V PC Fan to Raspi 4B

In my opinion you don't need extra heat sinks or fans , If you use the Pi to do low level current switching and not use it as a power house, Use the Pi out puts to switch higher current buffer stages . You can us transistors or Opto Isolators as voltage levelers , Why load the Pi up with all kinds o...
by boyoh
Wed Jun 24, 2020 11:32 am
Forum: Beginners
Topic: Monitoring A/C redundancy box outputs "dry contacts"
Replies: 9
Views: 343

Re: Monitoring A/C redundancy box outputs "dry contacts"

Is this project possible using OPTO ISOLATORS You can use the Relays N/C or N/O, You will have the option to do as you want Pi 5v to relay common Relay N/C--------------------( R )--------------( a opto k )--------------grd pi 3.3v Rail------------------------------------------( c T e )-------------...
by boyoh
Mon Jun 15, 2020 7:48 pm
Forum: Beginners
Topic: Pulse Generator question
Replies: 4
Views: 182

Re: Pulse Generator question

I am an amateur seismologist and would like to add a 1/minute pulse to the records Looking at myriads of posts, I see people have built function generators etc with these devices. I am looking for a very long duration pulse. I am brand new to this platform and while I have studied the pinouts for t...
by boyoh
Fri Jun 12, 2020 10:33 pm
Forum: Beginners
Topic: Detecting Photodetector Voltage with RasPi0
Replies: 1
Views: 90

Re: Detecting Photodetector Voltage with RasPi0

I am trying to build a voltage feedback system using the Raspberry Pi but am not incredibly familiar with it. I was really hoping somebody more experienced could make sure I'm not completely lost. To provide a bit of background, I will be measuring a pulsed source of light with a photodector, whose...
by boyoh
Wed Jun 10, 2020 7:14 pm
Forum: Beginners
Topic: Light sensor connected to GPIO
Replies: 5
Views: 239

Re: Light sensor connected to GPIO

drgeoff wrote:
Wed Jun 10, 2020 11:34 am
Agreed that the 100k resistor should be adjusted. However, no need for "protection" as even if zero ohms is there, nothing will be damaged.
drgeoeff
Not detrimental to circuit operation , but you have proved your point

Regards BoyOh
by boyoh
Wed Jun 10, 2020 3:31 pm
Forum: Beginners
Topic: Building a list of resources for low level GPIO
Replies: 1
Views: 114

Re: Building a list of resources for low level GPIO

Hello, Started messing around with hardware on pi 3b +. Used GPIO zero to get a feel of the components but have a interest in C/C++. Wanting to do more low level programming with libgpiod. I am currently look through kernel docs and very surface level blogs on running the basic 5 cli binaries (gpio...
by boyoh
Wed Jun 10, 2020 11:09 am
Forum: Beginners
Topic: Light sensor connected to GPIO
Replies: 5
Views: 239

Re: Light sensor connected to GPIO

Hi, I have created simple light dector. Schemea is below: https://i.ibb.co/2hRQVJj/light-detector.jpg Real circuit on breadboard: https://i.ibb.co/QN5RhvH/light-real-circut.jpg I have written code in python using GPIO library: import signal import sys import RPi.GPIO as GPIO import sqlite3 import d...
by boyoh
Wed Jun 10, 2020 9:36 am
Forum: Beginners
Topic: Choosing: Pull Up or Pull Down Resistor
Replies: 23
Views: 889

Re: Choosing: Pull Up or Pull Down Resistor

I updated the drawing to show octoisolators (they might be drawn in incorrectly, but that is where it would be), and I included resistors in series before each coupler. I'm not sure what size resistor this should be yet. If I set up this circuit as shown, do you think it would work as intended? htt...
by boyoh
Tue Jun 09, 2020 4:17 pm
Forum: Beginners
Topic: Raspberry pi 4 and 4-20mA analog input
Replies: 2
Views: 122

Re: Raspberry pi 4 and 4-20mA analog input

4 - 20 ma senses uses current loop in their operation ,Used a lot in Industrial operation sending signals to PLCs and micro processors. An example to tell if a motor is stopped, or just idling off load , A PLC or Microprocessor will want to know the difference. In a nut shell you want know if 4ma cu...
by boyoh
Tue Jun 09, 2020 3:14 pm
Forum: Beginners
Topic: Choosing: Pull Up or Pull Down Resistor
Replies: 23
Views: 889

Re: Choosing: Pull Up or Pull Down Resistor

Connecting 1000ft aerials to a digital circuit without isolation and protection is never a good idea. Using either coaxial cable or twisted pairs and/or a low pull down resistor (say 50 ohm) at the receiving end will help. Noise tends to be voltage related with little current, a low resistance, hig...
by boyoh
Tue Jun 09, 2020 9:33 am
Forum: Beginners
Topic: Choosing: Pull Up or Pull Down Resistor
Replies: 23
Views: 889

Re: Choosing: Pull Up or Pull Down Resistor

Thank you for all the helpful comments. There appears to be more ways than I originally thought to solve this problem. To minimize the learning curve of a new data transfer protocol and other large changes in code / hardware, I was kind of thinking along the lines that 1 or 2 of you touched on, sim...
by boyoh
Mon Jun 08, 2020 3:07 pm
Forum: Beginners
Topic: Monitor GPIO inputs
Replies: 22
Views: 962

Re: Monitor GPIO inputs

This is just an Idea of how it might be don , using more circuit control electronics to replace the Selector switch
for more auto control Push switches are momentary Bothe GPIOs set to Latch for 10 seconds Diodes to stop feed back

Just a Idea Regards BoyOh
by boyoh
Mon Jun 08, 2020 12:27 pm
Forum: Beginners
Topic: Choosing: Pull Up or Pull Down Resistor
Replies: 23
Views: 889

Re: Choosing: Pull Up or Pull Down Resistor

Would it be possible to use a higher voltage as the signal wires to the remote limit switches. Then the switch wires back from the limits switch's , then use opto isolators as voltage levelers 12v to 3.3 v to the GPIOs , Opto Isolaters are very good at noise isolation and signal isolation This is on...
by boyoh
Sat Jun 06, 2020 4:14 pm
Forum: Beginners
Topic: Powering Multiple Components
Replies: 9
Views: 438

Re: Powering Multiple Components

At least you are honest about your knowledge of electronics . this makes it much easier to give you some advice. The first thing is I think this project is a bit out of reach for you,, until you have more understanding of how the Pi controls things. My advice is don't use the Pi as a high current po...
by boyoh
Fri Jun 05, 2020 3:40 pm
Forum: Beginners
Topic: Powering Multiple Components
Replies: 9
Views: 438

Re: Relay Setup

It would be much easier to answer your post if we know what your knowledge of Digital electronics is Do you work in a electrical electronics environment . Your question evolves understanding how to interface with the Raspberry Pi Inputs and out puts ,this is a must if you want to do some design proj...
by boyoh
Wed Jun 03, 2020 3:45 pm
Forum: Beginners
Topic: Monitor GPIO inputs
Replies: 22
Views: 962

Re: Monitor GPIO inputs

I think the OP would like you to sort the problem for him Regards BoyOh 1. SaturdaySam (the OP) want to learn about Raspberry Pi. He may also enjoy learning about electronics but the most constructive response is how to do this with a Raspberry Pi. 2. I don't think he "would like you to sort the pr...
by boyoh
Wed Jun 03, 2020 10:43 am
Forum: Beginners
Topic: Monitor GPIO inputs
Replies: 22
Views: 962

Re: Monitor GPIO inputs

This is a typical Digital Logic Exclusive OR circuit ,it can be constructed using transistors or a IC , A good circuit to learn on A good basic electronics learning project on how to use Transistors....I've pointed you in the right direction, so get doing some research What you will need 2 / 2n 222...
by boyoh
Tue Jun 02, 2020 2:45 pm
Forum: Beginners
Topic: Monitor GPIO inputs
Replies: 22
Views: 962

Re: Monitor GPIO inputs

Hi everybody - new here, so please be gentle!! I have recently become interested in Raspberry Pi since retiring and I am gradually learning! I am working on a project idea but unfortunately I am a little stumped. I need to have 2 input pins on the GPIO constantly monitored so that when each pin goe...
by boyoh
Mon Jun 01, 2020 7:46 pm
Forum: Beginners
Topic: Monitor GPIO inputs
Replies: 22
Views: 962

Re: Monitor GPIO inputs

This is a typical Digital Logic Exclusive OR circuit ,it can be constructed using transistors or a IC , A good circuit to learn on A good basic electronics learning project on how to use Transistors....I've pointed you in the right direction, so get doing some research What you will need 2 / 2n 2222...
by boyoh
Tue May 19, 2020 3:11 pm
Forum: Beginners
Topic: Old Raspberries...
Replies: 15
Views: 869

Re: Old Raspberries...

Plenty of life in the Old Pi , If you use it as it was intended to do That was to learn Coding and Electronics. Why buy a more powerful modal, when you have not mastered the first one, Why buy something then stick it in a fancy box with a couple fans ,and not knowing how to use it . They read up wha...
by boyoh
Sat May 16, 2020 3:18 pm
Forum: Beginners
Topic: Understanding the pi 5V pins
Replies: 5
Views: 513

Re: Understanding the pi 5V pins

Nah I'm not running the pi anywhere near its limit at the moment. It's headless and averages about 8-10% CPU and a consistent 1GB RAM usage (out of 4). It's okay at the moment and runs on average around 54 degrees with a max spike of 62 rarely. But I'd rather keep my electronics cool if possible, e...

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