hybridfree/eevblog-posts huggingface dataset:
Applying Middlebrook method for open loop gain measurement - Page 1
Forum section: electronics / beginners

author: bonzer
author_rank: Regular Contributor
timestamp: January 13, 2019, 04:02:44 pm
content: Hello everyone! Could anyone help me please by taking a look to the way I applied Middlebrook method in this case. Here we have an amplifier with two bjt, the second one forms a closed loop by its own (it's kinda like a common emitter) and the first one is just there with and closes the whole circuit in another loop. I want to open the inner loop at the upper branch and apply middlebrook there as this way I open both loops (even the outer). As said by Rosenstark I should apply it directly tho the active part of the circuit (dependent generator of the BJT).Should I apply it to both transistors to study the open loop gain and therefore the stability?If I apply it to the other (first transistor) I get the open loop gain of the outer loop with the second loop closed letting it to behave like a single amplifying block. Is this needed to or it's enough to study the inner loop?
Applying pressure to a thermistor - not a good idea? - Page 1
Forum section: electronics / beginners

author: ledtester
author_rank: Super Contributor
timestamp: May 30, 2018, 06:06:18 pm
content: I salvaged a thermistor like the one shown below from a laptop battery pack.When I tested it it appeared to be of the 10K NTC variety.I wanted to use it to measure the temperature of a heatsink, so I applied some heat sink compound and pressed it against the heatsink with a paper binder. And then I started to get really weird resistance readings - like in the megaohm range.So I figure that applying a lot of pressure to one of these thermistors is a bad idea. So perhaps I should just use silicon/heat sink compound to affix the thermistor?

author: metrologist
author_rank: Super Contributor
timestamp: May 30, 2018, 06:29:18 pm
content: Captain Tape!

author: Zero999
author_rank: Super Contributor
timestamp: May 30, 2018, 06:35:40 pm
content: Quote from: metrologist on May 30, 2018, 06:29:18 pmI've never heard of it, don't you mean Kapton tape?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 30, 2018, 06:37:45 pm
content: Yeahhh... if you clamped down on the thermistor bead part, you probably cracked it, or the soldering, or the flex circuit.Would've been fine if you clamped before or after the bead, so the force bears on the flex (which is pretty flat and stiff, in thickness) instead.And yes, Kapton(R) (generic: polyimide) tape is good stuff, as long as the surface isn't greasy it will stick nicely. So, apply white goop sparingly where the thermistor sits, tape it down and you're good to go. If you want a permanent installation instead, use a loaded epoxy (loaded with some material to give better thermal conductivity, really -- any will do, JB Weld, etc., doesn't have to be insulating since the thermistor is already insulated), and maybe some strain relief nearby so the leads don't tear the flex (if applicable).Tim

author: metrologist
author_rank: Super Contributor
timestamp: May 30, 2018, 08:44:19 pm
content: Kapton®now I feel obligated to give acknowlegementhttp://www.dupont.com/content/dam/dupont/products-and-services/membranes-and-films/polyimde-films/documents/DEC-Kapton-Trademark-Guidelines.pdf

author: ledtester
author_rank: Super Contributor
timestamp: May 30, 2018, 09:11:59 pm
content: Or if you want something that's a lot cheaper but looks the same...
Approaches for MCU PWM -> JAMMA audio - Page 1
Forum section: electronics / beginners

author: jameswilddev
author_rank: Contributor
timestamp: April 22, 2021, 09:25:37 pm
content: Hello.I've got an ATMega outputting audio using a PWM pin (approximately 56kHz carrier). Currently I'm running that through a RC lowpass and into a line-in for testing.Something I'd like to do is to convert my design into something JAMMA compatible (JAMMA being a connector standard for arcade machines - PCBs with edge connectors are sort of "system on a board" allowing the brains of an arcade machine to be upgraded without replacing the cabinet/display/speakers/controls). Something unusual about this is that it seems to expect the amplification of the audio to be done on the game PCB rather than in the cabinet, so I need some kind of amplifiction. The general consensus seems to be that the speaker is 8ohm, and at capable of taking at least a few watts. There's often a potentiometer in series to act as a volume control.In my travels I did find a project where somebody made an ATMega644-based JAMMA board (https://www.hwhardsoft.de/english/archive/uzebox-jamma/). They seem to run the PWM directly into a LM386 without a lowpass. I've heard mention before that the MCU pin itself can form a lowpass through some form of capacitance at the pin; not sure if that's the intention here (I think the resistor network is just to bring down the ampltiude a little). The limited slew rate of the LM386 might also be a factor in filtering out the carrier but I'm not sure.What I was wondering was whether I can get away with something nice and simple like this if I'd be happy with 0.25-0.5W. I've already got the signal in PWM so it shouldn't have any problems driving transistors in saturation. I've done nothing before with discrete transistors. This is a BC327 + BC337; using their minimum spec hFE of 100. I'm assuming they don't need to be matched or anything if they're being used in saturation? Collector current seems to be peaking at 200mA in the simulator while the speaker is on about 350-400mW. Set the low pass frequency at 12.7kHz and the high pass frequency at 60Hz. Seems to be sinking/sourcing less than 3mA from the PWM input so that should be good.Thanks!
Appropriate cap size for USB Hub - Page 1
Forum section: electronics / beginners

author: Stonent
author_rank: Super Contributor
timestamp: December 25, 2015, 07:02:45 pm
content: I picked up a cheap USB hub to use with my tablet and Raspberry Pi. It has a socket for external power if needed.I took it apart and it's about as expected a single chip that fans out to all the ports.Each port has a footprint for a radial electrolytic capacitor that is unpopulated so I was thinking I'd just whack a couple in, but was unsure of an appropriate capacity. I don't want to go so big that it does something evil and fries something accidentally, but not so small that it doesn't help at all.I think I'm just interested in smoothing out the occasional device that needs a little extra juice to get going and then levels out.

author: Simon
author_rank: Unknown
timestamp: December 25, 2015, 07:12:56 pm
content: Does it work ok ? as for startup power demands even 100uF is not terrific, I'd not go more than 10uF per port if you have to mess with it.
Appropriate fuses for EEVblog BM2257 Multimeter - Page 1
Forum section: electronics / beginners

author: jj5
author_rank: Unknown
timestamp: January 30, 2025, 04:15:39 am
content: Hi there. I recently acquired anEEVblog BM2257 Multimeter. On page 16 of themanualit says the required fuses are:F1 Fuse (Dimension: 6x32 mm) for μA/mA input:ASTM HV620.0.63: 0.63A/1000Vac & Vdc, IR 30kA, F fuseF2 Fuse (Dimension: 10x38 mm) for A input:Bussmann KLM-12: 12A/600V, IR 50kA for Vdc & 100kA for Vac, F fuseorASTM HV110.11A: 11A/1000V, IR 30kA, F fuseMy reading of this is that I need 6x32mm 630mA fuses and 10x38mm 11A fuses. Is that correct? TheMultimeter Fuse Pack(which is out of stock) seems to come with 400mA fuses not 630mA fuses.It would be really helpful if someone could tell me what are the correct fuses to buy and link me to specific models available on AliExpress/eBay/Amazon/element14/etc.Thanks!

author: mwb1100
author_rank: Frequent Contributor
timestamp: January 30, 2025, 06:47:58 am
content: Dave's going to carry a new set of fuses. He's working out how he's going to package/sell them:-Re: New Brymen BM2257 MultimeterIf you end up needing or wanting fuses before that happens, read up and down that thread for other various bits of info, such as where you might source some and whether 400mA fuses might be OK, why Brymen used them in the first place in other meters with 600mA ranges, and why they changed to 630mA fuses in the BM2257.
Appropriate use for a triac-output optocoupler? - Page 1
Forum section: electronics / beginners

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: February 26, 2020, 02:35:59 am
content: Hi all.I am wanting to cheaply make a circuit that uses one noise to trigger the output of another. Namely, a live drum beat via a microphone to cause the audience to briefly hear the output of a piano-keyboard.I was thinking of using the attached circuit to detect the drum hit. But replace the LED with the input side of zero-crossing triac-output optocoupler whereby the triac output permits current to flow from the line-out of a keyboard which is already playing..Does this seem practical? I am not asking about the section of the circuit which is highlighted, I just happened to screenshot-it when that was happening. I am aware that it will need tuning for sensitivity and duration. I was however, considering dispensing with the comparator entirely and simply allowing the optocoupler's LED to fade-out gradually, according to the time constant of the capacitor.

author: Zero999
author_rank: Super Contributor
timestamp: February 26, 2020, 03:18:28 pm
content: No, a TRIAC is completely unsuitable for carrying an audio signal. It will introduce a horrible amount of crossover distortion. You need a photo-coupled MOSFET, i.e. a small solid state relay suited to both AC and DC operation.
AR488 with HP1630D - Page 1
Forum section: electronics / beginners

author: Vivis
author_rank: Contributor
timestamp: May 30, 2021, 02:16:31 am
content: Hi all,I have an HP1630D I'm trying to get an inverse assembler on. I've built the AR488 and can get the HP to respond to button press commands and rst, but i can't quite get an assembler to load. Honestly, I'm not even sure I'm sending it right. I've been trying to send the files via coolterm's send text/binary file function. The best I can get out of the 1630 is a CRC error. I have been able to successfully invoke the TC command but have not been able to reload the config that TC generates.Thanks for any suggestions in advance
Arc fault breakers … any good explanations of internal circuitry? - Page 1
Forum section: electronics / beginners

author: calzap
author_rank: Frequent Contributor
timestamp: August 19, 2024, 07:24:17 pm
content: Looking for an in-depth exploration of the internal circuitry of an arc fault breaker … any brand. Have tried Google and youtube. Best I found are sites that say something like “Hey look. There’s a circuit board in here!”. A few state something about waveform comparison but no reference to actual circuitry.Anybody have links to something better?To be clear. I’m not interested in general function, installation or code requirements … I’ve got a good handle on those.Mike

author: IanB
author_rank: Super Contributor
timestamp: August 19, 2024, 07:58:29 pm
content: Arcs will generate high frequency noise with a characteristic spectral fingerprint. The circuit will have a detector that looks for that fingerprint and breaks the circuit.Unfortunately, the arcs from the brushes on universal motors also match the fingerprint, so power tools like electric drills will often (always?) cause nuisance trips. May also be true of things like kitchen blenders.

author: Gyro
author_rank: Super Contributor
timestamp: August 19, 2024, 08:50:02 pm
content: Quote from: IanB on August 19, 2024, 07:58:29 pmNot "always" ... From about 21 mins in for the meat.

author: IanB
author_rank: Super Contributor
timestamp: August 19, 2024, 09:50:47 pm
content: Quote from: Gyro on August 19, 2024, 08:50:02 pmOh dear. I thought those things were supposed to save your house from burning down?

author: coppice
author_rank: Super Contributor
timestamp: August 19, 2024, 10:17:35 pm
content: Quote from: IanB on August 19, 2024, 09:50:47 pmThey are supposed to pass some qualification tests. They are proprietary, and don't really document what they do and don't do in their algorithms. Its all rather hit or miss, with little consistency between the quirks or one product and the next.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 20, 2024, 04:06:29 pm
content: Big Clive gets deep into it:https://www.youtube.com/watch?v=u6I7dKDk7hE

author: calzap
author_rank: Frequent Contributor
timestamp: August 20, 2024, 05:02:28 pm
content: Quote from: Terry Bites on August 20, 2024, 04:06:29 pmThanks. Good video on regular breakers. Nothing on arc fault breakers.Mike

author: coppice
author_rank: Super Contributor
timestamp: August 20, 2024, 05:05:55 pm
content: Quote from: calzap on August 20, 2024, 05:02:28 pmIts not Big Clive. Its John Ward. If you look through his channel he has several videos on arc fault breakers

author: Gyro
author_rank: Super Contributor
timestamp: August 20, 2024, 06:25:27 pm
content: Quote from: calzap on August 20, 2024, 05:02:28 pmYou want eFIXX...https://www.youtube.com/@efixx/search?query=afdd(in addition to John Ward, as coppice says)... or David Savery if you want more rants! (as the one I posted previously) ...https://www.youtube.com/@dsesuk/search?query=afddP.S. I don't know how these relate to the US ones which, I think, have been around a lot longer. The current European ones have ARM processors in them.
Arcade Machine: 5V or 3V3 for button wiring - Page 1
Forum section: electronics / beginners

author: NivagSwerdna
author_rank: Super Contributor
timestamp: January 31, 2018, 09:35:06 am
content: This is a really basic question!I have an arcade table I am restoring and planning to replace the control PCB with a FPGA based solution. The FPGA has many 3V3 i/o pins which are not 5V compatible.Previously the PCB operated (primarily) at 5V so the wiring to the buttons was that the button was grounded on one side and then the other side came back to a wire that ended up on the PCB at a 8255 (Intel old style Peripheral Interface) with 1kR pull-up and a 220R current limiting resistor.I'm planning on using a trio SN74HC165 to provide sufficient lines for the buttons... just wondering if I could get away with operating at 3V3 or I should operate the shift registers and buttons at 5V and level shift back down to 3V3?The total round trip distance to the furthest button is around 150cmWhat do I need to consider? R of wire, immunity to noise?

author: Ian.M
author_rank: Super Contributor
timestamp: January 31, 2018, 10:00:39 am
content: You also need to consider wetting current for the switches unless they have gold plated or carbon contacts. A rough rule of thumb for reliable switch sensing is to pass 10mA through each switch with 10V (or greater) across each when open. That ensures there is enough voltage to break down light oxide films and enough current for the contacts to be self-cleaning. 5mA and 5V was probably enough for good quality switches.The easy option would be to level shift the SPI interface and run the shift registers at 5V, keeping the 1K pullups and any existing signal conditioning circuits.
Archer 277-128 schematic required - Page 1
Forum section: electronics / beginners

author: Cliff Matthews
author_rank: Unknown
timestamp: March 27, 2016, 09:26:13 pm
content: Have a 70's headphone amp PCB for a children's soldering project. I've searched for schematic without success. So far, I took pics of both sides and Photo-shopped the layers to guess the following:- It appears to be some single rail IC with both grounded and floating inputs.- the 2-pin header's seem to be for volume- the 3-pin header's may be for a tone control- J is VCC to current limiting resistors and bypass caps- C/F/H are ground- G/K are ouputsAny guess what IC this thing is based on?

author: dacman
author_rank: Frequent Contributor
timestamp: March 27, 2016, 11:35:34 pm
content: My guess is that Z1/Z2 is an LM386. Pin 1 & 8 are for the gain. The three pin header on pin 5, if it goes through C5 and R3 to pin 1, is a bass boost.

author: Cliff Matthews
author_rank: Unknown
timestamp: March 28, 2016, 02:54:20 pm
content: Quote from: dacman on March 27, 2016, 11:35:34 pmThanks! App notes and spare parts are enough to go on from here.. Didn't think the LM386 existed way back then. Also, the 0.75" sizing looks funny for output caps (a 4700uF/25v would fit perfectly!).
Arduino 1 way walkie talkie device - Page 1
Forum section: electronics / beginners

author: dleebell
author_rank: Contributor
timestamp: February 16, 2015, 11:33:51 am
content: HiI've got a new project on the go where I need to create a one way walkie talkie system between two devices (1 device with a microphone the other with a speaker).I am also wanting to include a digital display on the speaker device and a control system on the other microphone device. The control system would be to +1 to the digital numbers each time you press it, and a reset button to go back to 0.I'm just wondering if you could give me some tips on certain components that I will need, and maybe a website that could guide me to build it too and any other tips on how I can go about in making this.I have an Arduino Uno that I was hoping to use but I am a complete beginner with using it apart from a few lessons.Many Thanks
Arduino 101 with 5V logic level is fully safe ? - Page 1
Forum section: electronics / beginners

author: ammjy
author_rank: Regular Contributor
timestamp: July 13, 2017, 11:31:02 am
content: Hello !Arduino 101 have just "resistance" from 5V logic level via TVS or Zenor diode ?or Arduino 101 have logic level shifter so, Arduino 101 fully supported from 5V logic level ?Please, let me know ! and Thanks you for reading.

author: newbrain
author_rank: Super Contributor
timestamp: July 13, 2017, 12:53:33 pm
content: It includes bidirectionallevel shifters, as detailed in theschematic.Outputs are limited to 3.3V unless external pull ups are added, inputs can span the full 0-5V and is clamped to 3.3V on the Curie side.

author: rstofer
author_rank: Super Contributor
timestamp: July 13, 2017, 12:54:27 pm
content: Google "5v tolerant" for more information.An IO pin, when used as an input, can accept voltages as high as 5V with whatever internal circuitry that may exist. This doesn't change the logic thresholds, it is still 3.3V logic.An IO pin, when used as an output, will have two configurations set by some register. When set for open drain, an external pull-up resistor will provide the 5V. When set for active pull-up, the output voltage won't exceed the normal 3.3V logic levels. This may be adequate for most 5V logic to detect a logic '1'.The device itself can not be run at 5V. It's just allowable to use 5V external logic. This may not apply to any ADC inputs and it's worth reading the datasheet to see if there are exceptions. There usually are!

author: ammjy
author_rank: Regular Contributor
timestamp: July 13, 2017, 02:19:27 pm
content: Thanks you a lot !
Arduino - Page 1
Forum section: electronics / beginners

author: Balakumaran Selvaraji
author_rank: Contributor
timestamp: December 25, 2017, 10:31:58 am
content: Hello,I am using Arduino to program my EEPROM for the Output of my 8-bit breadboard computer. This was the code which I was running ::#define SHIFT_DATA 2#define SHIFT_CLK 3#define SHIFT_LATCH 4#define EEPROM_D0 5#define EEPROM_D7 12void setAddress(int address, bool outputEnable){shiftOut(SHIFT_DATA, SHIFT_CLK, MSBFIRST, (address >>| (outputEnable ? 0x00 : 0x80));shiftOut(SHIFT_DATA, SHIFT_CLK, MSBFIRST, address);digitalWrite(SHIFT_LATCH, LOW);digitalWrite(SHIFT_LATCH, HIGH);digitalWrite(SHIFT_LATCH, LOW);}byte readEEPROM(int address){setAddress(address, /*OutputEmable*/ true);byte data = 0;for(int pin = EEPROM_D7; pin >= EEPROM_D0; pin -= 1){data = (data << 1) + digitalRead(pin);}return data;}void setup() {// put your setup code here, to run once:pinMode(SHIFT_DATA,OUTPUT);pinMode(SHIFT_CLK,OUTPUT);pinMode(SHIFT_LATCH,OUTPUT);Serial.begin(57600);for (int base = 0; base <=255; base += 16){byte data;for(int offset = 0; offset <=15; offset +=1){data = readEEPROM(base + offset);}char buf;sprintf(buf, "%03x: %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",base, data, data, data, data, data, data, data, data, data, data, data,data, data, data, data, data);Serial.println(buf);}}void loop() {// put your main code here, to run repeatedly:}Now, I ideally this must give me what is there in the contents of the EEPROM in the Serial Monitor. But, when I look at it - I get crazy kind of Fonts...For Example : (This was in My EEPROM btw)?? ??)a?O"??!5???CC?BB!B?BCD??B??!F??!B??&?C??Fic?!???HCBC???B!??!?BÆ@??K??B!B?F!!!¡DB???B!N?!?EB)#F?"??B?=!??C?"?

author: HecticZA
author_rank: Contributor
timestamp: December 25, 2017, 10:41:37 am
content: Quote from: Balakumaran Selvaraji on December 25, 2017, 10:31:58 amDid you copy and paste the code from a website?Sent from my SM-N950F using Tapatalk

author: Balakumaran Selvaraji
author_rank: Contributor
timestamp: December 25, 2017, 10:45:40 am
content: Nah man. I just started programming this stuff to check what is in my EEPROM

author: Nusa
author_rank: Super Contributor
timestamp: December 25, 2017, 10:46:39 am
content: My first thought is baud rate mismatch. Is your serial monitor also at 57600?Can you get a "hello world" program to work?Serial.begin(57600);Serial.print("hello world");

author: Balakumaran Selvaraji
author_rank: Contributor
timestamp: December 25, 2017, 10:49:22 am
content: Thank You Nusa.I tried doingSerial.begin(19200);and setting the baud to 19200 baud.So, now it is working properly and I am getting the desired output from my eeprom.
Arduino 30V 3~5A PSU - Page 1
Forum section: electronics / beginners

author: Frankie1AbC
author_rank: Newbie
timestamp: November 25, 2017, 03:53:54 pm
content: Can anyone write code and make schematic for Arduino PSU thats gonna be able to deliver 3 to 5 Amps of current at 30V

author: TheInfernoMan
author_rank: Contributor
timestamp: November 25, 2017, 08:47:29 pm
content: Can you give more details to your question? Like why you need this (Application?) and more details (like linear or a SMPS) and what the Code should do on the Arduino (LCD or Rotary Encoder, etc?) and what your part on the project is...

author: Frankie1AbC
author_rank: Newbie
timestamp: November 26, 2017, 02:18:05 pm
content: Im planning to build bench PSU that would have LCD display buck boost converter and decent accuracy.My idea is to use arduino nano as a main controller have it control the buck boost converter via push buttons and display the output voltage and current on LCDOn Vin i couldnt get anything more than 24V out of laptop PSU that has 4.5A

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 26, 2017, 09:15:25 pm
content: Sure ...https://media.giphy.com/media/1M9fmo1WAFVK0/giphy.gifTim

author: ogden
author_rank: Super Contributor
timestamp: November 26, 2017, 09:20:56 pm
content: Quote from: T3sl4co1l on November 26, 2017, 09:15:25 pmExactly.Whatever.OP shall check this open source supply project with HW and SW on github:https://www.crowdsupply.com/envox/eez-h24005
arduino - Page 1
Forum section: electronics / beginners

author: abdullahseba
author_rank: Frequent Contributor
timestamp: May 18, 2014, 12:05:41 pm
content: is there a way to make the arduino receive inputs & run batch files on the computer according to the input code

author: retrolefty
author_rank: Super Contributor
timestamp: May 18, 2014, 12:25:41 pm
content: The was a user contribution named gobetwino that could stuff like that, but I haven't heard if it's very current or heavily used:http://playground.arduino.cc/Interfacing/GoBetwino

author: abdullahseba
author_rank: Frequent Contributor
timestamp: May 18, 2014, 12:50:34 pm
content: Quote from: retrolefty on May 18, 2014, 12:25:41 pmthanks just what I want
Arduino - Page 1
Forum section: electronics / beginners

author: antonii
author_rank: Newbie
timestamp: January 19, 2015, 02:57:24 pm
content: Hello.I want to buy an Arduino programmer for my eeprom chip (ATMEL AT27C256R-70PU).Does Arduino supports this chip?

author: zapta
author_rank: Super Contributor
timestamp: January 19, 2015, 04:13:47 pm
content: Check out eevblog #411 episode and its forums thread. It's a general purpose programmer, not Arduino specific.

author: free_electron
author_rank: Super Contributor
timestamp: January 19, 2015, 04:26:51 pm
content: 27c256 is NOT an eeprom. it is an UV erasable EPROMthe 29c256 would be a flash EEPROMthe 28C256 ( don't know if that one exists. i think they top out at 28c64) would be an EEPROM

author: Kappes Buur
author_rank: Regular Contributor
timestamp: January 19, 2015, 06:43:28 pm
content: http://www.mcumall.com/comersus/store/comersus_dynamicIndex.asp

author: antonii
author_rank: Newbie
timestamp: January 19, 2015, 08:38:29 pm
content: So that chip is an eprom.But now can i still use it with arduino?

author: Ryano
author_rank: Regular Contributor
timestamp: January 19, 2015, 09:47:56 pm
content: I agree with Wilfred that knowing what you are trying to do is key, but a good place to start would be here.http://tronixstuff.com/2010/10/29/tutorial-arduino-and-the-i2c-bus-part-two/
Arduino Adventures! - Page 1
Forum section: electronics / beginners

author: zerorisers
author_rank: Regular Contributor
timestamp: April 06, 2015, 01:56:59 pm
content: Hello everybody,I am starting a blog of my adventures and studies with the arduino. Bills has sent me an arduino with various components as a care package. I decided to give back to the forum by starting a blog that others can learn from. Just starting out so those who are new to arduino can follow along and play along at home.zerorisers-arduino.blogspot.com

author: zapta
author_rank: Super Contributor
timestamp: April 06, 2015, 02:55:13 pm
content: Would be more useful to have this announcement after you have at least one real post in your blog.

author: zerorisers
author_rank: Regular Contributor
timestamp: April 06, 2015, 03:01:14 pm
content: Quote from: zapta on April 06, 2015, 02:55:13 pmYou would be correct in that aspect. This is just more of an entry post for people to get to know about it, and what its going to be.
Arduino and DHT-11 Problems - Page 1
Forum section: electronics / beginners

author: skillz21
author_rank: Frequent Contributor
timestamp: October 16, 2016, 01:06:35 am
content: Hi guys,I recently got a DHT-11. So far, i have been having a lot of trouble getting it to work... I have not been able to find a working code on google. do you guys know any codes that work? or is the problem with my dht-11?thanks

author: Len
author_rank: Frequent Contributor
timestamp: October 16, 2016, 01:35:56 am
content: Adafruit has published an Arduino library & sample code on their web site:https://learn.adafruit.com/dht?view=allI haven’t tried it myself, but since they sell the DHT-11 I would expect their code to work.It does say the code to read the sensor is "a little tricky" so it’s not surprising you had trouble.

author: SnipTheCat
author_rank: Unknown
timestamp: October 16, 2016, 08:32:25 pm
content: Quote from: skillz21 on October 16, 2016, 01:06:35 amI have been using the adafruit library with both DHT11 and DHT22 without any problem, however they are not that great sensors (especially de DHT11)If you have trouble installing the library, you need to create a folder DHT in your arduino /libraries/ subfolder and put the files there (mainly DHT.h/cpp and example subdir), you should then have a DHT test available form the arduino menu when you restart the IDE.Since I have discovered the HTU21D modules, I haven't touched the DHT11/22 anymore, much better accuracy, only drawback is that you need a logic level converter if your arduino is 5V

author: frenky
author_rank: Unknown
timestamp: October 17, 2016, 09:16:22 am
content: Another nice temp and humidity module is Si7021 (3.3V):https://goo.gl/d0fbQs

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: October 17, 2016, 09:35:23 am
content: Avoid the DHT11,their indications are close to none.I have recently bought 10 DHT12 which are supposed to be an improved version, but which in fact differ from the DHT11 only by the interface.After some preliminary testings, I have set up a more complete experiment with 9 sensors at the same time.They give answers that are extremely different for the humidity. Not at all within the advertised specs of the maker (AOSONG) which says 5% for the DHT11 (did not find the DHT12 datasheet)The temp seems OK, butI got 48%, 52%, 56%, 59%, 61%, 68%, 69%, 72%, 72% for the Humidity outputso a max difference of 24% which is huge.A same experiment with 5 DHT22 gave much better resultsDHT22Hum: 63.20 % 60.50 % 63.30 % 65.30 % 66.20 % Temp: 24.60 C 23.70 C 23.40 C 22.90 C 23.10 CHum: 63.20 % 60.50 % 63.30 % 65.30 % 66.30 % Temp: 24.60 C 23.70 C 23.40 C 22.90 C 23.10 CHum: 63.30 % 60.50 % 63.30 % 65.30 % 66.30 % Temp: 24.70 C 23.70 C 23.40 C 22.90 C 23.10 C
Arduino and LDR - Page 1
Forum section: electronics / beginners

author: mike_mike
author_rank: Super Contributor
timestamp: April 27, 2018, 08:34:11 pm
content: Hello,I want to make a project using Arduino. The project will light up a few LEDs when the night will come.The schematic and the code are attached.1. Is the schematic correct ?2. Is the code correct ?3. If I want to use in the place of the led and the series resistor a 2A load, are there any modifications that I should make in the circuit ?4. Is there any need to implement an hysterezis ?I tested the circuit on a bread board and it works.

author: Signal32
author_rank: Frequent Contributor
timestamp: April 28, 2018, 04:21:16 am
content: Code & schematic seems that they would work.Suggestions:- You don't really need Q1 since the MOSFET has a VGS(TH) of max 4v - under the 5v of your arduino.- You want to implement logic to avoid flickering - Imagine that the readings for the cell are 399 400 398 401 398 400 401 etc either because of noise or because your light is indirectly illuminating your sensor. So implement something like if < 350 turn_off if > 450 turn_on, etc ...- Also code could be written nicer but you probably don't care.This would (probably) work for 2A too, but I would get a better MOSFTET for that - IRF630 will end up dissipating 2W because of the 0.5R RDS(ON).The probably is because of hopefully the 2A load doesn't share ground with the 12V power supply.

author: JS
author_rank: Frequent Contributor
timestamp: April 28, 2018, 04:30:18 am
content: You could use an IRF540 for this, I think the BJT is a good idea as the mosfet at 5ish volts might not be completly on at higher currents.The thing here is that you don't need an arduino, just with a comparator you are good to go, still can implement the hysteresis Signal32 suggested, just one more resistor to it, and then you can miss the transistor with no problem and the entire 5V supply as you can run the comparator on the 12V directly.Maybe you are just trying to get something useful done with the Arduino so go for it.JS

author: mike_mike
author_rank: Super Contributor
timestamp: May 01, 2018, 06:56:03 pm
content: What will happen if the initial value read from the LDR will be between 400 and 500 ?I made some tests and when the value read from the LDR is between 400 and 500 (I suppose) when I power up Arduino, the led_night (the led which will notify that the mosfet is ON) is off and the load (output_fet) is on, and the load is powered up. Can this problem be solved ? I used as load a 20W/12V light bulb, powered from an 12V 3A power supply.If I power up Arduino with the LDR in direct light the load remains off and the led_night remains also off.If I power up Arduino with the LDR in darkness, the load is powered and the led_night is lighting.1. This problem will appear only when I power up Arduino ?2. Is there any possibility to solve this problem ?

author: picandmix
author_rank: Frequent Contributor
timestamp: May 02, 2018, 07:53:26 pm
content: Hi,Try putting a 100nf capacitor across R2 and adding a 1 second delay in the Setup part of your code.
Arduino and signals of different levels? - Page 1
Forum section: electronics / beginners

author: dog80
author_rank: Regular Contributor
timestamp: January 24, 2014, 07:35:03 pm
content: Let's say hypothetically that I want to control an output using the data from three inputs. The problem is that all these are at different voltage levels.The output is a PWM signal at 12 VoltsThe first input is an analog signal from 0 to 1.25 voltsThe second input is a square pulse at 3 voltsAnd the third input is a square pulse at 8 Volts.How can I implement that?

author: niekproductions
author_rank: Contributor
timestamp: January 24, 2014, 07:41:34 pm
content: What exactly are you trying to do? It might be accomplishable using just logic gates. That will save you a lot of touble.

author: Rerouter
author_rank: Super Contributor
timestamp: January 24, 2014, 07:59:09 pm
content: This is all assuming a 5V supply and schmitt trigger inputs for the PWM and square waves1 - 12V PWM, divide down by ~3 with a resistor divider (22K high, 10K low) then place a 4.7V TVS diode across the center point and ground to protect it, (assuming 5V supply) this you then feed into your first input, and is nice and safe for the outside world2- Buffer with an op amp 1-1, with a 10K or higher value on its input and a 4.7V TVS diode (to ground) between the resistor and op amp input, you could even use said op amp to increase the gain of the signal if you want, but pick a rail to rail type, (includes lower voltage rail is a must)3. Square 3V pulse, as long as you are confident it is 3V, then a 10K resistor and a 4.7V TVS diode to ground will be all the protection you need4. 8V Square wave, divide it by 2 with a resistor divider (10K high, 10K low), and a 4.7V TVS diode between ground and the center point, this is your 4th input,
Arduino Assisted Battery Characterization and Logging - Page 1
Forum section: electronics / beginners

author: jram112
author_rank: Contributor
timestamp: July 31, 2013, 06:15:52 pm
content: I need some help deciding if my battery characterization setup will work properly.Background: I have a few different single cell LiPo batteries (3.7V). I want to characterize them using similar loads that my circuit will use.Setup: I will use three LiPo's with each having a separate programmable load. I want to use arduino to log the battery voltages and to halt the discharge of each battery when they go below 2.7V. Attached is a schematic. Are there any concerns about having the three loads connected to the same ground? Should I use DPDT relays instead?

author: Bloch
author_rank: Unknown
timestamp: July 31, 2013, 07:11:18 pm
content: Look´s ok

author: mswhin63
author_rank: Frequent Contributor
timestamp: July 31, 2013, 11:19:36 pm
content: I haven't used LiPo batteries before but you will need to latch the relay as soon as you disconnect the load the Battery voltage may rise back above 2.7V otherwise it should work fine.

author: waoj
author_rank: Contributor
timestamp: October 12, 2021, 07:48:09 am
content: Would this same setup work just as well for 12v 7a SLA UPS batteries? I have a bunch to test to decide if I want to replace them or not, and I wanted to base that decision on actual performance.

author: ledtester
author_rank: Super Contributor
timestamp: October 12, 2021, 02:38:37 pm
content: To avoid overstressing your Arduino's GPIO pins I'd use base resistors on the transistors, like 1K.A even more robust circuit would use pull-down resistors on the base, like this:(taken from:https://stackoverflow.com/questions/20936347/spark-in-arduino-relay-and-bluetooth-module)The main reasons I've found for using a base-emitter resistor are:- prevents collector-base leakage current from turning the transistor on- increases EM noise immunity if the base is disconnectedIf you use a MOSFET instead of a BJT a gate-drain resistor is needed to turn the MOSFET off when no signal is applied to the gate.
arduino-bluetooth LE-transistor problem... - Page 1
Forum section: electronics / beginners

author: timcki
author_rank: Contributor
timestamp: March 11, 2016, 12:53:54 am
content: HI guys,I have an arduino with an Adafruit bluetooth le shield. I am using the BluefruitLE_nrf51822 sketch to control pins.I am turning on a small little ensemble from a greeting card that sings to youI have made a switch using a 2n4401 transistor controlled by digital pin 6. the whole thing works, however,When you first connect to the BLE shield the pins are set to input mode and are putting out about 1.47 volts.This voltage seems to be trying to power the circuit, as I am getting a noise out of the piezo.When you switch the pin 6 to output mode controlling it high or low the circuit works fine, on/off music/no musicWhen I hookup everything straight to the pins GND and pin 6 I do not get the hum....why is the pin in input mode putting out voltage?and is there a better way to do this?

author: michaeliv
author_rank: Frequent Contributor
timestamp: March 11, 2016, 04:11:03 am
content: Your setup is not clear. So pin 6 is connected to the base of a 2n4401 which controls a buzzer which is connected how ?How is bluetooth involved ?When is the 1.47v measured ? Do you measure it on the Arduino pin even if disconnected from the transistor ?One thing to keep in mind is that digitalWrite(pin, HIGH) will enable the pull up resistor on a pin if in input mode.

author: bobcat
author_rank: Regular Contributor
timestamp: March 12, 2016, 02:40:24 pm
content: Put a 10K pulldown resistor on the base of the transistor.

author: timcki
author_rank: Contributor
timestamp: March 12, 2016, 07:11:31 pm
content: 10K pulldown thank you, it worked.Thank you for your time..
Arduino compatible 14-20 pin MCU - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: February 06, 2025, 12:09:53 am
content: I was looking for MCU which i can program through arduino IDE should have 14 to 20 pins (ideally 14 pins)I belive ATtiny 8 pin can be used but i do not have any idea if i can go further.

author: themadhippy
author_rank: Super Contributor
timestamp: February 06, 2025, 12:30:19 am
content: LGT8F238P come in a 20 pin SSOP package,no idea were youd find the raw chips though as ive only used em on finished boards (https://hobbycomponents.com/development-boards/1076-lg8f328p-ssop20-mini-evb-development-board)

author: ledtester
author_rank: Super Contributor
timestamp: February 06, 2025, 12:32:44 am
content: How about the Raspberry Pi Pico:https://randomnerdtutorials.com/programming-raspberry-pi-pico-w-arduino-ide/It has 26 exposed GPIO pins.But you may find programming in micropython is easier since you can do things interactively (no compilation and uploading steps required).

author: pqass
author_rank: Super Contributor
timestamp: February 06, 2025, 12:48:48 am
content: Quote from: sairfan1 on February 06, 2025, 12:09:53 amATTINY84 works if you add an additional board manager URL to your IDE V1.8.5 (not sure it will work with IDE V2.x).Then use an UNO with the "Arduino ISP" program loaded to program the ATTINY84. Seehere.

author: brucehoult
author_rank: Super Contributor
timestamp: February 06, 2025, 12:54:02 am
content: Quote from: sairfan1 on February 06, 2025, 12:09:53 am- program via the Arduino IDE (and library API): ok- 14 to 20 pins: can offer 16 or 20- is 2k RAM and 16k flash enough for you? Similar capacity to ATMega328, way more than ATTiny- runs on either 3.3V or 5VDev board + programmer + 5x 20 pin chips: $8.35https://www.aliexpress.com/item/1005004895791296.html50x 16 pin chips: $6.68https://www.aliexpress.com/item/1005005036714708.html

author: westfw
author_rank: Super Contributor
timestamp: February 06, 2025, 01:56:07 am
content: The new tiny-0/1/2, AVR-DD, and AVR-EB, all have 14pin SOIC versions, and are supported by one of Spence Konde's "cores" for Arduino. (DIPs, not so much.)Something like an ATtiny3224 or AVR64DD14 should basically exceed the capabilities of an Uno, and cost less than an ATmega328p...
Arduino Due high-freq noise is not normal right ? - Page 1
Forum section: electronics / beginners

author: ammjy
author_rank: Regular Contributor
timestamp: July 10, 2017, 12:47:28 pm
content: Hello !!please, first, watch this video (https://youtu.be/bSq1ZN1H1EE)today, my new Arduino Due (official) came.and i found one problem.when board connected with USB. i can hear high-freq noise.i changed few times cables and USB power source ( PC ports, Power banks).but noise is same. i think it is MLCC maked. im not sure.is it not normal right ?please, let me know.

author: Aodhan145
author_rank: Frequent Contributor
timestamp: July 10, 2017, 01:27:24 pm
content: Probably just some coil whine from inductors or from some ceramic capacitors. It should be fine.

author: ammjy
author_rank: Regular Contributor
timestamp: July 10, 2017, 01:49:15 pm
content: Thanks you a lot.i choiced. ill change in market. this noise so big and not stop.and my ears still so young.
Arduino Json library query; Atmega2560 - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: October 14, 2016, 06:16:14 am
content: For JSOn format using this library:https://github.com/bblanchon/ArduinoJson1. I have defined Json using:StaticJsonBuffer<80> jsonBuffer;JsonArray& array = jsonBuffer.createArray();2. Now I keep on using add operator like as below & keep on adding values in array like this:array.add("Value");array.add(data);3. After one loop, I want to reinit the Json array index to 0 again. So that when I now add values , it should again start from index 0. How to do that?4. Second question is how to know how much array size is filled in Json array at any point of time. This will help in case, intiially I will define a large array, now when I keep on adding values in it, in the end I want to know whats its size know. So that I can optimize the size of initially defined Json array.In the end I have to send this JSON generated string on SIM800 on a known IP address & port number.

author: FreddyVictor
author_rank: Regular Contributor
timestamp: October 14, 2016, 08:17:25 am
content: Quotemaybe try using: removeAt(size_t index)Quotemaybe keep a count when you add ?there issome codeat the top of this to get array size in bytes so perhaps could try something like that
Arduino Labview Student Edition, Limitations? - Page 1
Forum section: electronics / beginners

author: solock
author_rank: Newbie
timestamp: February 06, 2014, 03:55:10 pm
content: Looking to see if anyone has any specific details on the limitations of NI Labview Student Edition.Generically looking at programming VI's for my own (hobbyist, ebay sourced ) gpib equipped test equipment.Labview pricing is far above the actual equipment, and I'm just learning the systems so the software investment is way out of line with what I can or want to invest.Student edition has some eligibility limitations, but it appears to support VI's to the level I want to do.Arduino Student Edition has no eligibility requirements, so that limitation is removed. BUT does it have any other limitations?Is it Arduino VI's only?Is it the same Student edition (currently shipping 2012 version with canakit or sparkfun arduinos) as the non arduino packed versions?The CD's dont appear to be arduino only on the labels so this seems to be a legitimate (license wise) way to experiment and learn Labview if it allows other VI's outside of the arduino space.Any insight is appreciated.Steve
Arduino Leonardo, Grounds - Page 1
Forum section: electronics / beginners

author: DanHamer
author_rank: Contributor
timestamp: May 05, 2013, 04:32:58 pm
content: I was studying the schematic for the Arduino Leonardo and something caught my attention. R3 ( and R2 ) are marked as NM and no other value. What are these resistors and what are they for? Why are the ground not just tied together directly?
Arduino MAX7219 question - Page 1
Forum section: electronics / beginners

author: neo
author_rank: Super Contributor
timestamp: September 06, 2017, 03:30:09 am
content: I will probably phrase this wrong, how do i use the arduino to read two 4 bit bcd codes and call the corresponding code for that, so for example 0000 0000 would call forCode:output(0x01, 0x00);and 0000 0001 would beCode:output(0x01, 0x01);the same digit except with 1 instead of 0.The code i have running the max 7219 now though it doesn't do what i described as of yet.Code:#define MAX7219_DIN 7#define MAX7219_CS 6#define MAX7219_CLK 5void initialise(){digitalWrite(MAX7219_CS, HIGH);pinMode(MAX7219_DIN, OUTPUT);pinMode(MAX7219_CS, OUTPUT);pinMode(MAX7219_CLK, OUTPUT);}void output(byte address, byte data){digitalWrite(MAX7219_CS, LOW);shiftOut(MAX7219_DIN, MAX7219_CLK, MSBFIRST, address);shiftOut(MAX7219_DIN, MAX7219_CLK, MSBFIRST, data);digitalWrite(MAX7219_CS, HIGH);}void setup() {// put your setup code here, to run once:initialise();output(0x0f, 0x00); //display test register - test mode offoutput(0x0c, 0x01); //shutdown register - normal operationoutput(0x0b, 0x07); //scan limit register - display digits 0 thru 7output(0x0a, 0x0f); //intensity register - max brightnessoutput(0x09, 0xff); //decode mode register - CodeB decode all digitsoutput(0x08, 0x04); //digit 7 (leftmost digit) dataoutput(0x07, 0x02);output(0x06, 0x00);output(0x05, 0x04);output(0x04, 0x02);output(0x03, 0x00);output(0x02, 0x04);output(0x01, 0x02); //digit 0 (rightmost digit) data}void loop() {// put your main code here, to run repeatedly:}EDIT: That is not my code, full credit for it goes to Julian Llett
Arduino Mega 2560 two interrupt issue - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: November 05, 2018, 12:18:09 pm
content: 1. I am using arduino mega 2560. Connected are 20 segments together, refreshed every 500us. After every 500us, one segment is enable & written.2. Also a PS2 keyboard is connected to read keys & display on segment. Library used is PS2Keyboard.cpp - PS2Keyboard library Written by Christian Weichel <info@32leaves.net>3. Ps2 & timer refreshing code of 20 segments works independently correctly. Problem arises when I merge both codes together. In that case what happens is I am not able to read correctly from keyboard. Probably due to when timer interrupt comes, it blocks rest of interrupt until it is processed.4. Timer 2 is used and for PS2 data line is pin 19 & clock pin is 18.5. Now how to resolve this issues. Refreshing leds is also important other flickering is observed.6. I read "http://www.gammon.com.au/interrupts", & read that inside interrupt function, below function can be used to enable interrupt again.interrupts (); // allow more interrupts7. this way code is working, but i am not sure how safe it is use.in top of timer2 isr I have written:void timer2_isr_500us(){interrupt();refresh_led()}

author: macboy
author_rank: Super Contributor
timestamp: November 05, 2018, 03:28:57 pm
content: Another way is to perform the LED refresh at "task" level, which means inside the main loop, by testing for a flag to be set. The ISR timer2_isr_500us() function will set that flag, then return. The main loop will test for the flag, and if set, call the refresh function and clear the flag. Then it can continue with any other periodic work.The LED refresh process may be briefly interrupted by the PS2 interrupt, but it should work fine. The PS2 ISR should be lean and fast and definitely not do any kind of delay. You may notice slight flicker in the display when typing, but most likely not, especially if all other ISRs are fast like they should be.