hybridfree/eevblog-posts huggingface dataset:
Esp32 controls a 12v coil relay through PC817 and 2N7000 - Page 1
Forum section: electronics / beginners

author: paoloros97
author_rank: Newbie
timestamp: July 12, 2024, 07:54:43 pm
content: HelloI need to control a 12v relay with an Arduino nano ESP32.Can somebody check if the circuit I designed is good?Components list:MOSFET: 2N7000Optocoupler: PC817Diode: 1N4007Relay: 40.31.7.012.0000 (coil needs 42mA @ 12V)Please find attached the picture with the circuit I made. (Updated 13/7/24)

author: selcuk
author_rank: Frequent Contributor
timestamp: July 12, 2024, 08:30:24 pm
content: I guess D2 LED direction is wrong.

author: Benta
author_rank: Super Contributor
timestamp: July 12, 2024, 10:49:42 pm
content: Quote from: selcuk on July 12, 2024, 08:30:24 pmAgreed.And don't use a 1N4007, but a 24...33 V Zener across Q1 instead.

author: paoloros97
author_rank: Newbie
timestamp: July 13, 2024, 02:43:16 am
content: Thank you!I did a mistake to place the LED in Kicad.I uploaded a new schematics.About the:Quote from: Benta on July 12, 2024, 10:49:42 pmmay I ask you why?thx

author: kripton2035
author_rank: Super Contributor
timestamp: July 13, 2024, 06:52:51 am
content: can someone explain to me the need for the pc817 ?

author: paoloros97
author_rank: Newbie
timestamp: July 13, 2024, 06:58:06 am
content: It's not really needed but good to have, IMO.

author: Benta
author_rank: Super Contributor
timestamp: July 13, 2024, 10:54:12 am
content: Quote from: paoloros97 on July 13, 2024, 02:43:16 amTo protect the relay contacts. Using a normal diode like in your circuit slows down the release time of the relay immensely, potentially causing contact burn.Allowing the coil a higher voltage when turning off, the contacts will open much faster.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 13, 2024, 05:27:25 pm
content: When beginning with electronics, it's good to build circuits like this on breadboards.Gate voltage of the 2n7000 can also be as high as 3V, which is getting uncomfortably close to the 3V3 of most microcontrollers. it works with this circuit (with 12V gate drive) but it's dubious when the gate gets connected directly to the uC. The 2n7002 is more common, and has a maximum threshold voltage of 2V5.
ESP32 Deep Sleep wake up debouncing - Page 1
Forum section: electronics / beginners

author: dynek
author_rank: Contributor
timestamp: March 21, 2022, 07:10:21 pm
content: Hello guys,I'm trying to wake up my ESP32 when in deep sleep using ext1 & multiple RTC GPIOs:https://randomnerdtutorials.com/esp32-external-wake-up-deep-sleep/Thing is, upon wake up it's not always able to determine which button was pressed, probably because of bouncing, so I used this method to debounce it and it's giving me good results:https://hackaday.com/2015/12/09/embed-with-elliot-debounce-your-noisy-buttons-part-i/Now I'm doing the opposite, pulling down the gpio and 3.3v when button is pushed.Is it then correct to hook the capacitor to 3.3v like in the attached schematic?Thank you

author: Venturi962
author_rank: Regular Contributor
timestamp: March 21, 2022, 10:29:38 pm
content: Can you describe the situation a little more? If you're only pressing one button (on one GPIO) to wake the ESP32 then whether or not the switch bounces shouldn't matter. Assume you're using ESP_EXT1_WAKEUP_ANY_HIGH?

author: dynek
author_rank: Contributor
timestamp: March 22, 2022, 05:58:20 am
content: You're totally right, I'm using EXT ANY HIGH.And thing is, I'm sometimes getting the right PIN mentioned, sometimes "GPIO inf".Upon wake up (setup), I'm making sure it's waking up from deep sleep usingCode:if(esp_sleep_get_wakeup_cause() == ESP_SLEEP_WAKEUP_EXT1)And getting gpio number usingCode:uint8_t buttonUsed = log((uint64_t)esp_sleep_get_ext1_wakeup_status())/log(2);

author: JustMeHere
author_rank: Frequent Contributor
timestamp: March 22, 2022, 06:01:02 am
content: I don't think your cap is helping. When the button is not pushed, the cap charges. When you close the switch, there's nothing really discharging the cap.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: March 22, 2022, 06:07:01 am
content: Here's your circuit.....https://gr33nonline.wordpress.com/2019/11/24/debounce/

author: dynek
author_rank: Contributor
timestamp: March 22, 2022, 06:55:36 am
content: Except there's an additional resistor, isn't it this?https://www.allaboutcircuits.com/technical-articles/switch-bounce-how-to-deal-with-it/

author: Venturi962
author_rank: Regular Contributor
timestamp: March 22, 2022, 08:20:05 am
content: Either should work, sample CircuitJS simulation (including original circuit):https://tinyurl.com/y73s8frm
ESP32 DevkitC breadboard adaptor - Page 1
Forum section: electronics / beginners

author: PlainName
author_rank: Super Contributor
timestamp: August 23, 2024, 09:37:40 pm
content: Wasn't sure where to put this, but the OSHW section seems rather too advanced for something this trivial, and maybe it will help a beginner...So, suppose you have an ESP32 DevkitC (basically the ESP32 plus programming gubbins) and want to attach stuff to play with. A breadboard might be the thing you reach for, and then you find this:Hmm. Where to put everything else...I don't usually use a breadboard but one time I had to so made an adapter. Now there is room for other bits too:But... that USB connector can be the right side or the wrong side, so I made these things double-sided and you just choose which way you want the cable to go when you assemble them:But note that due to it being a cheap double-sided board the traces are narrow and there are no planes. The power rails probably aren't up to powering a 20 WS2812 LEDs on full white.I've attached the gerber files necessary for JLCPCB, and the Altium project in case anyone wants to mod it. I had to remove the 3D models from the project since they made the zip file 40MB(!) but if you need the models they are easily obtained.

author: xvr
author_rank: Frequent Contributor
timestamp: August 24, 2024, 07:46:01 pm
content: QuoteGenerally for this configuration 2 coupled breadboard used, and DevkitC plugged between breadboards

author: PlainName
author_rank: Super Contributor
timestamp: August 24, 2024, 07:58:16 pm
content: Well, that's an option, certainlyDidn't appeal to me because a) it's starting to get big, and b) mechanically it starts getting messy. I guess there might be scope for a straight PCB with just pins to act as as a brace...
esp32 esp8266 Battery & other Template circuits ? - Page 1
Forum section: electronics / beginners

author: bilalinamdar
author_rank: Newbie
timestamp: September 15, 2024, 01:51:36 pm
content: Hi,I am beginner Hobbyist in electronics had a project in mind and want to do prototype to production but i have few issues.Isn't there a Ready made Template of circuits available for basic things such as 5V battery power projects, 3.3v battery power projects.Because whenever you try to build a product few things are always repeated that is circuits such as Power, Enclosure etcSince i will be working with nodemcu / esp32 i wanted to have a efficient power circuit which can also support low battery consumption plus deep sleep. But this is so basic need/requirement that someone already made it many times but there is no standardization or database to get it. Or AM i wrong is there one where i can get this ready made available. In short why to reinvent the wheel when it is already invented.There should be a templating or standardization or database should be available for this. There might be i am just missing it. Can some one guide me in the right direction ?
ESP32 in a reboot loop - Page 1
Forum section: electronics / beginners

author: Rapidice
author_rank: Newbie
timestamp: February 27, 2021, 08:02:32 pm
content: Hi, I have had a problem with my ESP32's. I am using these:https://www.aliexpress.com/item/4000992721907.html?spm=a2g0o.productlist.0.0.36ac3390NQen02&algo_pvid=fd7a531f-360c-4598-819a-ff7d79c4e3a9&algo_expid=fd7a531f-360c-4598-819a-ff7d79c4e3a9-2&btsid=0b0a119a16144557539773819ee991&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_When I connect the VIN pin to about 5v, the ESP seems to work fine, until I power on the wifi. As soon as the wifi turns on, the ESP will crash and this keeps repeating a few times before it successfully connects to the wifi. Sometimes this restart loop keeps going indefinitely. This is probably a power issue. Do I need to add a capacitor? And if so, what should the value be?Thanks

author: YurkshireLad
author_rank: Frequent Contributor
timestamp: February 27, 2021, 08:13:43 pm
content: The pins in that image show 3.3V, not 5V. Are you sure it takes 5V input?

author: florian-x
author_rank: Contributor
timestamp: February 27, 2021, 08:17:05 pm
content: I've had such a problem before. It was due to power wires having relatively high resistance connections between the power source and the board -- as I was using a breadboard and power wires were doing several hops. Upon starting the wifi, the ESP32 may require 500 mA, so a small resistance in bad connections can cause a large voltage drop. And the AMS1117 regulator in those boards, together with a diode, do not allow for a lot of voltage drop from 5V.I ended up connecting the power pins of the board directly to my power supply, without going through the breadboard.

author: Rapidice
author_rank: Newbie
timestamp: February 27, 2021, 08:19:58 pm
content: Ah, thanks. I will try that
ESP32 LED control PCB project - Page 1
Forum section: electronics / beginners

author: Babbsdrebbler
author_rank: Newbie
timestamp: June 02, 2024, 08:45:39 pm
content: Like a lot of people on the net I had a couple of DIY PCBs running WLED, most of them with duct taped buck converter PCBs on top of them.It wasn't pretty to say the least. So I started learning PCB design and went through a couple of iterations.1. 5V IO translation hat for the ESP32 (some of it discussed herehttps://www.eevblog.com/forum/beginners/first-pcb-power-connection-questions/msg5278597)2. Buck converter addon PCB which is capable of converting >=26V to 5V so the project can run from a single 24V supply which powers the LEDsThe current iteration combines both but this time I chose to use a ESP32-C3 WROOM module so I had to add in the 3.3V LDO and USB-C plus a TVS chip.Additionally I wanted polarity protection for the DC-in which is handled via a P-channel mosfet.Most components have been chosen since they are basic or preffered-extended JLCPCB parts. The order total is about ~60 bucks WITHOUT the ESPs since I plan to solder them by hand.I've broken out this many pins so I can potentially re-use these boards for other projects.I wouldn't mind comments that save me from a fundamental mistake that blows up the board since I'm a SW developer by day and this is my first "complex" PCB.It took me a couple of months to get here from my first thread.P.s.: Yes, I still don't have a nice case for this so the hole is currently more of a test than a valid mounting method.
Esp32-s2 based signal generator - help and advices needed - Page 1
Forum section: electronics / beginners

author: Mm
author_rank: Contributor
timestamp: July 16, 2023, 09:57:47 am
content: Hello,Im building a project and part of the project is kinda simple signal/function generator, but with extra feature in it.I have esp32-s2 as a "heart" of the operation. Im planning to use circuitpython in it, because I have some python skills. Esp32-s2 has two DACs so I should be able to use it as signal generator. For start I need only sine and square waveforms. The extra feature for the generator is capability to seek the resonant frequency of the external circuit I attach to this signal generator.To find the resonant frequency I was planning to use external voltage sensor module. The measured voltage should be highest when resonant frequency is used.Basic principal is that when I turn this device on the signal generator starts to transmit signal via wires to device/circuit I attached to this generator. Then python code starts to loop through different frequencies (changing the transmitted frequency). Voltage sensor is read after every frequency change and the highest voltage measurement + frequency is then stored to variable and used after whole frequency bandwith is "browsed" through. After the frequency is found the device stays on and keeps on transmitting the signal to the device attached to it with the frequency which found to be the resonant frequency.Have anyone build anything like this before? Anyone have any tips or pointers to give? My electronics skills are quite limited, I have build few very basic things before this. This is not for school, this is for my personal experimentation. Any help or advices are welcome. Thank you.

author: m k
author_rank: Super Contributor
timestamp: July 20, 2023, 04:54:04 pm
content: I guess your case is too well covered by google.If you want to start from scratch checkhttps://randomnerdtutorials.com/esp32-pwm-arduino-ide/Next you can do equivalent dimmer using a DAC pin.For starters internal reference is just fine, you may also need an amplifier transistor.
ESP32-S3 - IO15 & IO16? GPIO? - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: January 08, 2025, 01:13:26 pm
content: HelloShort question.Can I use ESP32-S3'sIO15andIO16as regular GPIO instead of resonator input?(Arduino)Thank you

author: tszaboo
author_rank: Super Contributor
timestamp: January 08, 2025, 04:00:50 pm
content: You need that crystal to have Wifi.And likely the software which is used, based on the ESP-IDF will not support using it for something else.

author: Tantalum
author_rank: Regular Contributor
timestamp: January 08, 2025, 04:41:37 pm
content: The DevKitC doesn't have it and the wifi works ;-)https://docs.espressif.com/projects/esp-dev-kits/en/latest/esp32s3/esp32-s3-devkitc-1/user_guide.html#hardware-reference

author: Chalcogenide
author_rank: Regular Contributor
timestamp: January 08, 2025, 05:19:47 pm
content: Those are the input for a low speed clock (i.e. 32 kHz watch crystal). As long as you don't plan to use the RTC with an external clock source, you can use IO15 and IO16 as GPIO. The main 40 MHz crystal is under the can of the WROOM module.

author: tszaboo
author_rank: Super Contributor
timestamp: January 08, 2025, 06:10:09 pm
content: Quote from: Chalcogenide on January 08, 2025, 05:19:47 pmI totally misread this ignore my comment.
ESP32 + SD card (Digilent Pmod) only works with very short GND wires? - Page 1
Forum section: electronics / beginners

author: sofakng
author_rank: Regular Contributor
timestamp: July 29, 2020, 03:21:05 pm
content: I'm testing a project for somebody and it uses an ESP32 DevKitC and a Pmod MicroSD slot.At first I plugged the ESP32 into the breadboard and then used jumper wires to connect the MicroSD slot but it didn't work. Next I removed the ESP32 from the breadboard and used jumpers to connect directly to the MicroSD slot. It still didn't work.It was determined that the GND wire needed to be very short and connect directly to the ESP32 for it to work. We tested 40 MHz, 20 MHz, and even 400 kHz but none of them worked with the long (4"+) wires.Is there any way to have this working with longer wires and/or a breadboard? Can I somehow use capacitors to remove the noise, etc?
ESP32 with ESP-IDF mute bootloader messages - Page 1
Forum section: electronics / beginners

author: npelov
author_rank: Frequent Contributor
timestamp: January 05, 2024, 02:39:30 pm
content: Hi everyone and Happy New Year!Can I mute this message in software:Code:ets Jun 8 2016 00:22:57rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)configsip: 0, SPIWP:0xeeclk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00mode:DIO, clock div:2load:0x3fff0030,len:1496load:0x40078000,len:13040load:0x40080400,len:3016entry 0x400805e4I've set bootloader log verbosity to no output but this message is still left. I don't want to solve software task in hardware - tie gpio 15 to GND.I couldn't find anything on the net and I think I was able to turn it off before but I don't remember how. Maybe I don't remember correctly.

author: tooki
author_rank: Super Contributor
timestamp: January 05, 2024, 04:44:03 pm
content: One page I found said that it can’t be done in ESP32, but can be done in later models (ESP32S2, -S3, -C3).https://esp32.com/viewtopic.php?t=24244#p86717What’s wrong with tying IO15 low with a pull-down resistor? Then you can still use it.

author: npelov
author_rank: Frequent Contributor
timestamp: January 06, 2024, 01:19:59 pm
content: If IO15 has pull up that means current draw (for deep sleep). But if it's not possible - no other choise. I wasn't sure if I did this before. But isn't everything compiled when using IDF? does that inculde bootloader? I can't get rid of this feeling that I was succesful of muting this message. Maybe I can inspect the IDF code and find the boot loader (couldn't find anything)

author: tooki
author_rank: Super Contributor
timestamp: January 06, 2024, 03:23:56 pm
content: No, the bootloader is in mask ROM, so you can’t modify it.Re: power draw in deep sleep: the pull-up is there by default, but once you’ve booted, you can configure the pin however you want (i.e. no pull-up) and it’ll stay that way in deep sleep:https://electronics.stackexchange.com/questions/622750/esp32-boot-strapping-pins-problem-gpio15-and-gpio5

author: npelov
author_rank: Frequent Contributor
timestamp: January 10, 2024, 11:42:28 am
content: Oh, so if I disable pull up:void disablePullUp() {// Configure the GPIO pin as an input with no pull-up/pull-down resistorgpio_config_t io_config;io_config.pin_bit_mask = (1ULL << GPIO_PIN_NUM);io_config.mode = GPIO_MODE_INPUT;io_config.pull_up_en = GPIO_PULLUP_DISABLE;io_config.pull_down_en = GPIO_PULLDOWN_DISABLE;io_config.intr_type = GPIO_INTR_DISABLE;gpio_config(&io_config);}it'll stay like this in deep sleep...Thanks.

author: tooki
author_rank: Super Contributor
timestamp: January 10, 2024, 08:34:17 pm
content: Let me know if it works in practice!
Esp32 - Page 1
Forum section: electronics / beginners

author: amir.razzaqi
author_rank: Contributor
timestamp: May 11, 2025, 08:14:45 pm
content: Hey guys,I want to start working with ESP32 development boards. I’ve previously worked with Arduino and have some familiarity with electronics. Which development board would you recommend for starting out, and why?

author: brucehoult
author_rank: Super Contributor
timestamp: May 11, 2025, 11:56:21 pm
content: https://www.aliexpress.com/item/1005005508686571.htmlLatest ESP32-C6 chip, from a good cheap dev board company (MuseLab). You could step down to an ESP32-C3, which have been around for a while, but if you only need one then why bother?He's using the official dev board, which you can do, but there's no real reason to ... MuseLab is fine.There's no good reason to use the old models using the obscure Xtensa ISA at this point.

author: amir.razzaqi
author_rank: Contributor
timestamp: May 12, 2025, 08:43:43 am
content: video couldn't play

author: brucehoult
author_rank: Super Contributor
timestamp: May 12, 2025, 10:57:17 am
content: Oh sorry, I might have cut off the URL. Just search "ESP32-C6" on youtube, there are plenty.
ESP32S3 I2C Configuration - Page 1
Forum section: electronics / beginners

author: sy
author_rank: Regular Contributor
timestamp: November 05, 2023, 04:23:13 am
content: I am attempting to configure GPIO4 and GPIO5 of the ESP32S3 for I2C communication. Based on ESPRESSIF's API, I have written the following code for the I2C set up:#define MST_TX_BUF_LEN 0#define MST_RX_BUF_LEN 0static esp_err_t i2c_conf_master(void) {i2c_config_t conf = {.mode = I2C_MODE_MASTER,.sda_io_num = GPIO_NUM_4,.scl_io_num = GPIO_NUM_5,.sda_pullup_en = GPIO_PULLUP_ENABLE,.scl_pullup_en = GPIO_PULLUP_ENABLE,.master.clk_speed = 400000};i2c_param_config(I2C_NUM_0, &conf);return i2c_driver_install(I2C_NUM_0, conf.mode, MST_RX_BUF_LEN, MST_TX_BUF_LEN, 0);}void app_main(void) {ESP_ERROR_CHECK(i2c_conf_master());}I require a 400kHz clock signal on GPIO5 to interface with another one of my modules, but the signal appears to jump to 3.2V when I probe it. Looks like a bunch of noise with no particular frequency.Wondering if anyone else has successfully set up their ESP for I2C? I have purchased my devkit from AliExpress and I am not sure if it could be a missing component issue? (GPIO48 was left open and I had to jump it with a bit of solder for the RGB LED to turn on)

author: liaifat85
author_rank: Regular Contributor
timestamp: November 05, 2023, 07:41:15 am
content: Use a logic analyzer or oscilloscope to monitor the I2C signals directly. This will help you visualize the signal and diagnose any issues.You can also post this question to the ESP32 forum.

author: CountChocula
author_rank: Unknown
timestamp: November 05, 2023, 01:22:32 pm
content: I'm not very familiar with I²C in Esp-idf, but I think you're missing some code to actually write data to the bus—otherwise, it's normal for the clock signal to just be pulled up, as I²C is amaster-driven protocol. You can look atthis examplefor a more complete code listing.Another suggestion is to try switching to Arduino and using its built-in I²C library, which is known to be working. If the circuit starts working, that helps exclude any hardware problems, and then you can go back to figure out what might be wrong with your software. If it doesn't, then you know it's something wrong with the hardware.You could also try different pins… just in case.
ESP8266 LED Board - Page 1
Forum section: electronics / beginners

author: XeroGravity
author_rank: Newbie
timestamp: October 06, 2020, 04:49:08 am
content: I am designing a pcb for an rgb lamp that I want to make. It's based off an ESP-12S module from ai thinker and it will be running WLED firmware. There will be 8 LED's in a circle around the center. Still a work in progress but I think im getting there.My goals for this circuit:Can be powered from USB or lithium battery. There should also be a switch to toggle between stationary and portable mode. Portable mode allows the battery to charge to full when plugged into USB. Stationary mode keeps the battery at 50% even when USB is connected, so the battery does not stay fully charged when the lamp is in a permanent location.IR sensor on GPIO4I want to use a USB C connector but I will use a micro usb for now since it is easier to solderThe ESP should be flashable through the charging portI am not very experienced and any tips would be appreciated. For example, should the decoupling caps be polar or non polar? Should there be resistors on USB data lines? Or does ch340 already have impeadance matching?

author: tooki
author_rank: Super Contributor
timestamp: October 06, 2020, 08:45:09 pm
content: I don’t know the other questions, but decoupling caps don’t care whether they’re polarized or not. In practice, since decoupling caps tend to be low (capacitance) value, they can be ceramic caps, which are inherently bipolar. (There’s no situation I’m aware of where polarity in a cap is adesirabletrait. It’s something wetoleratein exchange for high capacitance in reasonable amounts of space and cost, i.e. electrolytic and tantalum caps.)

author: XeroGravity
author_rank: Newbie
timestamp: October 06, 2020, 09:06:45 pm
content: Quote from: tooki on October 06, 2020, 08:45:09 pmOk, I understand it now. I have another question regarding about actually getting an assembled PCB. I do not have the time or patience to solder SMD components manually (with a few exceptions)What PCB assembly services would you recommend, and how do I check which parts they stock? I feel like choosing components is harder than designing the circuit itself.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: October 06, 2020, 10:46:41 pm
content: Find a schematic for an ESP12 based "dev" module. I don't see any battery management.

author: tooki
author_rank: Super Contributor
timestamp: October 08, 2020, 07:53:38 pm
content: Quote from: XeroGravity on October 06, 2020, 09:06:45 pmI’m afraid I have no experience with that.Some PCB houses (like JLCPCB/LCSC) require you to use their components. Others allow you to send in your own components (or have them buy them on your behalf). Just depends.
ESP8622 current measurement with the uCurrent - Burden Voltage Trap? - Page 1
Forum section: electronics / beginners

author: Zh4ng
author_rank: Unknown
timestamp: April 25, 2016, 04:32:16 pm
content: Hello everybody,I would like to measure the power consumption of a ESP8622 in Sleep mode. But I think the Burden Voltage makes life difficult for me.I use Dave's uCurrent. In mA range everything is OK, but the uA range I have a voltage drop of 3.3V to 1.9V and the circuit hangs.Am I correct? or am I doing something wrong?I think I went into the trap as a young player ....btw. i am a young player....Thx for helpZh4ng

author: zapta
author_rank: Super Contributor
timestamp: April 25, 2016, 04:40:25 pm
content: Will connecting a diode in parallel to the input help? It will conduct in the wake state but will give reasonably accurate reading in the sleep state.

author: borjam
author_rank: Unknown
timestamp: April 25, 2016, 04:46:48 pm
content: What about using a power supply with sensing inputs? I just got an AIM-TTI EL302R. I imagine that connecting the sensing after the point where I have inserted the µCurrent would help.Or is it just the syndrom of the brand new toy?

author: zapta
author_rank: Super Contributor
timestamp: April 25, 2016, 07:52:59 pm
content: If you use the sense approach, you need to make sure that the input current of the sense input is negligible.

author: borjam
author_rank: Unknown
timestamp: April 26, 2016, 06:26:21 am
content: Anyway I must do it and I purchased a µCurrent a month ago for that purpose, so I will let you know how it goes.

author: wraper
author_rank: Unknown
timestamp: April 26, 2016, 07:24:36 am
content: Shunt resistance in uA range is 10 ohms. No wonder it shuts down. You are exceeding the current rating at this range by more than 100 times. If you are desperate to use uA range, then short uCuttent's input terminals together then start the thing, put into the sleep. Remove the jumper wire between the terminals, measure. Or get higher resolution multimeter if current resolution is not enough and measure in mA range.Quote

author: Zh4ng
author_rank: Unknown
timestamp: April 26, 2016, 07:48:41 am
content: Quote from: wraper on April 26, 2016, 07:24:36 amAh ok,then my first guess is correct. Thanks for the tip.I use a 34401A.I'm going to jump a little in the rabbit hole .....

author: borjam
author_rank: Unknown
timestamp: April 27, 2016, 07:11:59 am
content: As I said, I am on the same bandwagon now and, given the enormous difference in power consumption between WiFi activity and deep sleep, I intend to do it in phases. I mean: how much does it take when deep sleeping? How much energy does this sensor reading routine use? How much when transmitting via WiFI?With all that, and measuring the energy usage of the different routines I can have a nice estimate of energy needs for a battery powered sensor and actually find out wether it's doable with an ESP8266 or not.
EspoTek Labrador Schematic - Page 1
Forum section: electronics / beginners

author: stafil
author_rank: Regular Contributor
timestamp: May 02, 2020, 01:24:29 am
content: I am reading the EspoTek Labrador Oscilloscope schematic to educate myself about the basics of oscilloscopes.Can somebody explain to me why do we need the circuit in red, and not just connect the input straight to the OpAmp?Thanks!StavrosPS: The complete schematic is here:https://github.com/EspoTek/Labrador/blob/master/PCB/AltiumPCB/labrador.pdf

author: ArthurDent
author_rank: Super Contributor
timestamp: May 02, 2020, 01:45:41 am
content: R4 and R5 form a voltage divider to bias the input to the opamps at VCC/2.Here is some information.https://ocw.mit.edu/courses/media-arts-and-sciences/mas-836-sensor-technologies-for-interactive-environments-spring-2011/readings/MITMAS_836S11_read02_bias.pdf

author: stafil
author_rank: Regular Contributor
timestamp: May 02, 2020, 03:17:26 am
content: Quote from: ArthurDent on May 02, 2020, 01:45:41 amSorry for being stupid, but in order to be a bias, shouldn't it be connecting to the inverting or non-inverting input of the OpAmp?

author: ArthurDent
author_rank: Super Contributor
timestamp: May 02, 2020, 04:02:52 am
content: It is actually connected to the + input. with no signal coming from the left, the + input and the output will be VCC/2. This is common for a single supply opamp whereas an opamp with both +VCC and -VCC wouldn't need the bias to get full rail to rail swing of the output. It is a virtual ground for a single supply opamp connected as a voltage follower.
:: ESR frontend? :: - Page 1
Forum section: electronics / beginners

author: 3roomlab
author_rank: Frequent Contributor
timestamp: March 22, 2014, 04:02:12 pm
content: Hello EEV folks, just happen i was tickled by looking at a number of ESR projects going around (and googling a screen full of schematics), i threw a couple of pixels into the multisim to have some "LEGO" time, and i came to this particular juncture.from this cropped diagram, is it safe to say i have a practical ESR frontend to "probe" stuff? the known current drive (1ma) gives a direct read off in "ohms" via the potential difference (XMM2), is that all to it or there is something i missed?the "signal" is injected from the top right "leg" (grounding return is on the left), 1kHz pseudo sine 200mv p-p. there seems to be some simulated internal resistance somewhere and R20 was "adjusted" so that a shorted test probe (replaced with a switch S1) will yield 1mA (or 997uA p-p seen on probe4)for C5 and C6, i found some low ESR 22u caps on element14, they rate at 0.015ohms. so in actual, i am assuming that the real C5/6 will not give a readout of 5.4ohms, am i right? (i did a re-run with C5/6 removed and it does seems to be so, see lower half of pic in black and white).any comments? (i keep wondering if i missed some theory somewhere as it seemed just too easy to just read off ohms from the mV scale)

author: jimmc
author_rank: Frequent Contributor
timestamp: March 22, 2014, 10:46:59 pm
content: You are using too low a frequency, the reactance of the capacitor is not negligible.See here for an explanationhttp://midwestdevices.com/_pdfs/Tnote3.pdf.Once the frequency is high enough, sine or square makes little difference although the harmonic content of the square wave can cause problems with the inductance of leads etc.Jim
ESR measurement of capacitors - Page 1
Forum section: electronics / beginners

author: decoder_82
author_rank: Regular Contributor
timestamp: December 15, 2020, 08:05:39 am
content: Hello everyone,I would like to use an ESR meter to check the health of the capacitors on an old CRT monitor (I know all the safety precaution and discharging procedure).Capacitors can fail short or open. Would the two cases be detected with ESR meter? Conceptually I would expect ESR value to increase at it gets open. Is that correct? And value would decrease if it goes open?

author: m k
author_rank: Super Contributor
timestamp: December 15, 2020, 04:10:41 pm
content: Test it, measure different things and compare.When you have few values and are wondering out loud what they are I'm pretty sure people will comment.

author: Vovk_Z
author_rank: Super Contributor
timestamp: December 15, 2020, 04:13:38 pm
content: Quote from: decoder_82 on December 15, 2020, 08:05:39 amShort or open capacitors won't have their rated capacity and ESR.

author: bob91343
author_rank: Super Contributor
timestamp: December 15, 2020, 06:39:44 pm
content: ESR is overrated. If you have an electrolytic capacitor that isn't doing its job, perhaps its ESR has increased. It's not a basic test and shouldn't be a concern most of the time.After all, how often do you measure transistor leakage? Or magnetic core saturation? Or meter sensitivity? Or test equipment input impedance? Diode breakdown voltage? Zener voltage or knee shape? Connector contact resistance or insulation breakdown?These are all perhaps secondary characterisitics and should be treated as such, along with capacitor ESR.
ESR - measuring out of range capacitance with Anatek Blue ESR meter - Page 1
Forum section: electronics / beginners

author: Scooter
author_rank: Newbie
timestamp: May 06, 2017, 06:13:38 am
content: I am trying to use an Anatek Blue ESR meter to gage the health of magneto capacitors (condensers). The electrolytic capacitor value is 0.375 microfarads. Unfortunately, the Anatek meter's range bottoms out at 1 microfarad. I tried measuring a small sampling of new capacitors to create a base line, and was getting an ESR value of 3.0 to 4.4 ohms.Can I reliably use this meter in this range?BK Precision has an ESR meter that can go down to 0.47 microfarads which is still not low enough.The only other information I have on the component is:(attachment)Thanks !

author: kripton2035
author_rank: Super Contributor
timestamp: May 06, 2017, 06:43:17 am
content: try building one of these (the analog ones) :http://kripton2035.free.fr/esr-repository.html
ESR Meter - Page 1
Forum section: electronics / beginners

author: ramin110
author_rank: Contributor
timestamp: March 02, 2018, 09:07:44 am
content: Hi,I designed my first PCB inferring from Alan Wolke ESR METER schematic but mine is not working, I haven't an oscilloscope to measure the waveforms output but at least I have a multimeter and I had checked the oscillator section works around 140 kHz. I know I made a mistake in my schematic but I fix it but still not working.here are pictures of Mr Alan Wolke design and mines.Thanks for any helps

author: ramin110
author_rank: Contributor
timestamp: March 02, 2018, 09:10:11 am
content: alan wolke video and picture about this ESR meter:picture of his design:

author: ramin110
author_rank: Contributor
timestamp: March 02, 2018, 09:17:30 am
content: Mines:3d view:my schematic:my PCBs:

author: ramin110
author_rank: Contributor
timestamp: March 02, 2018, 09:24:42 am
content: here is the real PCB:sorry for the brevity of my description because I'm not native English speaker

author: w2aew
author_rank: Super Contributor
timestamp: March 02, 2018, 03:27:24 pm
content: The DC Restore circuit will not work with the LM358. The AD8032 was used because its input common-mode range extends below the negative supply (ground), and the output doesn't exhibit phase reversal when the input voltage differential gets large (in open loop operation). There are likely other single supply rail-rail op amps that would work, but the LM358 isn't one of them.
Building an ESR Meter - 2nd Attempt - Page 1
Forum section: electronics / beginners

author: electronwaster
author_rank: Regular Contributor
timestamp: June 26, 2014, 05:08:23 am
content: Hi,I asked about 2 years ago about ESR meters (https://www.eevblog.com/forum/beginners/esr-meter/) - I was interested in changing a particular schematic I had found so that it didn't need a transformer. You all kindly helped, but it never did get built.I now have a renewed interest in building one of these meters. So I've been researching and learning, mostly from the ESR repository that kripton2035 kindly introduced me to (http://kripton2035.free.fr/esr-repository.html) - and I've found all sorts of methods of making these devices. The one that actually looked achievable for me to build was w2aew's design (https://www.eevblog.com/forum/projects/what-about-home-made-%28esr%29-meter/msg70878/#msg70878).I tried to build it up on a breadboard, and quickly ran into difficulties. My hex inverter, opamps and meter weren't quite the same and I could only get it to half work. I ended up dismantling it and starting again. Yes - I should have tried to debug it or ask for help debugging it.Call me mad, but I have since been clumsily trying to come up with my own design, based on sections of other people's circuits, but to suit the parts I have. I have built a simulation in LTSpice, just because that's faster to experiment with. I plan to breadboard it as soon as I have solved a problem I have.I have attached a screenshot of a current reading for the 'meter' (modelled as a resistor), and the schematic too. If I could figure out how to low pass filter this so that I get a smooth line between those peaks, that would be great, but I have so far failed to get that to work. How would you guys design a filter to provide a smooth non-pulsed DC output?Also - if you can suggest any other improvements before I build this in real life, I'm all ears!Cheers,electronwaster (Still a complete novice!)
ESR Meter buying Question - Page 1
Forum section: electronics / beginners

author: Albert101
author_rank: Newbie
timestamp: March 12, 2013, 05:16:19 am
content: Hello,I would like to know if I buy one of those ESR meters sold on Ebay for around 20 or 30 bucks from China will it work ok to do simple repairs to LCD monitors or other electronics ?If not, why and what should I buy instead ? I am on a small budget...Thank you very much.

author: ddavidebor
author_rank: Super Contributor
timestamp: March 12, 2013, 06:14:50 am
content: Where you've found and esr meter at 20-30$?

author: Albert101
author_rank: Newbie
timestamp: March 12, 2013, 07:19:20 am
content: On Ebay...

author: tld
author_rank: Regular Contributor
timestamp: March 13, 2013, 07:11:52 am
content: Quote from: ddavidebor on March 12, 2013, 06:14:50 amQuote from: Albert101 on March 12, 2013, 07:19:20 amWell, this needs to get checked out, doesn't it?I've ordered one. My guess is that it probably won't be the most accurate, and the build-quality and reliability probably won't be perfect, it might not last as long as some other products, but it *does* look interesting for hobby/learning.Note that some ESR-testers claim to be able to test ESR in-circuit, and that would be a significant advantage for repair-work.With the meter, I'm thinking you'll need to actually de-solder the caps to test them, and at that point you would probably solder in a new one anyway. In other words; Without testing them in-circuit, it's a matter of "replace all the caps", and this meter doesn't really change that.tld

author: Skimask
author_rank: Super Contributor
timestamp: March 13, 2013, 07:24:11 am
content: That particular version/brand/incarnation ESR meter has been on ebay for at least a couple of years now.I don't remember where I saw it, but the circuit/code/etc is basically a copy of some guys work from somewhere, sometime, somehow... Google would probably turn it up...if I was that ambitious.

author: mtdoc
author_rank: Super Contributor
timestamp: March 13, 2013, 07:46:23 am
content: Have a lookHERE. I recently got one of these myself. So far it looks good...

author: brainwash
author_rank: Frequent Contributor
timestamp: March 13, 2013, 07:59:18 am
content: These cheap units do work and most of the time you are able to test the parts in-circuit - circuit powered off, of course.It's a must if you are doing a lot of power/backlight supply repairs.

author: stryker
author_rank: Regular Contributor
timestamp: March 13, 2013, 10:27:36 am
content: Quote from: mtdoc on March 13, 2013, 07:46:23 amThanks for the link mtdoc. Having it in a case like that makes a lot of sense too.
ESR Value for Electrolytic Capacitor question - Page 1
Forum section: electronics / beginners

author: AndyA
author_rank: Newbie
timestamp: December 02, 2018, 11:35:09 am
content: I'm fixing a SMPS supply from my sound bar. I have discharged all the caps safely.If I measure the ESR with my DER EE-5000 on a Sam Young NHA 1000uF 35V I get 0.03. I can't find the ESR for any of the Sam Young caps online. So far as I can tell this one is OK.When I measure 2 of the Sam Young NHA 470uF 10V I get an ESR of 3.7 and 4.2. Is this within spec or are they bad?Can I test the ESR of a capacitor in circuit when in parallel or series and still get the correct reading?Thanks

author: Shock
author_rank: Super Contributor
timestamp: December 02, 2018, 12:34:37 pm
content: Quote from: AndyA on December 02, 2018, 11:35:09 amIf you check on google images for ESR charts it will tell you even 10/20 years ago whenever those charts were made ESR for a 470uF 10V should be around 0.2 ohm or less, so yes that reading is quite high.If there are other capacitors or resistances in parallel it can throw off the reading, remove them from circuit and double check. Check capacitance as well.If the electrolytic capacitor has brown gunk leaking out, a raised or domed top, a blown bung or any discoloration below it on the PCB it's venting and needs to be replaced. For SMD caps sometimes you will see faded printing which points to leaking electrolyte.

author: wraper
author_rank: Unknown
timestamp: December 02, 2018, 12:49:52 pm
content: Quote from: AndyA on December 02, 2018, 11:35:09 amCertainly bad. BTW you should measure ESR at 100kHz, just in case.

author: kripton2035
author_rank: Super Contributor
timestamp: December 02, 2018, 01:02:18 pm
content: +1 for bad caps. first to try to sap with a good one.how old is the soundbar ?

author: AndyA
author_rank: Newbie
timestamp: December 02, 2018, 01:16:56 pm
content: Do you mean 100Hz or 100kHz?The sound bar is at least 8 years old.

author: wraper
author_rank: Unknown
timestamp: December 02, 2018, 01:20:52 pm
content: 120 or 100 Hz is used to measure capacitance, 100kHz is frequency ESR is usually specified at except some rare cases.

author: wraper
author_rank: Unknown
timestamp: December 02, 2018, 01:26:07 pm
content: Although DER EE-5000 may refuse to measure ESR at 100 kHz if you connect large capacitance. In such case you can measure it as Rs. It's just that ESR at 120 and 100 kHz are quite different figures and the most difference will be with small capacitance like below 100uF.

author: AndyA
author_rank: Newbie
timestamp: December 02, 2018, 09:22:27 pm
content: Quote from: wraper on December 02, 2018, 01:26:07 pmRs mode is working great.I have a cap here that is 33uF 450V but its not on any chart that I can find. Do you know the worst ESR for this cap?Thanks

author: wraper
author_rank: Unknown
timestamp: December 02, 2018, 09:33:08 pm
content: Quote from: AndyA on December 02, 2018, 09:22:27 pmIf it's lower than few ohms, should be fine. Depends on series a lot, I'd say if more than 10 ohms, you can be pretty sure it's going bad.
Estimating the actual capacity of power banks - Page 1
Forum section: electronics / beginners

author: NikolayTodorov
author_rank: Newbie
timestamp: March 12, 2015, 04:17:25 pm
content: Hi guys, new member here. For the past few hours, I've been trying to estimate how many times a power bank can recharge a smartphone, but I'm not confident in my calculations, hence I'm writing this post. By "power bank" I mean those portable battery packs that have a 5V USB port for charging phones/tablets. (Here's one.) I know that a power bank advertised as having a capacity of 10,000mAh has a 3.7V 10,000mAh battery inside it. There's also a voltage booster increasing the 3.7V to 5V, which brings the effective charge capacity of the power bank to 7,400mAh (10Ah x 3.7V = 37Wh and 37Wh divided by 5V = 7.4Ah, if I'm not mistaken). Now comes the part that confuses me. Will these 7,400mAh at 5V completely recharge, for example, a 3,700mAh 3.7V smartphone battery exactly two times (since 7,400 divided by 3,400 = 2),ignoringother factors like the losses caused by the voltage booster and the smartphone's charge regulating circuitry? Or should I do the math in watt-hours? Is there anything else I might be missing? Thanks!

author: Fsck
author_rank: Super Contributor
timestamp: March 12, 2015, 04:38:47 pm
content: I assume you mean "(since 7400 divided by 3700 = 2)"conservation of energy means you don't need to care how you do the math though it's easier just to do watthoursif the world was perfect (batteries can output full power constantly and are temperature invariant, etc.) and lossless, you'd get more than two charges (something like 2.7?).in the real world, you'd probably still get around 2.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: March 12, 2015, 04:39:28 pm
content: Do the math in watt hours, and assume ~80% efficiency. Keep in mind that the phone will also likely be using power while charging.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: March 12, 2015, 04:44:14 pm
content: When mixing battery voltages, all calculations should be done in Wh. If the battery voltages are all the same, then you can leave voltage alone and just work in Ah.In your case, both the power bank battery and the phone battery are a nominal 3.7v, so you can just work in Ah or mAh directly, it doesn't matter that the voltage is being stepped up to 5v and back to 3.7v (ignoring the inefficiencies associated with those transitions).So...10,000 / 3,700 = 2.7 chargesOr in Wh(10*3.7) / (3.7*3.7) = 2.7 chargesBut as Fsck said, since you probably have an 85-90% efficiency in both voltage changes, your nominal efficiency will be more like 70%, so your 10 Ah will only be able to deliver 7-7.5 Ah to the phone, which would be more like 2 charges.

author: NikolayTodorov
author_rank: Newbie
timestamp: March 13, 2015, 07:39:29 am
content: Thank you for the help, guys. Looks like I was wrong to think that the voltage difference did not matter and only the charge capacity in Ah did. Therefore, in a perfect universe, we'd get exactly what suicidaleggroll stated - "(10*3.7) / (3.7*3.7) = 2.7 charges". Have a great weekend!
Estimating transformer current from L, ESR, R, V for Isolation transformer - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: August 12, 2018, 12:19:39 am
content: I have a big transformer from a 1970s floor model Zenith TV. There's 3 secondary windings1 is a 6V heater filament I think. 1 has seven outputs, from 5V to 24, 50, 90, and even 250VThe 3rd is pretty much 1:1, just 2 wires. Using a proper LCR meter I measured it and the primary at 100HzThe pri isLseries=240mH @100HzESR=30.2O @100HzDC resistance is 6.2OThe sec. is229mH26.6O4OhmI could measure the capacitance but I just put away the meter. There's a lot of transformer eq's, and I don't know anything on the magnetic side of this.I don't want to burn it out just trying a 100W light blub, but doesn't it look like a lot of the power is meant to go through that winding ?And should I dead short the other 2 windings (to themselves) and just try a light bulb ?

author: Jwillis
author_rank: Super Contributor
timestamp: August 12, 2018, 11:43:00 pm
content: Really depends on the gauge of wire used for each winding.Generally the the high voltage secondary will have a very low current.Measuring the inductance and capacitance really won't tell you much.The measurements you need to do is the gauge of each winding on the secondary.The gauge of the primary will usually be matched to the VA requirements.or a bit better. The core area will will be the maximum VA allowable before core heating occurs.This measurement is higher than the total requirements of the secondary winding's.Draw a schematic of the winding's .Measure the gauge of the wire for each winding.You can use the Maximum Amps for Power Transmission of 700 circular mils per amp .Or usehttp://www.litz-wire.com/New%20PDFs/Fusing_Currents_Melting_Temperature_Copper_Aluminum_Magnet_Wire_R2.011609.pdfand calculate 8% of the fusible current rating of the wire gauge.This will give you a ball park figure of a safe workable amperage through the winding.Measure the width and length of the center core and calculate the area . Download a simple stand alone program called Xformer Designer. Its free and open source.Enter known parameters and it will give you fairly descent information about your transformer. The flux is usually around 50000 to 60000 lines per square inch for laminate cores.I use this information often and all my rewinds operate within exceptional specifications.

author: lordvader88
author_rank: Frequent Contributor
timestamp: August 14, 2018, 01:16:09 am
content: Yeah this is all sealed up in a nice can.I ran a 40W bulb and the output drops from 115.5V to 112.5V, I never tried a 100W yet, but I guess this winding won't be much good for much more than that.I need to let it sit and watch the temp, but I guess that's no real guarantee either. The wire's insulation could be melting off before this massive thing heats up.Most of the power has to go to the other other rails, I'm just disappointed.

author: lordvader88
author_rank: Frequent Contributor
timestamp: August 14, 2018, 01:21:03 pm
content: With a 100W bulb it drops to 104VAC