hybridfree/eevblog-posts huggingface dataset:
MCN-UV80 Flux from Aliexpress - Page 1
Forum section: electronics / beginners

author: Cherenkov11
author_rank: Contributor
timestamp: July 11, 2018, 03:26:22 pm
content: I'm relatively new on soldering, but recently I am getting into it, so I bought some stuff for a next level soldering, Kester solder, a TS100, wick wire, etc.But, I know flux is a vital thing for proper soldering, I've seen a lot of types in aliexpress and I found a paste flux called MCN-UV80 from Mechanic, because of the videos of Androkavo.This FluxSo my question: Is it a good flux? Or should I buy another one?Thanks in advance

author: Nitrousoxide
author_rank: Regular Contributor
timestamp: July 11, 2018, 03:30:16 pm
content: I can't vouch for that particular brand and there doesn't seem to be much information available. But I can say that either flux pens or flux tubes are much easier to handle/work with.

author: Cherenkov11
author_rank: Contributor
timestamp: July 11, 2018, 03:33:52 pm
content: I bought a liquid flux from my local electronic store, and virtually is garbage, it spreads and evaporates so quickly that doesn't help too much, that's why I'm looking for a proper flux

author: thm_w
author_rank: Super Contributor
timestamp: July 11, 2018, 09:44:46 pm
content: Should be good if you don't mind applying with a tooth pick.As mentioned, if you prefer syringe style you can get something like this:https://www.aliexpress.com/item/MECHANIC-Solder-Flux-Paste-MCN225-No-cleaning-Syringes-for-BGA-repair-Apple-CPU-Disassemble-the-installation/32820054521.html

author: Cherenkov11
author_rank: Contributor
timestamp: July 12, 2018, 02:50:19 am
content: No, I don't mind applying it with a toothpick, I was just asking if "Mechanic " is a good flux brand for a hobbyist like me

author: Nusa
author_rank: Super Contributor
timestamp: July 12, 2018, 05:15:56 am
content: When buying directly from Chinese vendors, brand name doesn't mean a lot. If it's a well-known brand, it's often a fake, and if it's an unknown brand, it doesn't mean much anyway. In the case of Aliexpress, looking at the feedback on the item itself is probably more revealing than asking here.

author: Cherenkov11
author_rank: Contributor
timestamp: July 12, 2018, 01:48:31 pm
content: Yeah, I know, a lot of products from China are fake, but I´m going to trust in this one, thanks everyone for your help.
MCP16311 does not reach intended voltage - Page 1
Forum section: electronics / beginners

author: M@rcel
author_rank: Newbie
timestamp: June 09, 2014, 01:31:34 pm
content: Hello,(My first topic here. Please, be gentle)I have setup a circuit using aMicrochip MCP16311. The circuit is dimensioned for 5V output, the input is 8V (also tested with 12V, no difference).The output voltage is not the intended 5V, but no higher than 3.2V. The scope tells me that PWM duty cycle is at his max (PWM freq. is the expected 500kHz). The feedback voltage (FB pin) is 0.5V instead of the expected 0.8V.0.5V FB tells me that the reg will attempt to rise the output voltage and increases the PWM duty cycle to accomplish this. It, however, gets to it's max duty cycle (long) before the desired 0.8V on FB has been reached.Increasing capacitance on input and/or output makes no difference.I am usingthis Murata inductorin the setup (size is an issue).What might be the problem?Thanks!Edit: Current draw is about 50mA.

author: M@rcel
author_rank: Newbie
timestamp: June 09, 2014, 04:51:47 pm
content: It appears that the calculated output voltage is maintained by the circuit down to a minimum load of 1k. So, output voltage starts to drop when the output current rises above 5mA.Does this give anyone a clue?

author: JoeO
author_rank: Frequent Contributor
timestamp: June 09, 2014, 05:24:56 pm
content: What is your 8V input and how much current is the 8V input able to supply?

author: M@rcel
author_rank: Newbie
timestamp: June 09, 2014, 07:05:56 pm
content: To keep it safe, I am currently using a 9V alkaline battery (through a Schottky). I tried with a 12V car battery, too. No difference.
MCP1640 - Negative ramp sawtooth 125mV/38ms Vout? - Page 1
Forum section: electronics / beginners

author: paw
author_rank: Contributor
timestamp: July 27, 2015, 07:29:32 am
content: Hi all,Is this normal/expected? At 125mV (if I'm reading it right) it seems huge. I see the same powering from 1xAA, Cr2032 and power supply anywhere between 0.8-3.0V with no change. As probably expected changes in capacitance (decoupling) will affect the ramp length.I see the same across 3 boards and 2 layouts (1 closely resembling the one from the datasheet). With 5mA and without any load. Looking at it it seems something is getting charged and then discharges over 38ms (depending on the load presumably).My questions:- could this be right or is there something obvious wrong?Many thanks for any suggestions!
MCP23017 Forgets Direction of one bank - Page 1
Forum section: electronics / beginners

author: mentaldemise
author_rank: Regular Contributor
timestamp: February 13, 2017, 03:24:38 pm
content: Has anyone experienced anything similar to this? I have an MCP23017 hooked up to a PI and running some mosfets and reading some IR LEDs on different ports. The IR read port works all the time. The MOSFET out one seems to forget its direction at seemingly random. It's not blowback from the mosfet as it happened last night while the device was just idle. I ran i2cset -y 1 0x20 0x01 0x00 in console next to the python that was still running and the outputs started working again. It seemed to work for at least 24 hours this last go, just really not sure why it's "forgetting" which direction one bank is while it's idle.

author: senso
author_rank: Frequent Contributor
timestamp: February 14, 2017, 10:12:05 am
content: Lack of decoupling, reset pin is floating(since input is the default reset value, it might be related).

author: mentaldemise
author_rank: Regular Contributor
timestamp: February 14, 2017, 10:23:54 am
content: I wish it were that simple. I have RESET pulled high. The chip isn't resetting completely, as the IN lines don't stop working, only out. Also, a full reset from taking REST low will crash the python app and that doesn't happen either.

author: Ian.M
author_rank: Super Contributor
timestamp: February 14, 2017, 11:30:02 am
content: IIRC the MCP23017 is quite buggy, and there are a number of corner cases that Microchip support are aware of and have confirmed which haven't made it into the published errata.Googling:+"MCP23017" forum erratawill find a number of topics on various forums mentioning them, and if you dig through the dross, you will have some idea of the wide range of ways it can foul up.I would suggest adding code to read back and confirm the device configuration as frequently as you can without compromising the intended function, logging all I2C transactions to a ring buffer and if an unexpected configuration change is detected, dumping the ring buffer to a timestamped log file. Then, as a patch on the problem automatically restore a valid configuration. Its not a fix, but it will give you ammunition when you contact Microchip support. If you've go the kit to do it, also log the Vdd supply. You'll need a DSO that supports one-shot post-trigger with logging or a fast datalogger. Trigger it with aspare Pi I/O pin.
MCP23017 - unusual behaviour - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 21, 2020, 10:21:17 am
content: HiI have an MCP23017-E/SP and a simple Arduino sketch.The port A outputs all look ok but there is an issue with bit 0 of port B.It stays low regardless of what value I write to the port.However, if I swap the two IODIRx lines so port B is configured first, it works !Code:#include "Wire.h"void setup(){Wire.begin();// set I/O A pins to outputsWire.beginTransmission(0x21);Wire.write(0x00); // IODIRA registerWire.write(0x00); // set all of port A to outputs// set I/O B pins to outputsWire.write(0x01); // IODIRB registerWire.write(0x00); // set all of port B to outputsWire.endTransmission();}void outputByteA(int a){Wire.beginTransmission(0x21);Wire.write(0x12); // GPIOAWire.write(a); // port AWire.endTransmission();}void outputByteB(int a){Wire.beginTransmission(0x21);Wire.write(0x13); // GPIOBWire.write(a); // port AWire.endTransmission();}At first, I thought that I'd got a bad chip but another did the same.I'm sure that it's something really simple that I'm overlookingAny ideas please ?Thanks

author: Unixon
author_rank: Frequent Contributor
timestamp: July 21, 2020, 12:59:13 pm
content: Shouldn't there be two separate I2C transactions?I meanCode:Wire.beginTransmission(0x21);Wire.write(0x00); // IODIRA registerWire.write(0x00); // set all of port A to outputsWire.endTransmission();Wire.beginTransmission(0x21);Wire.write(0x01); // IODIRB registerWire.write(0x00); // set all of port B to outputsWire.endTransmission();

author: VooDust
author_rank: Regular Contributor
timestamp: July 21, 2020, 01:31:42 pm
content: He's right, you need two transactions. If you continue writing bytes instead, the target register is auto-incremented and written to with the consecutive byte, and so on, IIRC.

author: netdudeuk
author_rank: Frequent Contributor
timestamp: July 21, 2020, 01:42:51 pm
content: Thanks folks.I appreciate the prompt replies.I'll give that a go.
MCP3426 ADC: Bipolar or not? - Page 1
Forum section: electronics / beginners

author: Felicitus
author_rank: Regular Contributor
timestamp: January 17, 2014, 07:42:30 am
content: Hi,I'm having quite some trouble with theMCP3426 ADC. The datasheet says that it has an internal voltage reference of±2.048V, so I first assumed that it can do bipolar measurements (at least in differential mode). Also, it implements signed output in the I²C protocol.I have a few questions about this:The maximum differential voltage is specified as |Vdd-Vss|. What do the | signs mean?The maximum rating for all inputs and outputs is specified as Vss-0.4V to Vdd+0.4V. Do I assume correctly that this also includes the differential inputs?If I wanted to do positive and negative measurements, what would I have to do? Tie CH1- to 2.048V and use CH1+ for the input?

author: fcb
author_rank: Super Contributor
timestamp: January 17, 2014, 07:52:56 am
content: Differential input range is +/-2.048v.These inputs are (as you point out) Vss-0.3v to Vss+0.3v. This means that you can't go to -2.048v with respect to 0V.To solve the issue, either change your ADC or use a level shifter (that's what I would do - differential amplifier).
MCP41HV51 digtial potentiometer  - Page 1
Forum section: electronics / beginners

author: Gazello
author_rank: Contributor
timestamp: July 24, 2022, 05:03:25 pm
content: HelloI use the mcp 41HV51 as a pot from 10V but i only get from it 9,6V , i write 255 as max . Any ideas where or what to change ? the datsheet states it is rail to rail .No clue .thanksMArkus

author: mikerj
author_rank: Super Contributor
timestamp: July 25, 2022, 04:17:25 pm
content: Check "Full scale error" in the datasheet.
MCP42100 powered by 3V3 to control a circuit powered by 5V ? - Page 1
Forum section: electronics / beginners

author: ggchab
author_rank: Frequent Contributor
timestamp: March 13, 2018, 03:18:31 pm
content: Hello,May I use an MCP42100 powered by 3V3 (microcontroller and SPI bus in 3V3) to control a circuit (op amp) powered by 5V ?Thanks

author: MasterT
author_rank: Frequent Contributor
timestamp: March 13, 2018, 03:49:50 pm
content: It says on page 5 in data sheet :Absolute Maximum Ratings †VDD...................................................................................7.0VAll inputs and outputs w.r.t. VSS ............... -0.6V to VDD +1.0VFor your 3.3V maximum would be 4.3V. No way 5.

author: ovnr
author_rank: Frequent Contributor
timestamp: March 13, 2018, 04:00:32 pm
content: No; also, the spec'd input thresholds indicate that you can't power it off of 5V and still use a 3.3V SPI bus.Just use a level shifter and power it off of 5V - either a dedicated chip or some transistors and resistors.

author: mikerj
author_rank: Super Contributor
timestamp: March 13, 2018, 04:11:36 pm
content: Quote from: ggchab on March 13, 2018, 03:18:31 pmIt depends entirely on the actual voltage that is going to be applied to the digital potentiometer, provided this is not more than 3.3v then it will be fine. People seem to be assuming that because the op-amp has a 5v supply rail that 5v will be applied to the digitpot, this isn't necessarily the case (though equally it might be).Posting a schematic of your proposal would help.

author: Zero999
author_rank: Super Contributor
timestamp: March 13, 2018, 07:13:21 pm
content: My guess is the original poster has misused the word powered.The MCP42100 needs to be powered from the same power supply as the op-amp. Unfortunately the high threshold voltage is equal to 0.7*VDD, which would be 3.5V, in this case, so a level shifter is required.There's a small breakout board available or you can copy schematic off the Sparkfun website. Then there are ICs, such as CD4504, 74HCT126, 74HCT241, 74HCT244 (3.3V to 5V) and 74HC4050 (>5V to <6V).https://www.sparkfun.com/products/12009

author: ggchab
author_rank: Frequent Contributor
timestamp: March 13, 2018, 07:27:40 pm
content: Thanks to all.I'll power the MCP44100 in 5V and use a level shifter for for CS, MOSI and SCK lines. I don't have to care about MISO as it's not used
MCP4251 in rheostat mode, can't get full resistance - Page 1
Forum section: electronics / beginners

author: Infraviolet
author_rank: Super Contributor
timestamp: January 27, 2023, 02:59:22 am
content: I've got an MCP4251-104E/P digital potentiometer chip. I'm using this potentiometer chip as a rheostat, as per the datasheet's advice I've shorted end B of the pot to the wiper and am measuring resistance from the wiper to end A. But I can't seem to get the full resistance out, it won't go above 50Kohm, but it is supposed to go up to 100K. I've done a test cycling through giving it the 0 to 255 range of values and back, and it goes from a small resistance up to 50K then back down. It is as if this chip were the 50K version, but it definitely isn't, the chip and packet labels all say it is the 100K version.I've done the same test with a 100K MCP42100 and that behaves as it ought. Any idea why the MCP4251 won't?Could it be a mode issue with the SPI comms, maybe using reversed polarity or something causing a missed bit in the message to set the resistance? But if it were one would expect the MCP42100 which uses the same SPI protocol to refuse to go to full resistance, yet it goes to full happily.Thanks

author: mikerj
author_rank: Super Contributor
timestamp: January 27, 2023, 03:48:15 pm
content: Take a look at this thread:https://www.eevblog.com/forum/beginners/100k-digipot-only-reaches-63k/

author: Infraviolet
author_rank: Super Contributor
timestamp: January 28, 2023, 09:21:23 pm
content: Thanks, taking one terminal of the pot to ground fixed it, it runs up to 94K now which is definitely within specifications. I had been doing these tests with the pot floating and an ohm-meter across the wiper and one end of it. I assume in actual circuit use it does not need one end permanently tied to ground or to Vcc, so long as the ends are at voltages which do not outright float relative to this chip's power rails? I'm using the resistance (rheostat style) to control the speed of a 555 timer and while my circuit has feedback to a microcontroller which lets percentage errors in the potentiometer value be overcome I do need to be able to get values towards the higher and lower ends of the range. Thanks
MCP4812 10-bit DAC melting breadboard - Page 1
Forum section: electronics / beginners

author: justinm
author_rank: Newbie
timestamp: January 04, 2019, 06:12:53 pm
content: Hoping for suggestions on what to try next:I replaced a working MCP4725 I2C DAC with an SPI-driven MCP4812 (I wanted two channels from one component). 5V VSSwas connected from the output of an Arduino Nano board.I was able to confirm all the SPI signals were correct with the scope, but then before I could even get the multimeter on VOUTAor VOUTB(both floating, not pulled down) of the DAC I started to smell -- not the magic smoke -- but some melty breadboard.I then disconnected all the SPI signals, connected Vssand Vdd-- still got warm.I then swapped in a fresh chip and fresh breadboard -- same result.Is it possible that the absence of a decoupling cap, or the floating output pins, could explain the heat? Stumped and afraid of wrecking more chips in my quest to build the simplest possible MCP4812 circuit.Thanks for any debugging suggestions!

author: tsman
author_rank: Frequent Contributor
timestamp: January 04, 2019, 07:03:52 pm
content: Quote from: justinm on January 04, 2019, 06:12:53 pmUhh. You didn't wire up 5V to Vss did you?

author: justinm
author_rank: Newbie
timestamp: January 04, 2019, 07:15:01 pm
content: Yes! Okay. I read and re-read the datasheet, but my eyes transposed those pins every time. That'll do it! Will report back after putting 5V on the correct pin tonight

author: justinm
author_rank: Newbie
timestamp: January 05, 2019, 04:54:26 am
content: MCP4812: sturdy chip! Turns out it can get nice and hot and still come right back to life. Beautiful lines on the scope now. Thanks @tsman!

author: Buriedcode
author_rank: Super Contributor
timestamp: January 05, 2019, 04:04:47 pm
content: Current limiting in linear regulators and the fuses on USB power have saved a couple of micro's I've mis-connected. USB isn't a bad way to power up stuff for the first time - as long as it's 2.0, limited to 500mA, and adheres to the standard.
MCP48FVB21 DAC command help - Page 1
Forum section: electronics / beginners

author: UHF
author_rank: Contributor
timestamp: June 07, 2024, 12:36:25 am
content: Hello, I'm a middle-aged young player. I'm running a MCP48FVB21 DAC from an ESP32 via SPI. I can get it to produce analog values by sending three 8-bit bytes, but I can't get my head around how I set the other features, particularly the Vref source. Section 4.2 details this. I'm supposed to send xx to address 08h to set this. I assume it's three 8-bit bytes 08h, 00h, 01h? Any help gratefully received because it doesn't seem to work for me, thanks.https://ww1.microchip.com/downloads/aemDocuments/documents/OTH/ProductDocuments/DataSheets/20005466A.pdfI'm sending value data like this :Code:mySPI->beginTransaction(_spi_settings);mySPI->transfer((uint8_t)(data >> 16));mySPI->transfer((uint8_t)(data >> 8));mySPI->transfer((uint8_t)(data & 0xFF));mySPI->endTransaction();

author: bingo600
author_rank: Super Contributor
timestamp: June 07, 2024, 02:21:27 pm
content: Edit:Your suggestion 0x08 , 0x00 , 0x01 is "almost" correct ...But note that address bits starts in bit position 3, and R/W command bits in bit position 1.This would be my suggestion ....Cold be optimized quite much ...But i tried to split up the command & data building.Code:uint8_t command;uint8_t high_data;uint8_t low_data;command = 0; // Implicit write as C0:C1 = 0high_data = 0;low_data = 0;//// Build the command byte//commmand |= (0x08 << 3); // Set address 8// Uncomment below line if doing a read// command |= (0x03 << 1); // Set Read command//// Build the high data byte - bits 15..8//high_data = 0; // High data unused for Vref commands//// Build the low data byte - bits 7..0//low_data = (0x03); // Set whatever Vref command you want here - Now 3 ==> Bin 11 ==> VREF pin (Buffered); VREF buffer enabled - (NB - bits 0..1 = Channel 0)mySPI->beginTransaction(_spi_settings);mySPI->transfer((uint8_t)(command);mySPI->transfer((uint8_t)(high_data);mySPI->transfer((uint8_t)(low_data);mySPI->endTransaction();

author: UHF
author_rank: Contributor
timestamp: June 14, 2024, 08:41:26 am
content: Thanks very much, it worked.Code:void MCP_DAC::setVREF(){uint8_t command = 0;uint8_t high = 0;uint8_t low = (0x03);command |= (0x08 << 3); // Set address 8// DATA TRANSFERdigitalWrite(_select, LOW);mySPI->beginTransaction(_spi_settings);mySPI->transfer((uint8_t)(command));mySPI->transfer((uint8_t)(high));mySPI->transfer((uint8_t)(low));mySPI->endTransaction();digitalWrite(_select, HIGH);}
mcp6024 instead of mcp6004  - Page 1
Forum section: electronics / beginners

author: sımışka
author_rank: Contributor
timestamp: March 30, 2020, 10:57:52 am
content: Hi,I used in pcb MCP6004SL soic14 package. but now i have MCP6024 soic14 package. All pins same and rail to rail opamps even mcp6024 better than it. Opamp connected to mcp3424 adc via I2C. this circuit will use some analog voltage inputs. Can i use it ?Thanks.
MCP73831+uC+dummy load-->LiPo tester problem - Page 1
Forum section: electronics / beginners

author: Lukapt
author_rank: Newbie
timestamp: March 21, 2013, 11:53:51 am
content: Hi,It's my first post here, so I'd like to sayHELLO.Thanx, for great resource of info.I'm designing (simple) LiPo battery tester, and have problem with MCP73831 (actualy I put down 3 of those already).I've build attached circuit on breadbord, don't know the reason but, I every odd time when I connect battery MCP goes dead.Probably, I've made some simple mistake, but have no idea where.I'm not EE just the hobbyst, so can you help me find it out? Mayby some changes in schematic, but I prefer to stick with MCP73831 (2 left)
MCP73871 battery circuit problem - Page 1
Forum section: electronics / beginners

author: JonasStelz
author_rank: Newbie
timestamp: September 24, 2025, 10:47:28 am
content: Hello everyone,I recently used the MCP73871-1CCI/ML from Microchip in a project (Datasheet:https://ww1.microchip.com/downloads/en/DeviceDoc/MCP73871-Data-Sheet-20002090E.pdf). The exact circuit I used is attached.The power supply comes from a USB connector providing 5 V VBUS. Overall, the system works as expected. The IC switches between powering the PCB from USB and from the battery depending on whether USB is connected or not.The problem:The battery does not charge when USB is connected. The LED indicators show:STAT1: LOWSTAT2: High-ZPG (Power Good): LOWAccording to the datasheet, this LED state should indicate that the battery is charging. However, when measuring the current into the battery, there is no charging current, even though discharging works as expected.I have already tried lowering the Prog1 resistor R8 to 1 kΩ and bridging R10, unfortunately, neither change fixed the issue.I also tried fully discharging the battery. What happens is: when the battery is completely empty and USB is connected, the battery charges up to around 3 V and then stops charging.If no battery is connected, the Vbat pins rise to 4.1 V and the STAT1 LED goes to High-Z.If anyone familiar with this IC could help me, I would be very grateful.Thanks in advance!

author: JonasStelz
author_rank: Newbie
timestamp: September 24, 2025, 01:37:21 pm
content: Hello,resoldering the chip fixed the issue, i guess it was the VBat_sense pin, that was not soldered correctly. Now the battery is charging as it is supposed to.

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: September 28, 2025, 03:36:13 pm
content: Quote from: JonasStelz on September 24, 2025, 01:37:21 pmGood job! If the VBat pin is floating or poorly soldered, the IC either thinks the battery isn’t present or misreads its voltage. So it won’t drive charge current even though the status LEDs indicate “charging.”
MCT2E optocouopler equivalent - Page 1
Forum section: electronics / beginners

author: Griffin
author_rank: Unknown
timestamp: May 14, 2012, 12:58:04 pm
content: Hi every1I am building a fan control circuit based on the one form this link:http://extremeelectronics.co.in/avr-projects/avr-project-remote-controlled-fan-regulator/to learn more about optocouplers. My problem is it uses a MCT2E optocoupler that is not available from RS Components or digi-key in our country. Is there a spec similar optocoupler I can use that will do the same job?Thanks for the help.

author: TerminalJack505
author_rank: Super Contributor
timestamp: May 14, 2012, 06:15:06 pm
content: From the looks of the schematic none of the parameters for the part are too critical. You just need to find an optocoupler in the same package (6-pin DIP, 0.300" lead spacing) with the same pinout. That's a pretty standard pinout.Any of the following from the "4N" series optocouplers should work: 4N25 thru 2N28 or 4N35 thru 4N37. These are very common.

author: Griffin
author_rank: Unknown
timestamp: May 14, 2012, 09:30:10 pm
content: So far it looks good but will studdy the datasheets to make sure. Thanks allot.
MCU and 433MhZ RF Module recommendations for controlling Blinds - Page 1
Forum section: electronics / beginners

author: joshuaera1609
author_rank: Newbie
timestamp: August 21, 2022, 09:50:14 am
content: Hi Forum,I would like some advise on hardware selection (MCU and RF module) to communicate with my QMotion blinds - RF 433Mhz Modulation: ASK (OOK) with Manchester encoding . I have sniffed and decoded the protocol previously using RTL_433 -https://github.com/merbanan/rtl_433/issues/1766.I would now like to read (so I can update position database) and transmit the signal to control blinds. Maximum transmit about 30 metres.I have been trying to identify the hardware (MCU and RF module) to use. For the microcontroller my preference is one that has WiFi and that can run web server, as long term I would like to control the blinds via an API. For the MCU and RF module I would like ones that I just need to plug together or wire up. Soldering, resistors and are above my technical ability, but willing to if it offers best option.Budget for hardware upto $100 as I plan to use this as a education. Prefer to keep away from really cheap 433Mhz modules form ebay.I have been researching but there are just so many options and I am not sure of the technologies. (ie what is Lora - do I need it?)I was thinking following possible optionsa) ESP32-S2 Feather Development Board (https://www.adafruit.com/product/4769) and FeatherWing - RFM69HCW 433MHz (https://www.adafruit.com/product/3230)b) ESP32-S2 Feather Development Board (https://www.adafruit.com/product/4769) and CC1100 module (from eBay)I did look at raspberry PI 4 with the CC1100 module, but the PIs are very expensive currently. I own Beagle Bone Black and Odroid C2 that I could use that if the RF module is easy integrated.Could you suggest the best hardware options. I can program in C and C++.ThanksJoshua
MCU based inverter design - Page 1
Forum section: electronics / beginners

author: baoshi
author_rank: Regular Contributor
timestamp: December 21, 2013, 03:53:21 pm
content: Hi,I'm designing a VFD driving circuit. One of the challenge is the driving chip needs -22V negative bias.I found Dave has an inverter FF tutorial based on a MCU generate waveform. But it can only provide -VCC instead of "boost" the voltage lower.So I came out the attached design, basically combining a boost converter with Dave's inverter.Can someone scrutinize my design before I put it onto a board?ThanksBaoshi

author: Marco
author_rank: Super Contributor
timestamp: December 21, 2013, 04:14:02 pm
content: Heh, nice effort to try to modify such a simple circuit until it does what you want to do ... but you get so far away from Dave's circuit that it stops making sense to even use it as part of your design.You want a (inverting) buck boost converter with a P mosfet.

author: baoshi
author_rank: Regular Contributor
timestamp: December 22, 2013, 03:39:50 am
content: Quote from: Marco on December 21, 2013, 04:14:02 pmThanks Marco,I changed the design. Is this any good?
MCU controlling voltage output rails - Page 1
Forum section: electronics / beginners

author: Sarcarean
author_rank: Contributor
timestamp: December 31, 2015, 11:09:15 pm
content: Hey everyone!So I wanted to ask you all for your opinion on a design change I am working on. I have 4 lines of various voltage (5v, 3.3v, 2.5v, 1.8v) each at 200-500ma. And I want to use a microcontroller (Atmel in this case) to control / switch a line out that then connects to a level shifter IC. My current board, this is done with just a SPDT switch.So this is what I came up with:So I have 4 lines from MCU, going through a resistor array (220 ohm), and then each to a LED and then to the enable pin on a ADP197 (High-side power switch) and the output of all 4 of those tied together that then goes to the voltage-ref of the level shifter / translator (FXMA108).So my question, is there anything I am missing? I was thinking that there could be a problem with the boot-up, as vcc might try to enable all 4 of the power switches at once, but the level shifter is controlled via its own OUTPUT ENABLE pin, which I have a pull-up resistor (10K) so that it should remain in 3-state until the MCU is ready and can pull down the OE pin.

author: Robartes_m
author_rank: Contributor
timestamp: December 31, 2015, 11:43:06 pm
content: Quote from: Sarcarean on December 31, 2015, 11:09:15 pmI don't think that will work - when you set the I/O pin for one of the analog switches (eg PC16) high, the LED will probably light up, but the EN pin will not go high. In fact, you might damage the ADP197, as you're sinking a current through the pull down resistor on the EN pin which it will definitely not be designed to do.Connect the MCU I/O pin directly to the EN pin to get this to work.

author: Psi
author_rank: Super Contributor
timestamp: January 01, 2016, 01:16:16 am
content: Wouldn't it be simpler to have a precision reference on the ADC Vref then use a PWM DAC and an dual opamp to 2-order low pass filter&buffer.It's more flexible since you can have any voltage you want.You can use a high frequency for the pwm and heavily filter it because the shifter voltage level isn't something you need to change often or quickly.It's also not something that has to be super accurate.

author: Sarcarean
author_rank: Contributor
timestamp: January 01, 2016, 08:12:19 am
content: Thanks for the response@Robartes_m: Would something like this work instead?@Psi: I read somewhere else of something similar to this, do you know of a link to a schematic I can look at?

author: Robartes_m
author_rank: Contributor
timestamp: January 01, 2016, 06:03:38 pm
content: Quote from: Sarcarean on January 01, 2016, 08:12:19 amThat would work better in that it would pull up the EN pin of the analog switch, but you are still driving the LED directly from the MCU pin. This might or might not be a problem, depending on what current the MCU can supply. To avoid this, I would simply put the LED on the Vout of the analog switch.
MCU dc to dc converter  - Page 1
Forum section: electronics / beginners

author: jeffd1988
author_rank: Newbie
timestamp: September 02, 2015, 04:30:54 pm
content: hello i have been trying to make a inverting converter using a attiny45 i got it outputting a 125khz pwm and i hooked it to a p-channel mosfet the output works fine until i connect the inductor (test 281uh @ 100khz Q30) and a capacitor of 10uf and just a standard diode then it terns into a 16hz sail wave at the pin of the attiny it works just as if i was giving it a 16hz wave so it pulses at 16hz at the output i don't get why it changes to a 16hz sail looking like wave from almost perfect square wave running at 125khzand if i change the frequency to like 30hz to like 10hz and if i change it to 7hz to 10 like 4hz but once I'm higher then like 100hz it changes very littletack not of how the time scale changes from on image to the nextthe attiny output180ohm is the MCU's output at the pin with just a 180ohm resistor connected to groundthe attiny output is what the pin is doing at the lin with the converter connectedthe drain 180 is what the drain pin of the transistor is doing without the inductor connected to it but a 180ohm resistor connected to groundthe drain is with the inductor connected ectthe gate input is what is seen when the inductor is connectedoutput is well the output with a 180ohm resistor as load

author: jeffd1988
author_rank: Newbie
timestamp: September 02, 2015, 09:56:39 pm
content: i feel stupid now i put a 3k ohm resistor between the gate and the pin and it works instead of a 480ohm
MCU identification - Page 1
Forum section: electronics / beginners

author: labuwx
author_rank: Newbie
timestamp: July 03, 2025, 10:30:18 pm
content: Hi,Please help me to find out more about this MCU. The label is "FT62F168 23B1JTH".It is from a wireless doorbell. There is no external flash or RAM. The radio part is done by a Semtech chip (connected via SPI). The chimes and the audio are the job of the black blob below.It must have some some writable persistent storage to remember the additionally paired transmitters, selected chime and volume.Could the SC and SIO be Serial Wire Debug pads? Any chance it is reprogrammable?

author: golden_labels
author_rank: Super Contributor
timestamp: July 03, 2025, 10:56:50 pm
content: Looks like something fromFremtoFremontMicro Devices, They werediscussed in this thread. Unfortunately I have no further data.

author: radiolistener
author_rank: Super Contributor
timestamp: July 04, 2025, 08:35:12 am
content: probably this is some kind of Chinese MCU for mass production.As mentioned above, looks very similar to Fremont Micro Devices series MCU.Like FT62F132:https://lcsc.com/datasheet/lcsc_datasheet_2409280231_FMD-Fremont-Micro-Devices-FT62F132-RB_C708791.pdf
MCU power supply + PC supply - Page 1
Forum section: electronics / beginners

author: DzAnej
author_rank: Contributor
timestamp: December 11, 2016, 11:25:19 am
content: Hi, I've got a quick and hopefully easy question.I'm working a lot with microcontrollers (Arduino, ...) and quite often I am having pritty big loads. Project I am working on now I have a programmable LED strip that draws 7A at max, and the arduino needs to be connected to the computer. Then I have a power supply capable of those 7A to power the strip and the Arduino (5V pin of the arduino is connected to the 5V power supply). Now let's say that my power supply turns off for unknown reason and the only 5V supply comes from the computer. Then probably the load (LEDs) would try to pull that power from the computer and because it's not capable of that something would go wrong (either the fuse on the Arduino or the computer would turn off).Is there any way/method to prevent that?Oh, and the computer is not always connected to the arduino, so I can't power the arduino only from the PC...

author: Psi
author_rank: Super Contributor
timestamp: December 11, 2016, 11:34:11 am
content: Need a schematic of your system

author: Asim
author_rank: Regular Contributor
timestamp: December 11, 2016, 11:48:04 am
content: Don't power your arduino from the same 7A power suuply. Use the USB port to power the arduino & the 7A supply to power the led strip seperetley. Note that you need a common ground, so connect a ground from your arduino board to the ground of the led strip.

author: cowana
author_rank: Frequent Contributor
timestamp: December 11, 2016, 11:57:35 am
content: Quote from: DzAnej on December 11, 2016, 11:25:19 amAs Asim said, it's very bad practice to connect two power supplies directly together (which you have with your PC's 5v USB supply, and the external 7A supply).Best solution is to only power the LED strip from the external supply, and not the arduino.
MCU protection for motor driver - Page 1
Forum section: electronics / beginners

author: eb1984
author_rank: Newbie
timestamp: November 30, 2024, 11:52:42 am
content: Hi,I am driving a 12V DC motor with LV8548 motor driver IC, sometime the flash area of mcu is corrupted and some parameters in flash area is changed by itself. For protection the mcu, which components can be added? Would it be useful if I use CPDQC5V0U-HF tvs diode on the mcu pins? Or do you have any other suggestions? You can see my schematic from attached image.
MCU USB capabilities - Page 1
Forum section: electronics / beginners

author: chagli
author_rank: Contributor
timestamp: March 19, 2019, 07:03:42 pm
content: Hello,I am using an USB OTG (on-the-go) capable MCU.I would like to know if I could use onlyoneconnector to read an USB key and also connect to PC which send commands (not at the same time !).In the first case, the MCU would be host and in the second it would be device.As far I understand, I need the 5th pin 'ID' which is only available on mini and micro usb connectors, but I cannot connect a stick on these.Am I forced to add another connector ?Thanks for your advice.

author: MosherIV
author_rank: Super Contributor
timestamp: March 19, 2019, 07:18:55 pm
content: No, you can not 'share' a usb port with 2 devices let alone swap between device and host.

author: Monkeh
author_rank: Super Contributor
timestamp: March 19, 2019, 07:29:19 pm
content: Quote from: MosherIV on March 19, 2019, 07:18:55 pmThat's exactly what OTG does..

author: ataradov
author_rank: Super Contributor
timestamp: March 19, 2019, 08:07:08 pm
content: Yes, there is no way to get OTG capability on a full size Type A connector. It is against the standard to have USB device on a Type A receptacle.That last part does not stop some vendoers from China doing that anyway. And this is extremely annoying.Type-A to Type-A cables exist, but they are not specified in the standard either.

author: chagli
author_rank: Contributor
timestamp: March 23, 2019, 09:58:08 pm
content: Thanks for your answers. I think I will use two different connectors (A and B) and two separate USB MCU ports.

author: bson
author_rank: Unknown
timestamp: March 23, 2019, 10:48:47 pm
content: You can connect a flash drive to a micro-B connector if you get an OTG cable.
MD-PS002 pressure sensor from Aliexpress - pressure range - Page 1
Forum section: electronics / beginners

author: matkar
author_rank: Regular Contributor
timestamp: March 27, 2017, 10:31:39 pm
content: I bought two pieces of pressure sensor here:https://www.aliexpress.com/item/2pcs-lot-pressure-sensor-air-pressure-Tire-pressure-sensor-700kpa-diffusion-silicon-A1G1/32502253913.html?spm=2114.13010608.0.0.5GoaWWIn the title it says they are 700kPa sensors but down in description it says their range is 150kPa from absolute zero. I've asked the seller but doesn't seem to know which data is correct.I have found these datasheets:http://www.datasheetspdf.com/datasheet/MD-PS002.htmlThe second datasheet in chinese has a table with multiple sensor options. There don't seem to be any markings on the sensor body...How can I tell which model do I have without risking destroying the sensor?According to the table on the first page the 700kPa sensor has a full scale range of 100mV. Does this mean by applying 5V between IN+ and IN-, I should be reading 100mV differential between +OUT and -OUT at 7 bar (and proportionaly less with lower pressure)?

author: danadak
author_rank: Super Contributor
timestamp: March 27, 2017, 10:46:56 pm
content: Assume you have the lower pressure sensor, and place that DUT under maxpressure and measure output. That full scale V should indicate which part itis.This whole thing is risky if you are doing any life support work, definitely getmarked parts.Chinese knock off parts always tempting, but have a "real" price that may beunacceptable, like not telling you which part you have. Some parts are thecorrect part, but do not meet advertised specs.Regards, Dana.

author: matkar
author_rank: Regular Contributor
timestamp: March 28, 2017, 07:53:29 am
content: I did a very crude measurement.I've attached a hose filled with water to the sensor and measured the response by lifting the hose to a known level. With 5V applied at zero level the reading was 8,68mV. When the water level was elevated to 216cm (21,19kPa) the reading increased to 11,63mV.21,19kPa/2,95mV = 7,18kPa/mV -> 718kPa/100mV. This is close enough to 700kPa/100mV from datasheet so I guess it's save to say it's a 700kPa sensor.
MDO VS DSO VS MSO ? WHICH ONE IS BETTER ? - Page 1
Forum section: electronics / beginners

author: tonny_cassidy25@yahoo.com
author_rank: Newbie
timestamp: July 25, 2015, 08:54:41 am
content: so whats the dirfference between DSO oscilloscope , MDO oscilloscope and MSO scopes,and which one is better ,so today when i browsing on ebay i see the popular on ebay list and saw a listing of a HANTEK DSO 5102P and i check it but idk why i didnt like the looks of it ,anyone have experience with it ? is it good ? or bad ? ,and i have previously watched a review about agilent MSO X 2024A and it looks quite nice and i like it,and i know agilent make a good quality product (in my opinion),and i also found a mdo 3000 series from tektronix which is a brand that make a good test equipment,so which one is better and whyanyway thanks for reading,sorry if i make a mistake on my grammar(since english is not my primary language) ,and i dont really understand about oscilloscope specifications,im only a highschool student,electronic hobbyist and youtube content creator

author: JackP
author_rank: Regular Contributor
timestamp: July 25, 2015, 09:24:03 am
content: The MDO will cost upwards of £10k, so maybe not. Hantek are known for buggy firmware and poor build quality, but I'm sure that would do the job if you are on a budget (look at the Rigol DS1054z though). I can vouch for the MSO-X 2002A (I have a reviewhere). It can be hacked to 200MHz. If you want to know more about oscilloscope specification, I have a tutorialhereto (today's a good day for self-promotion!).Basically, a DSO can view analogue components of a signal. An MSO does the same, but adds capability to view digital signals (more), although you can't view analogue characteristics of the signal. An MDO (proprietary to Tektronix as of now), combines the previous two with a spectrum analyser, allowing you to view analogue, digital and RF.Hope this helps.

author: RogerRowland
author_rank: Regular Contributor
timestamp: July 25, 2015, 09:29:09 am
content: Dave does a nice explanation of what an MDO does and how it differs from DSO and MSO in this EEVblog:

author: Electro Fan
author_rank: Super Contributor
timestamp: July 25, 2015, 10:18:19 am
content: Quote from: JackP on July 25, 2015, 09:24:03 amThis is a pretty good response and summary for the OP but to clarify a MSO has both analog and digital channels so you can view analog characteristics on the analog channels.
Component compatibility - Page 1
Forum section: electronics / beginners

author: permal
author_rank: Regular Contributor
timestamp: April 30, 2017, 08:41:08 pm
content: Hi,I'm embarking on my first electronics project in many years and I'm feeling extremely rusty, not that I ever was much of an expert...Thedatasheet, first page, for PCF8574 states the following:QuoteThis means that to use the input as a simple on/off switch, all I need is a switch and resistor in series to ground, right?Also, I want to use the PCF8574 as outputs to drive anULN2803ADW. I am however uncertain whether the PCF8574 can source enough current to drive the ULN2803ADW. Thedatasheet for PCF8574, page 16 states the following:QuoteAm I understanding it correctly that the IOLmay be maximum 25mA when the output is "activated", i.e. pulled to ground, since it is an open-drain output. If so, then 25mA should be plenty considering 5V and 2.7kresistance in series on the input to ground (ULN2803ADW page 9), right?As to the IOH, does that refer to the maximum current of the weak pull up?Thanks,edit: changed topic to better reflect what I'm asking.

author: Paul Price
author_rank: Super Contributor
timestamp: May 01, 2017, 01:08:11 am
content: The PCF8574 has open drain outputs so it does not source current but sinks currents when any output is active, so the output pin needs a pull up resistor to +5V to drive the input of the ULN2003 and this means a 2.7K pull up to +5 will work fine and this resistor is not connected to ground as you describe, which wouldn't work because a pull up is required not a pull down resistor.

author: permal
author_rank: Regular Contributor
timestamp: May 04, 2017, 06:51:47 pm
content: Thanks for your answer Paul, and sorry for this late reply.Your're right of course, PCF8574drains, it doesn'tsource.The 2.7k resistor to ground I was referring to is the one seen in the attached block diagram, taken from section 8.2 inthisdatasheet, which, unless I've got it all backwards, is tied to ground (ignoring the internal voltage drop) when the darlingtron transistor is open.
Meaning of GREEN PHY - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: August 23, 2024, 01:20:39 pm
content: What does GREEN PHY mean that's present in this module as opposed to normal PHY such as LAN8720A?https://www.codico.com/en/white-beet-ei-evse-embedded-iso15118-module

author: perieanuo
author_rank: Frequent Contributor
timestamp: August 23, 2024, 01:31:04 pm
content: you got ethernet, you have a phy. green means all the b..shit you can put it to various sleep power modes to cut consumption

author: radiolistener
author_rank: Super Contributor
timestamp: August 23, 2024, 01:47:00 pm
content: I see at least two possible versions:1) PHY controller has energy saving features For example it may tune signal power during link establishment or can enter into low power mode.2) The PCB is manufactured with "green technology", it means that it has shorten lifetime and turns into garbage and contaminate Earth environment with cheap and harmful materials used in production... Usually such short lifetime products with toxic/poison materials have green picture with green leaves and nature and hands and many words like "safety"... Such picture allows to distract attention from the harm that the product may cause for environment and user

author: Nominal Animal
author_rank: Super Contributor
timestamp: August 23, 2024, 02:38:12 pm
content: HomePlug Green PHYis just the name of the specification (released around 2011 or so) the module conforms to. It is a subset of the HomePlug AV specification, and named "Green" because it uses a quarter of the power to communicate compared to AV. As I understand it, the specifications are now in the Public Domain.HomePlug Green PHY is also the communication protocol used in theCombined Charging System(CCS) used for charging electric vehicles.
meaning of INPUT VOLTAGE RANGE, ALL INPUTS +- 10mA ? (oops, I read that wrong) - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: August 03, 2014, 02:48:38 pm
content: When the datasheet for an old 4000 series IC like the CD4040BE I was just looking at says "INPUT VOLTAGE RANGE, ALL INPUTS +- 10mA"Does this mean that you can safely supply or sink 10mA from each of the 12 inputs/outputs even if all of them areon at the same timeor does it mean 10mA in total?I know you can just connect counters, multiplexers etc. to a Darlington array or even individual transistors so you don't have to worry about excessive current but that's not the point.I've seen this in a few datasheets and was wondering what it meant.

author: bance
author_rank: Contributor
timestamp: August 03, 2014, 04:15:45 pm
content: Thishttp://www.ti.com/lit/ds/symlink/cd4040b.pdfdata-sheet says per input......

author: dentaku
author_rank: Frequent Contributor
timestamp: August 03, 2014, 05:49:52 pm
content: Quote from: bance on August 03, 2014, 04:15:45 pmOops, INPUT VOLTAGE RANGE, ALL INPUTS is obviously the values for Voltage and not currentI was mixing the two together.Yup, it says "DC Input Current, Any One Input" so you could have a bunch of inputs/ouputs working at the same time andeachhandling a maximum of 10mA?

author: bance
author_rank: Contributor
timestamp: August 03, 2014, 06:52:15 pm
content: Up to the total max for the chip, yes....

author: dentaku
author_rank: Frequent Contributor
timestamp: August 03, 2014, 07:29:40 pm
content: As you might suspect from a beginner messing with counter ICs the first thing I did with it was to connect a string of tiny green LEDs to the outputs and they each blink at half the frequency of the one to it's lefthttp://1drv.ms/1lqhQ7KI can also see this being useful for generating sub oscillators for little synth projects.