hybridfree/eevblog-posts huggingface dataset:
Need help understanding ADC datasheet - Page 1
Forum section: electronics / beginners

author: m12lrpv
author_rank: Regular Contributor
timestamp: May 29, 2012, 03:53:26 am
content: I've got a couple of 16bit ADC's ( A Burr Brown ADS1110 and a Microchip MCP3425 ) and while I think I have a handle on what they're capable of I need know if I've read the datasheets right.They are basically the same specs but the microchip datasheet is more verbose and says the following...QuoteI take this to read that the maximum absolute voltage difference between the inputs is 2.048V. Initially I thought that this restricted me to measuring from ground on one input to 2.048v on another.I became unsure of myself when I take into account that both devices allow the inputs to go (just above) the supply voltage. Now I'm assuming that the 2.048V absolute voltage difference can be between input voltages that are anywhere within the supply rails. So I can measure the difference between an input at 4.5v and one at 2.5v. It's a logical assumption that the inputs can float within the rails but assumptions are more likely to get me in trouble than not hence I'm asking.Is my current thinking correct?MCP3425 datasheetADS1110 datasheet

author: free_electron
author_rank: Super Contributor
timestamp: May 29, 2012, 04:06:03 am
content: The inputs can indeed float between the rails. you can't really go 'over' as the input stage will saturate and distort...so , if you power the device with 5 volts one input could be at 0.5 volt and the other at 4.596 volts and you would still fall in the 4096 range ..

author: ejeffrey
author_rank: Super Contributor
timestamp: May 29, 2012, 04:23:42 am
content: Quote from: free_electron on May 29, 2012, 04:06:03 amThe range is only +/-2.048.Other than that, yes: the inputs can go anywhere within the common-mode range as long as they are within 2.048 V of each other.

author: m12lrpv
author_rank: Regular Contributor
timestamp: May 29, 2012, 04:39:36 am
content: Thanks guys.
Need Help Understanding How HP E3610a Can Output Above +5 Volts - Page 1
Forum section: electronics / beginners

author: Efe_114
author_rank: Contributor
timestamp: March 25, 2022, 05:44:31 pm
content: I couldnt figure out how the output can go above +5V. Isnt the op-amp keeping the output and the voltage at the non-inverting input (which cant go above +5V) the same which means the output cant go above +5V? Please help me figure this out

author: pqass
author_rank: Super Contributor
timestamp: March 25, 2022, 08:03:36 pm
content: Quote from: Efe_114 on March 25, 2022, 05:44:31 pmI looked into this schematic to fix my E3611A. Yeah, this one hurt my brain too.The thing to understand first is that +S is attached to the +OUTPUT, positive binding post. The +S is the common for the bipolar op amp supply on the other transformer secondary (not shown in your screenshot; labeled "Reference and Bias Supply"). That means that the op amps can go above or below the +OUTPUT by 12V (there is also a +5V available too). It may be easier to imagine this PS is a negative supply where the +OUTPUT=0V, and -OUTPUT is a negative output.The series pass transistor (NPN darlington pair in your model) emitter pins are on the other side of the shunt from the +OUTPUT and their bases are held to +12V via R3; thus are defaulted to fully-on. The "Voltage Error" op amp's job via CR5 diode is introduce a lower voltage (than +12V) to Q2 which shuts off the darlingtons.The -ve pin on the op amp is tied to +OUTPUT, whereas the +ve pin is the center of a voltage divider between R15 and R37 (voltage set pot); between +5V (relative to +OUTPUT) and the -OUTPUT binding post (CR7 via J2 just clamps center point to +0.7V, J1 is open). So varying R37 allows the -OUTPUT to be lowered or raised such that the +ve op amp pin strives to be zero (with the -ve pin).On power up, the darlingtons are fully-on, the voltage difference between +OUTPUT and -OUTPUT is ramping up but lower than demanded by the voltage set pot, therefore, the center of the R15/R37 divider will be positive WRT -ve op amp pin, thus op amp is outputting +rail. As soon as the voltage difference between +OUTPUT and -OUTPUT overshoots what is demanded by the voltage set pot, then the center of the R15/R37 divider will be negative WRT -ve op amp pin, thus turning off the darlingtons.Clear as mud?

author: Efe_114
author_rank: Contributor
timestamp: March 26, 2022, 10:08:49 am
content: Quote from: pqass on March 25, 2022, 08:03:36 pmOH everything makes sense now. So the +5 is actually Vout+5 and the formula for the voltage divider ratio is Vout/(Vout + 5)? Did not check the resistor values but im assuming it goes down to 0 volts up to a point decided by the value of R15? and the diodes must be there to improve transient as the difference between S+ and the noninverting input will be close to 0 unless there is an overshoot or an undershoot going on. Thank you so much
Need help understanding thermistor data sheet - Page 1
Forum section: electronics / beginners

author: hamiltont
author_rank: Contributor
timestamp: January 21, 2019, 01:29:03 am
content: Hi,I've attached the datasheet for my MF52A-103F-3950. I've carefully read the datasheet and have a question about the page 3 "rated resistance R25" column, which lists 5 ~ 100.However, that same page says the part number (specifically, the "103") identifies the resistance at 25C, e.g. 10*1000 = 10k. That aligns with what I am measuring empirically (about 10.5k at 26C), so what the heck is that column "Rated Resistance" talking about? Is "Rated Resistance R25" somehow different than the "Resistance value at 25C" mentioned directly above the table?I've readthis linkin depth and it didn't help to clarify what the datasheet means by "5~100"

author: hamiltont
author_rank: Contributor
timestamp: January 21, 2019, 02:23:59 am
content: QuoteSorry, maybe I'm being dense, but....The R25 value was already specified as 10k\$\Omega\$ by the 103, right? And 103 isn't in the 5 to 100 range?

author: wraper
author_rank: Unknown
timestamp: January 21, 2019, 02:33:37 am
content: Quote from: hamiltont on January 21, 2019, 02:23:59 amRated resistance means in what range resistance values exist for particular type of termistor. 10k is one of them. It seems they forgot to explicitly write kohm. At least it's obvious that it's impossible for that range to be in ohms.

author: hamiltont
author_rank: Contributor
timestamp: January 21, 2019, 03:06:00 am
content: Ahhh, OK! Thanks folks, it makes much more sense now...
Need help understanding this hybrid ultrahigh performance JFET amplifier - Page 1
Forum section: electronics / beginners

author: DanInvents
author_rank: Contributor
timestamp: March 31, 2025, 08:38:06 am
content: Hi! I'm currently studying Application Note 45 written by Jim Williams and there is a design of a low noise and Drift-Chopped FET amplifier (pages 2 and 3, figure 4) that caught my eye. He claims that this hybrid amplifier features 0.05 microvolt per ºC drift, 5 microvolt offset and 50pA bias current.The idea is to have a precision low-noise amplifier differentially feeding from a matched JFET pair. At the same time a chopped amplifier measures the differences between the amplifier inputs and adjusts the current of one of the JFETs to minimize the difference between the two transistors. There are a few points that I don't understand about this design.* I understand that A1 works as a differential amplifier. In that case, why the resistor at the non-inverting input and the feedback resistor have been replaced with 20nF capacitors?* I understand that the matched JFETs act as a current mirror. Why those particular resistor values. What is ther purpose, I suppose that the 51k ohm at the drain of Q1B creates a DC bias, yet I don't understand the function of the 47k, 10k, and 24.9k.* What is the bandwidth of the system? I suppose that it is limited by the bandwidth of the chopping amplifier A1, right?Thanks!

author: Kleinstein
author_rank: Super Contributor
timestamp: March 31, 2025, 09:01:36 am
content: With the capacitors at A1 this makes it a differential input integrator. The purpose is to have very high DC gain and less and less the higher the frequency. The divider part with the 47 K , 10 K is to reduce the gain from the integrator and reduce noise spikes from the AZ amplifier. The divider effectively also slows down the integrator.The divider is still relatively moderate, one could well have more than 47 K there. The 24.9 K are a bit odd choice - I would have expected a little more like 40 K, but it would not make it more symmetric and this way less sensitive to supply voltage changes.The bandwidth is not set by A1, but more from A2 in combination with the JFET stage gain (should be around 20) and overall gain from the FB. So I would expect roughtly 1/50 the GBW of A2.The integrator part sets the cross over between the AZ OP-amp and the JFETs. Here is a time constant of 20 nF*100K * 5.7.
Need help using ENC28J60 and PIC16F1939 SPI - Page 1
Forum section: electronics / beginners

author: Moondeck
author_rank: Regular Contributor
timestamp: November 22, 2015, 02:14:32 pm
content: Hi everyone,so, i have this board with a PIC16F1939 and an ENC28J60 chip on it, and i have tried to write some code for it, but it does not seem to work. Its supposed to make the 2 ethernet LEDs blink slowly. Here is the code:spicom.cCode:#include <xc.h>#define _XTAL_FREQ 32000000void SPI_init(void){LATA = 0x00; //Used Microchip Code Configurator to figure out the pins (for now)TRISA = 0xFF;ANSELA = 0x3F;LATB = 0x00;TRISB = 0xFF;ANSELB = 0x3F;WPUB = 0x00;LATC = 0x00;TRISC = 0xD7;LATD = 0x00;TRISD = 0xFF;ANSELD = 0xFF;LATE = 0x00;TRISE = 0x0F;ANSELE = 0x07;WPUE = 0x00;OPTION_REGbits.nWPUEN = 0x01;APFCON = 0x00;SSPSTAT = 0x00;SSPCON1 = 0x20;SSPADD = 0x00;}void SPI_writechar(char writechar){SSPBUF = writechar;}void ENC_WCR(char adr,char value){SSPBUF = (adr + 0b01000000);__delay_ms(1);SSPBUF = value;}main.cCode:#include <xc.h>#include "spicom.h"// CONFIG1#pragma config FOSC = INTOSC // Oscillator Selection (INTOSC oscillator: I/O function on CLKIN pin)#pragma config WDTE = OFF // Watchdog Timer Enable (WDT disabled)#pragma config PWRTE = OFF // Power-up Timer Enable (PWRT disabled)#pragma config MCLRE = OFF // MCLR Pin Function Select (MCLR/VPP pin function is digital input)#pragma config CP = OFF // Flash Program Memory Code Protection (Program memory code protection is disabled)#pragma config CPD = OFF // Data Memory Code Protection (Data memory code protection is disabled)#pragma config BOREN = ON // Brown-out Reset Enable (Brown-out Reset enabled)#pragma config CLKOUTEN = OFF // Clock Out Enable (CLKOUT function is disabled. I/O or oscillator function on the CLKOUT pin)#pragma config IESO = OFF // Internal/External Switchover (Internal/External Switchover mode is disabled)#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable (Fail-Safe Clock Monitor is enabled)// CONFIG2#pragma config WRT = OFF // Flash Memory Self-Write Protection (Write protection off)#pragma config VCAPEN = OFF // Voltage Regulator Capacitor Enable (All VCAP pin functionality is disabled)#pragma config PLLEN = ON // PLL Enable (4x PLL enabled)#pragma config STVREN = ON // Stack Overflow/Underflow Reset Enable (Stack Overflow or Underflow will cause a Reset)#pragma config BORV = LO // Brown-out Reset Voltage Selection (Brown-out Reset Voltage (Vbor), low trip point selected.)#pragma config LVP = OFF // Low-Voltage Programming Enable (High-voltage on MCLR/VPP must be used for programming)b#define _XTAL_FREQ 32000000void main(void){OSCCONbits.IRCF = 0b1110; //8 MHz, 32MHz with x4 PLLTRISA = 0;TRISB = 0;TRISC = 0;SPI_init();ENC_WCR(0x1F,0b11010010); //set Bank 3 in the ENC28J60ENC_WCR(0x14,0x14); //set MIREGADR to PHLCON addressENC_WCR(0x16,0b10111000);ENC_WCR(0x17,0b00001011);while(1);}spicom.hCode:#include <xc.h>void SPI_init(void);void SPI_writechar(char writechar);void ENC_WCR(char adr,char value);I have moved the topic from the Microcontroller & FPGA section to here
Need help wiring up a Microphone to my pc GSCH-A-18 - Page 1
Forum section: electronics / beginners

author: Skate96
author_rank: Newbie
timestamp: July 20, 2018, 10:59:02 am
content: I have this headset GSCH-A-18 it's a Helicopter headset,got the Audio working but i sure don't know how to wire up the microphone since it's all in russian, i'm gonna attach a pdf with the wire diagram.https://www.dropbox.com/s/lm9p7j9w1fevwfe/GSCH-A-18_RTYE.pdf?dl=0
Need help with a custom USBC circuit design - Page 1
Forum section: electronics / beginners

author: subhadeepbiswas!
author_rank: Newbie
timestamp: January 30, 2025, 04:46:47 am
content: Hi all,I'm trying to develop a USBC-based sensor accessory device that will be connected to a tablet via a USBC male plug.At first, the device will take power from the tablet and send some sensor data via the USBC male plug.Also need a USBC receptacle for a charger (PD with BC1.2 fallback) in the same accessory board. If the charger is connected the tablet needs to be charged through the accessory device and able to receive the sensor data as well.Recently I came across MCP22301(https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/DataSheets/MCP22301-Stand-Alone-USB-Type-C-Power-Delivery-3-dot-1-Controller-DS20006887.pdf.On page no.9 for the datasheet "2-PORT DUAL ROLE POWER/DATA APPLICATION ‘CHARGE-THROUGH ADAPTER" the block diagram looks promising.I couldn't find enough resources on the internet for this. I've also written to microchip for the concept check, but didn't get any reply from them. I also looks like I need to implement some firmware to get this chip working.Only this resource I found online :https://ww1.microchip.com/downloads/aemDocuments/documents/APID/ProductDocuments/UserGuides/MCP19061-Dual-Charge-Port-Board-User-Guide-DS50003562.pdfIs there any other standalone alternative IC/ICs available to do the same thing that I want?Block diagram of the concept attached.One confusion regarding USBC male plug :- The CC1 and CC2 pins on the male plug is CC and VCON, can I connect CC and VCON pins to CC1 and CC2 pins of the MCP22301?ThanksSubhadeep

author: xvr
author_rank: Frequent Contributor
timestamp: January 30, 2025, 11:33:41 am
content: If I understand right you have 2 USB-C ports with PD on both of them? (Charger input and Device with charging capability). But MCP22301 can control only one port. So in your configuration you need both chips - MCP22301 and MCP22350BTW, do you have programmer for MCP22301 ?DS:QuoteQuoteYou should.

author: subhadeepbiswas!
author_rank: Newbie
timestamp: January 31, 2025, 07:35:58 am
content: Yes, I have 2 USB-C ports, one is a receptacle and one is a male plug.Yes, I need both the chips.Is their any alternative standalone IC that can solve this problem?
Need help with a project involving small LCD screens - Page 1
Forum section: electronics / beginners

author: Marvio
author_rank: Newbie
timestamp: July 17, 2018, 05:35:25 pm
content: Hello everybody! Super newbie here!Let me put this up front, I'm not an electronics guy, I've always been interested in it but life took me down a different path, nevertheless I've watched pretty much every video Dave has ever produced, I find your filed fascinating, and you know what? I even managed to learn a little bit about it!At any rate, I'm trying to put together a proof of concept project for a client of mine, this is absolutely just to see if it will work at all, so as Dave puts it it can be "A dog's breakfast!"Basically what I'm looking for is:I need four small displays, no bigger than 8" with at least 1024X768 resolution, they will all display the exact same image, because of that they can all be driven from the same board (and ideally they would), this driver board should have HDMI input.Reason I came to you guys is the sourcing of this, one would think that in this day in age it would be simple enough, but Oh man was I wrong! trying to search for this simple set up returns a tsunami of results with some dubious specs. The closest I got was an offering at alibaba of a 7" 1280X800 LCD display with the driver board:https://www.alibaba.com/product-detail/7-inch-IPS-800-1280-mipi_60055176434.htmlThat would work, but I would end up with 4 driver boards and an HDMI splitter to feed the signal to each one.Again, just to see if the concept would work I guess is doable, but placement of the screens is also a consideration here, and with this much stuff to contend with I'm not sure I could place them correctly. So you know the screens will be flat facing up, each at a 90 degree angle from each other, so it will form a "flower" with a "hole" in the middle.So, what would you guys suggest, is there a driver board out there which could feed 4 of these small screen in one unit? am I screwed?Thanks in advance everybody

author: sokoloff
author_rank: Super Contributor
timestamp: July 17, 2018, 05:54:12 pm
content: For a proof of concept, what's the problem with COTS HDMI 1x4 repeater/splitter and 4 COTS HDMI displays?What's the constraint that prevents you just going to Ebay and buying 4 8" displays?Another possibility is using COTS tablets and building/using an app to display whatever you want if "thin and elegant looking" is critical to the PoC.
Need help with a Wireless Constant Current 4 channel LED driver - Page 1
Forum section: electronics / beginners

author: jgvicke
author_rank: Newbie
timestamp: July 12, 2017, 07:56:01 pm
content: Hey guys, new to the forum, but have been reading it for a while. I am not really a beginner at electronics, but I am mostly a digital guy so this is not my strong suit. Here is the situation I have. I need to set up a demo kit to drive a high current RGBW led (2.5A per channel), and to make the demo kit nice I want to be able to control with a remote or phone to make it easy on the sales guys.I have found lots of Constant Voltage drivers that can do this, I have this one to play around with (http://www.ecolocityled.com/product/bluetooth-rgbw-led-controller/4ch-led-controls).This one can be powered from 6-24V DC, has a common +V rail on the output, then 4 sinks for the low side of the LEDs. Because it is a very small package to handle lots of current, I assume it is using N Channel Low Rds FETs in there. To dim the LEDs, it just runs the current sinks at a 500Hz PWM signal.I was thinking about the following scheme to turn this into a current control version:1) using a cheap current control supply from Ebay to drive all 4 channels in series2) put a FET accross each channel to short it out when activated, gate tied to source with a pull up resistor so it is normally open3) control the gates with the bluetooth driver to pull them to ground to close the FET and short out the channel.I tried setting this up on the bench with just a single channel, and instead of using the bluetooth device just shorting the gate to ground, and while it turns the LED off, it appears to be shunting current through the gate to ground.I am probably making this way harder than it needs to be. Does anyone have any ideas I can try to accomplish my goal?Thanks,John Vickers
Need help with an external camera - Page 1
Forum section: electronics / beginners

author: Maccai3
author_rank: Newbie
timestamp: August 31, 2016, 09:29:14 pm
content: So i'm trying to connect a Git1 camera:http://www.gitup.com/home/8-gitup-git1-action-camera-pro-packing.htmlto a Rode VideoMicro:http://www.rode.com/microphones/videomicroUsing a GoPro Hero 3 adapter:https://www.amazon.co.uk/gp/product/B00A3MY7L8/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1but it's not working, the microphone works as i've used it with a trs > trrs adapter in my phone.I saw this video:and at 12:50 he has the same issue. I've been told at a forum that maybe it has the wrong resistor in the cable. Any ideas?

author: Maccai3
author_rank: Newbie
timestamp: September 01, 2016, 02:07:51 am
content: anyone?

author: Brumby
author_rank: Unknown
timestamp: September 01, 2016, 02:53:35 am
content: You might have to wait until someone who knows something shows up. It could be a few days.Be patient.
Need Help with Buck Boost DC-DC power supply - Page 1
Forum section: electronics / beginners

author: Cyanogen
author_rank: Newbie
timestamp: May 05, 2014, 05:37:38 am
content: Hi all,I have tried to build the boost converter from #110 using the MC34063 and am really having some trouble getting it to work. I am not sure what I am doing wrong. I troubleshot the circuit on my breadboard to makes sure there were no missing link but for some reason the voltage comes back too low and the current too high.I am trying to make a 12V source that supports 100mA from a 1.5V source (two AA batteries) The batteries provide more power than required but average at just under 2V, they still provide plenty of current. When I make the circuit it does boost the voltage to about 6 volts and a test LED is able to barely light up. The current is about 650mA. I have attached some pics of the circuit at different angles, maybe there is something I am just not seeing or the components have some incorrect spec I am not aware to look out for. I also attached pics of the list of components I used in the circuit. I tried two versions of the circuit, one with the 3uH inductor and .12 resistor and the other with the 1.5uH inductor and .6 resistor. The 3uH inductor is a choke so maybe that is a problem? Both versions of the circuit didnt work though so I am really not sure.I also put pics of my calculations, maybe I made a mistake there. Its so frustrating to make these circuits and then not have them work. Especially when anxiously awaiting the parts to come in the mail. I am so sad

author: sleemanj
author_rank: Super Contributor
timestamp: May 05, 2014, 08:17:04 am
content: I assume the 650mA is current on the source side, at 1.5v?Your diagram does not appear to show the load LED and it's current limit resistor (or other current limiter), you should show it.

author: mariush
author_rank: Super Contributor
timestamp: May 05, 2014, 08:46:48 am
content: If you actually check the datasheets (on semi,fairchild,st micro), all these 44063 switchers are designed to work with aminimum of 3vinput voltage. Even then, the efficiency will be very poor, when you try to output 12v.

author: Cyanogen
author_rank: Newbie
timestamp: May 05, 2014, 07:33:54 pm
content: Quote from: sleemanj on May 05, 2014, 08:17:04 amIts at the source side of the circuit output. The Voc is about 6V but I assume the power output is very low since a 20mA LED is hardly lighting up. I am just trying to power a 12V 90mA CPU fan off of two AA batteries. Maybe their is a better way? I already made a buck boost converter using a PNP NPN LRC combo but its very inefficient and only works with a very specific voltage input.

author: Cyanogen
author_rank: Newbie
timestamp: May 05, 2014, 07:35:20 pm
content: Quote from: mariush on May 05, 2014, 08:46:48 amThanks for the info, I will look into a better component.
Need help with Buck+boost or SEPIC circuit - Page 1
Forum section: electronics / beginners

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: February 07, 2016, 06:25:34 pm
content: Hello again.I am trying to build a small power supply that will output 12V and 1A, with the input from a suitable wall wart. I already have that working with a LM7812, but that limits me to wallwarts that output at least 15V.The I thought: why not have a circuit that will accept any wall wart from 6V to 20V (not precisely), and will output 12V/1A, as long as the wall wart has the proper current rating?Then I though of 2 alternatives:1) I have some MC34063 (and MC33063) ICs on my bin, but its datasheet only has circuits either for a buck or boost regulation, not for both. Is there any known schematic for this IC that will have a variable input and a fixed output? It will have to work as both buck and boost configuration.2) Use a MAX668 in SEPIC configuration. Using Maxim's EE-Sim online tool, it proposed the circuit in the image below. Do you guys think this circuit will do what I want? Another thing: how the hell do I get a suitable resistor for R4 = 45.3mR ?Thanks in advance.

author: chris_leyson
author_rank: Super Contributor
timestamp: February 07, 2016, 06:54:45 pm
content: You have got several choices, buck boost (flyback), boost buck (Cuk) or Sepic which is variation of the Cuk converter, they will step up or down. The Cuk converter option would have to be transformer isolated as it is an inverting topology so not much good Sepic is non inverting. Another option might be a transformer isolated buck or forward converter, you could 1:2 step up in the transformer which would help at low voltages but at higher input voltages the duty cycle is quite low. Wurths' WEFLEX six winding transformers are useful for step up or down and also flyback. An EFD15 OR ER14 core will handle 12W easy.

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: February 17, 2016, 05:37:06 pm
content: Thank you, Chris, and sorry for being so late for a feedback.In the last few days I did some search on the options you mentioned, and all of them are a lot more complex than my limited knowledge allows me do to design on my own.
Need help with DC -DC converter  - Page 1
Forum section: electronics / beginners

author: Migsmags
author_rank: Newbie
timestamp: June 25, 2023, 01:04:34 pm
content: Hello,Need some basic help - sorry if this is super noob, but electronics isn't in my wheelhouse..I have a water diffuser that's unfortunately corded and makes it difficult to move around, i was hoping i could somehow get a DC-DC converter to output from a power bank to the diffuser, making it more portable.The unit is rated at:12W, 24V, 500mAThe adaptor is 24v 500mAThe power bank is:Max Input5V=4A（5V=2A Max Per Port）Output5V=6A (5V=3A Max Per Port)I have no idea what i need or how to achieve portability this way. Any help will be greatly appreciated. Sorry its so basic!

author: mariush
author_rank: Super Contributor
timestamp: June 25, 2023, 01:09:05 pm
content: You need a different power bank or you need to open that water diffuser to figure out what voltages it actually needs.Maybe the unit converts that 24v into lower voltages, in which case you may be able to go around that conversion process.

author: jmelson
author_rank: Super Contributor
timestamp: June 25, 2023, 03:55:28 pm
content: Quote from: Migsmags on June 25, 2023, 01:04:34 pmThis is the rating, not the actual power draw. So, I have to make worse-case assumptions. But, that gives 12 Watts of power draw at the worst. That is a fair bit to run off batteries. At 5 V, you would need to supply 2.4 A assuming perfect efficiency. That will likely drain your power bank pretty quickly. If you can come up with a 24 V battery bank, then the draw would only be 1/2 Amp, and that would last a lot longer. Of course, the 24V battery bank would be larger and heavier.Jon
Need help with DC to DC converter to produce -70V - Page 1
Forum section: electronics / beginners

author: nitish111
author_rank: Contributor
timestamp: May 16, 2017, 03:44:05 pm
content: Hi there,I am working on bipolar current source using improved Howland Current source which can sink up to 15 mA with supply voltage of +70 V to -70 V or more. I was able to generate +70 V with required current parameter. I need help with -70 V. I am looking for a off the shelf components with required specs for negative rail. I found LT3462 which could generate up to -40 V. I am a beginner so any intuitions and suggestions are highly appreciated.

author: Zero999
author_rank: Super Contributor
timestamp: May 16, 2017, 04:52:44 pm
content: What's the input voltage to the whole circuit?

author: nitish111
author_rank: Contributor
timestamp: May 16, 2017, 05:50:13 pm
content: Input voltage is 5 V DC
Need help with faulty power supply - Page 1
Forum section: electronics / beginners

author: Jonathan
author_rank: Newbie
timestamp: July 07, 2013, 05:43:34 am
content: Hi guys,Need your help here:My friend's wife got a new sewing machine from the states (we live in the EU), and pluged it directly to the wall...I opened it up and replaced the blown fuse, but while plugging it back to the socket (via ac-ac adapter this time), the magic smoke appeared.I opened it up once again, and fond out that the MOV blew up...the voltage in the adapter was 120VAC.my questions:1. Is it possible that the MOV was damaged during the first operation?2. As the MOV is unidentifiable, and no schematics are available, what MOV should i pick for replacement?Thanks in advance,Jonathan

author: SeanB
author_rank: Super Contributor
timestamp: July 07, 2013, 05:56:01 am
content: If the AC-Ac adaptor is light enough to lift with one hand, or fits in it, it is the wrong type. That is a light dimmer in a glorified box that is meant to run US heaters like clothes irons and coffee cup warmers in the 230V world, not to run motors or electronics.You need a transformer that has the right current rating to run your sewing machine, probably around 300VA will do for most sewing machines. The MOV is a 130V unit that you will find at RS.
Need help with FTDI VNC2 - Page 1
Forum section: electronics / beginners

author: pwb
author_rank: Newbie
timestamp: November 24, 2014, 07:20:33 pm
content: Hello everyone.The company I work for has old control units that have a 25-pin parallel centronics printer output. We use this to print system reports. I want to be able to "print" a .txt file to a USB flash drive (not a computer) instead of using an old printer.In the past we have used this unit to do the job:http://www.ipcas.com/products/centronics-parallel-to-usb-printer.htmlIt works great, but we need more, and each unit costs $600There are many converters on the market that go from USB to parallel, but very few that go from parallel to USB.Somebody at FTDI recommend that I use their VNC2 module.http://www.mouser.com/ProductDetail/FTDI/V2DIP1-32/?qs=sGAEpiMZZMv6j61pBJaFjCwiX6tRhx1FNJUwUNUr0HU%3dDoes anybody have experience programming these units to do what I am trying to do? I am an electrical engineer, but I don't have much programming experience.Any help would be greatly appreciated.

author: edavid
author_rank: Super Contributor
timestamp: November 24, 2014, 08:27:41 pm
content: That would be a difficult programming project.I think it would make more sense to use a Raspberry Pi A+ ($20)... you would still have to write some software to read the printer port (or maybe you could find a driver for that), but the USB drive part would be much easier.

author: pwb
author_rank: Newbie
timestamp: November 25, 2014, 01:04:46 pm
content: I'll check it out. Thank you!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: November 25, 2014, 02:21:04 pm
content: Last time I looked, the VNC2 had pretty poor documentation.You could do it fairly easily using Microchip's PIC24 USB devices, e.g. PIC24FJ64GB002 (even comes in DIP!) - they provide a USB filesystem library, so all you'd need to do is read the data in & do simple handshaking while busy writing. I don't recall offhand if that device has enough 5V tolerant pins - if not the GB004 may do, otherwise just use some resistors.

author: marshallh
author_rank: Unknown
timestamp: November 25, 2014, 06:27:56 pm
content: The VNC2 is a black box. If it does what you need with no modification, it's perfect, if not, you're hosed. They don't provide any documentation on the hardware, it runs a proprietary RTOS which in itself isn't bad, except there is no information on it.
Need help with H-bridge motor driver board - Page 1
Forum section: electronics / beginners

author: Nitrus
author_rank: Contributor
timestamp: April 04, 2017, 07:25:12 pm
content: Hi guys,I've bought a board like this one:http://www.ebay.com/itm/Dual-Motor-Driver-Module-Board-H-bridge-DC-MOSFET-IRF3205-3-36V-15A-Peak-30A-New/401236483976However, I can't get it to work.For the PWM, I have anOmega 2with the dock and the PWM extension.I have verified Duty/Frequency with multimeter and a cheap DIY oscilloscope.So, if I hook up my motor to the Omega, I can control the Duty Cycle via WiFi, and I've tested this with a small motor, works fine (hooked up only through the Omega, without the driver board)But when I hook it all up to this board, with a 12V supply on the power pins for the motors, I can't get it to work. I mean, I can't get it to work with this board either with external +12v, or with +5v from the Omega.The instructions are vague and in Chinglish, so I'm not sure if everything is proper.I have it set-up like in the attached image.Can anyone be of assistance? I can't get the motor to spin at all.Thanks in advance guys

author: danadak
author_rank: Super Contributor
timestamp: April 05, 2017, 12:33:13 pm
content: If its an isolated design, eg. photo couplers in the data path, thengrounds do not have to be common, otherwise they do.See if you can get a schematic from seller. Or worst case, do yourown, so you can troubleshoot. Also try to locate a Chinese forumto see if you can get any info on controller chip.Regards, Dana.

author: mtdoc
author_rank: Super Contributor
timestamp: April 05, 2017, 04:36:38 pm
content: The eBay description of that board is useless. Do you need an input signal to Dir1 or Dir2 to specify direction?

author: Nitrus
author_rank: Contributor
timestamp: April 05, 2017, 09:36:48 pm
content: Quote from: mtdoc on April 05, 2017, 04:36:38 pmFrom what I understand, the DIR pins are just for direction, high or low. That being said, I tried running 5V across it, and also tried putting the PWM signal from the Omega on it, no dice.I've added some images in the attachments.The PWM signal seems to go to pins 8 and 9 of the NAND gate.No-go on the schematics, so I don't know if there's any routing underneath the chip.From thedatasheetI can see that pin 8 is 'data output' and pin 9 is 'data input'. Seems a bit odd to me to have those coupled, but that's how it is.EDIT: I've misread the Gate chip, it's actually74HC02D, which is a Quad 2-input NOR gate. The text I've written in the image would be wrong, that last 'D' looked like a '0' to me...Pins 8(3A) and 9(3B) are both 'data input' .What does the term 'data' suggest to you?EDIT2: I added another image, where I've combined the two sides. The top (red) side routes that go under chips I tested with a multimeter...All the MOSFETs are ST P75NF75, however some have a '&', some have a '@' at the end of the string (P75NF75& or P75NF75@)
Need help with ID-ing two 8 pin IC's  - Page 1
Forum section: electronics / beginners

author: onesixright
author_rank: Frequent Contributor
timestamp: June 05, 2017, 03:37:52 pm
content: I would like some help with ID-ing these two components (inside red square).On the left the "103" and on the right the "E01" (both ~ 1.5mm long). There both 8 pin. I tried (ofc) Google, but I'm not sure what it could be. Maybe a op-amp/comparator of some sort?The103is connected via a flat cable to 2 momentary push switches (G, C an D). The Pins A, B, C and D are all getting 3.2V and G=Ground (0V). C and D are connected via the push switch to G (ground). The pinsbelowI couldn't probe.The E01, I have no further info on. Does'n seem to be connected to the flat cable at all (nevertheless, would like to know the chip).Thanks!

author: Benta
author_rank: Super Contributor
timestamp: June 05, 2017, 03:48:21 pm
content: Resistor networks. They are both marked 103, but one is upside down. 1 or 10 kohm, depending on manufacturer numbering system. Probably just 4 resistors per pack for pullup/pulldown.

author: onesixright
author_rank: Frequent Contributor
timestamp: June 05, 2017, 04:25:20 pm
content: LOL! Didn't notice they where upside down. Well that explains it!Thanks!

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 05, 2017, 04:53:39 pm
content: I would say they are 10k, E24 series (5% tolerance)On the bottom left corner of your red rectangle, there is another10k0, but E96 series (1%).
need help with identifying fried resistor - Page 1
Forum section: electronics / beginners

author: torxt
author_rank: Newbie
timestamp: February 14, 2015, 10:28:17 am
content: Hi!I tried to replace the batteries in my Remington shaver mb42c, but I switched the power connectors resulting in a fried resistor.do you have any idea what the resistor could be?pics:https://www.dropbox.com/sh/o70sw0ydmkqmhr4/AADtC-2RkQ7pet7c8U4CMPXza?dl=0

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 14, 2015, 10:32:27 am
content: Not sure what the first photo is supposed to show?The photo of the resistor shows that it is too "fried" to be able to reliably read the color bands.Have you tried actually measuring it?

author: torxt
author_rank: Newbie
timestamp: February 14, 2015, 12:02:22 pm
content: Hello Richard,thank you for your reply.I'm not having messured it yet, because i dont own a multimeter. I'm going to order an UT61C (http://uni-trend.com/UT61C.html).Is there anything I can do now, without measuring? I could try drawing the circuit board.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 14, 2015, 04:51:00 pm
content: It would be instructive if you could trace out the circuit. If the resistor is shorted or open, and the colors are toasted, it would help to see the actual circuit to derive what the resistor value might have been.

author: 4cx10000
author_rank: Regular Contributor
timestamp: February 14, 2015, 05:32:38 pm
content: The only way, unless you haver another equal shaver to see what value the resistor got, is to draw your schematic. Resistors go open or get higher resistance, never shorted.

author: retrolefty
author_rank: Super Contributor
timestamp: February 14, 2015, 07:30:06 pm
content: Quote from: torxt on February 14, 2015, 10:28:17 amToo soon to worry about the size of the resistors. Resistors don't fail by themselves, rather they fail because of some other failure that allowed too much current to flow through it. So more troubleshooting is needed to determine how many parts you might require including the poor resistor that gave it's life. Change the resistor first and it will just burn up that one.

author: sunnyhighway
author_rank: Frequent Contributor
timestamp: February 14, 2015, 08:38:15 pm
content: Quote from: torxt on February 14, 2015, 12:02:22 pmSure, you could grow a beard.

author: xrunner
author_rank: Super Contributor
timestamp: February 14, 2015, 08:48:00 pm
content: Quote from: torxt on February 14, 2015, 10:28:17 amThere's some videos of people trying to fix Remingtons - some are different models than yours but if you look long enough you might be able to see a closeup of your model in one of the videos and see what the resistor value is supposed to be -

author: wraper
author_rank: Unknown
timestamp: February 14, 2015, 08:53:09 pm
content: Seem to be 10 ohms. What First band looks like is tarnished brown, second and third bands look to be black and 4th band is gold.
Need help with Light Sensor Design - Page 1
Forum section: electronics / beginners

author: Photocell213
author_rank: Newbie
timestamp: July 30, 2021, 01:47:57 pm
content: I am trying to create a small (easy to hide) unit which will sense a flash of LED light in any outdoor setting. The goal is to send or remove a 12 volt signal to a timer whenever it detects a Flash of light.The product will need to be able to detect the flash in all outdoor settings (Sunny clear sky, Dusk, and Dark Night). Is it possible to do this using a photocell? Won't the photocell be held open during changing sky conditions?I know light will be competing with light, so I do not know that this is achievable. Any suggestions of other ways are appreciated.

author: StillTrying
author_rank: Super Contributor
timestamp: July 30, 2021, 03:06:33 pm
content: "I am trying to create a small (easy to hide) unit which will sense a flash of LED light in any outdoor setting."It sounds impossible to me. Even if the flash of light was the quite bright LED light on a digital phone the phone and sensor would have to always be facing each other and quite close. LED light is not very bright compared with sunlight reflecting off shiny objects.

author: gcewing
author_rank: Regular Contributor
timestamp: July 31, 2021, 08:26:05 am
content: In principle, background light could be dealt with by using a receiver that only responds to a modulated signal, e.g. something likehttps://www.jaycar.co.nz/ir-led-receiver/p/ZD1953.But as mentioned in the previous reply, how feasible it is will depend on a lot of details such as the required distance and range of reception angles, brightness available from the transmitter, etc.Can you tell us more about the problem you're trying to solve? There may be other ways of approaching it.

author: Terry Bites
author_rank: Super Contributor
timestamp: July 31, 2021, 01:57:56 pm
content: In this circuit (TI) the integral of the ambient light is subtracted from the diode current seen by U1. Becasue the integration time is long compared with your flash, it will be amplified.Its a starting point. Clearly, if your flash occurs in a small volume compared to the total volume seen by the sensor, it isn't going to work so well. Use a photodiode or phototransistor as the detector.
Need help with LiIon charging Idea - Page 1
Forum section: electronics / beginners

author: MarkoTox
author_rank: Newbie
timestamp: December 17, 2014, 04:19:39 pm
content: Hello, im new here so i will introduce myself in my first post.My name is Marko and i live in Croatia, i am a big fan of EEVblog so i came here looking for help, english is my second language so sometimes i may struggle to write so bare with me pleaseI didnt know how to explain this so i drew a simple picture/circuit to show you my problem/ideaI want to charge multiple (3) LiIon batteries in series and i dont want to use big charger every time becase i want to inscorporate it in a simple project im doingI was gonna use 3 single LiIon charger module but im not shure if it would work and i dont wanna damage batteries or chargersI had an idea that i could use one charger for each battery connected in series but the problem is that chargers have common/shared groud, so input and output of the chargers have same output witch means i would short everything and probaby fry them, but if i put diodes on the input grounds of the chargers like in the image maybe i could prevent that from happeningCant wait for your responses, suggestions or solutions to my problems, thanxHere are the pictres:

author: mikerj
author_rank: Super Contributor
timestamp: December 17, 2014, 04:47:03 pm
content: You can't use diodes to isolate cells in series for charging, it just won't work.You have three choices:1) Charge the series connected cells from a single, higher voltage charger and implement cell balancing/monitoring on individual cells. This is how most commercial products with lithium ion batteries work (e.g. laptops), though most often the only implement over/undervoltage protection rather than full cell balancing. This means the cells can become unbalanced after a number of charge/discharge cycles.2) Use fully isolated chargers to charge the individual cells. Advantages are that cells are automatically balanced. Disadvantage is cost and complexity.3) Implement some kind of switching scheme to either connect cells in series or in parallel (not very practical in most cases).

author: MarkoTox
author_rank: Newbie
timestamp: December 17, 2014, 04:52:58 pm
content: Thanx for reply, i will read more about balancing, a have saw some modules available for couple of cells, so to use my method i would neet to have 3 power sorces that are issolated from eachother and dont have common ground? is there any circuit that would make 3 isolated outputs from one power source like fast switching between them so the chargers dont work at the same time?

author: mikerj
author_rank: Super Contributor
timestamp: December 18, 2014, 05:51:32 pm
content: Quote from: MarkoTox on December 17, 2014, 04:52:58 pmA transformer. Either a single transformer with three isolated secondary windings (current/voltage regulation would have to be performed separately), or three separate transformers. Driven by a high frequency switch mode regulator, the transformers could be pretty small.
Need help with MASCOT 2116 NiCd battery charger - Page 1
Forum section: electronics / beginners

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: February 09, 2024, 07:24:19 pm
content: Hi Guys/gals!Hoping someone might be able to help me here, I've got a Mascot 2116 NiCd battery charger for a specific battery pack, I've attached pictures of it and the connector on the end. It would seem to be some kind of constant current thingy as it says it can charge 5-10 cells and gives a current rating of 0.8A with no output voltage range. Long story short the power supply itself is dead, and I can only find units with a barrel connector on the end online, does anyone have any idea of what this connector type is called, what the pinout might be or if there are any alternatives to this specific model of supply??Thanks in advance!

author: SuzyC
author_rank: Frequent Contributor
timestamp: February 10, 2024, 09:56:36 pm
content: Since you have the old power supply, simply cut off the power cord and use it to replace the barrel connector on the new P/S.BTW: "no output voltage range"The picture shows the P/S open-circuit voltage 41V.
Need help with NC Drill files generated by Circuit Maker to Upload to OSH Park - Page 1
Forum section: electronics / beginners

author: Gurpreet
author_rank: Contributor
timestamp: May 04, 2016, 02:22:30 am
content: Hello Guys,I have completed routing a PCB in "Circuit Maker"and I have been trying to generate gerber files and NC drill files in it.I have chosen OSH Park for manufacturing. OSH park requires ".XLN" file format for NC Drill files but circuit maker doesn't seem to support that file format.I have read many people talking about using circuit maker to generate file s for OSH Park but I cant seem to figure out how do they do it.When I upload the files I get the message shown in the picture I have attached with this post.I have followed all the Guides that OSH has posted on their website for Circuit Maker andAltium but I got no success.I have also attached the picture of files that the software generates for NC Drill.Please let me know if i am doing something wrong.Any help would be appreciated. thanks.

author: Laen
author_rank: Newbie
timestamp: May 04, 2016, 04:17:33 am
content: Here's our docs page for Altium Circuitmaker:http://docs.oshpark.com/design-tools/altium-circuitmaker/cam-setup/The short of it is: We want just the .TXT file from the NC Drills directory, not the weird binary .DRL file.If you're still butting against the wall, our support address is support@oshpark.com, and we have _very_ skilled engineers on the other side that'll be happy to help.