hybridfree/eevblog-posts huggingface dataset:
Interesting OpAmp substraction circuit - Page 1
Forum section: electronics / beginners

author: homebrew
author_rank: Frequent Contributor
timestamp: September 21, 2016, 08:10:15 am
content: I reacently worked with a high side current sensing IC (LT6106) and thereby learned about an interesting way of subtracting two voltages.The basic operation is shown in the datasheet (http://cds.linear.com/docs/en/datasheet/6106fb.pdf) but I couldn't resist trying this out with LTSpice. And sure enough it works.So, while it is quite easy to understand, I've never seen it before in any book.Does anybody know how that way of subtraction is called?Edit: Added Link to Datasheet

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 21, 2016, 08:23:28 am
content: Not really called anything, but it has a voltage-to-current characteristic, thus it has gain in units of current/voltage, i.e., a transconductance amplifier. The output load resistor thus sets gain (Vg = R*Gm).Tim

author: Bukurat
author_rank: Regular Contributor
timestamp: September 21, 2016, 08:37:54 am
content: Your circuit is not the same as the IC. It has a pnp transistor, yours has an npn.Swap the transistor to the correct one and in the simulation again.

author: dom0
author_rank: Super Contributor
timestamp: September 21, 2016, 08:58:41 am
content: I don't think there is a set-in-stone name for this circuit, but it's been known and applied widely for high side shunt amplifiers and is usually just called that.One issue with it is that it requires an PNP/PMOS output, which makes it increasingly difficult to apply to voltages beyond 100 V. There is also a static error depending on the alpha of the PNP / PMOS (PMOS alpha is ~1). When used with a PMOS therefore that error will become rather negligible. Further errors are mainly caused by gain limitation, so transconductance of the PMOS matters as well.

author: bobaruni
author_rank: Regular Contributor
timestamp: September 21, 2016, 09:24:03 am
content: It's called an I/V converter (current to voltage).

author: dom0
author_rank: Super Contributor
timestamp: September 21, 2016, 09:28:14 am
content: There are dozen(s?) of I/V converter circuits.

author: homebrew
author_rank: Frequent Contributor
timestamp: September 21, 2016, 09:08:54 pm
content: Quote from: Bukurat on September 21, 2016, 08:37:54 amWTF? Unbelievable how stupidity combined with simulation can cause even more stupidity.Ok, I probably was not yet completely woken up to realize that the values of 4.95V was two orders of magnitude of .. should have been 49.5 mV. But BY ACCIDENT the rest of the component values EXACTLY caused a current of 495 mA to flow. What a coincidence. Altering the values lead of course to something completely different ...Anyway, using a PNP transistor it works fine, of course.

author: rfeecs
author_rank: Frequent Contributor
timestamp: September 21, 2016, 09:45:58 pm
content: It works with an NPN as well. Refer to Figure 5 of this app note:http://cds.linear.com/docs/en/application-note/an105fa.pdf
interesting vid about probing with a scope without floating. - Page 1
Forum section: electronics / beginners

author: ME
author_rank: Frequent Contributor
timestamp: March 08, 2025, 10:36:39 pm
content: Hope its of use to folks

author: watchmaker
author_rank: Unknown
timestamp: March 09, 2025, 12:03:40 am
content: Too bad he talks about an isolation transformer as a bad way to float scope; but he ignores it's primary use is to isolate the amplifier from PE.Good explanation of using differential probes though.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 12, 2025, 01:45:38 pm
content: see more interesting video
Interesting video on getting DIY IQ constellation diagrams on an oscilloscope - Page 1
Forum section: electronics / beginners

author: 240RS
author_rank: Regular Contributor
timestamp: May 27, 2023, 09:23:59 am
content: Interesting to see that a (small audience) YouTuber generates constellation diagrams on a scope we all have. Would work with 2 channels (I, Q) but what I found refreshing is that he uses the logic channels of his scope to feed in bit, symbol and even pseudo random sequence clocks to trigger the scope for different views.Probably not news for many, but since this is the beginner forum (and I am one) I wanted to share it:https://youtu.be/NB1n3BLKxJwApart from the experiment, he explains quite some fundamental stuff as well as explains how to use various instruments. For that reason I have watched hours of Dave’s and Signal Path’s videos. Not for repairing it (focus of the latter and impossible for me to replicate), but to see the inside (open it!!) and see it being in use. This YouTuber is giving you a lot on the the “use it” part.(I will be using his method for debugging clock recovery of a real signal)

author: barshatriplee
author_rank: Regular Contributor
timestamp: May 27, 2023, 03:22:51 pm
content: OMG! never really thought about such an application of oscilloscope. Thanks.

author: 240RS
author_rank: Regular Contributor
timestamp: May 28, 2023, 09:36:40 am
content: Noticed the maker is a frequent EEVBlog contributor: @RBBVNL9. Linking him probably doesn’t work though.
Interface for multiple status leds - Page 1
Forum section: electronics / beginners

author: ziggyfish
author_rank: Regular Contributor
timestamp: October 08, 2020, 11:08:52 pm
content: Hi,I am working on a system that will have about 28 power status LEDs, I want these LEDs to be on a separate daughter board.What is the best way to manage this amount of connections?Ideally I want these status signals on a I2C/SPI bus, so that a Microprocessor to process and monitor these signals.ThanksBrendan

author: Doctorandus_P
author_rank: Super Contributor
timestamp: October 09, 2020, 12:16:35 am
content: One way is to put a bunch of 74HC595 shift registers in series.Another way is to use a microcontroller on both sides. uC's are a bit more expensive then shift registers, but you only need one of them, and you can combine it with scanning a matrix of LEDS, combine it with buttons, maybe a HD44780 or other stuff that's common on a front panel.Then, there are all kinds of dedicated LED drivers. One of them is the MAX7219, which is a chip I do NOT like much. The "Maxim" variant is redicilously expensive, the clones from china are ... unreliable at best, and on top of that, the "dimmng" feature has far to few steps to be useful. On the plus side, this chip can handle a matrix of 8*8 = 64 LED's A lot of the bigger shops have whole separate sections for LED drivers.

author: ziggyfish
author_rank: Regular Contributor
timestamp: October 09, 2020, 12:31:11 am
content: Doctorandus, never thought about using shift registers.It would work very well with the rest of the system, and is extendable.Also I can put that signal into a microprocessor, do what I need to do.I can then either send it to a matrix led driver IC, or if I want to go real fancy send it to a LCD display of some sort.Thanks for the idea.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: October 09, 2020, 01:16:57 am
content: Those RGB LED panels are driven by shift registers. The library PxMatrix can drive them. They are basically driven as a long string individual LEDs. (Ex: 64 x 64 x 3 ~ 12,300 LEDs)So I can attest this will.work well. PxMatrix drives it via SPI. I get refresh rates over 700 frames per second. My MCU is an esp32. The 2 cores of the esp32 work well here. One core is dedicated the refresh. It reads from a frame buffer. The other core does the actual work and "drawing". This yields a very smooth screen experience.I'd attach a video, but no joy with the format.

author: tooki
author_rank: Super Contributor
timestamp: October 09, 2020, 03:31:43 pm
content: Another option (if you don’t need dimming) is generic port expander ICs. A couple of those and you’re set. (Using I2C.)

author: MarkF
author_rank: Super Contributor
timestamp: October 09, 2020, 04:25:32 pm
content: The MCP23008 is an 8-bit expander with an I2C interfaceThe MCP23S08 is a 8-bit expander with a SPI interface
Interface Keyboard to TRS-80 Model II - Page 1
Forum section: electronics / beginners

author: rthornqu
author_rank: Newbie
timestamp: November 24, 2017, 04:24:46 pm
content: I just acquired a TRS-80 Model II in great condition. One problem: It didn't come with a keyboard.I'm searching for a keyboard, but the Model II wasn't that popular and I think it'll be tough to find one. In the meantime, I was considering a way to interface a regular PC keyboard to the Model II. I have some documentation for the Model II keyboard pinouts, codes, and timing - please see attached.One idea was to use a Raspberry Pi. The Pi already has a keyboard attached to it so all I'd have to do is attach a few GPIO pins to the keyboard connector on the Model II and generate the required signals. However, I'm not sure the Pi has the ability to generate signals with such precision.If anyone has any ideas on how would be a good way to do this, please let me know. Thanks!- Rick Thornquist

author: Ian.M
author_rank: Super Contributor
timestamp: November 24, 2017, 04:58:02 pm
content: There is no way that you can reliably meet 1us scale timing requirements on a Pi (or on anything else running Linux or other high level OS) without hardware assistance.The easy option would be an Arduino or other 8 bit MCU with similar capabilities. The keyboard data and clock look similar to SPI but bit-reversed, and with an extra end pulse that would need to be bitbanged after each byte. There are existing Arduino libraries for PS/2 keyboards. Prototype it on an Arduino UNO then open up the keyboad and convert it to TRS-80 by shoe-horning in an Arduino Mini.

author: rthornqu
author_rank: Newbie
timestamp: November 24, 2017, 08:25:47 pm
content: Ian -I took a look at the Arduino and the PS/2 keyboard libraries and it looks like it should work nicely. Thanks for your help!- Rick Thornquist
interfacing 3.3V uC with 5V radio using keypad style buttons - Page 1
Forum section: electronics / beginners

author: doublec4
author_rank: Regular Contributor
timestamp: January 20, 2021, 11:52:59 pm
content: Hi all,I would like to use a 3.3V controller (Arduino) to "push the buttons" on a 5V radio. The radio uses key pad (carbon pill) style buttons to close the contacts. How can I get the 3.3V Arduino to essentially "push the buttons" with the minimal number of parts and not damage the Arduino by putting 5V through it's digital pins? A friend suggested putting the two sides of the keypad across a transistor/mosfet and using the Arduino on the base/gate of the mosfet... although I think this would work, a big mosfet seems like overkill to do this and then I would need one for each button on the radio...Is there a simpler way?Thanks!

author: EEauroro
author_rank: Contributor
timestamp: January 21, 2021, 04:19:13 am
content: 1) Can you identify the ground of the 5V radio. If yes, can you connect the ground of the 5V radio to your arduino ground ? Note: By connecting these two, you may introduce some ground loops that may affect reception / cause interference2) Check if one side of the keypad is internally connected to the ground of the 5V radio.3) If yes, Check if the GPIO of the arduino is 5V tolerant (some are). If it is, try to configure the GPIO output pin to be "Open-Drain" and connect the GPIO output of the arduino to one side of the tactile switch. The other side connect to your arduino ground. Polarity is important4) This should work.

author: mvs
author_rank: Frequent Contributor
timestamp: January 21, 2021, 09:13:27 am
content: Quote from: doublec4 on January 20, 2021, 11:52:59 pmKeypads are usually multiplexed. You can connect column and row lines throught 1K resistors to atmega and demultiplex keys in software.You may use Pin Change Interrupts to track level changes on strobe lines and assert correct levels on data lines.

author: VEGETA
author_rank: Super Contributor
timestamp: January 21, 2021, 12:01:26 pm
content: maybe look for voltage level shifter ICs, they are available with Arduino stuff. or just use transistors.

author: doublec4
author_rank: Regular Contributor
timestamp: January 21, 2021, 11:16:27 pm
content: Thanks guys,After prodding around a bit, I believe what is happening is that the one side of the button is constant 5V and when the button is pressed the line is pulled to GND and whatever controller on the radio then recognizes it as a button push.I've used the ULN2003A a bit in the past... was thinking of putting the 5V sides of the buttons into the output/load side of the ULN2003A and my 3.3V arduino inputs into the input side... then configure my GPIO pins to pull the radio buttons to GND through the ULN2003A.This way the Arduino is somewhat isolated from the 5V radio... and no resistors needed going into the ULN2003A because datasheet shows base resistors are built in... so its still pretty compact. What do you guys think?
Interfacing c code for AMC3336 - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: May 27, 2023, 03:00:53 pm
content: Trying to read for AMC3336, what protocol it is? Is it spi, i2c or uart?any c code example for interfacing?

author: barshatriplee
author_rank: Regular Contributor
timestamp: May 27, 2023, 03:18:31 pm
content: Hello, exactly which AMC3336? Is this the Delta-Sigma modulator?https://www.ti.com/lit/ds/symlink/amc3336.pdf?ts=1685199658590&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FAMC3336
Interfacing face recognizing module with PIC serial comm help - Page 1
Forum section: electronics / beginners

author: Veketti
author_rank: Regular Contributor
timestamp: July 24, 2023, 11:10:07 am
content: Dear All,I'm playing around with Hi-Link HLK-TX510 face recognizing module and trying to interface that with PIC 16F1847 micro. I've pretty much done the PIC program and decoded with scope that it sends the correct message. However I'm bit unsure with few things before I connect those two together and possibly fry the relatively expensive module, so I hope someone could be so kind and answer following guestions..1. In this pagehttps://blakadder.com/hlk-tx510/it is said that the connection should be from the TX510 side SD0 -> RX and SCLK -> TX. However in the schematic they look to be I2C and not UART. Is there error or should it actually be pins 4 and 5 which are marked CK805_UART_RXD and CK805_UART_TXD? If the web page is correct and it is SD0 and SCLK then should it be USI1_SD0 and USI1_SCLK or USI0_x?1. Should the serial communication be idle low, or idle high?2. PIC serial communication is 5VDC. Is that ok with the receiving unit, or should it be 3.3V or something?Documentation what available can be found from github:https://github.com/blakadder/HLK-TX510Thank you in advance!-----------------------------------------------------------------------------------------edit July 26th.I was able to get help from the manufacturer Hi-Link. I'll add it here if someone will be stumbling with the same thing.1. Pins are from TX510 connector P2 as following: RX -> pin 6 USI1_SD0 and TX -> pin 7 USI1_SCLK2. Idle HIGH3. 5 VDC

author: pierrem
author_rank: Newbie
timestamp: June 30, 2025, 02:57:56 pm
content: Hi,with same HLK_TX510 ... i just overwrite a V1.0011 (chinese) firmware without having backup ... with a not so functionnal V1.0006 (english)Can you send/give a link me a copy of the newest firmware you have ?Many thanksp

author: Veketti
author_rank: Regular Contributor
timestamp: July 04, 2025, 10:54:24 am
content: Sorry, I didn't mess with the firmware. Try to contact Hi-Link, they're quite helpful. I was struggling with the recognition through lens and they helped to troubleshooted it. Even though the end result was that the camera doesn't work through lens. Not plastic or glass.Otherwise it seems to be quite good module. Working almost two years already. One point to highlight though. It doesn't like sunlight. Most likely the infrared from sun is causing troubles for it to recognize. And I'm not talking about direct sunlight.
Interfacing flowmeter's - Page 1
Forum section: electronics / beginners

author: tridentsx
author_rank: Regular Contributor
timestamp: December 10, 2013, 01:40:32 pm
content: Are there a "standard" circuit for interfacing 3.3V logic to flow meters with pulse output?The flow meters normally has a either a-- reed relay output with contact bouncing-- hall effect sensor with open collector that needs a higher voltage to be driven normally 5 - 12 v .I would like one input that could handle both types of meters.Thanks Carl

author: matkar
author_rank: Regular Contributor
timestamp: December 10, 2013, 08:49:27 pm
content: Isn't the principle basically the same?If sensor needs 5V for alimentation or more then you should supply 5V. It doesn't influence the open collector sense line. You can supply the sense line with 3.3V.

author: tridentsx
author_rank: Regular Contributor
timestamp: December 11, 2013, 09:35:00 pm
content: Ok I see, the 10k is a pull up and the 10nF + 220Ohm is a low pass filter for the contact bounce.What does the two diodes do? Sorry for basic question but I am a beginner. Wouldn't it be suitableto replace the lower diod with a 3.3v zenner ?Thanks for all the help.

author: calexanian
author_rank: Super Contributor
timestamp: December 12, 2013, 07:03:30 am
content: They typically have a "clicks" (pulses) per gallon rating.

author: SeanB
author_rank: Super Contributor
timestamp: December 13, 2013, 07:37:53 pm
content: Diodes are for if you connect 12V to the input. Saves having to replace the microcontroller instead you get to replace one nicely cooked resistor.

author: matkar
author_rank: Regular Contributor
timestamp: December 13, 2013, 09:06:40 pm
content: You can use BAV99 dual diode in SOT23. It serves as a overvoltage protection to the microcontroller input pin. Yes, you can use a zenner diode as well.
Interfacing GSM module - Page 1
Forum section: electronics / beginners

author: A2
author_rank: Contributor
timestamp: August 05, 2014, 02:14:59 pm
content: I am interfacing wavecom M1306B module to send sms.When I have to sens sms via hyperterminal I am able to do that:1. Atenterok2. at+cmgs="9999xxxx",enter>my messagectrl+z+cmgs: 13OKHere bold are data which I receive, plain is what I send, & italic is computer control buttons which I press.1. Now I want to interface it will controller. Can I do this my using rxd & Txd pins only, or I need to use all pins on modem from microcontroller2. Do all characters send/reciev are to be in ascii. Like if I have to send 90. I have to send 0x39 & 0x30.3. Control button "ctrl+z", how to emulate it in microcontroller.4. What is that button '>' , byte received from modem

author: Wilksey
author_rank: Super Contributor
timestamp: August 05, 2014, 02:44:53 pm
content: Hi,1. Yes, unless you specifically need DTR / CTS etc, usually uou need flow control for flashing firmware, and on some 3G modules you require flow control, should be in the datasheet. Typically there is a minimal connectivity list in the datasheet.2. Yes, again, depending on the module, but all of the ones I have used process each character in turn.3. CTRL + Z is ASCII 26 (0X1A) (SUB)4. I don't understand the question, are you asking what the ">" is for? If so it is to tell you that the module is awaiting your input for the message. If not, please rephrase your question clearer.I am by no means an "expert" but I have worked quite a lot with 3G and 2G modules using the PIC and Atmel.

author: Jeroen3
author_rank: Super Contributor
timestamp: August 06, 2014, 06:41:31 am
content: 1. Yes, but keep an eye for the voltages. RS-232 is not a direct txd pin on your chip.4. Probably the "ready for command" byte, if it's not inserted by your terminal program.

author: bookaboo
author_rank: Frequent Contributor
timestamp: August 06, 2014, 08:27:49 am
content: 4. I don't think you need to insert the ">" yourself. I think its an automatic prompt from the module or the CLI
Interfacing High power LED Driver and PC with MATLAB? - Page 1
Forum section: electronics / beginners

author: abhaymv
author_rank: Contributor
timestamp: September 01, 2013, 05:44:27 pm
content: Hey all!I'm driving a string of high power LEDs (~700 mA) using an HV9910 LED Driver.http://www.premier-electric.com/files/supertex/pdf/hv9910.pdfThe output current of HV9910 (and hence LED intensity) is controllable by an input PWM_D of the LED Driver. PWM_D pin needsan external PWM inputwhose duty cycle controls the LED intensity.Can I use MATLAB to generate a PWM waveformand use one of the ports in my Laptop (USB/Ethernet/Audio) to send this waveform to the LED driver?I saw somewhere that computer ports do not support the bandwidth required for PWM signals. But can't I just send a sequence of binary data as PWM? Eg:11000000 for a duty cycle of 1/4?I'm a newbie when it comes to interfacing. Thus please forgive anything idiotic I may have said here.

author: Skimask
author_rank: Super Contributor
timestamp: September 01, 2013, 08:03:21 pm
content: Part 3Quote from: abhaymv on September 01, 2013, 05:44:27 pmPart 4Quote

author: c4757p
author_rank: Super Contributor
timestamp: September 01, 2013, 08:23:06 pm
content: Option one: just try it!Option two: tiny microcontroller listening over a serial interface/USB to generate the PWM signal.

author: AndrejaKo
author_rank: Frequent Contributor
timestamp: September 01, 2013, 08:27:23 pm
content: I see two ways to do this:The "good" one would be to get a microcontroller, have it create the PWM and then send commands to it from say Matlab or whatever you want to.The other option would the to simply connect the audio output to the input pin and hope for the best. If the PWM frequency should be in the range computer sound card can support, then you can create appropriate sound. Matlab should be capable of creating required sound and playing it. Another option would be to just make a fixed square wave with some for example audacity just to test if thins will work fine.

author: abhaymv
author_rank: Contributor
timestamp: September 02, 2013, 01:05:49 am
content: Thank you everyone!So I was thinking a microcontroller or a signal generator for the PWM needs. That takes care of output data.Now I need to receive three sets of data from the sensors. And all this needs to be done at the same time...I'm thinking a USB to Serial port and a MUX/DEMUX arrangement. Serial data is demultiplexed to two channels of Signal generator. Data from various sensors are multiplexed and sent as serial data. Would that work? I'd need info from an 860 samples/sec 16 bit ADC each for all the sensors.
Interfacing parallax ping with ATMEGA, programming in C  - Page 1
Forum section: electronics / beginners

author: Kdog44
author_rank: Contributor
timestamp: August 28, 2014, 05:34:13 am
content: hello,I am relatively new to programming the ATMEGA328 in C. My knowledge is shady when it comes to utilizing the counter/timing registers with the mcu. I am trying to interface the parallax ping ultrasonic sensor with the ATMEGA328 chip.http://www.parallax.com/sites/default/files/downloads/28015-PING-Documentation-v1.6.pdfTo communicate with the sensor I need to send a 5us pulse to the sig pin, then wait 750us and then listen for the signal pulse. The length of the signal pulse is related to how far away the object is.I started implementing the algorithm to do this with the help of:http://pomprocker.blogspot.ca/2009/01/adding-parallax-ping-to-avr-using-c.htmlhere is my code:note that the sig pin on the ping is connected to PB1 and a led is connect to PB0Code:void ping(void){DDRB |= (1 << PB1);PORTB |= (1 << PB1) | (1 << PB0);_delay_us(5);PORTB |= (0 << PB1);DDRB |= (0 << PB1);TCCR1B |= (1 << CS10); // No clk prescalingloop_until_bit_is_set(PINB, PB1);TCNT1 = 0;loop_until_bit_is_clear(PINB,PB1);time = TCNT1;if( TCNT1 < 1000){PORTB |= (1<<PB0);}}void main(void){{ping();_delay_ms(200);}}Is there a better way of doing this? my code is really messy and doesn't seem to work. Basically I was trying to light an LED when an object was detected about a couple of cm away from the sensor. Where did I make a mistake?thanks in advance

author: AndreasF
author_rank: Frequent Contributor
timestamp: August 28, 2014, 06:18:17 am
content: QuoteThis is not how you clear bits. You probably want ...Code:PORTB &= ~(1 << PB1);DDRB &= ~(1 << PB1);
Interfacing to I2C in PM2525 - Page 1
Forum section: electronics / beginners

author: cowasaki
author_rank: Frequent Contributor
timestamp: February 27, 2018, 04:26:24 pm
content: I'm trying to connect to the I2C bus in the PM2525. I've extended the lead which goes from the main board to the display board so that it goes to a breadboard in the middle and the meter works as it did before. Now if I connect the SDA & SCL lines to an Arduino the PM2525 keeps resetting. I only need to see the I2C data as it goes past and don't need to write to the bus. What would people use to connect to it? Diode & pull-up resistor, op-amp buffers, opto-couple, transistor?

author: rstofer
author_rank: Super Contributor
timestamp: February 28, 2018, 01:43:06 am
content: I don't understand how you have the Arduino set up. If it has an address that matches the display board, it will try to control the SCL and SDA lines as is the PM2525 main board. If it doesn't have a matching address, why would it listen to the conversation?I suppose you could do something to get the Arduino I2C into a promiscuous mode but I'm not sure what it is.If you are only monitoring the signals, like this 'sniffer', then it shouldn't interfere in any way with the conversation.https://hackaday.com/2011/05/21/arduino-i2c-sniffer/OTOH, the sniffer just captures edges, decoding is done elsewhere.
Interfacing wavecom M1306B GSM problem - Page 1
Forum section: electronics / beginners

author: A2
author_rank: Contributor
timestamp: August 06, 2014, 12:30:42 pm
content: I am interfacing wavecom M1306B & facing some problem.1. Sometimes when I send a command like "AT\r", I don't get any response from wavecom.Even if had 2 sec timeout for reception, after which I resend command but still don't receive anything from wavecom.2. I have only used rx & tx lines of wavecom. do wavecom needs all pins of uart for interfacing like CTS, etc.When I connect it to PC & use teraterm it works fine. I don't know if teraterm is using all pins of DB9. Buy CTS bit in teraterm shows green flag

author: A2
author_rank: Contributor
timestamp: August 06, 2014, 01:33:27 pm
content: Datasheet says we have to use flow control:hardware.But I have triedin hyperterminal without flowcontrol i.e None, it works fine.Should I ground CTS pin of modem to ground. There is 7V coming there.
interfacing with a a070vw05 v2 screen - Page 1
Forum section: electronics / beginners

author: carbon dude oxide
author_rank: Frequent Contributor
timestamp: April 02, 2013, 09:15:48 pm
content: helloi found this a070vw05 screen in my box of spares and i was wondering if there was a way of interfacing it to my raspberry pi so i can use it?here is the datasheet :http://www.avidia.com.tw/docs/product/A070VW05%20V.2.pdfso far i have been able to get the back light powered up and it does not look like it has any dead pixels so its looking like a nice 7in screen so fari do also have a "3609 SY 9901 FOR A070VW05 LCD" board that the screen connected to. This board also has a connector which i believe went into the small net book it came from.i do hope that it is possible to interface this screen as it would fit nicely in making my pi a portable games arcade

author: Zapro
author_rank: Contributor
timestamp: May 11, 2013, 10:04:08 pm
content: I am sorry to say this: If You have to ask, you won't get it working with your Pi.It's a very complicated affair to make it work with another controller than it was originally married to.// Per.

author: Rasz
author_rank: Super Contributor
timestamp: May 11, 2013, 10:16:45 pm
content: You can drive this lcd with beagleboard/bleaglebone as it has parallel interface for lcds

author: amyk
author_rank: Super Contributor
timestamp: May 12, 2013, 09:43:21 am
content: I can't open your datasheet for some reason, but given its origin it's most likely a standard LVDS panel. That board you have is the T-con for it and turns LVDS input into the signals needed to drive the panel.A quick Google suggests the RPi has LVDS output. How difficult it is to actually connect and get a display working, I'm not sure (Broadcom proprietariness)

author: Rasz
author_rank: Super Contributor
timestamp: May 12, 2013, 11:55:12 am
content: Quote from: amyk on May 12, 2013, 09:43:21 amnot an lvds panelRPI doesnt have lvds
Interfacing with adafruit breakout for maxim 31850 one wire thermocouple amp - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: November 25, 2014, 08:46:06 pm
content: Hi,After waiting eagerly for my amp to arrive and paying for next day courier delivery, I'm disappointed I still need a level shifter.I wasn't aware of this until I read the wire test tutorial on adafruit website after it had arrived DOH.My understanding is I need a bidirectional Level shifter therefore a simple resistive divider wont do. ON sparkfun website it shows BSS138 MOSFET being used to as a bidirectional level shifter however it's not easy for me to get parts in Manchester. Can I use a BS170 instead? Any help would be greatly appreciated!!https://learn.sparkfun.com/tutorials/bi-directional-logic-level-converter-hookup-guideAlternatively can not just power the atmega328 chip using 3.3v then I don't need to level shift right?

author: Zero999
author_rank: Super Contributor
timestamp: November 25, 2014, 09:58:42 pm
content: It won't work very well. The BS170 has a higher threshold voltage than the BSS138.See the app note where they got the circuit from for more information.http://dlnmh9ip6v2uc.cloudfront.net/tutorialimages/BD-LogicLevelConverter/an97055.pdf
Interfacing with an analog LCD screen and blanking - Page 1
Forum section: electronics / beginners

author: coaxialgamer
author_rank: Contributor
timestamp: May 18, 2018, 09:33:54 am
content: Hello,For a project of mine i need to generate a video display . I know how this works on CRT screens and i'm running the signal through VGA.However , i thought about those older LCD screens that accept a vga input and that accept a regular analog signal . Being more compact , these displays are ideal for me.My question is this : CRT's rely on blanking to move the beam around without drawing to the display . The extra time spent blanked is overscan.But LCD's don't have a beam . what happens when a CRT would usually blank ? Does the LCD simply abstract it , or are any modifications required to the signal?

author: bson
author_rank: Unknown
timestamp: May 18, 2018, 12:27:26 pm
content: Panels of all kinds are still scanned and still have blanking intervals (porches).
Interference in hearing protection radio from dust extractor/fluorescent lights? - Page 1
Forum section: electronics / beginners

author: Niels JL
author_rank: Newbie
timestamp: August 17, 2018, 06:49:41 am
content: Hi,I have a set of Peltor hearing protection buffs with a built-in FM radio:http://peltorcomms.3m.com/world/Product.asp?PageNumber=937&Product_Id=251&ProductCategory_Id=43When using a Festool CT 22 E dust extractor or fluorescent work lights - both connected to 240V mains *with* ground, I get a lot of interference when listening to the radio in the Peltors.I thought this might be a possible project for me, although I'm a beginner in the art of electronics - so maybe not :-)I've searched for possible solutions using Google, but found nothing much apart from "why the vacuum cleaner in the old days caused interference in the TV" type of answers.Is it possible to add something to the circuitry of the Peltors that could remove this interference?Cheers,Niels
Interference or something wrong with my scope? - Page 1
Forum section: electronics / beginners

author: ollihd
author_rank: Regular Contributor
timestamp: April 04, 2017, 11:02:42 pm
content: I'm getting these weird peaks every 5 to 10 seconds when the scope is idle, probe connected. Same with every channel. Any idea what might be causing this? I think I have removed anything that might cause an interference. Scope is a Rigol 1054z.

author: rs20
author_rank: Super Contributor
timestamp: April 04, 2017, 11:06:52 pm
content: Well, if the the spikes go away when you disconnect the probe, then the scope is fine. Disconnect the probe and see what happens then.

author: StillTrying
author_rank: Super Contributor
timestamp: April 04, 2017, 11:09:19 pm
content: A mobile phone charger plugged in somewhere?

author: ollihd
author_rank: Regular Contributor
timestamp: April 04, 2017, 11:18:44 pm
content: Thanks a lot, case closed! Didn't see the spikes when probes were disconnected. When I started looking under the table for my charger I realized I had my power line ethernet repeater connected and it had it's wifi-extender enabled...disconnected it, problem solved. Thanks again.
Interference source - Page 1
Forum section: electronics / beginners

author: h_ramsay2000
author_rank: Newbie
timestamp: February 02, 2023, 06:19:23 pm
content: First post here. Recently I've been setting up some equipment for some wind tunnel testing and have been getting some interference from somewhere entering the system. The power supply for all the measurement equipment is supposedly clean, filtered and from a UPS, so I think the interference is from somewhere in the same circuit but haven't been able to locate where. The attached image shows the pattern seen and appears every 30 seconds.Looking for suggestions where a signal like this could be coming from and any possible solutions to supress it?Thanks.

author: wasedadoc
author_rank: Super Contributor
timestamp: February 02, 2023, 06:30:47 pm
content: Possibly a site that has a wind tunnel has other "experiments" taking place. Maybe one of those is generating radio frequency interference which is getting into your equipment through the ether.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 02, 2023, 06:34:01 pm
content: WiFi Router?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: February 02, 2023, 06:43:26 pm
content: Is there an electric fence in your area?
Interference with motor start - Page 1
Forum section: electronics / beginners

author: Lee697
author_rank: Regular Contributor
timestamp: November 07, 2014, 03:47:02 am
content: I have a power board running various equipment for a tropical fish tank.One item is a 240V powerhead (water pump), another is a pH controller. The pH controller is an electronic device, measures water pH from an electrode in the tank, and switches a solenoid that controls flow of carbon dioxide into the water - more CO2, pH down, stop CO2, pH up etc. The pH controller runs from what seems to be 5V from a USB plug into what I assume is a SMPS.When I feed the fish, I unplug the pump, as it blows the food everywhere. When I plug it back in (no switches on powerboard), the pH controller often beeps, shows ERR on its display then seems to reset and go about its usual actions. I'm concerned maybe some sort of surge/interference from the pump starting is causing a problem.Any thoughts?Lee

author: HalfSpace
author_rank: Regular Contributor
timestamp: November 08, 2014, 09:07:01 pm
content: Hi Lee697,Does any of the equipment plugged into the power board have an earth pin?HalfSpace

author: Lee697
author_rank: Regular Contributor
timestamp: November 09, 2014, 12:12:10 pm
content: Only the pH controller PSU....

author: denelec
author_rank: Regular Contributor
timestamp: November 09, 2014, 02:27:10 pm
content: Try plugging the pump in a surge protector with EMI line noise protection.Or put a ferrite bead on the power cord of the pump.

author: Pillager
author_rank: Unknown
timestamp: November 09, 2014, 04:52:22 pm
content: Motors draw relatively high current when they start up. That, combined with more or less bad contacts in the powerboard and perhaps thin power leads results in a voltage drop. Same thing happens when you have a powerful vacuum cleaner or power tool and your lights dimm slightly, when you power it on. I can't really imagine your pump being very powerful, but it might be enough for the pH-controller-PSU to drop output voltage and the controller resets.You can measure the mains voltage or the PSU-voltage to determine, if this is the case.Or you could run a separate power cord to either the pump or the PSU and try it again.Greets, Tom

author: Lee697
author_rank: Regular Contributor
timestamp: November 09, 2014, 08:40:25 pm
content: Thanks gents - I did change out the powerboard yesterday, for one with surge protection/filtering, and also has individual switches.... Problem seems to have been corrected.
Interleaved PFC with Jellybean Components, will this contraption work? - Page 1
Forum section: electronics / beginners

author: hanzdolo30@gmail.com
author_rank: Contributor
timestamp: August 15, 2017, 11:25:20 pm
content: I threw this design together today and I'm wondering if it would work in real solder and components. My primary concern is the startup supply, I designed a buck converter (I guess) that operates at almost zero crossing where it picks up at the 45V region, being I have the MOSFET seeing 10% of the full voltage and clip it at 12V, but there are some nasty spikes in the first few ms.There was very little calculation done, it's still rough. I haven't added the short circuit protection yet, nor did I calculate the output filter, I just put 6 100u caps that I actually have. I'm also thinking of redesigning the PFC Control stage to use some logic where they kinda play catch with each other once the switch current reaches max. But I was just wondering if I'm going in the right direction.
Intermittent shorts causing problems - Page 1
Forum section: electronics / beginners

author: tyguy2
author_rank: Unknown
timestamp: March 03, 2020, 03:31:49 am
content: Hello all,Currently I'm working with the TI chipTUSB9261trying to connect an MSATA drive to a computer over USB 3. I've modeled the board offthis reference design. I've attached schematics of my current implementation along with the reference design, however I'm having some very strange issues. Without the chip installed, the resistance between the 5v, 3v, 1.8v, and 1.1v rails to GND is all in 50k-1M ohm range, which makes sense considering all that should be connecting them is bulk capacitance. When I power the board without the chip mounted, the power supplies all behave normally, outputting the correct voltages.When I soldered the chip to my PCB, however, the resistance across the 1.1v to GND rail dropped to a steady ~420 ohms. When I connected the PCB to my computer, Windows detected it, but gave me a "device malfunctioned" error, and it quickly disconnects. This looped for a while, with the board connecting, "malfunctioning," then disconnecting. After a while, the board ceased connecting altogether, and I measured the resistance across the 1.1v rail, which was now close to ~20 ohms. I left the board overnight and measured the resistance across the rail again, at which point it has returned to ~420 ohms. Removing the chip from the PCB gets rid of the short altogether.I'm not really sure what to make of all of this, or how to fix it. Does anyone have any ideas or advice?

author: tyguy2
author_rank: Unknown
timestamp: March 03, 2020, 11:39:28 pm
content: Quick update: Did some snooping, looks like the bulk capacitance on the 1.1v rail failed for some reason, causing the short. I cut the traces to that area of the board and ran a few wires to a perf board with new caps on it, and the short disappeared. Better yet, looks like things are starting to connect to the computer as well.

author: tyguy2
author_rank: Unknown
timestamp: March 05, 2020, 04:46:12 am
content: Another update: Looks like the short has returned. I removed the chip from the board, it looks like the short is internal to the chip. Any ideas?
Internal power connector identification for Nokia MP37H1 PAL TV - Page 1
Forum section: electronics / beginners

author: jameswilddev
author_rank: Contributor
timestamp: March 07, 2021, 07:09:31 am
content: Hello!I recently got an old CRT for testing a retroconsole, and the power cable is nearing 30 years old and the outer insulation is starting to crack and crumble a bit. Additionally, the design of the TV means that the power cable was kinked 90 degrees and probably crushed (it comes out of the bottom).I'd like to replace this cable, maybe route it out the back at the same time through a rubber grommet to prevent repeat incidents, but I don't recognize this connector:https://imgur.com/a/F7WySWOI might be able to reuse the connector (I don't have a crimp tool but I'm open to buying one if anyone can recommend)? Ideally I don't want to reuse any of this cable though.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 08, 2021, 04:46:31 pm
content: I'd upgrade the connector to something more contemporary. I can smell the 1970's plastic from here!How about a PCB C8?

author: jameswilddev
author_rank: Contributor
timestamp: March 09, 2021, 03:19:06 pm
content: Is the thinking here that I could desolder the socket currently on the PCB and run flying leads out to the back of the case with a C8 on it?
Internal wiring - basic guidelines - Page 1
Forum section: electronics / beginners

author: jeroen79
author_rank: Frequent Contributor
timestamp: August 13, 2015, 12:26:02 am
content: What are basic guidelines for running neatly ordered wires (instead of a bowl of spaghetti) inside a case?For example in a power supply where not everything is on a single PCB.(a seperately mounted transformer, controls on the front panel, etc)When should you twist wires together and when should you just let them run parallel?Which type of wires should be kept away from eachother?
Internal working of a Comparator - Page 1
Forum section: electronics / beginners

author: ender2336
author_rank: Newbie
timestamp: March 17, 2020, 05:36:15 am
content: HiI am looking for an explaination of the inner workings of a comparator. I understand the macro functionality.What I cannot find anywhere is an adequate explaination of the internal equivalent circuit.Any help would be appreciated.Ender

author: magic
author_rank: Super Contributor
timestamp: March 17, 2020, 06:55:27 am
content: Roughly like an opamp minus the frequency compensation stuff.Essentially, a long tailed pair takes a constant current through its emitters and splits it into two branches proportionally to the difference between base voltages. One of the branches (or the difference between the two) is fed into the base of a common emitter stage which moves the output either up or down.

author: Zero999
author_rank: Super Contributor
timestamp: March 17, 2020, 09:20:38 am
content: The heart of a comparator and any op-amp circuit is a long tailed pair. I advise building one from a couple of BJTs.https://www.allaboutcircuits.com/textbook/experiments/chpt-5/differential-amplifier/https://en.wikipedia.org/wiki/Differential_amplifier#Long-tailed_pairhttps://sound-au.com/articles/comparators.htm#s5

author: ggchab
author_rank: Frequent Contributor
timestamp: March 17, 2020, 10:32:08 am
content: w2aew has some nice videos on the subjectEx.:

author: Zero999
author_rank: Super Contributor
timestamp: March 17, 2020, 10:57:53 am
content: I think the easiest way to understand the circuit is to bias one of the transistor bases to 0V, with the other acting as the input. Now we have a two stage amplifier, with Q1 operating in common emitter and Q2 in common base configuration. Really a single BJT can be used as a differential amplifier, as it turns on when the base voltage is above the emitter by around 0.6V. The output of the emitter follower is connected to the input of common base circuit. Q1's emitter voltage is 0.6V less than the base voltage. When it falls 0.6V below Q2's base voltage, Q2 will turn on.This circuit is not very practical because the output voltage swing is tiny and depends on the input voltage. A simple enhancement would be to add a PNP transistor to the output, which will turn on, as soon as Q2 starts to turn on. Of course that would invert the signal so the inputs could be swapped to compensate. Swapping R2 for a constant current stage would increase the range of input voltages, by making the output swing independent of the input voltage and increase the gain.
Interpreting results from my scope - Page 1
Forum section: electronics / beginners

author: iamseth
author_rank: Newbie
timestamp: October 09, 2019, 11:19:15 pm
content: I have a 555 setup in monostable mode.I probed the output (pin 3) and the capacitor (pins 6 &7) to channels 1 and 2 respectively. The waveform looks like the one in the datasheet except I get some noise after the capacitor is charged up. I've attached the scope output image.My values for R1 and C1 are 1M and .1uF.Is this a concerning result and if so, what should I change to fix the issue?

author: StillTrying
author_rank: Super Contributor
timestamp: October 10, 2019, 12:35:10 am
content: It looks like the triggering pulse on pin2 is longer than the monostable time, and it needs 100n across its supply pins.I thinkthe GND is rising when the DIS pin starts to discharge the cap.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 10, 2019, 12:36:17 am
content: Quote from: iamseth on October 09, 2019, 11:19:15 pmIt is not unusual to get a bit of "overshoot" or "undershoot" with fairly sharp transitions in "real life".If you reduce the time/div & just look at the transitions, you will probably find they are sinusoidal.Because you are using a fairly long time/div setting, the 'scope makes a sort of "best guess"of the waveshape, hence the "squarish" look .On reflection, they are also low amplitude, so accurate representation of them will also be limited by the resolution of your ADC, so you will probably need to reduce the volts/div control as well.
Interrupt Power Momentarily - Page 1
Forum section: electronics / beginners

author: mentaldemise
author_rank: Regular Contributor
timestamp: April 01, 2015, 11:36:51 pm
content: Hi guys, a friend wants me to wire a switch into a USB cable for him so that he can interrupt the power to his Pi when it gets "weird" and he needs to restart it. Is there a better idea for that? I don't have a power transistor that would work on hand. And I'm not sure that putting a momentary switch between ground and vcc would be safe (the idea being he could hold it in for a second and let it out to reboot it.) Just looking for ideas before I go and put a big old throw switch in-line.

author: IanB
author_rank: Super Contributor
timestamp: April 01, 2015, 11:41:24 pm
content: Putting a switch between ground and Vcc would create a short circuit. Why do that? Why not simply put a momentary break switch in line with the power so that pressing the switch interrupts the power momentarily?

author: Ian.M
author_rank: Super Contributor
timestamp: April 02, 2015, 12:18:08 am
content: Google: Pi reset switchYou probably don't want to cut the power unless you actually want an on/off switch. Also if you cut the power while the SD card is doing internal wear levelling or bad block management, you can brick the SD card .

author: Marco
author_rank: Super Contributor
timestamp: April 02, 2015, 12:21:47 am
content: Here'san articleexactly about this, also the Pi has awatchdog timer.

author: mentaldemise
author_rank: Regular Contributor
timestamp: April 02, 2015, 01:35:38 am
content: Wow. Thanks guys. I didn't really consider him having not already looked at this sort of option. I think he has a 2, which means he'll have the RUN header I can just put some pins in for him.Thanks again!