hybridfree/eevblog-posts huggingface dataset:
PCD8544 (Nokia-style LCD) signalling - Page 1
Forum section: electronics / beginners

author: jameswilddev
author_rank: Contributor
timestamp: January 07, 2022, 06:58:41 pm
content: My displays arrived today so I've connected one up and had a go at controlling it from a AVR. It seems to be getting power (I see a black line when the power is pulled) but I can't get anything to display on it. I've been following the datasheet (https://www.sparkfun.com/datasheets/LCD/Monochrome/Nokia5110.pdf) and am sending the data listed in 13 APPLICATION INFORMATION steps 2-6 to see if I can get a single column of pixels on the display.Things I've checked:- The serial clock is 2MHz (half of the 4MHz limit).- All inputs (logic and power) are being driven at 3.3V (confirmed with oscilloscope).- The reset pulse is at least 100ns.- The polarity/timing of the serial clock vs. the data seem to match the diagrams in the datasheet.- SCE is connected to ground.- I've checked the bit order.I've got access to a logic analyzer and have captured the signals (the Sigrok file is also attached):Itlooksright... but if it was right it would probably be working!Any ideas what I might have done wrong?Thanks,James.

author: jameswilddev
author_rank: Contributor
timestamp: January 07, 2022, 10:00:05 pm
content: Since this post I've tried:- Another display.- Slower clock speeds (down to 150kHz).I've ran one of the Adafruit demos and thatdoeswork. But I'm looking at the signalling they're sending it and it doesn't look significantly different to me? I've decoded the commands they're sending the LCD and replicated them and I'm still not getting anything from my own program. Is there anything else I should be looking out for with SPI?

author: Benta
author_rank: Super Contributor
timestamp: January 07, 2022, 10:58:49 pm
content: My suspicion would be signal setup/hold times vs. clock edges.Always a hot issue...

author: amyk
author_rank: Super Contributor
timestamp: January 08, 2022, 01:15:52 am
content: According to the datasheet, there is no lower limit to the clock speed, so go as low as you want and see if it starts working. You could manually manipulate the display with debounced pushbuttons if you really wanted.

author: jameswilddev
author_rank: Contributor
timestamp: January 08, 2022, 07:08:16 am
content: So I figured out what it was. It's not something I can find in the datasheet.One difference between my captures and the ones from Adafruit's driver (and another one I tried) was that whereas mine was outputting one byte after another without much pause between (as I'm looking to refresh the display quickly then go straight back to sleep) there was a lot of gap between individual commands/bytes of data in other implementations.I don't believe these gaps were intentional (they seem to be internal overheads) but adding some delays to mine to match has got my code working!It's not something fixed by slowing the clock; it seems to need a few more clocks' worth of time following a command or some data to ready itself for the next byte.Thanks for the help everyone!
PCF8574 keypad with interrupt - Page 1
Forum section: electronics / beginners

author: bluevd
author_rank: Contributor
timestamp: February 18, 2020, 01:58:53 pm
content: Hello folks,I'm working on a project involving the usual I/O (LCD, Keypad, 4 tactile buttons and 2 IR detector switches) and a Pic18.Since my LCD already has a piggyback PCF8574, I figured I'd use one for the keypad and the 4 tactile switches (keypad is 3x4 so I can add another column for the 4 extra buttons).While googling out the PCF8574 keypad solution, I noticed all examples use constant pooling (even the ones that implement the PCF8574 without a breakout module and thus the INT pin could be used).Since the key input in my case accounts for less than 5% of the time (just for configuration and function select) I thought I could keep all columns high and tie the Interrupt pin from the PCF8574 to the PIC18. Then, when the user presses any key, it would trigger an interrupt and then I can do the usual pooling of the keypad (thus allowing the MCU to dedicate more time to other routines).Is there any flaw in my logic?PS: I'm awaiting for parts so I cannot test the setup yet, though I'd like to get started on the code
PCF8574 libraries ? - Page 1
Forum section: electronics / beginners

author: Ram80
author_rank: Contributor
timestamp: June 08, 2024, 10:33:54 am
content: I'm using an stm8s003f3p6 with a lcd1602(with PCF8574 interface board attached) .I'm using st visual develop and cosmic c compiler and st link v2.Any idea where to get a library to communicate with the PCF8574?I have code to connect to the GPIO pins on the LCD directly and I have code if using an Arduino and PCF8574.But I need code for the stm8s003f3p6 and PCF8574?

author: Doctorandus_P
author_rank: Super Contributor
timestamp: June 08, 2024, 12:16:55 pm
content: One way is to directly search on github. You will probably finds tens of different libraries for chips like that, and hundredths or thousands of forks.Another way is to install PlatformIO. PlatformIO has a built in system to search for and install libraries.

author: aliarifat794
author_rank: Regular Contributor
timestamp: June 08, 2024, 03:18:08 pm
content: This video may help you
PCF8575 IO Expander module schematic/manual? - Page 1
Forum section: electronics / beginners

author: LinuxHata
author_rank: Frequent Contributor
timestamp: March 26, 2023, 08:56:40 am
content: Hello.These modules are quite common (see attached photo), but I can't find out two things - why there's 3.3V LDO on board, while IC itself can deal with 5V supply and what are these two transistors for?

author: n4u
author_rank: Contributor
timestamp: March 26, 2023, 09:40:53 am
content: Transistors are for conversions between levels - when your i2c using other voltage, vdo may be bypassed (2nd side on the board) or it can provide 3.3V to IC.when u power it up with higher voltage and want to drive 3.3V outputs.

author: LinuxHata
author_rank: Frequent Contributor
timestamp: March 26, 2023, 11:05:35 am
content: Thanks!Speaking simply, I want it to use for driving LEDs from 5V power supply, my MCU will also run from 5V. Do I need to re-solder anything?

author: mariush
author_rank: Super Contributor
timestamp: March 26, 2023, 03:09:43 pm
content: There's better ways to be driving LEDs, like actual led driver chips.With that port expander IC, you still need 1 resistor for each led to limit the current, (unless you plan to rely on the port expander's pin current limit). With a led driver chip, you can set the limit for all leds with one resistor.There's led drivers that behave like shift registers, you basically just have to send 8 bits into the shift register and enable the driver to change the state of all leds at the same time to the new values. You can also chain multiple such led driver chips or you can use drivers with more channels.Here's an example of such basic "shift register" like LED driver IC :https://www.digikey.com/en/products/detail/stmicroelectronics/STP08DP05MTR/1653915Here's one with 16 channels, still "shift register" like driver, very easy to use (max 60mA per led) :https://www.digikey.com/en/products/detail/lumissil-microsystems/IS31FL3726A-ZLS4-TR/13281511or a more fancy one which also allows you to adjust brightness of individual leds :https://www.digikey.com/en/products/detail/stmicroelectronics/LED1642GWPTR/4441170

author: barshatriplee
author_rank: Regular Contributor
timestamp: March 28, 2023, 12:34:47 am
content: I found one here:https://www.utmel.com/components/pcf8575-io-expander-pinout-schematic-and-datasheet?id=411
PCF8575 - Page 1
Forum section: electronics / beginners

author: Sai Shoby
author_rank: Newbie
timestamp: October 13, 2020, 01:57:49 am
content: Hi all,I am trying to control switches in PCF8575 through I2C, when I press the switch which is connected in port0 in PCF8575, I want to glow the led which i connect in port1 of pcf8575. i attached schematics. Please help me to solve this

author: greenpossum
author_rank: Frequent Contributor
timestamp: October 13, 2020, 02:21:52 am
content: It's just an I2C to GPIO adaptor, not a FPGA or CPLD, you need a MCU to implement the action.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 13, 2020, 12:47:17 pm
content: would be useful to know, how you control the I2C bus?I have some C code for the PCF8575 on AVR, but no idea if it is for any help for you

author: Sai Shoby
author_rank: Newbie
timestamp: October 14, 2020, 03:55:21 am
content: Thank You for your reply. I am using pic 18f25k80 to connect scl and sda

author: HB9EVI
author_rank: Frequent Contributor
timestamp: October 14, 2020, 11:22:52 am
content: ok, as you maybe know the PCF8575 is widely used in I2C-backpacks for HD44780-compatible LCD displays, so I normally use the following code to control them, here a write sampleCode:void lcd_write(uint8_t data, uint8_t type) {uint8_t temp=0x0;uint8_t i=2;do { // verify is LCD is ready to receive commands)i2c_start();i2c_write(LCD_ADDR + I2C_WRITE); // address PCF8575 in write modei2c_write(0x8a); // write commandi2c_write(0x8e); // latch command (toggling Enable pin)i2c_start(); // I2C restarti2c_write(LCD_ADDR + I2C_READ); // address PCF8575 in read modetemp=i2c_read_nack(); // read PCF8575 pin status with non-ACKi2c_start(); // I2C restarti2c_write(LCD_ADDR + I2C_WRITE); // address PCF8575 in write modei2c_write(0x8a); // write commandi2c_write(0x8e); // latch command (set Enable pin)i2c_write(0x8a); // reset Enable pin}while(temp & 0x80); // do loop all over till LCD is readywhile(i) {if(i==2) {temp=data & 0xf0;}else {temp=data & 0xf;temp*=0x10;}if(type==1) {temp+=1;}i2c_write(temp+0x8);i2c_write(temp+0xc);i2c_write(temp+0x8);i--;}i2c_stop();}the I2C commands are AVR compatible, so I thing they are not fully portable to PICs, but the manual should give you a clue about it

author: Sai Shoby
author_rank: Newbie
timestamp: October 15, 2020, 01:02:13 am
content: Yes. got it. Thank you
PCI-e Power - resistance??? / cheap+efficient HS Current limit - Page 1
Forum section: electronics / beginners

author: HeartOfGermany
author_rank: Newbie
timestamp: October 27, 2019, 03:31:07 pm
content: I am trying to implement a TL494 for a 12-24V Boost converter with a continous power output of 120W (200W peak for >50ms / <20% of the time).There is however one problem. I want to get the booster working and have no proper way to verify some parameters.The TL494 is configured, to switch off for a short time, if the voltage drops below 10V on the TL494.The configuration is as follows in my simulation:PCI-e 6 Pin Power input: 12.6V at 100mOhm, PCI-e Power input via PCI-e Connector 200mOhm. This however gets spikes into theoutput capacitors (10x1mF [100mOhm/capacitor], 10x 10uF [50mOhm/capacitor]for higher frequency). The spikes rise to a max of aproximately60A!!! This also means a very very high current on the input. This could lead to system instability or even crash the PC...What is arealistic resistance on the PCI-e connector VCC and the PCI-e 6 Pin? 12.6V is idle voltage on many supplies. Definitely would drop a bit... Whatever.I would love a very cheap IC (tiny+SMD!), that just gives a logic output. The lower, the detect voltage is, the better for efficiency. It is absolutely required, to be a very low voltage drop detecting high side current monitor with digital output (don't mind, if output inverted or so). The V_detect should be less than 60mV for a max of 1W of TDP for the shunt.Thank you.

author: HeartOfGermany
author_rank: Newbie
timestamp: October 30, 2019, 05:20:17 pm
content: Hey, biggest E-Forum in the WWW I guess, but no one knows, how to current limit? I doubt it.

author: thm_w
author_rank: Super Contributor
timestamp: November 01, 2019, 12:38:11 am
content: Its a bit hard for me to understand what you are doing.It sounds like you are trying to power a boost converter, using a PC power supply from 6 pin PCI-e connector, and are worried about the high surge currents. Thats a valid concern.In PCs/servers usually you will see something called "hot swap IC",https://para.maximintegrated.com/en/results.mvp?fam=hot_swapwhich can limit the current.There may be other ways to approach this as well:https://www.electronicdesign.com/power/use-smart-load-switches-current-limit-protectionBut usually hot swap stuff is optimized for low voltages and very high current found in PCs.
PCI-E x16 power - Page 1
Forum section: electronics / beginners

author: Alana
author_rank: Frequent Contributor
timestamp: November 15, 2012, 01:02:30 pm
content: I have 2 faulty motherboards that do not work with pci-e VGA cards.Question - is it normal that 12V lines in pci-e x16 and pci-e x1 are not connected to any of the 12V pins on power connectors? Are they switched on/off by motherboard or do i have a culprit - burned out power trace.

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: November 15, 2012, 08:33:41 pm
content: I need pictures please because I am not understanding ... Well make sure the card is fully seated and also make sure attach the power connector on the side if the card has them or other wise the card will not work...Here is a pic of my card with with 2 6 pin power connector

author: Alana
author_rank: Frequent Contributor
timestamp: November 15, 2012, 10:05:34 pm
content: I'm trying to fix a faultymotherboardthat stopped recognizing pci-e vga cards.What i want to know is:does +12V lines in pci-e slot are somehow switched by motherboard?DMM shows no direct connection from +12V lines in pci-e slot and any of power +12V pins.on +3V3 lines there is a direct connection to ATX header +3V3 lineorcan i add jumper wire from ATX power header to pins 1,2,3 of pci-e slot to ensure that VGA is powered?

author: Psi
author_rank: Super Contributor
timestamp: November 16, 2012, 12:20:06 am
content: I don't have a spare pci-e motherboard, so cant check it for you.Can you measure the 12V line on the videocard while it's plugged in and running (or should be running)You may find there's 12V present at that point, in which case the 12V is fine and must be switched.But if its still 0V then yeah, it's definitely possible the 12v tracks got cooked, the current is pretty high.
PCIe Bifurcation - Page 1
Forum section: electronics / beginners

author: Underscore
author_rank: Newbie
timestamp: November 04, 2023, 04:38:58 am
content: Hey there!I've been searching around for a PCIe x16 to x8x8 bifurcation card, and there seem to be quite a number of them... for over $50.So, does anyone have tips on designing one (or a design they are willing to send if they feel like it)? Despite its supposed simplicity, this is completely beyond me as I'm a complete noob at designing PCBs. I checked outhttps://www.eevblog.com/forum/beginners/pcie-lane-switching/,but I'm not sure what to do from there.Any help would be appreciated.P.S. I understand that BIOS needs to enable bifurcation beforehand.

author: sasesa
author_rank: Newbie
timestamp: November 05, 2023, 10:57:26 am
content: Take a look a this project, there's some good information in the post:https://www.mattmillman.com/rolling-your-own-pcie-bifurcation-riser/

author: abeyer
author_rank: Frequent Contributor
timestamp: November 05, 2023, 07:52:55 pm
content: It's worth noting that you're likely to spend $50 just to do a pcb run to make one of these, not to mention the bom cost (and not even starting to figure in your time, which given what you say about your experience is likely to be significant.)It's a fine project if you want a project. It isn't going to save you money if you just need a widget, though.
PCIe Gen4 NVMe M.2-to-SFF-8673 cable without an adapter? - Page 1
Forum section: electronics / beginners

author: aBavarian Normie-Pleb
author_rank: Unknown
timestamp: April 12, 2021, 11:51:27 pm
content: Hi,I'm trying to connect anU.2 NVMe Backplaneto the CPU-PCIe M.2 slot of an X570 motherboard to use a Samsung PM1733 SSD with it.- According to the German FAQ, the backplane supports PCIe Gen4 (bottom of the FAQ page).- I tried going the route with anM.2-to-SFF-8643 adapterand anSFF-8673-SFF-8673 cable, this solution leads to WHEA ID 17 errors when the SSD is transferring data.- I've also tested multiple units of each part to rule out a random defect but that didn't change a thing.- To further reduce the signal loss due to multiple adapter/cable connections I'd like to find a Gen4-capable M.2-to-SFF-8673 cable to not need an M.2-to-SFF-8643 adapter anymore. Something like this Intel part that shipped with 900P/905P U.2 Optane SSDs, but not with an SFF-8639 connector at one end:https://www.intel.com/content/dam/support/us/en/images/memory-and-storage/optane-memory/25739_image2.jpgHas anybody here seen such a cable or can help otherwise?Thanks for any assistance!Regards,aBavarian Normie-Pleb

author: Electro Fan
author_rank: Super Contributor
timestamp: April 13, 2021, 01:29:29 am
content: You might also have some/more luck posting this question here:https://www.eevblog.com/forum/general-computing/

author: aBavarian Normie-Pleb
author_rank: Unknown
timestamp: April 13, 2021, 03:56:00 pm
content: @Electro FanThank you for your response - I was unsure where to post this topic.It might be too much of a niche's niche in the general computing sub-forum, the detailled signal integrity issues might also qualify it for the RF section?Since I was unable to even find a single model of such a cable I wondered if it would be possible to solder one yourself......but is there a way to get a PCIe Gen4-quality M.2 M-key PCB where you can solder the ends of an SFF-8673-SFF-8673 cable to where one connector has been removed?
PCIe- mPCIe - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: June 06, 2018, 12:35:01 pm
content: Other than connector form factor is there any difference between PCIe and mini PCIe.??Also is there any processor chipset that coulds support mobile-PCIe??

author: viperidae
author_rank: Frequent Contributor
timestamp: June 07, 2018, 03:20:04 am
content: mPCIe connectors also have USB connections in them too. Some have sata as well, other than that the PCI express parts are the same.The USB is usually used for wifi and modems and the sata is used for cheap SSD's
PCIE riser cards and connecting cable - Page 1
Forum section: electronics / beginners

author: dutchdog
author_rank: Newbie
timestamp: April 10, 2017, 10:00:21 am
content: Hi,Hope you are well. I would need some help from someone that knows about computerboards and specific PCIE slots.I am looking into PCIE riser cards and flat cables.Can I connect multiple GPU's wit a single PCB or would that divide/split my busspeed and every GPU requires its own connection.These riser cards seem to split the lanes rightLian-li has a flat cable for 1 PCIe card to move it from the PCB but perhaps anyone knows of a cheaper supplier of such a thing.Also. this is male/female. Are there connectors that are female female to link two PCI cards straight together.The idea is to add a graphics card or cards to this formfactor boards without the use of a baseboardhttps://www.picmg.org/openstandards/shb-express/

author: Rerouter
author_rank: Super Contributor
timestamp: April 10, 2017, 11:58:21 am
content: In general, each PCIE slot on a motherboard can only support 1 device, due to limitations in the bios of the machine. on the flip side, in some cases a x16 gpu can run in a 1x slot providing the bios doesn't restrict certain devices to certain slots, (again not much to be gained by running on a single lane)
PCIEXBAR Base Address for PCI Express Configuration Space - Page 1
Forum section: electronics / beginners

author: karim
author_rank: Newbie
timestamp: August 13, 2025, 04:28:03 pm
content: The processor has 3 outputs: one for RAM, the second for DMI, and the third for the PCIe bus which is directly connected, for example, to a PCIe card like a graphics card. So, when the processor receives an address, it needs to know which output to use. Therefore, there must be internal registers that help it decide. For example, TOLUD contains the address range available for RAM below 4GB, and TOUUD contains the range available above 4GB. So, if I have 8GB of RAM, these two registers (TOLUD and TOUUD) would represent, for example, 7.5GB available for RAM, because 0.5GB is reserved for device addresses. The remaining 0.5GB will be allocated for MMIO addresses, starting, for example, at 0xE00000000. This is stored in the PCIEXBAR, which is directly connected to the processor. Then, the graphics card takes, for example, address 0xE0001000. Now, when the processor receives an address, it checks whether it falls within the ranges defined by TOUUD and TOLUD. If yes, it routes it to RAM. If not, it checks the PCIEXBAR; if it falls within that range, it routes it to the graphics card via the direct PCIe bus. If not, it routes it through DMI, sending it to the chipset. The chipset also has its own register defining its MMIO address range. All these registers are configured by the BIOS, and then passed to the operating system through the ACPI tables. Is what I said correct?
PCM1794 audio dac, current output questions ... - Page 1
Forum section: electronics / beginners

author: atum
author_rank: Newbie
timestamp: June 01, 2021, 01:32:38 pm
content: Dear all,I'm currently using a PCM1794 audio dac (whith current type outputs).Actually, i'm using it in stereo mode with the datasheet schematic (I/V converter followed by diff amplifier for each channel).If i use the DAC in mono mode, is it possible (a good design practice ?) tu use in parrallel the current sources each outputting the same signal ...L+ // R+L- // R-to increase current strength (and improve signal/noise ratio ?)thank's a lot for your help !
PCM1795 Reset Function - Page 1
Forum section: electronics / beginners

author: avogadro
author_rank: Contributor
timestamp: September 18, 2020, 02:09:41 pm
content: Hello,Im a bit confused with the power-on/external reset function of this DAC. In my circuit im using CS8416 as the receiver and I have the RMCK of CS8416 driving the SCK of PCM1795. Now the datasheet of the DAC says that the initialization sequence for resetting the DAC requires 1024 system clocks and after that the DAC is in its default reset state.From my understanding this pin is only needed to set the registers in the device to their default states after power-on and these default states can be programmed before.Now the problem is that CS8416 is outputting a clock on its RMCK pin only when its receiving audio data and this clock is sync with other data lines to the DAC (I2S). This means that there will be no SCK input to the DAC until the receiver starts receiving some audio data but ideally I should provide a separate clock to DAC just for setting the device to its default state.So my idea is to have an MCU provide this clock and resetting the device then quitting after 1024 clock cycles. I would then have a high-speed buffer to select which clock is applied to the SCK pin (MCU or RMCK) but due to the delay in this buffer I would have to have all the data lines going through this buffer because they are in sync with this clock. Something like this is done in the TI development board but that board provides PC control and I think thats the main reason they have a solution like this. Also Im not sure if this delay will somehow affect the DAC.Other idea is to have a MCU set all the registers over SPI on each power up and just forget about the RST pin but Im not sure if its necessary to run this reset function after power-up or after changing the registers.I assume Im either overcomplicating this and theres a simple solution or Im just not understanding the datasheet that well.Can somebody give me a better idea or correct me if Im wrong?Also Im quite a big noob, this is my first proper project.
PCM2900 suspend flag - Page 1
Forum section: electronics / beginners

author: teus
author_rank: Contributor
timestamp: January 11, 2020, 02:55:56 pm
content: I'm trying to understand the SSPND flag of the USB DAC PCM2900. Does the suspend go active when the USB data lines are disconnected... or when the DAC is connected to a USB host, but the host isn't expecting the DAC to do any decoding?My PCM2900 always has 3.1-3.2V on the SSPND when connected by USB to my PC. Nothing else is connected to SSPND. I was hoping SSPND would go down when there's no decoding going on, because I get a click sound every time I start or stop playing sound. Putting the amplifier IC in suspend, with or without a small time delay, would fix this problem.http://www.ti.com/lit/ds/symlink/pcm2900c.pdf
PDB protection against Battery suply  - Page 1
Forum section: electronics / beginners

author: Vrouuum
author_rank: Newbie
timestamp: September 21, 2018, 04:29:07 pm
content: Hello allI'm looking for some help regarding some drone application.I'm not used to design electronic circuit so please be kind !What I want to do is to protect my drone's electronic from being injured as best as I can.I just had a bad soldering that failed during a crash and created a short circuit on the battery supply leading to an expensive replacement ..So the battery is a 6s lipo which means 6 * 3.7V = 22.2V Nominal. It can be charged between 25.2V and 19.2V.It can deliver 1800mah with a discharging coefficient of 95C. My circuit will only need at maximum 60A in peak so let's say less than 70A to be large.I would like to protect it against short circuit so i guess I need a fuse rated to 70A 32V fast blowing. Does it exist for small application ? I can't install a big one as i have no space. If someone knows a good reference, I have been looking for long ...What I also want to do is to protect the circuit against OverVoltage.I allready have a capacitor that is filtering and smoothing the voltage.Is a DVS diode good to connect on this kind of circuit. I dont want my circuit to blow each time i have some small overvoltage.I would like to limit the voltage of the circuit as much as possible bellow let's say 26V ?How would I do that in an easy and tiny way ?Thanks to all.
PDF/Vector to Gerber? - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: September 10, 2021, 06:24:14 pm
content: Hello, I have a race of a vintage PCB that is a PDF, and I was wondering if there is any way to make that a copper layer in something like Eagle, so I can then generate Gerber files from it? (fine with having to add holes/drill file, just wondering about the copper traces as they are hand-drawn, so very hard to replicate from inside Eagle).Thank you for your time!

author: figurativelythedevil
author_rank: Contributor
timestamp: September 10, 2021, 06:26:45 pm
content: Not sure if it works the same in Eagle, but in KiCad you can import .svg graphics as a copper layer, so if you can clean up the image in something like inkscape and export it to .svg, that might work.

author: peps1
author_rank: Regular Contributor
timestamp: September 10, 2021, 06:51:42 pm
content: Quote from: figurativelythedevil on September 10, 2021, 06:26:45 pmThank you, will take a look at KiCad (hope it has a shallow learning curve!), I should have no problem switching it from PDF to .svg or .dfx in Adobe Illustrator. Thank you!

author: MarkF
author_rank: Super Contributor
timestamp: September 11, 2021, 12:33:26 am
content: You can also import an image as a copper layer in DipTrace.Actually, you can put the image on any layer: signal, silk, mask, etc.

author: peps1
author_rank: Regular Contributor
timestamp: September 11, 2021, 12:41:32 am
content: Quote from: MarkF on September 11, 2021, 12:33:26 amThank you, I will check it out!
PDM Mems Microphones - how fast can they be clocked? - Page 1
Forum section: electronics / beginners

author: ralphrmartin
author_rank: Frequent Contributor
timestamp: November 20, 2018, 06:40:31 pm
content: I want to use a (PDM) mems microphone for some ultrasonic work. None of the datasheets seems to indicate what maximum clock frequency can be used for these devices. Can anyone give me any idea? Typically they are used at a few MHz. Can they be pushed to 10 or even 20 MHz - or more?Please let's not get side-tracked into a discussion of the frequency responses of these devices (some mems devices do target ultrasonics), attenuation in air, etc. Those issues are secondary...Thanks!
PDN design workflow (AC only)  - Page 1
Forum section: electronics / beginners

author: learnfromfailures
author_rank: Contributor
timestamp: February 08, 2024, 12:19:06 am
content: I'm new to PDN design flow. To design a PDN system below the target impedance, I'm trying to follow these steps. Can someone let me know if I'm missing anything ?1) Calculate transient current requirement (delta I)2) Voltage is 1.8v (limit 5% of that)3) Calculate target impedance4) Simulate that PDN system (VRM, decoupling cap, traces and power planes) with that transient current and get impedance frequency response5) Select an LDO and analyze the frequency range. Check if it necessary to constrain the design6) add decoupling capacitor to provide low impedance from VRM frequencies up to almost 100MHz.Am I doing this right ? or going in a wrong path ?How do I choose the value of the caps ? How can I simulate a VRM which has an exact non linear VRM model (inductance especially ) ?
PE on dual adjustable output supply - Page 1
Forum section: electronics / beginners

author: queennikki1972
author_rank: Regular Contributor
timestamp: September 19, 2019, 01:40:05 pm
content: I know from the past I could use PE on the negative or positive side on a single output supply as an external option but this one is different.In this example image provided, it shows each side of the center tapped transformer being positive and negative and sharing the center as ground when only using positive 30vdc or negative 30vdc and getting 60vdc across the + and - combined. My question is, where is PE in this scenario? Can you safely connect PE to the GND pin even though its technically the center of the transformer?Im sure this has been covered but I must have missed it and wanted to provide the drawing to be sure my question was understood.Nikki

author: ledtester
author_rank: Super Contributor
timestamp: September 19, 2019, 01:41:54 pm
content: If the power supply is isolated you can connect PE (physical earth) anywhere.
Peak Detector Circuit Self Resetting - Page 1
Forum section: electronics / beginners

author: N3xus
author_rank: Contributor
timestamp: March 28, 2016, 07:02:14 am
content: Dear all,I am currently facing a problem with one of my circuits and hope that someone can help.Attached you can find the schematic. It is a normal peak detector circuit which resets after about 25ms. This is also shown in the simulation which is also attached. The incoming signal is a 40 kHz Signal coming from an ultrasound receiver plus gain.In the attached pictures TP2_3_1..3 you can find the measurement on the testpoints TP2 and TP3 with my Rigol oscilloscope. There is this strange app. 2V voltage offset. I then measured the voltage directly after the capacitor C10 and saw (Figure TP_2_C10_1) that after the capacitor the voltage offset is introduced.Can somebody explain me why this happens?What can I do do improve the situation?btw: This is a already manufactured print so I hope there is a modification that does not lead to a redesign.Best RegardsArmin

author: amspire
author_rank: Super Contributor
timestamp: March 28, 2016, 07:28:58 am
content: I am not familiar with the LMH6654 myself, but if it is a normal opamp, it has to have a resistor from pin 3 to somewhere - probably ground to provide the input bias for the opamp. Currently, the DC voltage on pin3 looks undefined. The input bias current can be just over 10uA, so assuming you want less then 10mV DC error, a 1K resistor from pin 3 to ground would be good.A resistor in series with the output may improve stability as well.

author: danadak
author_rank: Super Contributor
timestamp: March 28, 2016, 01:08:53 pm
content: From datasheet (also there is a graph in datasheet) discussing Riso.Regards, Dana.

author: N3xus
author_rank: Contributor
timestamp: March 28, 2016, 07:01:04 pm
content: Thanks for your replies so far! I tried to add the resistor which is connected to ground and pin 3 and it worked as expected. Unfortunately I did miss to discover the whole datasheet and so I missed to add Riso but I don't really have the chance to add one in this design. Seems to work without it so I will skip to add one. I also tried to short the DC blocking cap C10 but this did not work as good as when I add the resistor to gnd.Thanks for your fast help!
Peak detector for frequency measurement in a noisy environment - Page 1
Forum section: electronics / beginners

author: Warhawk
author_rank: Frequent Contributor
timestamp: May 20, 2015, 05:55:22 pm
content: Guys, I am experimenting with a noisy signal and trying to gather a frequency of specific peaks.Yes, it comes from my 12V car plug and I want to use it for a simple RPM meter. I do it for fun and experience, nothing else. The car is old Corolla e11 with a four stroke engine. I used my ds1074 scope to take a sample (5 MSPS, 1,2Mpts) of the AC coupled signal on 12V voltage rail in a car.You can see the results below. It can be seen that ignition peaks are significant but simple voltage level triggering would not be sufficient. There are additional random (spurious?) peaks. The difference between the peak of my interest and the other unwanted noise is in the duration. The real ignition peak has about 50us duration. The false one is much shorter.I think it should be enough to measure revolutions between 500 to 6000rpm so frequency corresponds to 33,3 to 400 Hz (RPM/60 * 4strokes).I have few ideas but before I post them I would appreciate your first.Thanks in advance

author: Warhawk
author_rank: Frequent Contributor
timestamp: May 21, 2015, 10:43:18 am
content: Nobody ?

author: bktemp
author_rank: Super Contributor
timestamp: May 21, 2015, 11:14:32 am
content: I would start by adding a low pass filter to remove anything above a few kHz.Then do a FFT using a more useful range (0-10kHz instead of 0-2.5MHz). Then you probably can see the peaks in the spectrum.

author: Tom45
author_rank: Frequent Contributor
timestamp: May 21, 2015, 11:37:01 am
content: Rather than look at the 12 volts how about wrapping a turn or two around one of the spark plug wires to inductively couple to the spark itself? That should give a more distinctive signal.

author: Warhawk
author_rank: Frequent Contributor
timestamp: May 21, 2015, 11:46:06 am
content: Quote from: Tom45 on May 21, 2015, 11:37:01 amThat is a sure thing but strong temptation forces me to try this maybe "no-go" solution. I thing it is a good place where to get more experience in signal conditioning and processing.

author: Marco
author_rank: Super Contributor
timestamp: May 21, 2015, 12:29:55 pm
content: Bandpass filtering, center frequency around 30 kHz I think but needs experimentation, should get rid of the spurious spikes and the low frequency stuff. Then threshold it, then calculate time between pulses independently for each pair of signals above threshold for the last X signals and median filter the result (or use some more sophisticated outlier rejecting filter, I can't offhand remember one at the moment).Autocorrelation would be more precise, but that's going to take a fair bit of processing power.

author: Warhawk
author_rank: Frequent Contributor
timestamp: July 07, 2015, 08:00:05 am
content: Update:So, the idea works, somehow :-)I am probably the first guy in the world with Fluke 83-V in his car turned into RPM meterBut it still needs some modifications. At the moment it goes only from 500-3100rpm.
Peak detector - Page 1
Forum section: electronics / beginners

author: thefatmoop
author_rank: Contributor
timestamp: May 30, 2013, 01:18:28 pm
content: Hey everyone,I'm trying to make a peak detector to detect the maximum amplitude of a 1kHz to 100kHz - possibly up to 500kHz sine wave. I followed the peak detection circuit herehttp://en.wikipedia.org/wiki/Precision_rectifierbut looks like my 4Mhz op amphttp://www.adafruit.com/products/808can only do peak detection up to about 20Khz or so. I'm using a 1N1418 for the diode.Video demonstrating limitationshttp://youtu.be/MzKXaQ6AHoMSo looks like I need an op amp with more bandwidth. If that's the case, does anyone know of a good/semi cheap 8pin DIP MOS (single rail psu) op amp to do the job?

author: thefatmoop
author_rank: Contributor
timestamp: May 30, 2013, 01:56:54 pm
content: Here's what i've narrowed the choices down to so farhttp://www.digikey.com/scripts/dksearch/dksus.dll?pv1291=862&FV=fff40027%2Cfff800dd%2C1140050%2C7b80007%2C7b80008%2C7b8000c%2C7b8000e%2C7b8000f%2C7b80010%2C7b80012%2C7b80015%2C7b8001a%2C7b80025%2C7b80027%2C7b80039%2C7b8004a%2C7b8009b%2C7b800ae%2C7b80101%2C7b8016c%2Ca4c0081%2Ca4c00a7%2Ca4c00e6%2Ca4c0123%2Ca4c0178%2Ca4c019a%2Ca4c01e0%2Ca4c01f0%2Ca4c024f%2Ca4c0268%2Ca4c0290%2Ca4c02b9%2Ca4c02e4%2Ca4c02ea%2Cc340002%2Cc340003%2Cc340004%2Cc340006%2Cc340009%2Cc34000a%2Cc34000e%2Cc34000f%2Cc340010%2Cc340014%2Cc340016%2Cc340019%2Cc340020%2Cc340021%2Cc340022%2Cc340023%2Cc340024%2Cc340025%2Cc340027%2Cc34002b%2Cc340030%2Cc340031%2Cc340033%2Cc340038%2Cc34003c%2Cc340042%2Cc340044%2Cc340045%2Cc340048%2Cc340049%2Cc34004d%2Cc340054%2Cc340061%2Cc34006b%2Cc34006c%2Cc34006f%2Cc340073%2Cc340077%2Cc340078%2Cc34007a%2Cc340090%2Cc340092%2Cc340093%2Cc34009d%2Cc3400a4%2Cc3400a5%2Cc3400a8%2Cc3400a9%2Cc3400ba%2Cc3400bb%2Cc3400be%2Cc3400c0%2Cc3400db%2Cc3400e9%2Cc3400eb%2Cc3400f0%2Cc3400f2%2Cc3400f3%2Cc3400f8%2Cc3400f9%2Cc340112%2Cc340113%2Cc340123%2Cf3c0002%2Cf3c0003%2Cf3c0006%2Cf3c000d%2Cf3c0018%2Cf3c0019%2Cf3c001a%2Cf3c001e%2Cf3c001f%2Cf3c007b%2Cf3c0094&k=op-amp&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25big link is BIIIIIIGGGG

author: qno
author_rank: Frequent Contributor
timestamp: May 30, 2013, 02:12:48 pm
content: Use the improved version from Wikipedia.It will have higher bandwith and ledd slew rate limits.
Peak ESR70, calibrated or not ? - Page 1
Forum section: electronics / beginners

author: Erincka
author_rank: Newbie
timestamp: August 29, 2021, 05:25:13 pm
content: Hello, I wanted to buy a Peak ESR70, there are two versions, one calibrated at 100 €, the other normal classic at 60 €, is it necessary to take the calibrated version? Thank you

author: bd139
author_rank: Super Contributor
timestamp: August 29, 2021, 05:39:47 pm
content: They are both calibrated after they are assembled. One just has a bit of paper with it so it can be filed as traceable cal. So no you don't need the calibrated version

author: Erincka
author_rank: Newbie
timestamp: August 29, 2021, 06:43:37 pm
content: Thanks you just saved me 40 €, how do you know that? If you have other more interesting alternatives in these prices do not hesitate, I think it is one of the best

author: bd139
author_rank: Super Contributor
timestamp: August 29, 2021, 06:50:58 pm
content: I asked them about it when I bought one of their products a few years back. Can't think of anything better TBH. Their products are excellent as a whole. I have an LCR45 which I rather like.
Peak hold vs anti-aliasing in DSOs - Page 1
Forum section: electronics / beginners

author: Sigmoid
author_rank: Frequent Contributor
timestamp: September 11, 2013, 05:41:44 pm
content: Hey,I'm wondering about the aliasing in DSOs, and the various ways to avoid it. I saw the Rigol DS1052 vs 2000 series comparison, with the anti-aliasing in the 2000 demonstrated, and I'm wondering how they do it.I'm guessing if you turn on peak hold, it should essentially remove aliasing, right? Is that the way better scopes do anti-aliasing?

author: Lukas
author_rank: Frequent Contributor
timestamp: September 12, 2013, 05:47:41 pm
content: Quote from: Sigmoid on September 11, 2013, 05:41:44 pmNope, since better scopes provide statistical information (aka intensitiy grading) of the sigal. My guess (based on what HP wrote in some HP Journal issue, don't remember which one) is that they run the ADCs at full speed all the time and instead of taking every nthsample they take every n+-random valueth.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: September 12, 2013, 07:43:10 pm
content: Quote from: Lukas on September 12, 2013, 05:47:41 pmThat makes a lot of sense.
Peak to peak voltage from an audio jack - Page 1
Forum section: electronics / beginners

author: mathk
author_rank: Contributor
timestamp: May 09, 2012, 06:05:47 pm
content: All is in the subject. I have done some search on google here and there but did not found any answer. So what is the typical peak to peak voltage of an audio jack?I have the idea to do a project that would take the audio sound out from my laptop sample it and transmit it wirelessly to my home cinema.Any advice are welcome.i just want to do it for fun and practice so it might sound pointless for you.

author: SeanB
author_rank: Super Contributor
timestamp: May 09, 2012, 06:18:02 pm
content: Nominally it should be 700mV RMS ( 2V peak to peak) into 600R but often it varies from manufacturer to manufacturer, it can be 150mV into 1k to 5V ( BMW head ends).Laptop audio out is normally meant to drive 32R headphones, so at max it will be around 4V P-P, with some pretty bad distortion. At a more sane level it will be 0.7V RMS, and use a load resistance of around 1k, so it will pretty much work direct into the audio side of the transmitter. Quality will not be the best, is it not possible to use an USB cable and an USB audio device instead?

author: mathk
author_rank: Contributor
timestamp: May 09, 2012, 06:23:36 pm
content: It is a macbookpro.Spec says: Audio line out/headphone minijack (digital/analog)What would digital means?

author: saturation
author_rank: Super Contributor
timestamp: May 09, 2012, 08:01:55 pm
content: Mostly probably dual analog and S/PDIF optical. Most all PCs with analog earphone jacks are mostly TOSLINK optical capable using S/PDIF cables. Its the consumer version for optical quality audio output.Quote from: mathk on May 09, 2012, 06:23:36 pm

author: T4P
author_rank: Super Contributor
timestamp: May 10, 2012, 03:32:11 pm
content: Quote from: mathk on May 09, 2012, 06:23:36 pmSPDIF i had that on a HP laptop before , you could see the laser if you inserted the jack slowly

author: mathk
author_rank: Contributor
timestamp: May 13, 2012, 09:13:34 pm
content: Quote from: SeanB on May 09, 2012, 06:18:02 pmThanks SeanB. Would it be difficult to build my own USB Audio device? And if yes what do you recommend for my project?

author: Psi
author_rank: Super Contributor
timestamp: May 14, 2012, 01:08:52 am
content: If you plan to sample it why not just use the digital out, then the sampling part is already done.

author: electroguy
author_rank: Regular Contributor
timestamp: May 14, 2012, 11:36:01 pm
content: I also agree using digital output, saves you the trouble of sampling.Good luck. If you don't get your project working, buy a ready made audio transmitter for $5 to $8. Plenty for sale on ebay.You can even get USB to FM. Or audio to blue tooth and then convert blue tooth back to audio.
Peaks in PDN frequency-impedance profile - Page 1
Forum section: electronics / beginners

author: matrixofdynamism
author_rank: Regular Contributor
timestamp: July 02, 2023, 01:09:04 pm
content: The PDN is dominated by different parts of the PCB at different frequency ranges. This includes the bulk capacitors, decoupling capacitors, PCB plane capacitance, parasitic inductance and capacitance on the PCB, capacitors inside the IC packages (if they exist) that are closest to the die and thus effective at the highest frequency ranges.The combination of all these gives us a curve that could look something like the attached image.From what I know, we would like a flattened PDN profile. This means that the peaks must not be very sharp. There is also the concept of target impedance that I am trying to understand. The question here is, what problem do sharp peaks in impedance profile create? Why is this a problem at all that we need to flatten the profile? This could be done by adding some resistance possibly via controlled ESR capacitors but I am not sure about other methods.

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: July 02, 2023, 02:14:22 pm
content: Sharp peaks are signs of resonance. If your current waveform has the same frequency content at which the PDN is resonant, then your voltage ripple can become very high. If the current waveform is periodic with any harmonic content falling within the peak, then the voltage will keep building up and reach a point where your circuit can malfunction. It is like a resonant circuit which gets periodic supply of energy which is in phase with its oscillation. Sharper the peak, higher the Q and lower the damping. This means increased peak voltage drops.

author: matrixofdynamism
author_rank: Regular Contributor
timestamp: July 02, 2023, 03:17:46 pm
content: If I see a graph that shows V-I characteristics, the gradient of the curve shall represent resistance (assuming V is on Y-axis). If there are peaks in this graph, I can see that at some places if we have AC signal, a small change in current shall lead to a change in voltage. This makes sense.I am not able to relate an impedance-frequency profile with the concept of large voltage drops across a component. How is this link made mathematically?

author: joeqsmith
author_rank: Super Contributor
timestamp: July 02, 2023, 03:37:43 pm
content: Quote from: matrixofdynamism on July 02, 2023, 01:09:04 pmEmissionsThere are lots of very good videos on this subject. Some of the better ones I have watched were from Steve Sandler and Eric Bogatin.I attempted to use one of those $50 VNAs to make some PDN measurements and work some examples.

author: jmw
author_rank: Frequent Contributor
timestamp: July 02, 2023, 04:14:51 pm
content: QuoteOhm's law: \(V=I Z\)The load attached to the PDN appears in series with the PDN's impedance and forms a voltage divider. Any transient current (noise pickup, surge demand from component) passing through the PDN's impedance causes a voltage drop across the PDN that is seen by the load.
Pearl CM2000 - electret microfone. Phantom power? - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: August 18, 2015, 09:28:30 am
content: Hello,So i've got a 70s vintage Pearl CM2000 electret - condenser microphone that has a battery compartment for a 1.5V AA battery. It connects via XLR jack on the bottom. I've yet to power it on, however I wanted to know if I need to supply 48V phantom from my mixer?The fact that it is powered would suggest that I do not, and I don't want to give it phantom and fry it. Is the battery a pre-amp circuit thus bypassing the need for phantom power to the mic? If I give it phantom, will it fry? Or will it just amplify the signal even more?Thanks,

author: flynwill
author_rank: Regular Contributor
timestamp: August 18, 2015, 01:28:29 pm
content: If it has a battery, then the answer is almost certainly "no it doesn't need phantom power". Before phantom power became common, Electret mics with batteries like you've found were fairly common. Look close at the battery compartment for labels, many of these took 9 or 18V cells not AAs.

author: Zero999
author_rank: Super Contributor
timestamp: August 18, 2015, 04:59:07 pm
content: An electret microphone doesn't need a 48V phantom power supply. The electric field is provided by an electret (the electrostatic analogue of a permanent magnet), hence the name.The 1.5V battery is required to power a JFET pre-amplifier, as the output impedance from the microphone transducer is so high, even the capacitance of a short piece of cable would attenuate the signal below the noise floor.