hybridfree/eevblog-posts huggingface dataset:
Using USB3.0 and USB2.0 data lines on a Type-C connector separately - Page 1
Forum section: electronics / projects

author: rents
author_rank: Newbie
timestamp: July 28, 2024, 05:26:44 pm
content: Hi all,My idea is to connect the USB2.0 lines to an USB2.0 hub IC and connect the USB3.0 data lines to an USB3.0 device. This way i will have 3 more USB2.0 ports. I have looked at some USB3.0 hub ic's (USB5533B and TUSB8040 to be precise) and it looks like there is two separate hubs for USB2.0 and USB3.0 inside the IC. I don't need more than one USB3.0 so i have come up with this.Can i use USB2.0 and USB3.0 separetly? Will this couse enumarating issues for the USB3.0 device? Can i get away with this or do you recommend i should just use an USB3.0 hub IC? I have attached a block diagram;

author: Aiy
author_rank: Regular Contributor
timestamp: July 28, 2024, 07:18:50 pm
content: Hi there,Here is a link to a whitepaper which discusses this kind of solutionhttps://numato.com/kb/usb-3-0-a-cost-effective-high-bandwidth-solution-for-fpga-host-interface/Best regards

author: rents
author_rank: Newbie
timestamp: July 29, 2024, 04:35:10 pm
content: Yea thank you. I didn't see this before. It's nice to see someone else thougth of this aswell

author: spostma
author_rank: Regular Contributor
timestamp: July 29, 2024, 07:43:31 pm
content: You can passively split an USB3.0 port into an USB2.0 only and an USB3.0 only port, but without Power Delivery so 5V bus only.https://nl.aliexpress.com/item/1005005144932848.htmlI have attached the schematic of a similar splitter PCB with a Type-C socket to the host and a dual Type-A socket to fixed USB3 and USB2 devices,but the schematic has incorrect values for R90 and R91, which should be 5K1 and unpopulated, respectively for an upstream facing USB port.Microchip AppNote AN1953 explains the required resistor values clearly.

author: rents
author_rank: Newbie
timestamp: August 01, 2024, 05:56:33 pm
content: Thank you. Wouldn't have thinked that receive and transmit signals cross connected.
Using VDIP1 to communicate with GPIB controller - Page 1
Forum section: electronics / projects

author: franciscoPT
author_rank: Contributor
timestamp: February 27, 2025, 03:59:59 pm
content: Hi im working on a project where we need read data from a Hioki equipment from the GPIB, we have a GPIB to USB converter from prologix and on our PCB i have a STM32F401 microcontroller, we have bought a VD1P module to communicate with the prologix by USB and to the microcontroller by UART but im not being able to get the VD1P module to work. We chose this because of being able to be a USB host wich is needed because of the prologix, we also have tried with a simple FTDI FT232RL but didnt work because of not having a host on the USB line. Does someone have experience with this type of module ?

author: fchk
author_rank: Frequent Contributor
timestamp: March 01, 2025, 02:36:48 pm
content: USB comes with several standard predefined classes like keyboard/mouse, basic printers, hubs, mass storage,... If a device uses one of the standard classes you don't need a driver.However, most USB-serial chips don't use the standard USB CDC-ACM class but need a specific driver from the chip manufacturer. FTDI is one example, and a FTDI chip is used for the USB side of the Prologix adapter. It's very difficult to use vendor specific USB devices with something other than Windows/Mac/Linux (or for whatever the vendor provides drivers for). The VD1P module won't solve this problem for you.It's easier to implement GPIB directly on your STM32. GPIB is over 40 years old, has lots of open accessible documentation, and works well on hosts with very limited computing power. You will need about 20 free GPIO pins and strong level shifters (my recommendation: 74LVC8T245, they can provide ±32mA on a 5V supply). If you don't have the 20 or so free GPIO pins you need to choose a bigger package. STM32F4's are available with up to 216 pins.There are GPIB-RS232 gateways commercially available, which might work for you, but they are very expensive (>1000€).
uSupply - alternate design - Page 1
Forum section: electronics / projects

author: BCard
author_rank: Newbie
timestamp: September 20, 2018, 03:59:52 am
content: I needed a battery powered supply that used stuff I had available i.e. low-cost 8x2 character LCD, ADC, and DACs.The attached design follows Dave's with some changes.I have prototypes, but so far have operated them in manual mode i.e. using Pots.Attached is the design.Reviews and comments are welcome!

author: 001
author_rank: Super Contributor
timestamp: September 20, 2018, 05:03:51 am
content: looks goodand what is "original uSupply"?

author: wilfred
author_rank: Super Contributor
timestamp: September 20, 2018, 05:14:22 am
content: Quote from: 001 on September 20, 2018, 05:03:51 amYou have to go back to EEVBlog #221 for the story of the original PSU design. It was quite a saga. There is work going on on a new generation version. EEVBlog #1055 is related to the new version.

author: 001
author_rank: Super Contributor
timestamp: September 20, 2018, 06:08:55 am
content: did You mean videos?Can I read/see schematics anywere else?

author: BCard
author_rank: Newbie
timestamp: September 20, 2018, 05:07:38 pm
content: Dave's original project is at:https://www.eevblog.com/projects/usupply/My version uses a modified voltage and current monitoring method.Also, the battery holder is mounted to the rear of the PCB for convenience.The board+ battery holder is designed for BUD Industries plastic enclosure CU-1874-B

author: Kleinstein
author_rank: Super Contributor
timestamp: September 20, 2018, 05:39:23 pm
content: Daves original µSupply circuit does not work well in current regulation mode. This is a common problem with circuits that try to add an adjustable current limit to a voltage regulator chip. So likely there is no good easy fix to this. It would be more like a completely different design, avoiding a regulator chip like LT308x.

author: BCard
author_rank: Newbie
timestamp: September 20, 2018, 05:57:55 pm
content: Agreed.This version relies on firmware to provide programmable current limiting.I have no data yet as to the reliability of this approach, but the LT3080's built-in current limit will kick in to prevent smoke.

author: Howardlong
author_rank: Super Contributor
timestamp: September 20, 2018, 06:04:29 pm
content: Very nice!For true travel use, the cherry on top would be an option for USB charging, looks to me like you have plenty of space left on the board to implement that

author: BCard
author_rank: Newbie
timestamp: September 20, 2018, 07:53:16 pm
content: I'll investigate if the charger circuit will work off 5V from the USB and post a reply.
uSupply, Elektor Professional lab PS - Page 1
Forum section: electronics / projects

author: dougg
author_rank: Regular Contributor
timestamp: October 01, 2014, 03:15:56 pm
content: In the September 2014 edition, Elektor have published a 'Professional Lab Power Supply' project. It takes a dirty 12 volt input, typically from a ATX desktop PS, inverts, transforms and rectifiers it to a voltage about 2 volts above what it wants, then sends it through a linear regulator. So it has electrical isolation between the input and output and claims up to 70% efficiency.Is there anything uSupply could learn from this Elektor project? For example it gets around op amp voltage rail problems by using several DC/DC converters to obtain +- 15 volts.For those that can't see the schematic, it uses an Atmega32 for control, and opto-couplers for feedback. The output voltage is 0 to 30 volts, adjustable in 10 mV steps while the output current is 0 to 1 amp, adjustable in 10 mA steps. IMO more current (say up to 2 amps) at lower voltages would be useful.

author: Marco
author_rank: Super Contributor
timestamp: October 01, 2014, 03:24:56 pm
content: Quote from: dougg on October 01, 2014, 03:15:56 pmReally? I could see designing a bench supply by buck/boosting an ATX supply, but inverting to use standard transformer action seems a bit silly.

author: mikerj
author_rank: Super Contributor
timestamp: October 01, 2014, 04:58:08 pm
content: Quote from: dougg on October 01, 2014, 03:15:56 pmThe uSupply was supposed to be a reasonably simple design. Adding in multiple switching regulators to move the supply rails outside an op-amps required output swing is fine, but it adds complexity and cost.
uSupply revisited - Page 1
Forum section: electronics / projects

author: matherp
author_rank: Contributor
timestamp: March 09, 2016, 12:38:55 pm
content: I've built and tested a version of Dave's power supply. My version doesn't try to be clever with batteries but is intended for use with an old laptop brick as the power source. Full details including fully worked code (to run on the Micromite) is available herehttp://www.thebackshed.com/forum/forum_posts.asp?TID=8417&PN=1&TPN=1The user interface uses a colour TFT display and touch-screen input

author: spacedementia87
author_rank: Contributor
timestamp: August 02, 2016, 11:43:37 pm
content: Hello, thanks for this post. I have been looking to build a power supply like this but Dave's blog fizzled out and I had no idea how to start the software or mod it to run off a laptop brick!How easy would it be to adjust it to just use a 16x2 LCD?Sent from my ONE A2003 using Tapatalk

author: b_force
author_rank: Super Contributor
timestamp: August 03, 2016, 12:02:37 pm
content: Quote from: wilfred on August 03, 2016, 12:18:24 amI have actually never seen real tests with the step up convertor which is in Dave's design.The ripple of step up convertors is pretty high, so it could be that ripple at the output of the regulator isn't going to be very nice because the ripple rejection isn't very good at these frequencies.
Usupply speculation - Page 1
Forum section: electronics / projects

author: nealz
author_rank: Unknown
timestamp: March 29, 2019, 02:25:06 am
content: Like many trashy Newspapers let’s speculate on the Usupply specifications and features.Idea here is to have fun. Let’s avoid giving David advise on how he shoud build the UsuppyMaybe David can give free unit go a patreon guest that guesess closeHere is my Guess of technical specifications:unit will supply3.3 / 5 /7.5/9/12 ranges possibly moreunit will this in the 0-3 amp rangeCUSTOM DISPLYHAND image WILL BE SOMEWAE on the systemunit can be hacked to output will out 121GW ofpower. Accessories not incudedUSB or battery suppied[/list]
uSupplyBenchRevB - Page 1
Forum section: electronics / projects

author: Sivand12
author_rank: Contributor
timestamp: November 18, 2014, 11:25:15 am
content: I made a bench supply based on thishttp://www.eevblog.com/uploads/uSupplyBenchRevB.pdfand ATxmega32E5. There is error in that schematic. Current set opamp inputs are wrong. In the revAhttp://www.eevblog.com/uploads/uSupplyBenchRevA.pdfthey are right. Sadly I trusted too much to that schematic and made my PCBs before noticing that but it can be fixed with two jumper wires.

author: janengelbrecht
author_rank: Regular Contributor
timestamp: November 18, 2014, 11:40:19 am
content: The rule in the business are...never trust anyone but yourself
uSupplyBenchRevB - Page 1
Forum section: electronics / projects

author: Jippu
author_rank: Newbie
timestamp: October 07, 2014, 08:41:58 am
content: I made a bench supply based on thishttp://www.eevblog.com/uploads/uSupplyBenchRevB.pdfand ATxmega32E5. There is error in that schematic. Current set opamp inputs are wrong. In the revAhttp://www.eevblog.com/uploads/uSupplyBenchRevA.pdfthey are right. Sadly I trusted too much to that schematic and made my PCBs before noticing that but it can be fixed with two jumper wires.
UT61E Li-Ion Conversion and RGB Backlight - Page 1
Forum section: electronics / projects

author: h3po
author_rank: Newbie
timestamp: December 15, 2015, 02:45:23 pm
content: Hi Everyone!I want to convert my UT61E to a rechargeable battery and add a backlight. As I later plan to also add an AVR to extend the button functions, I was thinking of using 3x RGB LED for the bl and allow me to indicate status by changing the color.The LED i have in stock are PLCC4 common anode, Red 2V@30mA, Green 3.5V@20mA, Blue 3.6V@20mA. Sadly there is no datasheet, but from similar devices I guesstimate that they have about 100mA peak current at 10% duty Cycle and 1kHz.For batteries I have a pile of (new, fake) 700mAh protected Nokia phone cells and appropriate charge modules for 1S and 2S.Now I'm wondering, since the meter needs at least ~5.6V, should I:a) use a 1S battery and a boost converter to power the meter, risking problems with noise orb) use a 2S battery and piss away half of the power in LED current limiting resistors orc) use a 2S battery and PWM drive the led without current limiting?I whipped up a circuit with 2N7002 N-MOS for quick testing, currently with 100e current limiting between Source and GND (see attachment).Looking forward to your suggestions, thanksedit: found thedatasheet, the maximum ratings are 70/30/30mA and 100/250/200mA at 100kHz and 0.5% duty cycle.edit: it just came to my mind that I could also use the avr to create a 3.7V buck converter, but that's something i've never tried.
Utility of ferrite tiles / sheets for inductive charging - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: July 19, 2025, 03:28:34 pm
content: Commonly available inductive charging coils (both transmitter 'Tx' and receiver 'Rx') employ a ferrite backing plate.Is this only to suppress EMI issues or does this improve power transfer efficiency?What would happen if the tile was "only at Tx" - would this still be better than no tiles at all?Same question for "only at Rx"Why are distinct (presumably having different properties) Tx & Rx coils made - is it basically Tx has to cope with more currrent?https://www.mouser.co.uk/c/passive-components/inductors-chokes-coils/wireless-charging-coils/?number%20of%20coils=1%20Coil%2C%201%20Layer~~1%20Coil%2C%202%20Layer&rp=passive-components%2Finductors-chokes-coils%2Fwireless-charging-coils%7C~Number%20of%20Coils&sort=function%7C1

author: MariuszD
author_rank: Regular Contributor
timestamp: July 19, 2025, 05:55:22 pm
content: A ferrite plate improves the coupling coefficient. In other words, it focuses the field on the coils and limits the penetration behind the coil. This improves efficiency.In tightly packed portable devices, behind the ferrite plate, there is a PCB. Ground plane on the PCB close to the coil is like shorted winding

author: bson
author_rank: Unknown
timestamp: July 20, 2025, 08:01:33 pm
content: It's a dielectric spacer. It being ferrite doesn't matter - copper could be used too, and it is neither iron-based nor magnetic. The choice of a ferrite probably is so a charger can adhere to it magnetically.

author: johansen
author_rank: Super Contributor
timestamp: July 20, 2025, 09:07:33 pm
content: It significantly increases the coupling because because it is nearly effortless for the magnetic field to flow through the 1000+ permiability ferrite compared to flowing through the air to get to the coil.magnetic circuits are sort like hydraulics in the sense that its hard for many people to understand the cubic flow rate friction relationships.except magnetic fields drop off even faster.Imagine a pressure washer being used to spin a generator 50 feet away, and lets say, 5% of the water hits the pelton wheel and of that, only 40% of the kinetic energy is recovered and then of that, only 80% of that is recovered.that's sort of what its like to try and charge a phone from a coil 2 inches away.so here's an example coilhttps://www.mouser.co.uk/ProductDetail/Wurth-Elektronik/760308104113?qs=qtDkSVtAUTsFSydUa0dmIg%3D%3D12uh at 8 amps at 125khz is 75 VA of power flowing, and more importantly, the dc resistance of the coil alone will be dissipating 5 watts.lets say you can get 10 watts out of the phone coil a few millimeters away. so the efficiency at best might be just 70%.without the ferrite backing plate on both the sender and the receiver, you might get 1watt.
UTP SW for Arduino  - Page 1
Forum section: electronics / projects

author: AGRAIL
author_rank: Contributor
timestamp: February 20, 2017, 06:06:40 pm
content: After many project with different register configuration just to verify some ideas before ordering parts I start thinking about some universal project for desing verification .So idea was to configure MCU just using terminal windows .Project was done on AS7 and it`s Arduino based as it cheap and many use it . Also document with commands under link below.If someone has additional ideas what can be added to increase functionality - thanks in advance .Need to finalize project in AS7 and will be also attached later<img src=http://www.filedropper.com/download_button.png width=127 height=145 border=0/><div style=font-size:9px;font-family:Arial, Helvetica, sans-serif;width:127px;font-color:#44a854;> <a href=http://www.filedropper.com >online backup</div>

author: AGRAIL
author_rank: Contributor
timestamp: February 27, 2017, 07:47:55 pm
content: AS7 project atached - maybe someone can advice what other usefull function can be added .All function was verified in Proteus , some of them on Uno PCB .
UV-sensitive negative photoresist with 50µm resolution? - Page 1
Forum section: electronics / projects

author: mavey
author_rank: Newbie
timestamp: December 29, 2014, 05:26:26 pm
content: Hello,I'd like to pick your brains regarding your experience with super-fine detail etching using a negative photoresist.I built a laser positioning system with a 405nm UV-blue (Blu-ray) laser head for automated direct printing of PCB (i.e. not etching/milling). The laser exposes the UV-sensitive layer after which the PCB is etched as per usual. The PCBs I use in this process are standard FR4 with thinner Cu plating (18µm, i.e. ½ oz), but I'm having a real difficulty finding a reasonably priced photoresist capable of such resolution. The etching process itself is not a problem since the thin plating in combination with a rapid etching technique allows for short enough times that almost all resists survive undamaged.In my desperation, I've been coming up with even such exotic notions as dusting the PCB with a thin layer of fine laser toner and having it laser-melted onto the board.That one has yet to see the light of day, but it may illustrate how badly I need your collective expertise!Thanks!
UV sensor size, why is bigger better? - Page 1
Forum section: electronics / projects

author: aris
author_rank: Newbie
timestamp: April 28, 2014, 09:36:05 am
content: Hello,First post follows:I have been looking at some UV sensors for a little project of mine. I settled on a little breakout board by DFrobot which uses the GUVA-S12SD UV-A sensor and my project is working. Then, a few days ago I discovered a breakout board from Sparkfun that uses the ML8511 UV-A/B sensor.From the specs, the sensor size of the GUVA-S12SD is 0.076 square millimetres.From looking at the photos the sensor size of the ML8511 is about 1 square millimetre.Though either sensor would be good for my project,what would the advantages be of a significantly larger sensor area?My project is a little UV light integrator for screen printing. It will be used to indicate the correct time to expose emulsion coated screens under sunlight regardless of time, angle and cloud cover.Thanks!Here are the links to both modules:https://www.sparkfun.com/products/12705http://www.dfrobot.com/wiki/index.php/UV_Sensor_(SKU:TOY0044)

author: David Hess
author_rank: Super Contributor
timestamp: April 29, 2014, 10:04:57 am
content: Larger sensors in general have lower noise and higher sensitivity but usually at the expense of slower response.

author: ajb
author_rank: Super Contributor
timestamp: April 29, 2014, 04:47:45 pm
content: Note that sensor size is not the only difference between those two--they also have different spectral responsivity. The GUVA drops off gradually from 320nm to 240nm, whereas the ML8511 has a sharp dropoff at ~290nm. This may not matter much, since sunlight at sea level drops off pretty sharply below 320nm, but ideally you'd want to pick a sensor with a responsivity curve that matches the relative effectiveness of the wavelengths you're monitoring as closely as possible. In your application, you'd likely need to look at the absorption spectrum of the emulsion you're using. Since I imagine you'll be integrating over a fairly long time span (minutes? hours?) the response time and noise errors of the sensors should tend to average out over the integration period, but a mismatch of sensor and process spectral response could integrate into a substantial error.
UV-VIS - Page 1
Forum section: electronics / projects

author: olsenn
author_rank: Frequent Contributor
timestamp: February 03, 2014, 09:57:55 pm
content: Does anybody know of a good variable wavelength light source and meter? I would like something reasonably cheap that I can hook up to my spectrum analyzer and measure the properties of chemicals. Nothing too fancy, just to play around with

author: electronics man
author_rank: Frequent Contributor
timestamp: February 03, 2014, 10:03:46 pm
content: I have been looking for one too and have found nothing I want to analyse some chemicals as well.

author: calzap
author_rank: Frequent Contributor
timestamp: February 04, 2014, 12:32:26 am
content: Why not buy a used spectrophotometer on eBay? Analog Spectronic 20s can be had for US$100 or less; digital for US$200 or less. Documentation is easily found.Mike in California

author: SpectrHz
author_rank: Contributor
timestamp: February 04, 2014, 02:11:21 pm
content: HPLC uv/vis detectors can be had fairly inexpensively from ebay, I picked up a uv/vis absorbance detector for a measly 20 dollars because they "couldn't test." My detector was complete and functioning with a deuterium source and scanning monochromator.
UVLO with "zero" standby current in case of undervoltage. - Page 1
Forum section: electronics / projects

author: rsd
author_rank: Newbie
timestamp: January 06, 2021, 06:25:43 pm
content: I am looking for a circuit to protect battery powered devices. It should be able to switch off power supply in case of low voltage and remain off until the battery is removed and plugin in again.The under-voltage detection itself is not final my circuits. It is just for reference, i don't know exactly what i will use in the end.Since i am looking for minimal current consumption after shutoff i powered all circuits behind the power switch. The only leakage after shutoff is the mosfet leakage itself.I designed the circuit which uses a p-channel mosfet for the power switch first and then moved to the n-channel version. I would like to use an n-channel for the power mosfet.I am asking for some tipps or concerns of the internetIn the end I can not be the first one to need a circuit like that so be free to show your google skills, which i don't seem to have.With the p-channel circuit I am kinda happy, but the n-channel circuit is in my opinion just a shit show
V-by-One to DisplayPort (4k60) - Page 1
Forum section: electronics / projects

author: VEGETA
author_rank: Super Contributor
timestamp: May 26, 2021, 12:22:00 am
content: Hello,I am willing to design a product which scales video signals to bigger resolutions, mainly 1080p 60fps and 4k 60 fps.In short, the scaling IC is very powerful but it only outputs via 8-lanes of V-by-One HS.I cannot use HDMI due to licensing, this is never an option unfortunately... despite having VBO-HS to HDMI 4k60 ICs to do the job, but they require HDCP licensing which starts at 15k a year... therefore, I went to look for DisplayPort solution.the most I got is this:Convert VBO-HS 8-lanes to 8 channels of LVDS using 2 of THCV226 IC from Thine (their support directed me to this). However, these signals cannot be fed into any known and well used digital video and audio connection.I am open to suggestions, since this is the only thing left to determine.thanks!
V-mount camera battery I2C sniffing - Page 1
Forum section: electronics / projects

author: ckambiselis
author_rank: Regular Contributor
timestamp: August 01, 2014, 11:29:22 am
content: Hello everyone,I´m trying to make a custom interface to read battery data from an intelligent V-mount camera battery, and translate it to Nikon battery data.The battery uses SMB, I2C data lines, the pins used are the same but the battery switches between the data types automatically. My main problem is that I don´t have access to the insides of the battery to check the IC used for transmitting the data, as it is glue sealed and cracking it open is not an option since the battery is brand new and costs 250 euros :-P.I´m thinking about using a Bus Pirate v4 I just ordered to check if I can read any data, but do I actually need the datasheet of the IC, for the addresses, to be able to get any kind of data or is it possible to get started with some basic commands for ''trial & error'' style searching of the data?Any help appreciated!ThanksOscar

author: amyk
author_rank: Super Contributor
timestamp: August 01, 2014, 12:09:37 pm
content: It's possible they used a standard SBS-compliant standard monitoring IC in which case you'll find the communication makes sense when interpretedaccording to the standard.

author: ckambiselis
author_rank: Regular Contributor
timestamp: August 01, 2014, 03:24:00 pm
content: Quote from: amyk on August 01, 2014, 12:09:37 pmFrom the available messages I see in the Data Specifications sheet, this could be a possible candidate. I will have a look at it when my Bus Pirate arrives.More suggestions are welcome in the meantime!
V-regulator or v-reference for battery powered voltage ladder? - Page 1
Forum section: electronics / projects

author: okw
author_rank: Frequent Contributor
timestamp: November 23, 2024, 09:01:16 pm
content: I'm using a voltage ladder to determine the position of a rotary switch, which is read by a ESP32 (max 2.5V input on the ADC). (It also switches on/off the gadget, that's why I connect it this way).In a first attempt, i just fed the divider directly from the LiIon battery, but the values would greatly differ depending on the battery level, and sometimes overlap if battery is very low, or fully charged. If I carefully choose resistor values, the voltage won't overlap.A better choice would probably be to feed it with a known voltage. I'm looking at both a 2.5V LDO and the TL431.The v-reg is easy to implement, but how would I go about using a TL431?And which would be my best choice, considering power usage? The regulator/reference would always be connected to the battery.

author: Someone
author_rank: Super Contributor
timestamp: November 23, 2024, 09:23:37 pm
content: Cute way to do "off".99% of the time people solve the ratio problem by either:feeding the ADC reference with a ratio coming from the same sourceorreading another ADC channel with a ratio from the same source

author: okw
author_rank: Frequent Contributor
timestamp: November 23, 2024, 09:56:39 pm
content: Quote from: Someone on November 23, 2024, 09:23:37 pmGood advice. I already read the battery voltage from another ADC channel. So I can correct itAny good technique to manipulate the voltage or readings? Battery will probably never go under 2.8V and not above 4.3V, but the ADC is 0 - 2.5V.I don't need high precision (it's just sending the battery voltage as a percentage over bluetooth every 5 minutes).

author: Kleinstein
author_rank: Super Contributor
timestamp: November 24, 2024, 05:20:20 pm
content: The L431 may be a bit cheaper than a votlage regulator, but it is also more power hungry. I would go for a low power LDO, like MCP1702 or similar, that could also power the ESP32. For the different resistor settings one may get away with a chain of mostly equal resistors and this way less resistor values. Some 4 or 5 switch settings is still easy and no real need to read the 2.5 V seprate.
Vacuum fluorescent display multiplexing -- max current?  - Page 1
Forum section: electronics / projects

author: thefatmoop
author_rank: Contributor
timestamp: October 19, 2021, 04:00:51 pm
content: Hi all,I've purchased a few IV-4 16 segment display tubes. I've got an MCU running a boost converter and using the tube grids to multiplex.Question - with 5 tubes multiplexed, my max brightness when driving at the rated current is ~1/5th compared to static driving the tubes at their rated current. Does it put additional wear on the fluorescent material if I just crank up the anode segment voltage, so that the average current is the same as it were for static drive at rated current?Question2 - Running the grids at the same voltage as the anodes creates illumination hot spots (even when running far below rated currents/voltage). I haven't found much information on this sort of problem mentioned elsewhere. Running the girds at let's say 12v where anodes are at 30v decreases overall brightness but removes shadows. Any thoughts on this?

author: David Hess
author_rank: Super Contributor
timestamp: October 19, 2021, 08:38:35 pm
content: I checked a few datasheets and VFDs intended for multiplexing include a duty cycle specification, which I assume means that you must remain within the given maximum current specification.

author: thefatmoop
author_rank: Contributor
timestamp: October 20, 2021, 02:11:58 am
content: Yeah IV-4 has no mention in the translated datasheets i've found. I think you're right. Likely it's how hard electrons are hitting (voltage) the fluorescent material that breaks it down early.

author: David Hess
author_rank: Super Contributor
timestamp: October 21, 2021, 03:24:35 am
content: Quote from: thefatmoop on October 20, 2021, 02:11:58 amThat would be the anode voltage and not the anode current.

author: thefatmoop
author_rank: Contributor
timestamp: October 21, 2021, 08:16:59 pm
content: number of electrons hitting = currentindividual electrons 'speed' = voltageAnyway I found the official datasheet and found another post that clarified things. The IV-4 tubes in static drive = 25v anode, but in 'pulsed' (multiplexing) mode, they allow up to 50v on anodes with a duty equation mentioned. FYI for anyone in the future building with these great little tubes.
Vacuum fluorescent display multiplexing problem - Page 1
Forum section: electronics / projects

author: neo
author_rank: Super Contributor
timestamp: September 19, 2016, 03:40:36 am
content: How on earth are vacuum fluorescent displays that are multiplexed meant to be used? i got so many multiplexed ones lying around and its driving me crazy because i have no clue how to use them, like say i have a 4,7 seg display with arrows below each 7 seg and a : in the middle but it only has 20 pins + the filament pins or another 8, 14 segments and 11 indicators with only 25 pins.

author: edavid
author_rank: Super Contributor
timestamp: September 19, 2016, 04:13:38 am
content: Read all about it:https://www.noritake-elec.com/display/vfd_operation.html

author: neo
author_rank: Super Contributor
timestamp: September 19, 2016, 04:41:29 am
content: But that doesn't say how it just gives basic concept as far as i can see. it does give an example circuit but no actual circuit or even ic numbers.

author: jaycee
author_rank: Regular Contributor
timestamp: September 19, 2016, 04:48:33 am
content: neo, there was indeed custom IC's in the past to drive them, but they are mostly obsolete as any microcontroller can be used.The principle is exactly the same as Common Anode/Cathode LED displays. You drive each grid one at a time for the segments you want lit in that grid, and switch between them very fast. Persistence of vision means that the display appears to be static.

author: neo
author_rank: Super Contributor
timestamp: September 19, 2016, 05:05:32 am
content: Quote from: jaycee on September 19, 2016, 04:48:33 ammy only trouble with micro controllers is their programmers cost about 45 bucks well that and i woudl'nt know how to program even if i had one

author: ebclr
author_rank: Super Contributor
timestamp: September 25, 2016, 07:35:09 am
content: You need only this IC, and a -25V power supplyhttp://www.ec66.com/market/sheet/PT6312.pdf
Vacuum Lifter Automation - Page 1
Forum section: electronics / projects

author: teachme
author_rank: Newbie
timestamp: August 24, 2020, 01:21:18 am
content: I'm designing a simple automated vacuum lifter, from a converted 3D printer.The application: this only requires one movement on the Z axis. The manifold needs to move down, activate air (picking up parts), move back up, and release the parts onto a placed tray.I have little experience with the electronic side of things.I need to program and coordinate the pneumatics with the Z travels/timing, activation, etc.EX:The manifold moves down the Z axis... how do I set up the pneumatic part to activate. Do I need a solenoid valve and how I would integrate something like that, with the rest of the program/setup?Most likely a solenoid doesn't use G-code.
vacuum pump messing with sensitive electronics - Page 1
Forum section: electronics / projects

author: basbr
author_rank: Newbie
timestamp: October 18, 2016, 10:32:20 am
content: hello smart people of the internetlet me start by saying im a young player as dave would say and a bit of a newbie on this subject.the situation is this, we have 5 DLP 3D printers and one vacuum chamber + pump that we use to cure the prints with.every time that we turn on the pump the printers spit out a load of gibberish and stop printing, presumably because of the sudden current draw on startup of the pump.i dont have any equipment to measure the noise it kicks out. it happens mostly on start upright now we can only use the pump when all printers are off/idle and some prints can take up to 40 hoursthe pump: 230V 50hz , 3/4HPwhat is the best way to solve this problem so we can use the pump without affecting the printers.thanks to anyone that can help/steer me in the right direction

author: Jeff_Birt
author_rank: Regular Contributor
timestamp: October 18, 2016, 01:14:00 pm
content: Motors are great electrical noise generators, especially when they start and stop. The electrical noise is both radiated through the air and conducted back down the mains. The extent of each type of noise depends on the type of motor and if it used some sort of electronic speed control.For a simple AC induction motor or 'universal' motor you may be able to get by with plugging the motor into a different mains circuit. Ideally you would want to stop the noise at its source though. The motor itself generates noise and I like to say the first line of defense is to put a line filter on the mains feed to the motor as close to the motor as possible. Here is an example of the type of filters I use for small AC motors:http://www.soigeneris.com/line_filter_kit-details.aspx(this is my website and I am not posting this as advertising, it is just the easiest link for me to find and post).Filtering the AC input to other devices that might be affected is the next line of defense. In my small shop I also used one of these type of filters on the mains going to my shop PC after finding that a small florescent lamp above the workbench would generate enough noise to cause the 5V on the USB bus to go negative briefly.You can find these types of filters inside a lot of different types of equipment so even if it is hard to source in your country or you need one quickly you might be able to salvage one from an old photo copier, etc.
Vacuum Rectifers X-Ray Report - Page 1
Forum section: electronics / projects

author: cdev
author_rank: Super Contributor
timestamp: January 06, 2018, 11:16:46 pm
content: Seems some of those (very) old rectifier tubes are kind of dangerous.http://4hv.org/e107_plugins/forum/forum_viewtopic.php?106277

author: Unknown
author_rank: Unknown
timestamp: January 07, 2018, 12:11:42 am
content: Put 50kV across you and you'd probably emit x-rays too

author: amyk
author_rank: Super Contributor
timestamp: January 07, 2018, 12:22:00 am
content: Bremsstrahlung... a lot of early HV tubes had warnings printed on them:

author: helius
author_rank: Super Contributor
timestamp: January 07, 2018, 12:35:42 am
content: Of note are the warnings printed on CRTs from the 1980s or newer: "This device contains integral protection circuitry. Operation without the protection circuit may emit harmful X-Rays." It refers to the beam current limit and shutdown circuit.

author: floobydust
author_rank: Super Contributor
timestamp: January 07, 2018, 06:52:06 am
content: Old TV's had the "high voltage cage", with6BK4shunt regulator inside.It's rated 25kV to 55kV max. at about 1.5mA. Quite the triodeI hated running TV sets with the cage open, troubleshooting HV problems.

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 07, 2018, 09:22:56 am
content: Quote from: cdev on January 06, 2018, 11:16:46 pmAnything can be dangerous if you don't know what you are doing and it is not practicable to print warning labels on everything. Component manufacturers usually have appropriate warnings in data sheets. Many high power devices use materials internally that are poisonous and carcinogenic yet fools on youtube and elsewhere delight in dissembling them. Components do not have to be old to be dangerous, just in the hands of an idiot is enough!!
VAG-COM compatible OBD reader - Page 1
Forum section: electronics / projects

author: masster
author_rank: Regular Contributor
timestamp: February 28, 2015, 05:52:07 pm
content: HiI have this OBD2 interface:http://www.scantool.net/obdlink-ci.htmland I have been told that with reasonable effort can be modded to be recognized by VAG-COM (VCDS) software from Ross-Tech (http://www.ross-tech.com/). Basically it is about connecting one more pin of DB9 connector to existing circuitry.I couldn't get the schematics of my interface, all I can do is to show you the front/back of the PCB (click for high resolution photos).Can you guide me to mod it, please?
Valentine's day project - Page 1
Forum section: electronics / projects

author: gevv
author_rank: Contributor
timestamp: December 23, 2020, 01:03:56 pm
content: Hi,Atmega8 led heart, df player music box, rgb mood light cardboard ring box demohttps://youtu.be/_e_OXBEYOR8led heart source:hxelfaer.ru/?p=606rgb led:picprojects.org.uk/projects/bigmosfetrgb/index.htm

author: aiq25
author_rank: Regular Contributor
timestamp: December 26, 2020, 01:02:22 am
content: Cool project! I'm working on a LED based heart shaped PCB using RGB LED's.

author: gevv
author_rank: Contributor
timestamp: December 26, 2020, 01:24:20 pm
content: Good idea. Can only be done with RGB effectneed to work

author: gevv
author_rank: Contributor
timestamp: February 05, 2021, 05:07:26 pm
content: Hello all,rgb moon light versionhttps://youtu.be/roYNQEgcK00
Valhalla 2705 operation - Page 1
Forum section: electronics / projects

author: rodd
author_rank: Regular Contributor
timestamp: January 27, 2017, 09:20:23 pm
content: I bought one of these at Ebay for a reasonable price.Unfortunately I had no time to read the instructions and now I have found the I it only works together with a 2703 (actually the main unit).So here is my question:Is there any way to operate the 2705 as a standalone unit.Is it possible to emulate the 2703 signal that is sent to the 2705?ThanksEnviado do meu iPhone usando Tapatalk

author: e61_phil
author_rank: Frequent Contributor
timestamp: January 27, 2017, 10:50:40 pm
content: I own a 2703, so if you have any questions on signals or anything else I can try to measure it. I think you should read the manuals firstYour questions is better placed in the metrology subforum, perhaps.
Validity of HF RF path - Page 1
Forum section: electronics / projects

author: farsidefarewell
author_rank: Newbie
timestamp: February 08, 2025, 06:43:07 pm
content: Hey all! I recently started some work on this direct sampling HF sdr, and i came up with the attached schematic (sorry about the image, I cannot seem to attach the pdf properly). On the input side there is a 30MHz cutoff 8th order chebyshev LPF, with an ideal simulated -51dB attenuation at 50MHz (as this is meant to be 0-30MHz, with a 80MSPS ADC), through a VGA, the ADL5206, then to the ADC driver, the ADA4938-1 set at around 14dB gain, then finally to the ADC differential input itself. However, I am concerned about only having a proper LPF directly at the input. The VGA has its negative differential input decoupled to ground, as it appears to be okay in the datasheet. In addition, the ADL5206 has a datasheet that lists pin 20 as "DNC INTERIM", stating "Do Not Connect. Tie to resistor divider..." Was the resistor divider instruction accidentally left in for testing, or is this a legitimate pin? Now, the datasheet of the AD9641 has a figure (attached below) with a network between the driver (same ADA4938) and the ADC diff inputs. I modeled it, and the response was strange, but perhaps that was just my simulation. What is the purpose of this? Finally, are there better ways to protect against ESD than this TVS across the input?Thanks in advance!(oh no this was meant to be in the RF section of this forum! sorry..)

author: moffy
author_rank: Super Contributor
timestamp: February 08, 2025, 09:55:32 pm
content: The network between the Driver IC and the ADC is a deglitch network, the ADC when it samples the input creates a glitch that needs to be controlled/compensated for which is what the caps are for, the resistors help the driver IC as well.
Valpey Fisher VFT22H-100.00MHz OCXO oscillator output waveform - Page 1
Forum section: electronics / projects

author: rfclown
author_rank: Frequent Contributor
timestamp: November 08, 2023, 03:20:34 am
content: Just got a 100 MHz OCXO on eBay: Valpey Fisher VFT22H-100.00MHz. No item info from seller. Google search didn't find datasheet. I'm not super interested in the specs, but I'm curious about the output waveform. Another eBay seller shows the pinout (picture below). The one ground pin is attached to the can, and the other labeled ground in the picture is indeed shorted to the can. If I current limit my power supply to 100 mA, I get a nice sine wave output... but the compensation doesn't work. If I don't current limit, I see the compensation work, and I can warp the frequency with the control pin. About 0.77 V makes it 100 MHz. But the waveform is wonky. I found another person asking a question about the waveform here:https://www.febo.com/pipermail/time-nuts/2016-January/095792.htmlPicture below shows my waveform with 50 ohm load. Open circuit is also wonkey.Looks like xrunner has one of these:https://www.eevblog.com/forum/projects/recommend-me-an-ocxo/msg663439/#msg663439I don't think the waveform matters so much to me, but it is odd, and wondered if anyone knew about these beasts. After I typed this, I looked back at my purchase and see the seller's description: 100MHz OCXO 20dBm out Step Recovery Diode driver -154dBc/Hz@2KHz OS P.N. VP. So maybe the high output drive is important, and the waveform is not.

author: colorado.rob
author_rank: Frequent Contributor
timestamp: November 22, 2023, 09:23:30 pm
content: Here's a datasheet that shows how to adjust the frequency of some of their other OXCOs:https://www.quartz1.com/price/techdata/VF155.pdf-- looks like it expects a variable resistance to ground from VADJ rather than an input voltage.What is the open circuit voltage at VADJ?
Value for money rotary encoder? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: August 19, 2019, 09:29:20 am
content: I am looking for alternatives, on cost grounds, to the Bournes PEC11.Say 12 detents (not critical) and a push-button (ideally). I'd tend to look on eBay and I hope to avoid really poor quality types by asking for recommendations here.

author: rhodges
author_rank: Frequent Contributor
timestamp: August 19, 2019, 12:37:28 pm
content: I like this Alps rotary encoder. It goes on sale for fifty cents from time to time:https://www.goldmine-elec-products.com/prodinfo.asp?number=G20056I have code for the STM8 here:https://github.com/unfrozen/stm8_libs/blob/master/lib_rotary.chttps://github.com/unfrozen/stm8_libs/blob/master/lib_rotary.hQuote

author: ehughes
author_rank: Frequent Contributor
timestamp: August 19, 2019, 12:50:00 pm
content: Just posting this so it is not forgotten:http://www.mkesc.co.uk/ise.pdfProbably the most robust and simplest decoder I have seen.

author: 741
author_rank: Frequent Contributor
timestamp: August 19, 2019, 01:19:38 pm
content: Thanks all.It is good to know of a "value for money supplier" more stable than eBay, a known make too.I'm currently using firmware incorporating the very neat 'mkesc' code as part of its design.What do you use for pulse cleanup? I found the Bournes RC circuit not so useful, and am using one which recognises the fact that 'noise' = brief signals opposite to switch closed level.That is, for an open switch I do not expect much in the way of spurious closed contacts. However, for a closed swich, the scraping will joggle the wiper to open-circuit in an erratic, noisy manner.Thus far, I have found the attached RC network to be better than that on the PEC11 datasheet.
Value of color coded fuse? - Page 1
Forum section: electronics / projects

author: MattisLind
author_rank: Newbie
timestamp: September 10, 2020, 06:53:47 pm
content: Hello!I am trying to repair an IBM 3279 terminal and as usual for IBM stuff there are no schematics to be found. And since field repair is on the board level the fuse is not in any parts list.The fuse is violet / yellow in the ends. It is in series with the vertical deflection yoke. The vertical deflection system is fed by 25V. No idea about inductance of the coil especially since there is likely to be a problem with the yoke itself. The resistance is far too low.What is a proper value for the fuse?

author: floobydust
author_rank: Super Contributor
timestamp: September 11, 2020, 08:12:03 am
content: I've never seen datasheets on fuses like that, or have a clue who makes it.For that size screen, vertical deflection IC's (i.e.LA7837) are about 2Apk at 24VDC power.I would guess a fast acting Picofuse orTR5or similar 2A fuse. Look at the fuse curves (370) and a 2A part clears 5A in a second or two.

author: MattisLind
author_rank: Newbie
timestamp: September 19, 2020, 10:19:46 pm
content: I happened to be able to solve this mystery when I came a cross a few old 1965 vintage IBM SMS modules in my father's stash of things.Exactly the same type of fuse. Searched a bit and found Ken Shiriff's excellentSMS card databasewhere thisDJLcard was listed!The schematic showed a fuse named GFA 1,5 A.Google "GFA Fuse" gave amatching datasheet!. Seems to be a quite standard Bussmann fuse after all!

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 20, 2020, 03:09:56 am
content: Wait, you have an IBM 3279 terminal?

author: MattisLind
author_rank: Newbie
timestamp: September 20, 2020, 06:39:41 am
content: Quote from: Alex Eisenhut on September 20, 2020, 03:09:56 amYes, I do. The intention is to connect it to the Hercules mainframe emulator. If I get the damn thing working.I had to reverse engineer the PSU to understand it so that I could fix that one. The PSU now seems to work just fine. Then i tried to run the entire terminal but a 200 ohm resistor in the vertical deflection circuit smoked and this fuse blow.Since posting the first message in the thread I have learnt that IBM field service manuals state that the resistance of both defelection coils should be less than 2 ohms. I measured them to be 1.9 for horisontal and 1.2 ohm for the vertical which probably is allright then.So I still have no idea what the root cause of the blown fuse is. Unfortunately the IBM board has five square aluminium covered chips which it seems to be impossible to find a cross for. So reverse engineering it fully will not be possible.My next step is to apply 5V and 8.5V to the card and study parts of the board to see if I can understand vertical deflection better.A schematic would be great but I doubt I ever find one..

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: September 25, 2020, 05:48:51 am
content: Quote from: MattisLind on September 20, 2020, 06:39:41 amSo cool. Do you mean thesehttps://en.wikipedia.org/wiki/IBM_Solid_Logic_Technology