hybridfree/eevblog-posts huggingface dataset:
4-wire Capacitive Touch Controller? - Page 1
Forum section: electronics / projects

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 22, 2020, 05:36:36 am
content: I seem to have found some displays with this type of touch screen attached --1. No, it's not resistive! There is no top conductive film to push down.2. It has a resistive grid just like a 5-wire resistive touch. Silvered contacts route around the edge of the panel, and presumably ITO spans across the viewing area. Four wires connect to the four corners.3. The 5th wire isn't even on the right side! It connects to ITO on the back. Apparently it's just a shield?4. Manufacturer doesn't seem to know anything about it. (It's old, but not that old..?)5. I can't find much info about this method. Probably it's deprecated for good reason. That helps with expectations, but not implementations...This seems to be the best article I've found about it:http://walkermobile.com/December_2007_ID_Selecting_Surface_Capacitive_Touch_Screen_Controller.pdfSeems to suggest the panel is bootstrapped (i.e., all five pins are driven at the same voltage). Small errors in current are then due to capacitance to the surface, and the distribution between corners should correspond to position.The grid has quite low resistance (100s ohms), so the bootstrap better be damn good.This also largely rules out direct RF methods, like measuring the impedance (magnitude and phase) of any given pin with respect to the others: you'd need a damned good bridge to measure fractions of a pF, against the ~100pF of the panel, and the 100s of ohms of the grid. Or you'd need to do it at a frequency where resonances of the wires themselves (or even wave propagation across the panel itself) dominate.Also suspect it can be done with a slower pulsed drive method. For example it might be possible to drive all four corners high, then tristate them and wait for the charge to dissipate (grounded with a large value resistor). Same way that [single button] C-touch is done with MCUs. That allows touchdetection, but not location. To get location, drive alternate pairs high and low, to get the X and Y gradients, then tristate them. The panel's resistance pulls its voltage to the average, i.e., VCC/2. But the touch capacitance will imbalance the average, giving a small error from VCC/2. Amplify and acquire it. Repeat for X and Y. Hmm, also measure the capacitance in the detect cycle, and divide by it here. Since the imbalance is proportional to location AND touch capacitance.Anything else?Not holding out hope of an integrated controller, but not opposed to the idea. Nothing's turned up in searching, just spam from the more common types ("4-wire" but it's resistive; interfaces that support either kind of controller but guess what the capacitive touch interface is merely I2C to a COG controller; capacitive touch controllers, but they're only the single-button kind; etc.). Just looking for a few, I'm playing with these surplus displays:https://www.seventransistorlabs.com/Images/DisplayFirstLight.jpgTim
4-wire probes - Page 1
Forum section: electronics / projects

author: cncjerry
author_rank: Unknown
timestamp: February 19, 2024, 03:57:18 am
content: I did some searching and it seems like decent kelvin probes, not clips, are a little pricey. I have all kinds of clip style but recently needed sharp probes. I can roll my own but I'm tired of having to do something else before doing what i want to do. I remember not that long ago there was a person on here that made lots of probes, who was that and is he still in business? Other ideas? The pomona brand were like $150.ThanksJerry

author: TomWinTejas
author_rank: Regular Contributor
timestamp: February 19, 2024, 05:48:06 am
content: Similar thread in the test forum just the other day:https://www.eevblog.com/forum/testgear/kelvin-probes/

author: bdunham7
author_rank: Super Contributor
timestamp: February 19, 2024, 06:10:13 am
content: If you're referring to these specifically, it's not as easy as it looks to make them. I tried to set up some universal ones with replaceable (and varied) tips that could be manufactured, but didn't succeed. You can make one-offs using pogo pins from circuit board testers but making nice probe handles that hold those pins firmly takes some doing.https://www.digikey.com/en/products/detail/pomona-electronics/6303/745128

author: cncjerry
author_rank: Unknown
timestamp: February 19, 2024, 05:24:38 pm
content: thanks, I searched around last night, didn't see that post. I ordered the first pair. I didn't look all that closely to see if the removeable tips were for sale and available on the 2nd set. At that price, I would just purchase two sets. Both are a little clunky, though.thanks again.Jerry
4 wire remote voltage sense implementation - Page 1
Forum section: electronics / projects

author: Tinkerlad
author_rank: Newbie
timestamp: September 19, 2019, 02:25:04 am
content: Hi All,First off I will describe my project for context followed by my problem.I am building a cluster of SBCs, namely I am using the Orange Pi Zero. The OPi Zero lists PoE as a feature however this is not true PoE and isnt standard compliant, what it actually means is the the PoE power pins are expected to carry 5v power. More details here:https://linux-sunxi.org/Xunlong_Orange_Pi_Zero#Passive_PoEhttps://parglescouk.wordpress.com/2017/04/14/getting-the-orange-pi-zero-working-with-poe/I plan to have a few of these but dont want to have to put the 5v regulator on the Pi side of the Ethernet cable.So here is my plan, I want to make a board that will have an RJ45 jack on either end, no magnetics. The data signals will pass straight through. Then I will have a power input to a (preferably switchmode for efficiency/heat) that will place 5v on the power lines in the RJ45 that is facing the Pi.Now here is my problem, whilst the 'passive poe' uses two pairs of power conductors, I am worried about the voltage drop over the cables. So my plan is to do the following, only use one pair as power conductors and use the remaining pair as a sense return to do remote voltage sense (the pairs are connected at the Pi just out of the Pis ethernet jack).But I cannot find anything on implementing 4 wire remote sense... I have found application notes on 2 wire virtual remote sense... But this is not what I am after.Can anyone point me in the right direction on how to implement this? Also thoughts on the project?

author: Tinkerlad
author_rank: Newbie
timestamp: September 20, 2019, 03:44:53 am
content: After looking around some more..... I want to try just extending the feedback to the switching regulator along the second pair so that it senses the remote load, the feedback current should be minimal so shouldn't be affected by the distance I think... I have a couple of MP1584 modules laying around I might try modifying.

author: viperidae
author_rank: Frequent Contributor
timestamp: September 20, 2019, 04:13:35 am
content: You'd probably need an instrumentation amp to sense the remote voltage, since the switch mode controller probably expects the feedback referenced to ground.I'd be concerned about oscillations too, since you're added a bunch of inductance and capacitance to the feedback loop.
4 wire RTD cable shortening vs accuracy - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: August 18, 2019, 10:29:18 pm
content: I bought a cheap no name 4 wire PT100 RTD that originally came with a 2m long cable that I had to shorten by about 5-10 cm or so to solder some banana connectors.My question is will this have any affect on the accuracy of the temperature reading since it is my understanding that it uses the 4 wire kelvin resistance measurement so theoretically the cable resistance should not affect the reading but I just wanted to make sure it was ok to do so.Also, the wires are 2 red and 2 white so does it matter which one of the red or white goes to the sense terminals or is it just important to have the polarity in order (red=red and white=black)?

author: Vgkid
author_rank: Super Contributor
timestamp: August 19, 2019, 01:02:37 am
content: Nope, by using 4 wires, you mitigate lead resistances(up until a point).
4 x 7 segment common anode - Page 1
Forum section: electronics / projects

author: Skylimit
author_rank: Newbie
timestamp: January 09, 2020, 08:17:20 am
content: HiI have a 4 x 7 segment common anode display, which i will be driving from a PIC micro.I need some help in calculating resistor values and selecting the correct PNP transistors.Can anyone help?Thanks in advance.
400-800Hz 115VAC PFC (100w, 28vout) with dual interleaved flyback (isolated) - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: May 21, 2019, 07:00:15 pm
content: Hello,We are thinking of doing an isolated dual interleaved Flyback PFC on 400-800Hz 115VAC input.Its 28Vout +/-2V at 100W. (so that’s 50W for each of the flybacks of the dual)We are certain that due to peak charging and poor cross regulation, we will not be able to do the vout regulation by regulating the voltage of a low power (<300mW) bias coil on the primary side….instead an isolated TL431/opto type feedback will be needed.UCC28064Ahttp://www.ti.com/lit/ds/symlink/ucc28064a.pdf…so We are going to have to drop a divider down from the primary side Vcc rail and pour the opto collector out into this, and then the divider point into the VSENSE pin of the UCC28064A.This is more components than wanted, do you know why nobody does a dual interleaved flyback controller IC with a typical common emitter opto coupler connection?Both flybacks will dump out into the same 28v output.

author: dmills
author_rank: Super Contributor
timestamp: May 21, 2019, 08:23:57 pm
content: Treez does aviation electronics? (28V DC, 400Hz AC is classic in that space)!You are aware that anything going into that market has something of a gnarly development and quality process (And is actually expected to pass fairly stringent EMC for real).

author: Someone
author_rank: Super Contributor
timestamp: May 22, 2019, 01:09:02 am
content: Quote from: dmills on May 21, 2019, 08:23:57 pmMilitary use 400Hz for some of their power standards too.Its the brave new world, no need to hire engineers, just ask for their work/advice for free. The music industry went down this route too many years ago.

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 22, 2019, 10:07:29 am
content: Quote from: treez on May 21, 2019, 07:00:15 pmWhy in the world would you resort to a dual, interleaved flyback for a mere 100W?! Interleaving flybacks only makes sense above 400-500W, and even then there needs to be a very compelling reason to use the flybacks vs. a boost PFC stage followed by a single two-switch forward (arguably the most economical and robust choice up to around 500W).That said, the DCM flyback can automatically do PFC all on its own, so any conventional interleaved controller IC with an appropriate duty cycle range could work. I am rather partial to controller ICs from OnSemi and IR (now swallowed up by Infineon) and avoid TI like the plague; I've just had too many bad experiences with their recent chip designs and have sworn them off entirely as a result.
4017 LED chaser reversible? - Page 1
Forum section: electronics / projects

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: May 10, 2014, 12:24:25 pm
content: Probably a dumb question, but anyway I have an application where it would be useful to have an LED chaser (comprising a circle of LEDs) that can be reversed in direction (switchable clockwise/anticlockwise).The simplest approach for a plain chaser seems to involve the 4017 (eghttp://www.diy-electronic-projects.com/p169-LED-Chaserhttp://www.circuitstoday.com/dancing-light).Does anyone know if the 4017 chaser can be made to light LEDs in the opposite order? Or would you need two 4017s (one powered up at a time, but sharing the LED connections)?Thoughts, including alternatives, appreciated!

author: David_AVD
author_rank: Super Contributor
timestamp: May 10, 2014, 12:33:47 pm
content: Yes, the 4017 can only be clocked "forward". Using two in parallel would not really be practical.Maybe use a (reversible) BCD counter in conjunction with a 4-to-16 line decoder (only use the first 10 outputs) ?It's been a long time since I fiddled with TTL / CMOS functions like that so not sure of the part numbers.Of course you could use a PIC (or AVR) micro with enough outputs and code this very easily.

author: amyk
author_rank: Super Contributor
timestamp: May 10, 2014, 12:41:31 pm
content: Applications of CD4034include being able to shift left/right. It's only 8 bits, however.

author: SeanB
author_rank: Super Contributor
timestamp: May 10, 2014, 12:43:59 pm
content: Use a up down counter, and connect a BCD to decimal decoder to the output. You then can use another flip flop to control the direction signal by simply detecting the terminal count and the zero and changing the direction. For 8 outputs a 74LS138 does an 8 way decode ( active low) very simply.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: May 10, 2014, 01:22:00 pm
content: Use one 4017 add apply a negative frequency on the clock pin to reverse the direction.The use of a small micro is probably the best way to go.When I was doing these kind of things, many years ago, I would use an EPROM. I would drive the lower order address with a binary counter. The higher order address lines from a pattern select switch and take the outputs from the data pins.Jay_Diddy_B

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: May 11, 2014, 12:31:54 pm
content: Thanks all. There's a few other functions needed, so may end up trying an Arduino.
4028 chip in LTSpice subcircuit - Page 1
Forum section: electronics / projects

author: lamja
author_rank: Contributor
timestamp: August 07, 2010, 04:26:42 am
content: Just wanted to share my 4028 simulation in LTSpice.I made it as an subcircuit by first creating an equivalent circuit.Then I labeled the nets used by the chipThe voltage sources are actually arbitary behavioral voltage sources to simulate the output of the 4028 chip.B1 : V=(!(V(In3)) & !(V(In2)) & !(V(In1)) & !(V(In0)))*V(Vdd) (logical AND of all inverse In signals times Vdd)B2 : V=(!(V(In3)) & !(V(In2)) & !(V(In1)) & (V(In0)))*V(Vdd)B3 : V=(!(V(In3)) & !(V(In2)) & (V(In1)) & !(V(In0)))*V(Vdd)B4 : V=(!(V(In3)) & !(V(In2)) & (V(In1)) & (V(In0)))*V(Vdd)...B10 : V=((V(In3)) & !(V(In2)) & !(V(In1)) & (V(In0)))*V(Vdd) (logical AND of all In signals times Vdd)Then save this file as 4028.ascThen you have to create a symboleCreate the pinsAdd the same Labels you used in the .asc-file. Netlist Order should be the pin number on the chip. If you use for example number 16, all pins from 1-15 must also be defined.Save the files as 4028.asy in the same folder as the .asc-file.I made an extra folder in the "sym"-folder of LTSpice to have my chip located in.Then I made a test circuit with two cascading 4028'sThats it. Then there is only about 200 chips to go...I attach the files to save you some work if you're interrested in checking it out.

author: gbowne1
author_rank: Contributor
timestamp: September 06, 2010, 08:48:02 am
content: I'm still learning LTSpice IV v4.09. I also just got Cadsoft Eagle 5 off the site.But I have some old circuits I'm trying to debug and update them because about half the components used are old and no longer available.Took me a while to move from the old hand drawn schematics to the model space onto the board level.One of them involves a complex RF board that I did in the 1980s. I have to move the board design from a muliti-board layout to a backplane style and a large main board, PLL, PSU and other things. Its quite a mess. I could use some help.Thanks for the visiualization of the CD4028, etc model.
40x4 LCD not working - Page 1
Forum section: electronics / projects

author: JuanGg
author_rank: Regular Contributor
timestamp: February 06, 2020, 08:38:48 pm
content: I have purchased a character LCD from here:https://www.buydisplay.com/40x4-lcd-module-datasheet-commands-arduino-pinout-hd44780-black-on-ygFollowing the datasheet, I tried to initialize it manually using dip switches, but I could not get it to work.The LCD uses the standard Hitachi interface, with two enable pins.On power up, the usual black squares do appear, and contrast adjustment works fine.I tied the second enable low, and connected the first one (E1) to a de-bounced switch.With E1 high, I tied RS and R/W low, wired the data bus to 00111000, and changed E1 to low. That should initialize the display, but I see no changes on the screen, I suppose it should go blank. (I've moved the contrast pot around).I've checked the connections a dozen times, soldered some decoupling capacitors right to the connector, but no luck.I don't know how to proceed. It could have been damaged by ESD, but in such case, would it even show the initial squares?Any ideas are welcome.Juan

author: rhodges
author_rank: Frequent Contributor
timestamp: February 06, 2020, 09:00:38 pm
content: Okay, 0x38 chooses 8 bit mode and display lines. That is what I use, except mine uses 4 bit mode (0x28).Here is my init code: (RS pin is low)lcd_comd(0x28); /* 4-bit mode, 2 lines */lcd_comd(0x0e); /* turn on diplay and cursor */lcd_comd(0x06); /* auto increment and move cursor */Then send characters with RS pin high.My code for STM8 might be of some help:https://github.com/unfrozen/stm8_libs/blob/master/lib_lcd.c

author: JuanGg
author_rank: Regular Contributor
timestamp: February 07, 2020, 10:15:03 pm
content: Thanks. Found the issue in the end. I copied the pinout on a piece of paper and missed the order of the data bus...It's working now.Juan

author: JonInPalawan
author_rank: Newbie
timestamp: July 09, 2022, 04:09:56 am
content: How did you get contrast adjust to work? My display is Surenoo, and I tried to follow their conflicting instructions. Can't make the faint 5x8 dot pattern to adjust out.Initializing was easy. Just set the required data, then pull both enables low then high again. Repeat for next data. The two controllers work independently, though they share the common data bus.
417 295 transistor replacement? - Page 1
Forum section: electronics / projects

author: ttx450
author_rank: Regular Contributor
timestamp: August 17, 2021, 01:05:35 am
content: Hello all,I have an old transistor that needs replacing. I think that it's obsolete, it came out of a Heathkit clock kit. Need a replacement, having a hard time finding the datasheet? I dont know manufacture, it's a 417 259. Any help appreciated.. thks.

author: bdunham7
author_rank: Super Contributor
timestamp: August 17, 2021, 01:13:41 am
content: That is a Heathkit part number, a 100V PNP TO-92 transistor, and it crosses to an MPSL51, which is mostly obsolete. NTE and Central Semiconductor still show it, so you may find it somewhere either as a current offering or as NOS from Amazon or eBay.

author: ttx450
author_rank: Regular Contributor
timestamp: August 17, 2021, 01:29:16 am
content: Thanks, did not realize that. da.. I did not know HK put there own part numbers on there stuff.. thks..

author: WattsThat
author_rank: Frequent Contributor
timestamp: August 17, 2021, 06:11:21 pm
content: If its the TO-92 417-295 (not -259) you’re looking for, I have a few original old stock Heathkit parts. Send me a pm if you want one.GC-1005 or -1092?

author: ttx450
author_rank: Regular Contributor
timestamp: August 17, 2021, 10:19:53 pm
content: Thanks, got 5 NTE MPSL51 & free shipping coming from amazon. for 5 bucks plus tax.. not to bad with free ship. thks for your offerGC-1005
4:2:2 YCbCr video -- Centering lower-res on a higher-res display? - Page 1
Forum section: electronics / projects

author: smoothVTer
author_rank: Regular Contributor
timestamp: April 29, 2017, 03:02:59 pm
content: I am in search of a method to process a 16-bit YCbCr video bitstream at 640x480 resolution and center it on a panel with a native 800 x 600 resolution.The panel itself has some built-in adjustability for image centering but only for +/- 10 pixels in either direction. I know conceptually that in order to achieve this centering, the 640x480 bitstream requires processing and timing changes to the HSYNC/VSYNC signals, as well as 'adding in' blank pixels to the left/right/top/bottom of the lower resolution image and making adjustments in timing to account for these extra blank pixels.Many people say to do this in an FPGA ... but is there a simpler solution? I have zero experience in FPGA's and the learning curve seems steep. In my search for non-FPGA IC's I find a dizzying selection of video processing / decoding chips out there that have an overabundance of functionality ( and power consumption ) which my application does not need. I already have a decoded and formatted YCbCr video stream, so I don't need any kind of decoder/encoder IC. I just need some way of generating blank pixels and timing changes to HSYNC/VSYNC.Is there a non-FPGA, one-chip solution out there to achieve this video centering?Any other recommendations, or perhaps I am thinking about this the wrong way?

author: bktemp
author_rank: Super Contributor
timestamp: April 29, 2017, 03:38:03 pm
content: It can be done without an FPGA, but the circuit will be huge if done without an ic dedicated for that purpose:Before adding more lines you need to make room for them. That means you need to store some lines in memory, because you are adding 60 lines at the top, therefore your output image starts later. That's why there is no simple solution using some discrete logic.Most display controllers designd for LCD monitors typically scale the image, but can probably also configured for placing the unscaled image in centre of the output image if there is enough memory.The main problem with using such a one chip solutions is, they are designed for high volume products. Unless you are going to build many thousand devices, it is nearly impossible to get those parts from official distributors.With a bit of experience in FPGAs it can probably done in one or a couple of days, because FPGAs have everything needed for this: Logic, PLLs for generating the higher output clock and memory for storing a small part of the image.If you aren't willing or have no time for learn FPGAs, find somebody who can do this for you. Even if you pay somebody for doing this, it will still be the most economical solution.
433MHz RF Sniffer and Audacity  - Page 1
Forum section: electronics / projects

author: kumarb
author_rank: Newbie
timestamp: March 28, 2018, 07:22:59 am
content: 433MHz RF Sniffer to capture the signal from remote using Audacity softwareCapturing RF Signals - Audacity:More Information:RF Snifferhttps://www.codrey.com/electronic-circuits/433mhz-rf-sniffer/
433MHz RF Transmitter and Receiver Schematic - Page 1
Forum section: electronics / projects

author: arul
author_rank: Regular Contributor
timestamp: May 04, 2020, 10:23:47 am
content: Hi,I need a schematic diagram of 433MHz RF transmitter and receiver module.I have attached the data sheet and images of the RF module.http://www.mantech.co.za/Datasheets/Products/433Mhz_RF-TX&RX.pdfIf anyone have, please share.Advance in thanks
47K 2KV capacitor on Mouser - Page 1
Forum section: electronics / projects

author: gaminn
author_rank: Frequent Contributor
timestamp: December 11, 2023, 01:33:21 pm
content: Hi, I'm looking for this capacitor on Mouser and can't find any suitable. Is it 47nF 2kVAC rated, right? Can you please help me find one? It has approx. 7mm lead spacing. Thanks

author: jmelson
author_rank: Super Contributor
timestamp: December 11, 2023, 04:24:03 pm
content: 1t might be 47 pF and the "K" is the tolerance.Jon

author: gaminn
author_rank: Frequent Contributor
timestamp: December 11, 2023, 04:32:22 pm
content: Thanks. I didn't know "K" can be tolerance. Anyway, where can I get this part. It seems Mouser has no 2kV rated capacitor like this.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: December 11, 2023, 05:18:17 pm
content: I'm not sure what that is, but if it were really 47 nV and 2 kV, it would be a lot bigger! 47 pF makes more sense. Can you take it out and measure it?

author: wraper
author_rank: Unknown
timestamp: December 11, 2023, 05:22:24 pm
content: I'm 99.99% sure this capacitor is just fine, will be still perfectly fine 50 years later, and does not need replacement.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 11, 2023, 05:25:39 pm
content: That cap is most likely 47pf, not 47nf.I'm not sure I've ever seen 47nf marked like that - usually "473"

author: Zero999
author_rank: Super Contributor
timestamp: December 11, 2023, 06:34:47 pm
content: I found this on Mouser, but it's probably not broken, as wraper said.https://www.mouser.co.uk/ProductDetail/TDK/CC45SL3FD470JYVNA?qs=sGAEpiMZZMsh%252B1woXyUXj1nTw%2FKm%2FcPwAWAemNsH0fg%3D

author: gaminn
author_rank: Frequent Contributor
timestamp: December 11, 2023, 06:39:15 pm
content: Thanks. I have another board where this component is damaged and needs to be replaced.
+/-48 or +/-96VDC isolated psu by serial connection of +/-24V DC2DC converters? - Page 1
Forum section: electronics / projects

author: awallin
author_rank: Frequent Contributor
timestamp: October 19, 2013, 06:56:52 am
content: I want to provide adjustable DC-bias voltages around -100 to +100 volts (zero current drawn) for an experiment.The plan is to use either a single OPA454 op-amps (+/-50V) or the three op-amp connection shown in the datasheet for +/-100V. Use them in non-inverting connection with a gain of 5x or 10x and take a +/-10V input from a DAC.Is it a good idea to generate +/- 48V (or maybe 96V) rails for the op-amp by connecting the output side of two (four?) DC-to-DC converters in series?There is no current drawn on the op-amp output by the experiment itself, so I just need enough power for the op-amps. Maybe small 2W DC-to-DC converters (e.g. XP POWER - IH1224S-H)?Any potential problems or dangers?What's the best way to filter out the switching-noise of the DC-to-DC converters? I've seen e.g. NFE61 with caps on both sides - but is there a good tutorial or 'best practices' for this?AW

author: Psi
author_rank: Super Contributor
timestamp: October 19, 2013, 07:30:22 am
content: As long as the modules are isolated it shouldn't be an issue.Digikey have a 72V isolated module with taps at 48V and 24V @ 14mA for $14Two of those in series would give you a few combinations, 72V, 96V, 120V5V versionhttp://www.digikey.com/product-detail/en/NMT0572SC/811-1583-5-ND/192714412V versionhttp://www.digikey.com/product-detail/en/NMT1272SC/811-1584-5-ND/1927145
48V DC to 300V DC - Page 1
Forum section: electronics / projects

author: podericof
author_rank: Newbie
timestamp: September 13, 2025, 11:18:11 am
content: Hi guys,I need to design a 48V DC to 300V DC 150W. It doesn't need to be isulated.I have tried to use 5 AG7100 in "series", each of them can give up to 57 V each (so I almost had 300V).with 4 AG7100 I have no issues, with 5 They start to get damaged. I have tried protecting each of them using TVS at both input and output, and this has made things even worst.So I have arrived to the conclusion that using isolated DCDC converter in "series" it's not a good idea, probably they fight each other.Any suggestion is welcome!Thank you!Fancesco

author: voltsandjolts
author_rank: Unknown
timestamp: September 13, 2025, 12:22:25 pm
content: There are off the shelf options, for an easier lifehttps://current-logic.com/shop/index.php?main_page=product_info&products_id=305

author: podericof
author_rank: Newbie
timestamp: September 13, 2025, 12:36:13 pm
content: Thank you for your answer!500W its a bit too much, I need less than 200W.I don't have space for a 500W in my application.

author: voltsandjolts
author_rank: Unknown
timestamp: September 13, 2025, 12:42:41 pm
content: What is the application?

author: podericof
author_rank: Newbie
timestamp: September 13, 2025, 01:04:25 pm
content: Cosmetic industry

author: Psi
author_rank: Super Contributor
timestamp: September 13, 2025, 01:34:08 pm
content: Quote from: podericof on September 13, 2025, 12:36:13 pmSo small physical size is the key?How small does it need to be?It's always going to cost more to build one than to buy something close and modify its output voltage.Normal 220V inverter will put out a bit over 300V peak after rectifier. Should be able to find many that take 48V DC input as its 4x 12V SLA

author: Terry Bites
author_rank: Super Contributor
timestamp: September 18, 2025, 05:52:22 pm
content: Is that 150W max or 150W with some headroom?I think you really do need isolation@300V.I put your specs into TI's online power designer.https://webench.ti.com/power-designer/It spat this out. Looks inexpensive on paper, no rare parts.https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=63FD3FC1112C92DBThe non-isolated designs are simpler eghttps://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=6479D9F75103AD69But beware that fb compensation may be missing from these shematics!The only faff is winding your own transformer, but they give you all the specs.Click on the schematic and open the BOM listing.seehttps://circuitdigest.com/tutorial/how-to-design-your-own-transformer-for-smps-power-supply-circuits

author: Seekonk
author_rank: Super Contributor
timestamp: September 21, 2025, 03:01:33 pm
content: While maybe not the best option, those supplies should work. Did you add the extra output capacitance to EACH board as required? Yes, some instability can happen. I always suggest a diode in parallel with each output and a bleed resistor sometimes to insure minimal current draw of a couple percent to make it more stable.
48V PSU - Fried trimpot - Page 1
Forum section: electronics / projects

author: lesabb
author_rank: Contributor
timestamp: February 09, 2015, 10:38:30 pm
content: Hello all,I've built a PSU to power up a mic pre. Attached schematic. Meter reads 24VDC and ~68VDC on the doubler (48pk*1.4 I guess). If I try to adjust the voltage on the 317, I fry the trimpot. I'm using a 3296 KT, 28 turn 5k (0.5W) is that a problem? Also, what is the purpose of C1 and C2 if they are directly hooked up to AC, before the bridge. ThanksLuc

author: void_error
author_rank: Frequent Contributor
timestamp: February 10, 2015, 12:17:23 am
content: It looks like you've got a bit of learning to do... then to go back to the drawing board (it would be nice to also include component values on the schematic).Other than that your LM317 for the +48V rail is probably fried if you set the output voltage too low. You actually have a thread on this project so I suggest going back and taking a look at what other people suggested. No need to start a new thread.

author: lesabb
author_rank: Contributor
timestamp: February 10, 2015, 12:40:05 am
content: I am in the learning phase. Just looking for troubleshooting advice here. Taking into account previous suggestions (from previous thread), the output voltage on the 317 is 68V, which makes me think the 317 is fried since it does not respond to trimpot and has fried it

author: void_error
author_rank: Frequent Contributor
timestamp: February 10, 2015, 01:05:49 am
content: I'd suggest you get away from the LM317 for the +48V rail since, as it was previously said, itwillbe fried in case you accidentally short it to ground. You could easily avoid this by using discrete parts (transistors) - it's easier to find transistors which can withstand 70V and above than a regulator IC and you can even get short circuit protection by adding one transistor and one resistor.I assume the preamp you intend to power only draws a couple of miliamps at most so it shouldn't be too difficult to find a suitable discrete circuit. Googling 'discrete voltage regulator schematic' might give you a few hints. If I'm not lazy enough I'll take a picture from a book about voltage regulators dating back to 1983, google results aren't good enough.

author: mij59
author_rank: Frequent Contributor
timestamp: February 10, 2015, 05:34:00 am
content: You need a high voltage regulator like thishttp://www.ti.com/lit/ds/symlink/tl783.pdfRemove R2 and C4, and connect the - of C5 to the + of B2.

author: Zero999
author_rank: Super Contributor
timestamp: February 10, 2015, 12:25:14 pm
content: Yes, it sounds like you've fried the LM317.It's true it's a floating regulator and it's the difference between the input and output voltage which is important but the capacitors on the output charging will easily fry it. You could put a 39V zener diode between the input and output terminals and that will ensure the maximum voltage rating isn't exceeded but it will still blow up when short circuited, unless another current limiting circuit is added.You could also use the LM317HV which is rated to 60V.
4D Systems IoD-09TH LCD Display Module - Page 1
Forum section: electronics / projects

author: 0b01010011
author_rank: Regular Contributor
timestamp: May 27, 2020, 02:22:21 am
content: Hi guys,I'm looking for a small display that will fit in an old-school (we are talking 20 year old VZJ95) Toyota switch blank (21mm x 39mm).Closest thing I have found that will foot the bill is this:https://au.rs-online.com/web/p/lcd-colour-displays/1647079But this isn't a raw display, it's a whole 'internet of display' thing, 99% of which I won't need. Has anyone else used them or had experience of them? I'm trying to find out if it's easy to address the display directly via something like SPI or serial. I'm a PIC fanboy so would just do my sensor stuff (analog measurement and 1-wire sensors) on a PIC for simplicity then interface to this - or at least that would be my plan.If you know of any other small displays that would fit the above size I'd be interested to hear about them. Don't really have any other constraints at this stage, colour is not mandatory. It's just a hobby projectThank you.

author: dmendesf
author_rank: Frequent Contributor
timestamp: May 27, 2020, 03:35:36 am
content: Maybe this one, without the pcb:https://www.ebay.com/itm/183540471393
4g /lte serial modem, where to find? - Page 1
Forum section: electronics / projects

author: Rerouter
author_rank: Super Contributor
timestamp: December 06, 2016, 11:11:32 am
content: Hello,For an old system I have that uses a serial 2g modem (intercel sam2s) A friend wants to set up the same on a French island that only uses 4g/lte for data (we tried a few brands of 2g/3g modems with no luck, and the telecom say it is 4g only), as such I am wondering if anyone knows of a lte serial modem, one that behaves like a 2g/3g one controlled by the serial port (at commands)All that I have so far come up with have a serial port, but it's not for control, but as a peripheral,The device connects to a server I have no control over, and would prefer to buy a solution than try and make one.

author: Gabri74
author_rank: Regular Contributor
timestamp: December 06, 2016, 02:29:08 pm
content: Have you checked the Telit modules?http://www.telit.com/cellular/UART connection is listed in datasheets for the 4G family.Keep in mind that using a serial connection your effective speed couldbe limited to 115200 or less!

author: voltsandjolts
author_rank: Unknown
timestamp: December 06, 2016, 03:35:42 pm
content: Yeh, maybe a Telit arduinio shield or:http://www.roundsolutions.com/en/products/terminal-modems/product-overview/2725/4g-terminal-aarlogic-ter-lx910-eu(Disclaimer: I've never used this!)

author: nali
author_rank: Frequent Contributor
timestamp: December 06, 2016, 04:26:53 pm
content: Check command compatibility. We use Sierra Wireless modules, and their LTE version now uses QMI as a data interface so won't work with our legacy PPP dialler which uses AT commandsAlso, do you have flow control on your RS232? As Gabri74 pointed out you may have data coming in a lot faster than your UART can handle (I've seen a few 3-wire RS232 interfaces on old systems before)

author: Rerouter
author_rank: Super Contributor
timestamp: December 06, 2016, 10:00:22 pm
content: Thank you voltsandjolts, the data sheet for that device supports the command set (apparently called Hayes AT command set that I know the intercel ones use ) and looks very promising.
4in Flat Vector CRT - Page 1
Forum section: electronics / projects

author: zitt
author_rank: Regular Contributor
timestamp: August 27, 2021, 06:39:09 am
content: Probably not a new idea; but I recently watch Adrian's CRT video:And immediately thought I'd buy one or two and try my hand at Converting it to a Vector CRT for a micro Asteroids game.Of course; I somewhat certain I'd have to rewind the yoke to get vector deflection; but I've never done it so.... clueless.Probably nothing more than a silly hobby phantasy; but curious what other "experts" might have as far as ideas go.I stopped short of actually ordering any of these from Alibaba... because the shipping costs were high enough that I'd be disappointed if it arrived broken.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: August 27, 2021, 12:38:34 pm
content: I don't know how common they are where you live but here we have the same style of crt in video doorbell panels.They aren't cheap but neither something hard to come by.

author: oPossum
author_rank: Super Contributor
timestamp: August 27, 2021, 04:25:26 pm
content: Quote from: zitt on August 27, 2021, 06:39:09 amhttps://github.com/NiklasFauth/sony-scopeman
4mm ESD button connect for watch band - Page 1
Forum section: electronics / projects

author: Zmrbill
author_rank: Newbie
timestamp: March 31, 2019, 10:34:32 pm
content: 30 years ago I worked with an EE that had put together an ESD button that attached to his watch wrist band that he could just attach the grounding cord instead of having to wear a wrist band. Now I want one and instead of making one I wanted to see if one already existed for 4mm button stud type connection. Is anybody aware of one?Also in searching all I can find is wrist straps, where can I find just the 4mm connector? Data sheets and mechanical drawings...Thanks in advance, Bill

author: ajb
author_rank: Super Contributor
timestamp: March 31, 2019, 10:52:13 pm
content: All the wrist straps I've seen use standard snap fasteners available at any decently sized fabric or craft store.
4n25/35 optocoupler detect led on/off - Page 1
Forum section: electronics / projects

author: Stealthrt
author_rank: Regular Contributor
timestamp: October 18, 2017, 05:32:29 am
content: Hey all i am just wondering if my drawing below is correct in order to have an arduino detect an on or off led on another board using a optocoupler?My thoughts of the above drawing is that when the led is on it will trigger the relay inside and send 5v to the arduino digital pin to read. 0v if the relay inside is not connected.I also would possibly need to tell the arduino digital pin that its an input pullup like this:Code:pinMode(pin, INPUT_PULLUP);please advise if this is correct or not.

author: george.b
author_rank: Frequent Contributor
timestamp: October 18, 2017, 06:07:17 am
content: Quote from: Stealthrt on October 18, 2017, 05:32:29 amKinda, yeah. It'd be good to add a 1k to 10k resistor from pin 4 to ground.Quote from: Stealthrt on October 18, 2017, 05:32:29 amThere is no relay as such inside - it's a phototransistorQuote from: Stealthrt on October 18, 2017, 05:32:29 amNope, if anything, you'd need a pulldown. You could save the one resistor I mentioned by setting the input as you said, then connecting optocoupler pin 5 to the digital input, and pin 4 to ground.

author: eblc1388
author_rank: Frequent Contributor
timestamp: October 18, 2017, 07:57:37 am
content: Quote from: Stealthrt on October 18, 2017, 05:32:29 amYou cannot directly connect the optocoupler inputs to the LED you want to monitor. The original LED will not be able to light anymore if you do so.There are two possible ways to do so as shown in the image. Method#1 is the preferred method.

author: george.b
author_rank: Frequent Contributor
timestamp: October 18, 2017, 11:21:09 am
content: Quote from: eblc1388 on October 18, 2017, 07:57:37 amAh, true, the LED in a 4N25/4N35 is infrared, with a lower forward voltage than a red LED. I didn't think of that.

author: Stealthrt
author_rank: Regular Contributor
timestamp: October 19, 2017, 06:38:35 am
content: im hooking the 4n25 up to the hm-10 led:

author: woody
author_rank: Frequent Contributor
timestamp: October 19, 2017, 07:06:14 am
content: I skimmed the datasheet on the HM10 for 30 seconds so I might be completely wrong, but it seems there is a command to query the status of the system LED: AT+PIO1?If that works it saves you a couple of components
4R02 1% 2512 SMD Resistor, equivalent to Stackpole RMCP2512FT4R02? - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: August 26, 2022, 03:49:24 pm
content: Hi!Does anybody know where I can obtain 10 off 4R02 ±1% 2W 2512 chip resistors, equivalent to Stackpole Electronics RMCP2512FT4R02 or an equivalent?It's to build the Front Board of Paul Vee's Curve Tracer Mk. 3 described in "Paul's Electronic DIY Blog".Chris Williams

author: exmadscientist
author_rank: Frequent Contributor
timestamp: August 26, 2022, 05:11:29 pm
content: You have a couple of options at second-tier distributors:https://octopart.com/search?q=2512+2w+4.02ohm&currency=USD&specs=0&in_stock_only=1You can buy these and overdrive them:https://www.mouser.com/ProductDetail/71-CRCW25124R02FKEGH, knowing that getting 2W out of a 2512 in the first place is something of a dicey proposition, so what's another half watt between thermal enemies?Or you might call up Venkel and try to buy a small reel.

author: floobydust
author_rank: Super Contributor
timestamp: August 28, 2022, 07:00:11 pm
content: OP, just to point out this resistor is part of the magical unicorn series that many resistor manufacturers offer. Stackpole and Yageo.2W in a usual 1W package, for a given resistor size the only way to obtain a higher power rating is using materials good for higher temperatures - which means it runs super hot."The thermal resistance of the RMCP will be similar to the RMCF. For example, the RMCF2512 and the RMCP2512 will have similar surface temperatures at 1W; the RMCP is designed to withstand higher temperatures associated with high power levels."Graph: at 1W it's 150°C surface temp. RISE? for the 2512 size so lets cook the unicorn at 2W. It's just unrealistic but sorting by that parameter when buying parts and seeing "2W" people will believe it's true.Yageoalso offers a "2W" 2512 i.e. RC2512FK-7W4R02LNeither datasheets mention the actual 2512 temperatures at 2W, it's just a marketing fantasy.

author: markallie
author_rank: Newbie
timestamp: August 20, 2024, 05:35:56 pm
content: I like the name Flobbydust. I have one of the original Flobbydust books around my lab somewhere. Yes the 2W rating is a joke. I did find that the 2 or even 3 W rated 2512's have larger solder pads. That is why we chose them. Not that we think they can actually dissipate that much power. However they can dissipate more than the smaller pad sized 1W resistors. We also relied on more footprint dissipation on the PCB. The power that needs to be dissipated by these resistors is not 2W. It varies by duty cycle and current maximum settings.
5$ Singing Musical Tesla Coil Music Box ! - Page 1
Forum section: electronics / projects

author: Kedar264
author_rank: Regular Contributor
timestamp: August 12, 2016, 02:20:54 pm
content: Love musical singing Tesla coils and Music Box ,Well Today i made a mini singing Tesla coil music box using very common modular parts ,which you can buy online for just 5 $ , and its very interesting project if you are electronics geek like me !Musical Tesla coils generate high voltage pulses according to beats of the music , each bit of high voltage spark create an pressure wave which is similar to what speakers do you can play any song since it has standard 3.5mm audio jack.https://youtu.be/1KWiDo-Gqvs# Instructibleshttp://www.instructables.com/id/5-Singing-Musical-Tesla-Coil-Music-Box-# Music Tests on Tesla coil Music Box1:58 SKRILLEX - Bangarang2:32 Turn it down for what# Parts List1. Amplifier Board (PAM8403)http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_sop=15&_nkw=pam+8403&rt=nc&LH_BIN=12. High voltage Generatorhttp://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_sop=15&_nkw=high+voltage+generator&rt=nc&LH_BIN=13.Mp3 Playerhttp://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_sop=15&_nkw=mp3+player&rt=nc&LH_BIN=1# Facebookhttps://www.facebook.com/pages/Kedar-Nimbalkar# Twitterhttps://twitter.com/kedar264

author: Fungus
author_rank: Super Contributor
timestamp: August 12, 2016, 02:25:03 pm
content: You're not going to build a Tesla coil likethatfor $5Edit: Yep. It's just an ebay sparker.(They're fun, sure, but let's have truth in advertising...)

author: Kilrah
author_rank: Unknown
timestamp: August 12, 2016, 02:39:40 pm
content: Meh, indeedfor "false advertising"...
5.1 Digital Audio Control Circuit - Page 1
Forum section: electronics / projects

author: gevv
author_rank: Contributor
timestamp: October 20, 2022, 05:52:02 pm
content: Hello,5.1 Control board project for sound system Bass, treble, mid, 3D effect, volume control of all channels Remote control LCD Encoder. PCB size 90.3x 100m and single deck design. There are source and library codes.https://youtu.be/uG-_xrnBvxs07:00 General circuit description02:22 Circuit test and explanations07:35 👍07:40 Ready sound modes08:57 PCB description, encoder resistors11:34 Arduino program, driver installation and settings13:05 Arduino library upload14:07 Arduino program upload (attention)14:42 Determining and adding control codes to the code16:22 preset sound modes code16:27 Circuit Diagram16:32 PCB Drawing (with Arduino module)16:37 PCB Drawing (No atmega328p module only)16:42 Surprisesource:http://rcl-radio.ru/?p=62504