hybridfree/eevblog-posts huggingface dataset:
Schematic symbol to indicate link of two different system grounds - Page 1
Forum section: electronics / projects

author: beaker353
author_rank: Unknown
timestamp: June 25, 2017, 05:11:02 am
content: I have a schematic design I'm woking on that has a digital and analog ground that I will keep separate except for single well-placed tie point. Layout-wise, I know what I want to do works well electrically speaking. Schematic-wise I've historically used a little component symbol that looks like two side-by-side test points connected to indicate the link so it popery transfers over to the layout application. Works as long as I'm the only one reading to the schematic, but potentially confusing for someone else. I would like to start using something more standardized (I know, I know, I've seen the XKCD comic) as this particular schematic will go into permanent company records, but I'm not finding much consistency with what I can get my hands on. Any suggestions from the greater hive-mind on what I should be using? Thanks!-EM

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 25, 2017, 06:00:42 am
content: 0. Don't. Just don't. You're likely making an EMC nightmare. (And, the fact that you qualified that as "works well electrically speaking", makes me suspect you haven't tested it electromagnetically, i.e., measured its emissions or susceptibility. Both of which are very important factors to an ADC -- especially one that is, apparently, sensitive enough to be considering layout options this aggressive!)1. What you're looking for is usually called a "net tie". Whatever tools you're using, there's probably a documented way to create this. You can also use a zero-ohm jumper, as evb149 said.Tim

author: beaker353
author_rank: Unknown
timestamp: June 25, 2017, 06:24:00 pm
content: Maybe I should of re-worded "works well electrically speaking" to "a well respected manufacturer applications engineer suggested I use a specifically designed and thoroughly tested power and grounding layout". He provided a Altium file as well as a graphic PDF, but I sure don't have the cash to spend on an Altium license. So I am basically re-creating this layout in my own EDA. It's a mixed mode IC chip with ADCs, DSP, and DACs, so there is no way I can keep AGnd and DGnd separate and still have the thing function correctly. I'll continue to use my little jumper schematic symbol I guess and add some text explanation. Unfortunately it doesn't appear that DipTrace has a NetJoin or NetTie feature built-in. I can manually define my own component and pattern, but it seriously ticks off the DRC and ERC in layout. I would gladly make the jump to Altium, but I just can't justify the price.-EMQuote from: T3sl4co1l on June 25, 2017, 06:00:42 am
Schematic wanted for FLUKE 5100A - Page 1
Forum section: electronics / projects

author: Crambone
author_rank: Frequent Contributor
timestamp: August 22, 2023, 02:23:14 pm
content: I’m looking for schematics and service manual/ notes for the FLUKE 5100A.Thanks, Drew

author: liaifat85
author_rank: Regular Contributor
timestamp: August 23, 2023, 03:36:39 pm
content: I could not find a PDF. But here they are selling this meter with a manual CD:https://www.ebay.co.uk/itm/372553348113
Schematics Review: NRF24l01 controlled Relay - Page 1
Forum section: electronics / projects

author: Aodhan145
author_rank: Frequent Contributor
timestamp: December 23, 2014, 01:54:13 am
content: Hi,I am reasonably new to electronics. I have stared this project where I need plugs that can be radio controlled individually by an NRF24l01 module. There will be multiple plugs with different id's, so they can be differentiated between and I also want to read wattage from each plug. I have drawn up some quick schematics in eagle and I want to know if it will work. I am using an arduino pro mini because I have a couple of them lying around. I have an ACS712 to measure the current, but these are on small breakout boards, so I put a pin header in the schematics leading to its Voutpin. I also have a seven segment display to show the id of the plug which it gets from the EEPROM. The seven segment display is hooked up to a I2C port expander as I would of run out of pins connecting it directly to the pro mini and I have a 16A relay actually switching the load. Do you have any opinions on how I should change it? Thanks in advance.
Schmitt to throttle 555 timer based boost circuit - Page 1
Forum section: electronics / projects

author: mikeinfodoc
author_rank: Regular Contributor
timestamp: November 17, 2017, 04:40:34 pm
content: I have a simple/typical DC-DC switch-mode Boost circuit. (with typical inductor, switch, diode and cap)It uses a 555 for its switching.I wanted to limit the output voltage of this boost circuit to a defined range, by adding a inverting schmitt to the reset pin of the 555 timer. (so the schmitt would serve as the "feedback" to the 555 timer via the reset pin)Such that:when the 555 boost circuit output exceeds a certain HIGH threshold voltage, the schmitt forces the 555 reset pin low.when the 555 boost circuit output becomes lower than a certain LOW threshold voltage, the schmitt forces the 555 reset pin high.Therefore, any Vout within the defined voltage output range (aka: the schmitt "hysteresis") would keep the 555 reset pin unchanged.In other words,if the boost output goes too HIGH, the astable 555 stops switching.if the boost output goes too LOW, the astable 555 starts switching.Before I submit my schematic, I want to see if this makes sense, from a conceptual standpoint.Thank you for any "feedback."

author: boostbuck
author_rank: Newbie
timestamp: November 17, 2017, 11:54:23 pm
content: Here's my minimal part count 555-based boost for a 12v battery. It has served well as supply for various jobs. Changing the zener alters the output voltage. Not very regulated, but follow it with a 317 to clean it up if necessary.

author: boostbuck
author_rank: Newbie
timestamp: November 18, 2017, 08:05:08 am
content: My typo: R4 is 150R not 1K5

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 18, 2017, 09:12:32 am
content: Yikes, no current limiting! No input filtering!If you MUST use a 555, use it this way:https://www.seventransistorlabs.com/Images/555%20Boost.pdfBut much preferable to use a UC3843. Just as many components, but it's actually safe to use.Tim
schmitt trigger external ic despite stm32h750 has one - Page 1
Forum section: electronics / projects

author: jealcuna
author_rank: Contributor
timestamp: September 15, 2021, 02:11:55 am
content: Hi folks,Does it make sense has an external schmitt trigger ic for read a optocoupler despite the stm32h750 has one?I am attaching pictures.

author: Bassman59
author_rank: Super Contributor
timestamp: September 15, 2021, 03:12:09 am
content: I would think that the micro's internal Schmitt trigger by itself should suffice.I wonder if the circuit example was taken from something else and used with a micro that does not have a Schmitt trigger input.
School Piezo Energy Harvesting Experiment - Page 1
Forum section: electronics / projects

author: boatanchorguy
author_rank: Newbie
timestamp: January 16, 2018, 02:12:25 am
content: Helping my granddaughter with a HS project on the piezoelectric effect and renewable energy. She placed a 30mm piezo disc under the heel of her sneaker that inputs into a Schottky (1N5711) full wave bridge whose output is across a 47uF 50V electrolytic. Wearing the PCB with bridge/cap on the outside of her sneaker she walked on a treadmill at a casual rate (1 step/second) and we data logged the slow charge up of the capacitor. It took just about 7 minutes to plateau at around 5.25 VDC. Without the capacitor - the open circuit voltage from the bridge is quite high --- 20-60 Vdc but when the capacitor is added it loads down to initially a few mVdc and slowly comes up as the cap is charged by the piezo. We want to get some estimate of the energy generated per step recognizing this is on the microjoule or nanojoule level. I was going to use the equation for stored energy in capacitor = ½ C x V^2 and divide by total seconds to reach the exponential plateau of the 5.25Vdc maximal charge. Next step will be to add a tiny LiPo charger or play with the LTC3588 chip. Any advice on how to get this estimate of piezo power per step would be appreciated.Thank you in advance
school react time measuring system, quite fun - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: December 12, 2022, 08:05:35 pm
content: really cood unit, ended playing a bit who is fast game with my kidshttps://youtu.be/08CPbp-rFe4maybe an idea for a little arduino project for the holidays ?program it together with your kids, and then play who is fast ?

author: bidrohini
author_rank: Regular Contributor
timestamp: December 15, 2022, 05:22:11 am
content: I especially like the casing. Very compact and easy to use.

author: Faranight
author_rank: Unknown
timestamp: December 15, 2022, 06:39:58 am
content: Reminds me of those arm speed tests that teachers sometimes had us do back in elementary where you had a board on the desk that had three large metallic contacts. You would sit down in a chair and place your right hand on the middle contact. Then with your left hand you were supposed to hit the left and right contact in an alternating way as fast as possible and the machine would count the number of hits. You only had a limited time to do it, so the faster you swung your arm the higher you would score.
Scope DIY Battery question - Page 1
Forum section: electronics / projects

author: BiOzZ
author_rank: Regular Contributor
timestamp: May 31, 2013, 09:47:47 pm
content: So many years ago i bought my self an Owon PDS 5022s scope because it had a nice big screen and cost only $350 new on ebaybut i later learned that it has a battery compartment on the back and allows you to use it in order to run the scope portably! (honestly thought it was just some sort of compartment to store somthing or external modules or whatever) ... this is not very useful for me but i quickly pieced together that a portable scope means it runs offline of the earth ground!so i opened up the battery compartment and of course ... no battery ... and i cant find one online that wont cost an arm and a leg so i thought i would simply throw in my owni ran some tests ... the battery compartment says "7.4v lithium battery" and the scope says "15W max" ... no mAH ... nor can i find that info online with a quicko google searchso what i did is i rigged up an adjustable voltage supply and measured currentat 6.2V (least i can run it while stable) it draws 0.75A ... at 7.5 volts it draws 0.6A and at 12v it draws 0.56v hinting to me some sort of switchmode supply bult in ... or maybe even a standard regulator ... but im not sure about thatANYWHOi turned off the scope and measured the voltage to see if there was any charging voltage across the terminals ... nothing ... turned it on and bam 8.6v while plugged inso clearly its the charging voltage and seeing how it was stable im guessing the charging circuitry was built in to the battery ... and it has just 2 terminals clearly marked + and -the battery compartment is (estimating) 1 inch deep, 2.25" tall and 5.5"wide and fully milled outany one know what would be a good battery to use for that draw? and so i can get atleast an hours battery?i know nothing about batteries so i need some help herei can make up a little circuit to charge the battery off the 8.6v or insert a plug to charge it that way so im not looking for a battery to fill the entire compartment ...thanks guys and gals!EDIT: i did find one online but its near $100 USDhttp://www.audon.co.uk/test_acc/pdsbatt.html... not paying thatalso found a pic of what the back looks like without me having to take it!http://www.aidetek.com/New_products_info/Photo/Oscilloscopes/Owon/PDS6062_back.JPG

author: qno
author_rank: Frequent Contributor
timestamp: June 01, 2013, 08:23:01 am
content: That may be the voltage of the battery charge circuit going into cc mode.For test you could connect a 2 cell LiPo battery and see if the voltage drops.
scope pick up - Page 1
Forum section: electronics / projects

author: m3vuv
author_rank: Super Contributor
timestamp: July 26, 2020, 08:55:19 am
content: not sure if this is the rite place to post but here goes,ive 3 scopes,one is a tek 453,also a kenwood dso and an old heath computer dso,on all 3 when i touch the probe tip with my finger i get a trace that measures about 200volts,it does this on all 3 scopes!,its still the same with a 10x probe on 10x or 1x,is that sort of reading normal,or is my house wiring iffy?,cheers m3vuv.

author: bd139
author_rank: Super Contributor
timestamp: July 26, 2020, 09:31:02 am
content: It’s completely normal.

author: m3vuv
author_rank: Super Contributor
timestamp: July 26, 2020, 09:49:37 am
content: what its normal for it to read several hundred volts?

author: bd139
author_rank: Super Contributor
timestamp: July 26, 2020, 10:01:27 am
content: Yep.I can't remember the precise mechanism but you're basically a current source with a high compliance voltage and the input is high impedance so it'll show much higher voltage than you might expect.Here's mine. Yes 214 p-p volts.

author: m3vuv
author_rank: Super Contributor
timestamp: July 26, 2020, 11:03:29 am
content: ok cheers for that,learn something new every day,cheers,m3vuv.

author: magic
author_rank: Super Contributor
timestamp: July 26, 2020, 06:14:13 pm
content: You are a capacitor(okay, one plate thereof)
Scoping a current spike drawn by my Ooma Telo VOIP box - Page 1
Forum section: electronics / projects

author: Peabody
author_rank: Super Contributor
timestamp: May 27, 2022, 03:41:26 pm
content: Yesterday my Ooma Telo box operated normally on outgoing calls and retrieving voicemails, but started going into reset on answering an incoming call. It turned out to be a bad power brick, and after wiring into the power jack terminals I was able to power it from a good power brick (2A), and it appears to work fine. The new replacement brick is due tomorrow.However, in an attempt to see what amp rating I needed for the replacement (the old one is 5V 2A), I measured the current drawn by the Telo using an ancient Weston ammeter, model 301, which goes up to 70mA. It's probably from the 1940's, has a ".02 MFD" capacitor across the terminals, as well as a 5-inch length of copper wire, probably 28 gauge, as a shunt. Taped to the face is a hand-written sticker saying "20mA = 1A".Based on this, I find that the Telo idles at about 1A, and goes up to 1.25A when I place a call. But when I answer an incoming call, there's a sharp, short current spike that appears to go above 2A. But I don't know if the needle actually shows the extent of the spike because of the capacitor, or possibly even overstates it because of the inertia of the needle once it gets moving.So I thought I would try to display the current draw on my scope (battery powered, non-referenced to anything). But the smallest resistor I have is 0.51 ohms, which would cause too big a voltage drop if the spike is really 2+ amps.What can I use as a shunt that would be 0.1 ohms or less that wouldn't also introduce inductance issues? Would a foot of 30 gauge wire wrap wire work, or even six inches, if I still have some of that? Is there anything else that's commonly used that I'm likely to have in the junque box?And I guess I should ask what would cause the big spike on answering a call. I've tried disconnecting all the house wiring and plugging a single phone into the Telo, but I still get the spike. And as I said, I do not get the spike if I pick up the same phone to make a call. It's very puzzling. The replacement brick is 3A, but I'm wondering if I should plan on replacing the Telo too. It just seems this current spike shouldn't be happening, but for all I know it could have been happening from the beginning - about 10 years ago.

author: Peabody
author_rank: Super Contributor
timestamp: May 27, 2022, 05:32:33 pm
content: Well I think this is a nevermind. Today, all the phones and the house wiring are working ok. No current spike when answering a call. So either it healed itself, or Ooma updated the firmware overnight.
SCPI Commands Help :PRIV - Page 1
Forum section: electronics / projects

author: Teun
author_rank: Regular Contributor
timestamp: December 04, 2024, 09:24:27 am
content: Hi,I was looking into SCPI commands to take screenshots of my RIGOL DSA815-TG. Now I found this command online, "PRIV:SNAP? BMP", which indeed gives me a snapshot of the device.But the ":PRIV" command isn't really mentioned much in documentation on SCPI. Where does it come from? And how would I have known about it if I wouldn't have found it online? It isn't even mentioned in the DSA815 Programming guide.I might want to eventually write some test program in C# to control some of the test equipment we have here at the office. So where could you find information about these commands that obviously work but aren't mentioned in the documentation?

author: Messtechniker
author_rank: Frequent Contributor
timestamp: December 04, 2024, 09:36:58 am
content: If there is some software from the manufacturer, you might want to sniff the SCPI commands to find out any undocumented SCPI commands. Did this with my Uni-T UT 622E

author: Teun
author_rank: Regular Contributor
timestamp: December 04, 2024, 01:02:03 pm
content: Ultra Spectrum is the standard program for it. And while it does have a history list of the SCPI commands sent to the spectrum analyzer, I don't see any method for finding out additional commands. Also I have to say that I find these standard programs by rigol a bit cringing.I found the :PRIV command because someone mentioned it was used in rigol-bildschirmkopie which I used before. (couldn't find it anymore) But if it was used there it should have been available somewhere I guess, right?

author: Fenstergucker
author_rank: Regular Contributor
timestamp: December 04, 2024, 01:26:52 pm
content: Hello Teun,here you can find SCPI commands for Rigol devices:https://www.eevblog.com/forum/testgear/lists-of-rigol-scpi-commands/I have read out the SDRAM of my Rigol devices via JTAG. A self-written program can then create a list of the available SCPI commands.But there are actually no other useful commands on the DSA800, except for the command used to create license codes.Here is a list of the commands, but without parameters, from the current firmware.Peter

author: Teun
author_rank: Regular Contributor
timestamp: December 04, 2024, 01:41:10 pm
content: Ah thank you

author: Fenstergucker
author_rank: Regular Contributor
timestamp: December 04, 2024, 01:59:17 pm
content: If you are looking for the old programs, RigolBildschirmkopie and Rigol-DSA815(Remote) I have made.Here are the links to the archives of the websites:[Links removed]Peter

author: Teun
author_rank: Regular Contributor
timestamp: December 04, 2024, 04:07:29 pm
content: And thank you again
SCPI interface on old power supply - Page 1
Forum section: electronics / projects

author: junkelec
author_rank: Newbie
timestamp: February 11, 2023, 09:28:53 pm
content: Hello everyone,New on this forum, have heard about it for quite a long time now thx to a certain yb creatorI'm creating this topic to have your opinions on my plans to make an old powersupply of mine (the STD 601 from Sodilec, datasheet can be found online) programmable through ethernet and usb 2.0 using SCPI commands.The power supply has a few ports at the back, and with them i can control the voltage with a voltage source (so gonna use a DAC for that) and the current limit with a variable resistor (not sure how i'll do that, programmable resistors through SPI can't handle much current, haven't tested the current through resistor with this setup, anyway all on datasheet, in french unfortunately). The analog part of things I think I can manage... but for the digital world...I have some experience with uart, but nothing as complex as usb. To begin with, stm32 with built-in PHY for usb2.0 and just MAC (using a phy on a pcb that i'll have to design) is sufficient ? (of course next there's software, but I want to make sure I don't forget something important)Thanks for any advice++

author: dobsonr741
author_rank: Frequent Contributor
timestamp: February 11, 2023, 09:52:29 pm
content: You'll find quite a few SCPI C libraries on github. I've usedhttps://github.com/SAFedorov/CE-cryo-manifold-driver/tree/master/External/oic.Using it via USB is fairly simple as long you stay with CDC serial port USB class. Then use VISA as the foundation for the client, the serial port naming will go like ASRL4::INSTR in VISA. My personal preference is VISA (the native NI stack) + PyVisa and a Jupyter notebook to run the measurements.
SCR di/dt Protection - Practical rule - Page 1
Forum section: electronics / projects

author: 2X
author_rank: Frequent Contributor
timestamp: July 20, 2016, 11:25:14 pm
content: Hello,I know that a dv/dt protection is possible with a snubber circuit which is a series combination of resistor "R" and capacitor "C" (design 1) and mustdv/dt <= 0.632*(Vdrm/RC). di/dt protection is possible with a series inductor (design 2) with the SCR and I found the formuladi/dt = Vs/L => L = Vs/(di/dt). Do you know if there is a practical rule of how lower must be the calculated di/dt value from the di/dt that given from each SCR's datasheet?

author: moffy
author_rank: Super Contributor
timestamp: July 20, 2016, 11:55:05 pm
content: Personally I have never had to worry about di/dt protection as there was enough inductance in the cabling and load to keep it safe even under short circuit conditions, but dv/dt was another issue. You need to ensure that the snubber can absorb the energy from the installation inductances, and that is mostly trial and error. You work form low power up to high power.
SCR False Triggering [SOLVED] - Page 1
Forum section: electronics / projects

author: anishkgt
author_rank: Frequent Contributor
timestamp: February 20, 2018, 09:04:52 pm
content: Hi All,I've been trying to get my First SMD boards working. Seems every time i fix something another one seems to be popping up. First, it was the USB bridge not being detected and now the SCR seems to be triggered and conducts continuously after powering on the PCB.The through hole version works very well but the SMD does not seem to be working. Are there are in standard procedures that needs to be followed when selecting SMD that would run on the mains. Should they be THD. I've got only 4 MOVs(R16, R40), one Cap (C10) and another Cap (C16) that are through hole.The load for the moment is the a Incandescent bulb but was designed to switch a microwave oven transformer for spot welding.The schematic is quite simple, the peak of a sine wave is detected and the SCR are triggered. i am certain its the MCU that is triggering, i've removed the optocoupler (OPT2) and still load conducts.

author: anishkgt
author_rank: Frequent Contributor
timestamp: February 20, 2018, 11:55:08 pm
content: After removing each component i was able to isolate the problem. Removing the scrs stopped the bulb from switching on when the pcb was. i checked the resistivty of Cathode to Anode on both the scrs both read OL.So it wasn't the SCR either, then what could it be ?

author: anishkgt
author_rank: Frequent Contributor
timestamp: February 21, 2018, 12:32:33 am
content: Thank you Blueskull. Appreciate it. just checked my through hole design and i was surprised.
SCR identification - Page 1
Forum section: electronics / projects

author: IO390
author_rank: Regular Contributor
timestamp: May 01, 2014, 06:54:09 pm
content: Hi,I recently obtained some SCRs (at least I think they are), and I'm having a hard time finding any data on them.Here's a few images.Any help with this would be greatly appreciated.IO

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 01, 2014, 07:02:15 pm
content: The device symbol would appear to confirm that it is an SCR.The manufacturer's logo could likely be matched by spending a few minutes on Google image search.The "8243" is almost certainly the date code (43rd workweek of 1982)If you can't Google the "SRH060" or "SPL120", they are probably "house numbers" for some OEM.You might be able to characterize them for yourself with a curve-tracer or equivalent.

author: envisionelec
author_rank: Frequent Contributor
timestamp: May 01, 2014, 07:03:48 pm
content: The logo is SGS-Thompson, now ST Semiconductor.

author: IO390
author_rank: Regular Contributor
timestamp: May 01, 2014, 08:08:32 pm
content: Thanks awfully, both of you.I really can't find shit on them, I guess I'll just have to play around with them and see what happens, like you say.IO

author: SeanB
author_rank: Super Contributor
timestamp: May 02, 2014, 12:27:37 pm
content: The package typically tops out with a 16A device, and guessing from the part number yours is a 12A variant. It might have a reverse voltage of 70V or 700V, about the easiest way to tell is to connect it to AC with a series 25W lamp and nothing connected to the gate and see if it breaks down. If it does it is a 70V device, if not 700V.
SCR phase angle control - Page 1
Forum section: electronics / projects

author: vovoj
author_rank: Newbie
timestamp: December 26, 2018, 09:49:40 pm
content: Hey guys,I would like to ask you if any of you recommend an SCR phase angle driver IC for a thyristor driven power supply project. I saw on internet one called TCA785, but it looks like it's been discontinued.I searched on the topics and couldn't find anything on this matter.

author: Wolfgang
author_rank: Super Contributor
timestamp: December 26, 2018, 11:26:18 pm
content: Hi,I have some SCR (pre) regulators described here:https://electronicprojectsforfun.wordpress.com/power-supplies/preregulator-circuits-for-linear-power-supplies/

author: vovoj
author_rank: Newbie
timestamp: December 27, 2018, 03:46:15 pm
content: Cool. I didn't know about these SCR regulators. The power source for which I am designing a controller has the following specs 15-40V/1000A. I am using a three phase thyristor bridge on the secondary side of a 380V/36V transformer.I saw that in one of these pre-regulators they use a L120A IC to drive the TRIAC gate, which is very similar to the TCA785 IC. I wonder if there's any newer IC for SCR gate driving, perhaps able to do digital communication with a microcontroller, for example.

author: David Hess
author_rank: Super Contributor
timestamp: December 27, 2018, 06:53:37 pm
content: I am not sure there have ever been any common phase control ASICs but everybody seems to have made one at some point. They are not difficult to implement with discrete parts even when operating directly off of the line voltage.The biggest problem tends to be that the simplest circuits rely on a DIAC or other medium voltage trigger device and most of them have been discontinued also; PUTs and DIACs are still available though if you want to go that route.

author: vovoj
author_rank: Newbie
timestamp: December 27, 2018, 08:08:10 pm
content: Yeah... I see I will probably have to build one myself... The kind of phase controller I am looking for uses the idea of the diagram attached, because these allow closed loop control. The kind I know that uses DIACs can't be used with closed loop control because it relies on setting a potentiometer resistance.

author: David Hess
author_rank: Super Contributor
timestamp: December 28, 2018, 09:20:30 am
content: Quote from: vovoj on December 27, 2018, 08:08:10 pmA DIAC or PUT just takes the place of the comparator. When the voltage reaches the DIAC's trip point, it discharges.

author: Circlotron
author_rank: Super Contributor
timestamp: December 28, 2018, 09:31:39 am
content: I hope you are using 6 SCRs and not 3 SCRs and 3 diodes. Had one of the latter for control of a 15kW furnace and it really made the transformer growl. 6 SCRs made a nice clean buzz sound. And most definitely use a choke input filter if the DC output is to be filtered.

author: vovoj
author_rank: Newbie
timestamp: December 28, 2018, 06:08:47 pm
content: Thanks for the information. I didn't know about that. Fortunately I am using a 6 SCR bridge.
SCR power control for electric blanket - Page 1
Forum section: electronics / projects

author: soldar
author_rank: Super Contributor
timestamp: November 15, 2023, 08:36:50 pm
content: I have several LIDL electric bed warmers where the power control thing on the cord has failed. (BTW, I believe their repair might make be interesting for Big Clive but I know of no way to contact him. If anyone knows you can tell him I would send them to him.)So I thought I would make my own power control. I measured the resistance of the blanket and it is too low to connect directly to 230V. I suppose I could design a simple astable with a duty cycle of , say, 1/3. 3 seconds on, 7 seconds off. That should work reasonably well but it would require separate low voltage supply.Another option I considered was using one of the many unused triac "dimmers", modifying it so the max power was about 80W. But i did not go that route. Too easy.I have a box full of *really* old SCRs and decided to have some fun. After some tinkering I have a working power control. It has a switch with three positions, High, Medium, Low which produce about 75, 50 and 30 W respectively. I preferred that rather than a continuous range with a pot.I played with the values of the components and determined the best values by trial and error.Because it is an SCR I rectify the voltage first. The capacitor is charged through the three resistors in series. When the voltage reaches a certain level the two transistors conduct and fire the SCR. It is very simple.It works reasonably well. It seems it needs to warm up and stabilize before settling on a give power. I suppose the transistors are to blame.Nothing special. Just a fun project.
Scraping a 100W stereo and making PSUs for my desk - Page 1
Forum section: electronics / projects

author: lordvader88
author_rank: Frequent Contributor
timestamp: January 18, 2018, 06:27:12 am
content: I found a "cheap" 2004 5CD stereo in the garbage, fuses are good, probably worked. So thats great, now I have a 100W transformer of the size I want for breadbroading on my desk.So far I have taken it apart and set aside the 100W transformer (no center tap tho) and its main PCB which is just pretty basic and I think only analog on that board. And the PCB is wide open with lots of unused places, which is great because I can reuse the board and mod onto it some LM723s and what not that I bought for making my own stuff. So I'll make an adj voltage and adjustable current supply. And also make another separate split rail supply that I can switch over too. And I can put it all back in the bottom/back of the plastic case and add a wooden cover, dials, switches, etc.Also there was an audio output filter board the size of a chocolate bar (2cm*3cm*7cm). It has L/R RCA plugs and the spring loaded speaker outputs. It also has a 8pin ribbon cable. So I took all the LCR stuff off the PCB and soldered up a basic LM317 adj. voltage regulator with an LED so far. I have some nicely secured alligator clips on there as well and a switch. I have to find my little drills and add in some current regulation and opamps too for fun. Blinky LEDs too like on STAR TREK. I didn't map it all out for using the traces for the next steps, but thats fine. I'll dead bug it and wire it with more switches. And I'll put it in a remote control case. For now I'll just use that with a 24V laptop PSU I guess, and stop using the 12V modem PSU. Add its a nice little compacted thing that will further reduce the wire clutter I hopeI have the radio section PCB, a TOSHIBA TA8258H 80W 4ch mixer audio amp, all the motor stuff. And how hard is it do re-purpose the non-LCD display with wires inside, can't remember name. I don't know/remember much digital or programing. But even just lighting up any part is fine so long as u control it and then it can represent whatever u want.Most of the chips in the stereo I can't find anything on. Look forward to seeing what all that stuff looks like on a scope. Probably not like much, but the radio and motor PCBs I'll power up and see.

author: cellularmitosis
author_rank: Unknown
timestamp: January 18, 2018, 08:14:01 am
content: cool! great project.some of those old amps have very low value, high wattage ceramic resistors. those are useful for high-amperage RLC filters.
Scratch build: LED Flasher Project + Blender Render - Page 1
Forum section: electronics / projects

author: noSun
author_rank: Contributor
timestamp: June 29, 2015, 08:00:18 pm
content: Completed another scratch build project. LED Flasher project #11Video features Blender render, 3D printing, schematic, breadboard, board fab, assembly & demo.Video LinkThanks for watchingPlease like/subscribe.
Scratch Build: RGB LED Project #10 - Page 1
Forum section: electronics / projects

author: noSun
author_rank: Contributor
timestamp: June 11, 2015, 10:11:03 pm
content: Adding some color to my workstation....Part 1: Schematic & Breadboard CircuitPart 2: Build Board & Demonstration

author: noSun
author_rank: Contributor
timestamp: June 12, 2015, 12:42:05 pm
content: Added part 2.thanks for watching,-steve
Screen grabber for Tektronix TDS 3xx series oscilloscopes - Page 1
Forum section: electronics / projects

author: jundar
author_rank: Contributor
timestamp: September 23, 2022, 04:27:32 pm
content: Screen Capture Utility for Tektronix TDS340, TDS360, TDS380 oscilloscopes.I've created a small Windows program to grab screen of Tektronix TDS3xx Series oscilloscope.Uploaded short demonstration video atThe program:1. ..is very small and fully portable.2. ..saves grabbed screen as PNG file.NOTE: If real RS232 port is absent on PC, RS232 to USB adapter + Null modem cable can be used.Windows OS and Option14 with RS232 port is required.Hope, someone will find it helpful.
Screen Ground on a PoE application - Page 1
Forum section: electronics / projects

author: TwinScroll
author_rank: Contributor
timestamp: June 28, 2020, 07:08:19 pm
content: HiJust after peoples opinions/suggestions on a screen ground location/path.Please see the attached image, The setup will be powered by a PoE switch - it is connected to an Audio Encoder (AXIS C8033).The Encoder creates a local 12V supply and this is used to supply (in my case) a microphone (the mic works between 9-18VDC)The output from the microphone is balanced line level (consumer) and via a 1:1 transformer this is routed into the audio encoder as an unbalanced input.My question is with regards to screen ground connection point for the multi-core cable from the microphone.The cable is physically (2 x) 22AWG twisted pairs, each individually foil wrapped and the cable has an overall screen braid (with drain wire).1 of the pairs is microphone 12VDC & 0VDC and the other pair is for the balanced audio output from the microphone.The enclosure for the encoder / transformer is plastic so a case screen is not possible.If I use the 0VDC from the encoder for the screen ground I am curious if this is going to be a bad idea.... any noise I pick up will have a long path through the encoder internals and I presume back down the PoE power wires.Presenting this noise to the encoders 0VDC feels wrong?Should I be thinking along the lines of maybe using a common mode choke on the DC power wires? and dare I say no screen?Best RegardsTS

author: Simon
author_rank: Unknown
timestamp: June 28, 2020, 08:20:14 pm
content: As an audio application does it matter that much? The 0V of the encoder is not a bad place to start.

author: David Hess
author_rank: Super Contributor
timestamp: June 28, 2020, 10:04:31 pm
content: The screen should be connected to a low impedance point near the input amplifier which will usually be common or the negative supply but could be the positive supply. This is the same point that a metal shield would be connected.
Screw lock DIN connector - Page 1
Forum section: electronics / projects

author: ezalys
author_rank: Frequent Contributor
timestamp: November 05, 2024, 01:46:22 am
content: Does anyone know where I can find a receptacle for this screw lock DIN connector? It’s off an LVDT gage.

author: edpalmer42
author_rank: Super Contributor
timestamp: November 05, 2024, 02:19:43 am
content: I can't be sure about the size, but it looks like an Amphenol C091 series connector. Mouser has them. I didn't see them at Digikey.

author: Zipdox
author_rank: Regular Contributor
timestamp: November 05, 2024, 02:24:01 am
content: I think this the companyhttps://uk.rs-online.com/web/c/connectors/circular-connectors/din-connectors/?applied-dimensions=4294431159

author: tooki
author_rank: Super Contributor
timestamp: November 05, 2024, 12:21:37 pm
content: Quote from: edpalmer42 on November 05, 2024, 02:19:43 amDigikey has them, not sure why you’d think they don’t:https://www.digikey.ch/short/rzvpntr5

author: tooki
author_rank: Super Contributor
timestamp: November 05, 2024, 12:28:07 pm
content: Quote from: ezalys on November 05, 2024, 01:46:22 am- Amphenol series C091 A and D (C091 B is bayonet-lock)- Binder series 680 and 723- Lumberg series 03- Hirschmann MAB series

author: ezalys
author_rank: Frequent Contributor
timestamp: November 05, 2024, 07:35:54 pm
content: Are C091 A and D compatible?

author: tooki
author_rank: Super Contributor
timestamp: November 06, 2024, 06:39:19 pm
content: Yes. The datasheet says on both of them that they are “screw locking according to IEC 61067-2-106” which is the relevant standard.They’re just IP40 and IP67 versions of the same thing.
Screwed up pfet SOT-23 design. Swapped Source and Drain - Page 1
Forum section: electronics / projects

author: Ribster
author_rank: Frequent Contributor
timestamp: December 20, 2019, 09:54:48 pm
content: Hey everybody.So what the title describes. I've swapped pin 2 and 3 of a SOT-23 pFET.Respinning my boards would be a bit of a shame and wastefull.I'm looking at some P MOSFETs that are like this: 1- GATE, 2 - DRAIN, 3 - SOURCE.I've really screwed the pooch, since i now see that every one of them is DRAIN on pin 3...Suggestions ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 20, 2019, 10:47:54 pm
content: If you have just a few, turn over the part and bend the leads down. It'll be cocked at an angle.An N-FET wouldn't short out the path, but you'd have to figure out some way to invert (and most likely boost) the gate voltage, which will be a tall order in most circuits.Tim

author: Someone
author_rank: Super Contributor
timestamp: December 21, 2019, 12:06:05 am
content: Depends on how your pads are arranged/shaped, a different package (SC-70 for example) might fit as is.

author: Ribster
author_rank: Frequent Contributor
timestamp: December 21, 2019, 07:34:59 am
content: Quote from: T3sl4co1l on December 20, 2019, 10:47:54 pmI did just that and my design works as intended.I just made 12 boards, and i want them to be ready for a client.Quote from: Someone on December 21, 2019, 12:06:05 amThanks! I’ll have a look for SC-70 pinouts
Screw/Fix PCB - Page 1
Forum section: electronics / projects

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 19, 2019, 03:26:03 pm
content: I need to screw (I guess) my battery holder (4xAAA) to my PCB.The holder already has two countersunk holes of diameter 3.2mm.What is the normal was to do it? Is the best solution to have a hole put in the PCB then use a self-tapper or use some kind of tiny bolt?Either way, what make/model of screw/bolt should I use?Thanks.

author: soldar
author_rank: Super Contributor
timestamp: June 19, 2019, 03:50:44 pm
content: Countersunk M3 should work for the holder. Depending on the PCB material and the holding needs maybe it will get a grip on the board. If you can use a nut on the other side that solves it.And you can always use glue.

author: Benta
author_rank: Super Contributor
timestamp: June 19, 2019, 04:11:05 pm
content: Self tapping M3 into a non-plated 2.6 mm hole in the PCB (provided it's FR-4).

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 19, 2019, 05:37:18 pm
content: Cheers both.FR-4?

author: mdszy
author_rank: Unknown
timestamp: June 19, 2019, 07:08:49 pm
content: Quote from: PerranOak on June 19, 2019, 05:37:18 pmFR-4 is the fiberglass material that most PCBs are made out of.

author: Benta
author_rank: Super Contributor
timestamp: June 19, 2019, 07:09:29 pm
content: FR-4 is the term for the ubiquitous green fibreglass/Epoxy PCB material. My apologies for being "nerdy" here.

author: Bud
author_rank: Super Contributor
timestamp: June 19, 2019, 08:13:21 pm
content: I would not go with self tapping screws. Batteries are heavy, chances are good the screws will become lose with time and the holder will fall off. A countersink head screw and nut on the other side and perhaps a drop of threadlocking compound.

author: bd139
author_rank: Super Contributor
timestamp: June 19, 2019, 08:22:30 pm
content: I’d put down a pad with a big annular ring or a suitably sized hole depending on your preference and put a shake proof washer and nut on the bottom with an M3 countersunk scree through it all.

author: Benta
author_rank: Super Contributor
timestamp: June 19, 2019, 08:46:06 pm
content: My apologies. I used the wrong term.What I actually meant was "thread cutting screw", thus my reference to M3.Like these:https://www.valuefastener.com/screws/thread-cutting-screwsThey hold excellently in 1.6 mm FR-4, and 4 x AAA ain't heavy.

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 21, 2019, 01:24:14 pm
content: Thank you all very much.
Scuba diving headset connection - Page 1
Forum section: electronics / projects

author: Entropia
author_rank: Regular Contributor
timestamp: June 08, 2014, 06:51:49 pm
content: Hi. A friend of a friend asked me to design a scuba diving phone for him. A surface unit contains two amps, a speaker and a mic. When the surface person depresses the PTT button he/she can talk to the scuba diver below surface. The diver has a headset with speakers and a mic. Nothing fancy thus far. However, this guy tells me the defacto connector for underwater headset is two banana plugs, i.e. one ground and one signal.How is the underwater headset wired up exactly? I tried to Google it but didn't find anything useful.

author: SeanB
author_rank: Super Contributor
timestamp: June 08, 2014, 06:56:01 pm
content: Same as a telephone, with a transformer to split the 2 signals inside the headset. Look at phone systems or intercoms where they use a transformer or a few opamps to combine the audio and split it on each side.
Scullcom DC Voltage Calibrator – Expandable to 100 and 1000V DC? - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: March 28, 2019, 05:49:07 am
content: Hi!I have just bought Louis Scully's DC Voltage Calibrator PCB as a future construction project!It is my future intention to construct this as a bench unit operating off the mains that (I hope!) can be expanded with 100VDC and 1000VDC max outputs, now that pcb designs can be obtained cheaply from JLC, additional pcbs for the 100V and 1000V ranges are no problem for me!Is it possible to stabilise 100V and 1000V to the same degree and stability as the basic 10V design, for use with multimeters? (I'm looking at 10mA @ 100V and 5mA at 1000V max) – basically the 100V and 1000V would consist of x 10 and x 100 d.c. amplifiers added to the output of the original design, with control relays for the outputs and switching transistors to select revised code selection in the Arduino by earthing suitable pins, etc.Can anyone point me in the direction of suitable circuits for x10/x100 high voltage d.c. amplifiers, and/or precision regulator circuits capable of stabilising up to 100/1000V please?Also, what would be needed to be added to Louis's Code for 100 & 1000V ranges and where can I find resources for this please?Finally, what about a.c. high voltage calibration sources? Datrons & Flukes use power HF generators for this, feeding whacking great ferrite core h.t. transformers – has anyone produced an a.c. source project capable of 1000V at 10/20mA up to 5 or 10kHz that can be sufficently well stabilised?(Unless that lot from the Postcode Lottery that jump up and down on the telly ranting and raving at big wins give me a very kind smile, the chances of me ever being able to buy a Datron or Fluke high voltage calibration source are absolutely NIL!)Chris Williams

author: coromonadalix
author_rank: Super Contributor
timestamp: March 28, 2019, 11:32:03 am
content: If it was designed for 10v, not sure you will end with good results at higher voltages, you may add noise and instability than intended, find a way to contact him and ask him ??Some people used electrophoresys psus with good resultsAll the codes and snipets are here :

author: David Hess
author_rank: Super Contributor
timestamp: March 28, 2019, 07:03:21 pm
content: Quote from: Chris56000 on March 28, 2019, 05:49:07 amStability will depend on the resistor divider used for feedback.Since a gain of 10 or 100 amplifier will amplify the input noise and drift just as much as the signal, there is a performance advantage to stacking 10 or 100 10-volt shunt references so that the voltages add directly but the noise in only increased by 3.2 or 10 times respectively.
Scullcom Electronic DC Load - Page 1
Forum section: electronics / projects

author: Spark-Doctor
author_rank: Contributor
timestamp: December 09, 2019, 10:05:44 pm
content: Hi AllI have taken the leap and decided to try to build Scullcom's DC Load project,He published the Gerber files and i was placing an order with JLCPCB so ordered 5 of his design at the same time. After watching Dave's video on laying out PCB's, i was a little horrified with his layout,I decided that i wanted to change the layout and also try to incorporate more SMD parts to the design. Has anyone here made this project and did you run into any problems i should be aware of?Many ThanksIan/img]

author: intabits
author_rank: Frequent Contributor
timestamp: December 16, 2019, 11:15:40 am
content: He often makes follow up videos to enhance and/or fix problems with his initial designs, and this this one has lots - 10 parts!I imagine that you've watched these followups, but if not, you should.And there are a number of threads on this forum covering this subject, so you could get ideas and learn a lot by reading through those also.