hybridfree/eevblog-posts huggingface dataset:
Print Code 128 barcodes on EM205 thermal printer - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: March 07, 2018, 02:09:44 am
content: 1. Need to print Code 128 barcodes on EM205 thermal printers. I am using arduino library here:https://github.com/adafruit/Adafruit-Thermal-Printer-Library2. printer is EM205 running at 9600 baud rate. I am able to print characters & barcodes as attached.3. barcode in pic is 14 characters max as u can see & below is code for that:printer.print(F("CODE128:"));printer.printBarcode("12345678901234", CODE128);4. Problem is when i increase the characters to 15 or more, nothing prints. How to solve this? I need to printer around 55 characters.

author: eliocor
author_rank: Unknown
timestamp: March 07, 2018, 07:49:34 am
content: The resolution of your printer is too low for printing a such long (large?) barcode!Maybe you can create your barcode in graphic mode and send it to the printer through longitudinal printing (no limits in length)Please take care that it will be rather difficult reading your 75chars CODE128 code with a standard reader: your code will be about 4 times larger than the 14chars one!!!Otherwise, study how 2D codes work and develop a routine to graphically create them and how to dump them on the printer.You can also set the command 'GW w n' (https://cdn-shop.adafruit.com/datasheets/CSN-A2+User+Manual.pdfpage 43) to '2' instead of '3' like in the library:https://github.com/adafruit/Adafruit-Thermal-Printer-Library/blob/master/Adafruit_Thermal.cppat line 258Maybe you have to modify also the constant 'CODE128', but it depends on the version of the printer firmware: maybe this is the reason you can't print more than 14 chars barcode. See the manual and the .h file.
printed coil inductance - Page 1
Forum section: electronics / beginners

author: yalect
author_rank: Regular Contributor
timestamp: March 09, 2015, 07:42:10 am
content: Hello,I would like to ask you how to calculate the inductance of printed coil of LC which comes on some electronic board?Thank you

author: Rory
author_rank: Frequent Contributor
timestamp: March 09, 2015, 01:49:53 pm
content: I know you're going to hate this answer...Insert these words in your favorite search engine:pcb spiral inductor calculation

author: ConKbot
author_rank: Super Contributor
timestamp: March 09, 2015, 03:41:10 pm
content: Quote from: Rory on March 09, 2015, 01:49:53 pmHate? Nah, hate would be "solve"

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: March 09, 2015, 03:42:58 pm
content: Quote from: yalect on March 09, 2015, 07:42:10 amhttp://www.saturnpcb.com/pcb_toolkit.htm

author: katzohki
author_rank: Frequent Contributor
timestamp: March 09, 2015, 05:22:00 pm
content: TI also has a tool:http://www.ti.com/lsds/ti/analog/webench/inductive-sensing.page

author: KJDS
author_rank: Super Contributor
timestamp: March 09, 2015, 06:04:33 pm
content: Use the method of moments to solve Maxwell's equations.

author: Chris Jones
author_rank: Regular Contributor
timestamp: March 21, 2015, 03:19:08 pm
content: Quote from: yalect on March 09, 2015, 07:42:10 amYou can use the open source program FastHenry from MIT.
printer 110 to 220 volt - Page 1
Forum section: electronics / beginners

author: firas
author_rank: Contributor
timestamp: March 01, 2018, 01:01:32 pm
content: i have hp printer 4350 (board rm1-1173)printer 127 volt work i need change to 220 volt can you help me

author: Paul Price
author_rank: Super Contributor
timestamp: March 01, 2018, 10:04:19 pm
content: Printers are so cheap to buy. It would be costly in time and money to modify the P/S to work at 220v. Quite complicated. It is much more easier and would cost less to just buy a 220V model.However, I notice most HP printers that are shipped with 120V power cords are also capable to run at 220V using a different power cord. You can try this and either your printer will either immediately emit smoke and you will hear a loud pop..or else work perfectly.

author: helius
author_rank: Super Contributor
timestamp: March 01, 2018, 10:51:16 pm
content: The 4350 used different power supplies for input voltages. Here is one for 220V:https://www.ebay.com/itm/RM1-1071-000CN-Power-supply-assembly-For-HP-LaserJet-4240-4250-4350-220V/323077598526Replacing it is an involved process:http://www.lbrty.com/tech/articles/4200/swingplatelong/swingplate_long.html

author: Paul Price
author_rank: Super Contributor
timestamp: March 01, 2018, 11:36:29 pm
content: If you are really interested in using this printer you might find a 220V to 120V converting mains transformer as a solution option. A replacement OEM P/S would cost at least USD $70, but a stepdown transformer requires no installation.

author: Brumby
author_rank: Unknown
timestamp: March 01, 2018, 11:38:33 pm
content: You want the quick and easy answer....?Quote from: Paul Price on March 01, 2018, 11:36:29 pmYep.Have a look at this sort of thing:https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Delectronics&field-keywords=240+volt+step+down+transformer+2000wThese come in various capacities, but just make sure you get one that is at least "rated" 50% higher than the printer draws. Personally, I'd go double. For the 4350 I have found a figure of 790W - so I'd be looking at something with at least a 1500W rating. 2000W seems to be the commonly available figure. Always go high here ... it adds a safety margin.Also - such a unit is self contained and universal. If the printer gets replaced, you could use the transformer for something else ... or sell it.
printer cartridge memory - Page 1
Forum section: electronics / beginners

author: deadshort
author_rank: Newbie
timestamp: May 22, 2014, 09:22:53 pm
content: My printer died today with the error print cartridge incompatible, had been working ok for some time. To cut a long story short it was a bad connection on one print cartridge and it now working. But it got me wondering how dose it all work? The faulty cartridge is a cheap one not the genuine Epson one. I think, please correct me if I got this wrong, when a cartridge is printing the printer increments a counter in the cartridge when the printer reads the cartridge and the counter has reached a set count the printer sends to the computer out of ink.so how dose this work? are all the cartridges on the same data bus with address for each colour? How dose a cartridge chip resetter work?

author: Alexei.Polkhanov
author_rank: Frequent Contributor
timestamp: May 22, 2014, 10:31:04 pm
content: I would start by connecting it and sniffing communications between printer and cartridge with an oscilloscope/logic analyser. You may want to try men-in-the-middle attack of some sort afterwards. These cartridge/toner riddle problems can be a lot of fun to solve! Just check online to make sure someone did not do it already for your printer model.

author: amyk
author_rank: Super Contributor
timestamp: May 23, 2014, 01:51:26 pm
content: Been done before for older Epson at least, it's a serial EEPROM:http://www.eddiem.com/photo/CIS/inkchip/chip.htmlMore recent work here (note that it references a patent containing the details of the proprietary protocol):http://www.instructables.com/id/Reverse-Engineering-to-Emulate-Ink-Cartridges-for-/

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: May 23, 2014, 04:05:08 pm
content: You can get some software for older epson printers that can reset the counters,amongst other things .http://www.ssclg.com/epsone.shtml

author: Stonent
author_rank: Super Contributor
timestamp: May 23, 2014, 04:46:30 pm
content: Lexmark used to have so-called Pre-Fill cartridges for laser printers. (I'm not sure if they still do).They would sell you a cartridge at a much lower cost if you sent them back your old one, but the catch was the serial EEPROM on the cartridge would tell the printer to stop printing after a predetermined number of prints no matter how much toner was left.I used to just pop-off the board and replace it from another cartridge that was empty but wasn't a pre-full. Or remove the toner "tank" and mate it to another cartridge. Lexmark (and Dell) used the same cartridge designs for their laser printers but had a different part that fit a keyed slot so you couldn't fit it in. But the keyed part was easy to remove and I used to use really old 12PPM toner on 24PPM prints with no issues.

author: deadshort
author_rank: Newbie
timestamp: May 24, 2014, 07:10:13 pm
content: Thanks for all the reply's. I found all very interesting but the link to the reverse engineering in particularly was very interesting and more complicated than I thought.http://www.instructables.com/id/Reverse-Engineering-to-Emulate-Ink-Cartridges-for-/tnx Andy
Prismatic Lithium Cell mounted monitor - Page 1
Forum section: electronics / beginners

author: syncro
author_rank: Newbie
timestamp: April 05, 2018, 12:06:28 am
content: Hello allI'm attempting to modify a cell monitor circuit that I found on github.[urlhttps://github.com/scttnlsn/cell-monitor].Apparently Scott has his boards talking to an Arduino and is going to build a separate microcontroller board to complete his project. I'd like to do similar, but one step at a time.Since I bottom balance the cells and thus dont need a balance circuit, there are enough pins on the tiny 85 to drive a high and low voltage cutoff. So I added 2 TLP175A photorelays, the output of which will trigger a relay which in turn deactivate the contactors on either the charge or discharge circuit. While the cells power the board, the outputs are driven by a separate 5v supply, shared with relays and eventually the controller. I also added a fuse and laid everything out so the boards can be assembled onto the cells with the connectors lined up so they can be neatly wired up in a daisy chain.This all sounds good to me, but I really have no idea if Ive chosen the right coupler, and it wouldnt suprise me to hear Ive made some elementary errors, let alone the pcb since Ive never tried to lay one out before. I'd be very appreciative if anyone took a look at the attached files and gave an opinioncheersJohn
Probably a Stupid Question About a Schematic, some help appreciated - Page 1
Forum section: electronics / beginners

author: scdreger
author_rank: Contributor
timestamp: January 20, 2018, 09:20:00 pm
content: Hi all,I've found a circuit I want to tinker with this weekend. I'm a little unsure about what is being shown for the DPDT switch wiring. In the schematic's switch "up" position it's clear what's happening, but in the "down" position, does that dotted line indicate a connection between those two areas? Via the switch of course. It's a little confusing for a relative newb.

author: helius
author_rank: Super Contributor
timestamp: January 20, 2018, 09:22:50 pm
content: A dotted line on a schematic is a mechanical linkage. In this case it shows that the switch is 3PDT (3 pole, dual throw). With the switch in the up position, all three contacts are in the upper position, and vice-versa.

author: scdreger
author_rank: Contributor
timestamp: January 20, 2018, 09:43:01 pm
content: OK. I get it now. Told you it was probably a stupid question.Thank you!!!

author: Brumby
author_rank: Unknown
timestamp: January 21, 2018, 03:03:06 am
content: Don't fret.Until you know the answer, there's never a stupid question.It's only after you know that the face palm moment happens.

author: helius
author_rank: Super Contributor
timestamp: January 21, 2018, 05:58:50 am
content: Oh another minor point: when the switch contacts are drawn in the middle like that, sometimes it means the switch has a center detent, where it doesn't connect to either throw. But not everyone uses that convention; I don't think the above schematic intends it that way.

author: Zero999
author_rank: Super Contributor
timestamp: January 21, 2018, 09:07:08 am
content: Another thing of note is that momentary push-buttons and non-latching relays, should always be drawn with the contacts in the non-energised state.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: January 21, 2018, 11:43:25 am
content: Helius +1 for TPDTHelius -1 for center detent
Probably really stupid filter question about two way speakers? - Page 1
Forum section: electronics / beginners

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: March 15, 2015, 08:01:46 am
content: So I just got in to my dream home basically and I have been spending the last few day setting up all the wiring in the house the way I want it, from the mains, to the low voltage and now the home theater.Long story short I have an old sony 2 channel reciver that puts out 15 watts rms per channel. Its nothing fancy but its enough for me. Im wanting to do alot more work to it like add a filter and woofer and wifi capability. Well I tore the speakers apart tonight for the for the first time since 1993 or whenever it was made (It was a hi dollar system in its time, even has a 5 disc changer lol). I took the speakers apart to replace the speaker wire to a thicker gauge thats color blends in more with my house. These are two way speakers with a woofer and a tweeter... I noticed there is only a 2.2uf cap on the hot wire between the woofer and tweeter.What is this cap for? I would think its just there to filter any DC offset but my mind keeps telling me there should be some sort of inductor or resistor running to ground to make a hi pass filter. Does a 2.2uf cap magically work as a hi pass filter in some way?

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 15, 2015, 08:06:57 am
content: Yes, the 2.2uF cap forms a high-pass filter. No "magic" involved.The impedance of the series capacitor (the 2.2uF) and the impedance of the tweeter (undisclosed) form a simple and basic high-pass filter, or "crossover" if you wish. There is presumably nothing on the woofer because it mechanically doesn't have response above the crossover frequency. This is the simplest of "crossover" circuits and is commonly found in low-end consumer speaker systems.

author: Seekonk
author_rank: Super Contributor
timestamp: March 15, 2015, 11:24:36 am
content: Infinity had a two way speaker. Besides the cap for the tweeter they weighted the woofer with putty, a mechanical crossover. That speaker was TISS TISS BOOM BOOM.
Probably simple ground problem - Page 1
Forum section: electronics / beginners

author: Ricardodavinci
author_rank: Contributor
timestamp: January 26, 2015, 09:39:01 am
content: Hi! I've got a simple problem, that I can not figure out why it behaves like that. The circuit is simple, a power supply connected to a LED-stripe, and a separate ground cable attatched to the same point at the PSU. Here is the problem:When I measure the resistance in the cable between PSU and LED's (A to C), the resistance is almost 0 ohm. The same if I put the meater btw A and B. But when I measure btw B and C, the resistance is more than 50 ohm. How could this be?

author: electr_peter
author_rank: Unknown
timestamp: January 26, 2015, 09:51:40 am
content: Picture of connections would be helpful. Do you need that ground cable at all?Resistance may be increased because of poor connection or ground current.Points B and C maybe at different potentials, thus there is some current in B-C link. This messes up resistance measurement on DMM.Remove all connections and measure separately or use special function on DMMs like Agilent/Keysight U1272A called "Smart Ohm".

author: Ricardodavinci
author_rank: Contributor
timestamp: January 26, 2015, 09:54:06 am
content: Attached a picture of the connection in the original post.

author: electr_peter
author_rank: Unknown
timestamp: January 26, 2015, 10:11:45 am
content: Do you measure resistance in circuit? Is this circuit on?Measuring resistance in circuit can turn on diode junctions, measuring resistance with power flowing is invalid in most cases unless compensated. Also, try measuring A-B, B-A, B-C and C-B (that is, swap the leads).
Probe and maximum voltage - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: October 13, 2017, 08:53:45 am
content: For each probe,there is maximum voltage specification.There is also voltage divider specification,1:10 or 1:100 and many others division ratios.If there is device under test that is 1000 V and I have probe that is specified as 1:100 10V,does that mean I can use it?If its 1:100 that means 1% of voltage,so for 1000V voltage source that will result in 10V going through probe and that is within spec so everything is going to be alright,or not?

author: danadak
author_rank: Super Contributor
timestamp: October 13, 2017, 10:14:21 am
content: Yes if the probe itself and its cable has the 1000V rating, with some margin.Regards, Dana.

author: fonograph
author_rank: Frequent Contributor
timestamp: October 13, 2017, 11:56:51 am
content: Quote from: danadak on October 13, 2017, 10:14:21 amBut the probe doesnt have 1000V rating,it have 10 V rating! And why should the cable be 1000V rated? If its 100:1 probe,only 10V should go through cable.

author: Zero999
author_rank: Super Contributor
timestamp: October 13, 2017, 12:40:51 pm
content: Quote from: fonograph on October 13, 2017, 11:56:51 amYour question is confusing.What's the probe's rated input voltage? Is this a passive oscilloscope probe or is it active? 10V does sound low for a passive probe. If your probe is rated to only 10V, then of course you shouldn't use it for 1kV.

author: fonograph
author_rank: Frequent Contributor
timestamp: October 13, 2017, 01:29:40 pm
content: Confusing? Its brutaly simple,let me try again,there is 1000000 V voltage source and and I have 1:1000000 probe rated for 1V maximum voltage,can I use it?If the 1V maximum voltage rating is for the probe tip,then I cant use it.If the 1V maximum voltage rating is for voltage divider output then I can use it becose 1000000 V through 1:1000000 divider is 1V.My point is,does the 1:X probe spec matters for maximum input voltage? If I have 100V rated probes,and one is 1:2 and other 1:10,is the maximum input voltage same,or does thr 1:10 have 5x higher maximum input voltage than 1:2?

author: Brumby
author_rank: Unknown
timestamp: October 13, 2017, 01:38:23 pm
content: Quote from: fonograph on October 13, 2017, 01:29:40 pmNo. You would need a probe rated for 1000000V.When it comes to ratings, forget the output voltage!The rating for a probe will be the maximum input voltage. Actual voltage.The 10:1 or 100:1 or 1000000:1 division just gives you the arithmetic factor to calculate the output voltage you would get for a given input voltage.

author: tggzzz
author_rank: Super Contributor
timestamp: October 13, 2017, 03:46:58 pm
content: Quote from: fonograph on October 13, 2017, 08:53:45 amThere is also a voltage-vs-frequency specification; note it carefully.A probe rated at 300V at 50Hz may only be rated at 10V at 100MHz.
Probe Question for Kikusui 5520GR - Page 1
Forum section: electronics / beginners

author: wanderer
author_rank: Contributor
timestamp: November 25, 2015, 03:14:25 am
content: I am hoping someone can provide some guidance. I just picked up a Kikusui 5520GR for about $58. It doesn't come with probes so I'm going to need to get some. I found the manual,www.kikusui.co.jp/kiku_manuals/NUMERIC/5520GR_E.pdfbut still not sure from reading through it if standard connector or if there is more to probe selection than I know.Section 5 Page 40 says resistance is 10 M ohm Capacitance is appox 20 pFIt also has a chart that list connection methods as covered wire, shielded wire, probe, coaxial cableIn the covered wires section it mentions a BNC type adaptor type 942ACan anyone help me out with a recommendation on what probes I need and a possible source to pick them up.Thanks

author: tautech
author_rank: Super Contributor
timestamp: November 25, 2015, 03:36:08 am
content: Welcome to the forum.Usually scope probes connect with BNC connectors.Any of the P6100 probes listed on eBay will do the job, no problems.They are vey well priced, usually under $20 a pair delivered.

author: wanderer
author_rank: Contributor
timestamp: November 25, 2015, 03:41:43 am
content: Thanks, I was hoping it was just a standard probe.
Probe ratio setting - 1X vs 10X - Page 1
Forum section: electronics / beginners

author: Slappy_g
author_rank: Regular Contributor
timestamp: September 02, 2016, 03:32:19 pm
content: Hey guys...I wanted to ask what may be a stupidly-basic question. When doing a firmware update on my MSO2000 series scope, I started checking all the settings. I realized that the probe ratio was set to 1X on both channels. Since the probes that ship with the scope are fixed 1:10 ratio, should I be setting that value to "10" in the channel settings?If so, it seems odd that Rigol would not default it to 10X since that's what they pack in the box. On a different note, I've got my scope software upgraded to 300MHz, but is it worth investing in higher-end Tek or Agilent probes? Those look pretty pricey, even for passive probes.Thanks guys!- Slappy
Probe the Primary and the secondary of a transformer - Page 1
Forum section: electronics / beginners

author: manytoolsmike
author_rank: Contributor
timestamp: March 31, 2021, 03:14:41 am
content: Hello everyone,I am trying to compare a 40 kHz signal before and after it passes through an output transformer to step up the voltage. The primary signal is 12 Vac from the H-bridge the secondary is 200 Vac and drives a large ultrasonic transducer. The power is 5 watts.Im assuming I cant probe the primary and secondary at the same time without shorting them, is this correct? I guess this is a reason to use a differential probe? can I use the differential probe on the secondary and a passive probe on the primary?Thank you for taking the time to read this. I appreciate your help.Mike.

author: PartialDischarge
author_rank: Super Contributor
timestamp: March 31, 2021, 03:31:46 am
content: If the primary comes from an H bridge then you also need a diff probe, so 2 differential probes for both of pri and sec

author: bob91343
author_rank: Super Contributor
timestamp: March 31, 2021, 03:58:45 am
content: And be careful not to exceed the common mode voltage ratings of the probes.Another way is to use transformers to couple to the scope but you need to make sure those transformers will faithfully transfer the signal without loading.
Probe tip for lithium ion battery slits? - Page 1
Forum section: electronics / beginners

author: Amish
author_rank: Newbie
timestamp: January 26, 2014, 09:09:18 pm
content: Is there a special narrow tip for probing lithium ion battery slits? I'm trying to check the voltage of a laptop battery.(On another note, how do you resize images on this forum? The [IMG width={}...] method doesn't seem to work)

author: KD0CAC John
author_rank: Frequent Contributor
timestamp: January 26, 2014, 09:28:50 pm
content: Wrap a short piece of copper wire around the tip of the probe you have and leave a short bit straight for a small point to probe with .

author: Zbig
author_rank: Frequent Contributor
timestamp: January 26, 2014, 09:37:49 pm
content: Quote from: Amish on January 26, 2014, 09:09:18 pmThis was never the right way to do it. It doesn't affect the original image and its download times in any way. It just makes the browser download the whole large image as usual AND THEN resize it (often crudely) in place. The proper way to do it is to actually shrink the image using one of the myriad free tools available (e.g. there's Paint on every Windows system) before posting it.

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 28, 2014, 12:29:38 pm
content: Get a reasonable size piece of 0.8mm copper clad fr-4, cut strips of it about 3 cm long, 1 cm wide, on one end, cut the copper on one end of the board on both sides, put the strips in the slots and solder together, then you can just solder probe wires onto the pcb.
Probes - Page 1
Forum section: electronics / beginners

author: daedalus13
author_rank: Newbie
timestamp: August 12, 2016, 11:31:17 pm
content: Hello all,I am a fan of Daves and decided to join the forum. I have been tinkering with electronic for many years as a hobby. Today I bought my first oscilloscope on ebay, I have always wanted one. I'm sure I will get some eye rolls for this question but here it goes anyway. The scope didnt come with probes and its a 20mhz scope, when I buy probes for the scope must I buy 20mhz probes, or will any work? Sorry for the dumb question and thanks ahead of time for any answers.

author: ataradov
author_rank: Super Contributor
timestamp: August 13, 2016, 12:01:59 am
content: This question was asked many times before. Short answer - any probes will do.

author: joeqsmith
author_rank: Super Contributor
timestamp: August 13, 2016, 02:28:51 am
content: Check out the Hantek PP150 100MHz probes for less than $10/ea

author: w2aew
author_rank: Super Contributor
timestamp: August 13, 2016, 11:45:19 am
content: Quote from: ataradov on August 13, 2016, 12:01:59 amYes, but.... ....make sure that the *Compensation Range* of the 10x probes you buy include the actual input capacitance of your scope's vertical inputs. This will be printed on the front panel of the scope. If the terms like 10x probe, compenstation, input capacitance, etc. are new to you, then check out my video on the basics of 1x/10x oscilloscope probes:

author: Brumby
author_rank: Unknown
timestamp: August 13, 2016, 11:59:09 am
content: I was just glad there weren't any images of monkeys here.
Probes compensation issue? - Page 1
Forum section: electronics / beginners

author: M84AB1
author_rank: Contributor
timestamp: September 30, 2011, 03:51:56 pm
content: Hi guys,I recently purchased a Tektronix TAS 465 100Mhz Analog oscilloscope. It did not come with probes so I ordered a pair of Uni-T UT-P05 probes rated at 200Mhz from eBay. Now the problem that I appear to have is that I cannot perfectly compensate them. The input impedance of my scope is 1Mohm 20pf, and the probes capacitance at 10x is 20pF +/- 2pF with a compensation range of 15pF-30pF. The probes should therefore have no issues to compensate properly, but they don't.I have attached pictures of RIGOL DS1052E probes and the UT-P05 probes. As you can tell RIGOL compensates perfectly without issues (RIGOL probe is the top signal)1Khz1Khz10Khz10Khz23Khz23Khz50Khz100Khz200KhzThe Rigol probe (the top signal) only starts to look under compensated at 23Khz and beyond. Does anyone have any explanation as to what is going on? Maybe the Uni-T probes are just sh*t?Some words of advise would be appreciated. Thanks guys.

author: Unknown
author_rank: Unknown
timestamp: September 30, 2011, 09:36:35 pm
content: Probe compensation is usually specified at one particular time base setting, a faster time base will always suggest under compensation due to the limited rise time of the signal. It does look like the Uni-T probe fails to compensate. There are definitely some crappy probes out there, these ones may either be lousy QC (both of them?) or lousy design.Does the adjustment trimmer do anything? Is there only one or is there an extra HF adjustment that you may be adjusting? Any 1x/10x switch that may be in the 1x position? Not a whole lot you can do about it except complain to the seller. Modern probes are not usually designed to be user repairable.

author: vk6zgo
author_rank: Super Contributor
timestamp: October 02, 2011, 03:10:56 am
content: Just to be dead sure,swap the probes between channels,& recheck.If you have a faulty channel,you won't be able to adjust that out on the probe.VK6ZGO
Probing powered circuit board with oscilloscope - Page 1
Forum section: electronics / beginners

author: dalpets
author_rank: Contributor
timestamp: April 02, 2024, 06:07:25 pm
content: As a first venture I want to use my Siglent 1102CML 100Mhz oscilloscope to probe a Velleman EDU06 circuit board, powered by a 240V/9V AC, 2 pole battery.I have read Dave's post 279 re earth referencing & related safety issues & I want to make sure that it is safe to do so with this setup, without any additional isolation measures.Thanks

author: thm_w
author_rank: Super Contributor
timestamp: April 02, 2024, 11:31:39 pm
content: Velleman EDU06 circuit board:https://ca.robotshop.com/products/oscilloscope-tutor-boardAssuming the input plug you are powering it with is an isolated wall adapter (most AC adapters are, some DC adapters are some aren't).There should be no mains reference on the board, which means its safe to connect anywhere. Also the voltage is stepped down to a safe level (9V).
Probing techniques for MOSFETS with high RF about and heavy current switching? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: February 23, 2017, 01:47:18 pm
content: Lots of interesting posts recently about MOSFET driving and gate and source waveforms, I am not alone in having issues with these devices it seemsI have a mid range 2 channel digital USB scope. 150 MHz with the spec here:http://www.dataman.com/oscilloscopes/dataman-526-150-mhz-usb-oscilloscope.htmlI want to look at the the source pins of both MOSFET's used in a push pull Class D amp running at 136kHz. If I set the probes to X10 and read either source pin on either channel on its own the waveform is fine. if i use both probes and both channels to look at both waveforms simultaneously I get a noisy waveform on both channels. Similarly if I look at a gate on one MOSFET and a source pin on the other. Looking at gate and source on one MOSFET at the same time is no problem. This thing runs 50V at 20 Amps.Is it technique ( I have tried with short ground pins made with stiff wire wrapped around the ground shoulder of both probes, rather than the long standard ground leads, with no change), the probes (Ebay, Chinese, described as 200MHz probes...), or the scope itself? Thanks.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 23, 2017, 02:07:54 pm
content: Protip: first, check that what you think is ground, is actually ground.At AC, ground can bounce all over the place. Probes don't have particularly good common-mode rejection, partly because of the ground clip (in bad cases, yes, even a short spring won't save you), and partly because of the lossy shield on the cable.Easy way to tell: connect the probe tip to the ground clip, and probe ground with that. If you see noise, it ain't "ground" (relative to the scope chassis).You can improve CMRR by wrapping the probe around big ferrite beads, but this can only do so much.The best approach is to find a point whichis"ground", and track backwards from there to the signal you want to probe.Remember, most of all, that voltage is a difference. The scope measures the voltage at its connector. What you do to get that voltage there, is up to you.Tim
Problem: Atten ADS1202CL+ update firmware with Siglent! - Page 1
Forum section: electronics / beginners

author: spano
author_rank: Newbie
timestamp: April 03, 2016, 09:35:45 am
content: Hi all,I update Atten ADS1202CL+ oscilloscope with Siglent SDS1000CNL. Now functions work good. But the Time/Div Not ?Valid.oscilloscope tested with 1Khz:Frequency is 1Khz But when calculate with Time/Div Frequency = 40Hz.can back to Atten firmware?if No how it fix?Many thanks in advance for any answers.(excuse me My English is poor!)

author: alsetalokin4017
author_rank: Super Contributor
timestamp: April 04, 2016, 04:48:31 am
content: 5 x (0.000500 sec) = 0.0025 sec1/0.0025 sec = 400 Hz

author: spano
author_rank: Newbie
timestamp: April 04, 2016, 06:45:01 am
content: thanksBut my Frequency is 1Khz not 40 or 400 hz!!

author: spano
author_rank: Newbie
timestamp: May 11, 2016, 02:29:46 pm
content: nobody can help me?
problem in creative 2:1 Speaker reg..... - Page 1
Forum section: electronics / beginners

author: techguru
author_rank: Regular Contributor
timestamp: January 15, 2018, 08:12:15 am
content: Hi to all,,I own creative 2:1 speaker system attached to my personal computer. Now the volume control becomes loose. how to resolve it.

author: kalel
author_rank: Frequent Contributor
timestamp: January 15, 2018, 08:22:36 am
content: Quote from: techguru on January 15, 2018, 08:12:15 amDoes it produce noise when you turn the potentiometer?

author: techguru
author_rank: Regular Contributor
timestamp: January 15, 2018, 10:16:55 am
content: yes, it creates noise when it is turned on and volume get reduces slowly.

author: Gregg
author_rank: Super Contributor
timestamp: January 15, 2018, 07:14:19 pm
content: It looks pretty crusty and it looks like the strain relief has pulled out of the case. To quote Dave, "Take it apart". Blow out as much dust etc as possible with canned air and try some contact cleaner on the pot and blow that out with some more canned air. If it still is bad, you may have to try and find a replacement pot.
problem in designing multi-stage amplifier  - Page 1
Forum section: electronics / beginners

author: massprog
author_rank: Newbie
timestamp: January 20, 2017, 04:19:51 pm
content: hi dearsI should design an amplifier as soon as possible and for this reason I got confusedamplifier description is : input resistor 250K, output resistor 50, gain = 80 and minimum swing 3VI know how to analyse amplifier and how them works.I got confused that how should start design,what structure should I use and ...thank you

author: LvW
author_rank: Frequent Contributor
timestamp: January 20, 2017, 05:17:48 pm
content: You can use BJT`s, FET`s, classical opamp(s), other amplifying IC`s,....Any preference?

author: dmills
author_rank: Super Contributor
timestamp: January 20, 2017, 05:19:14 pm
content: Missing half the spec.Frequency range? Noise performance? What 1/f corner? Supply voltage? Current consumption?50 ohm output resistor or capable of driving a 50 ohm load, these are very different objectives....Something jfet input feels right (High Z input), but it very much depends on the other parameters, this could be a single opamp maybe with an additional current booster, or it could be several pages of clever circuitry it depends.73 Dan.

author: massprog
author_rank: Newbie
timestamp: January 20, 2017, 05:26:50 pm
content: Quote from: LvW on January 20, 2017, 05:17:48 pmI should design simple bjt amplifier with description that I mentioned

author: massprog
author_rank: Newbie
timestamp: January 20, 2017, 05:32:28 pm
content: Quote from: dmills on January 20, 2017, 05:19:14 pm50 ohm output not loadsupply voltage could considered 12vI want design very simple not advanced designthank you
Problem in driving two segment together - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 28, 2016, 05:10:00 pm
content: 1. I have attached two pic 1 & 2. Driving together two segment as in circuit attached.Since segment pins are drived from same data pins, so I have done multiplex them using bc557.2. problem is when I display two different character on segments, there is shadow of each segment on another segment. Foe example in pc1, 12 is displayed. First segment as 1 on it & second segment has 2 on it. As can be seen, there is shadow of 2 on segment 1 ans 1 on segment 2.3. I dont know why it it is happening. Pic2 shows 11 displayed on it which is correct probably because both overshadow each other.4. Ckt attached shows thee segment & MCU is powered by +5V. BC557 base is driven by MCU open drain pins at T1 & T2. Code is while 1 loop where eac segment is refreshed every 1ms. I have also increased time to 10ms, but same result.

author: pelule
author_rank: Frequent Contributor
timestamp: February 28, 2016, 05:22:58 pm
content: If there are "shadows" in a muxed display, possile the display switching sequence is not correct.Sequence should as following:- all ports and Qs offloop:- U1 data to ports- switch on Q1 transistor (U1 shows data)- short wait (depend on the brigthness of the LEDs)- switch off Q1 transistor- U2 data to ports- switch on Q2 transistor (U2 shows data)- short wait (depend on the brigthness of the LEDs)- switch off Q2 transistorgoto loopBRPeLuLe

author: newbrain
author_rank: Super Contributor
timestamp: February 28, 2016, 05:55:12 pm
content: An addition to pelule's advice:you should not be driving the transistors directly from the open drain output of the MCU.The B-E junction will draw as much current as possible (possibly in the order of tens of milliamperes) when the OD output is set to 0, so you risk damaging either the transistor or the MCU output (or both).A suitable series resistor should be used.If you want to keep the 1kohm resistors to +5V (though I would use much weaker pull-ups), 2.2 or 2.7 kohm should be fine, very rough calculation:Vbe ~= 0.7 so (Ohm's law) you'll have 0.7mA through the 1kohm pull upneeded collector current (Ohm's law, again): (Vcc-Vled)x7/Rsegment = (5-1.5)x7/510 ~= 50mAhfe for BC557: min 110, so 0.5mA through BE are enough to drive it, let's double it to 1mAV across the series resistence: Vcc-Vbe = 4.3Vfor 1+0.7=1.7mA (Ohm's law, you've guessed by now!): 4.3V/1.7mA ~= 2.5kohm

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 29, 2016, 12:14:20 pm
content: Modified the circuit as attached.Also code is bit changed. I had enabled segment first & then data was written.Now have put data & then enabled segment.Now it is working fine. Thanks for help.
Problem in forum email notification - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: February 12, 2015, 11:05:45 am
content: There is some problem in forum email notification.Whenever 1st reply is posted to forum, an email is received. But few reply there are no further email notication even if everytime I click "Notify by email"

author: george graves
author_rank: Super Contributor
timestamp: February 12, 2015, 11:10:23 am
content: That's normal - at least on the other forums I'm on and have moderated. It assumes that if you cared about a thread enough to get one notification, it will assume you'll log into to check it.
Problem simulating MAX492 + IRF540 on a controlled load - Page 1
Forum section: electronics / beginners

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: January 19, 2016, 08:18:50 pm
content: I am on the very early stages of creating myself an eletronic load, and I started with simulating how the IRF540 works with several voltages. I drew the circuit below using Multisim 14.My idea is to have the MAX492 (rail to rail) configured as a voltage followed, because later in the project I'll replace its non-inverting input with a PWM output (passed through a RC filter to smooth it) from an Atmega8.Question: I though that the once the input of the IRF540 was near 5V, it should be letting a little below 4A. In the simulation below, however, it is stuck at 1.06A. Can someone please explain me why?Question 2: I know that the IRF540 is not a really proper NFET to be controlled logic-level voltages, but I bought it by mistake. I should have bought a IRL540. Now it's done, and I can't find anyone who'll sell a logic-level N-FET around here. The closest I have is a SSS7N60A, that starts conducting at around 3.5V (@ 25C - I attached the graph below) and seems to have a more controllable drain current than the IRF540. Am I thinking correct?Thank you.

author: dadler
author_rank: Unknown
timestamp: January 19, 2016, 09:43:15 pm
content: The current across the resistor after your FET is reducing your Vgs by Id * R (a form of feedback).Resistor after FET:Resistor before FET:

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: January 19, 2016, 10:37:54 pm
content: Quote from: dadler on January 19, 2016, 09:43:15 pmThank you so much!
Problem solving a exercise for exam - Page 1
Forum section: electronics / beginners

author: 97hilfel
author_rank: Regular Contributor
timestamp: February 05, 2017, 01:47:19 pm
content: Hello everybody,I am currently studing for my electronics exam and I Cant figure out where some certain values come from, It would be really kind if somebody could explaim my the solution of the exampls (privided in the pdf).Its example 62 with the following question:Calculate the following system using the nodal analysis the equationsystem for the voltage U_a.The line after the matrix:The outputvoltage U_a is:Ua=U_30.I dont understand the following things in the matrix:- Why is in field (1, 2) -G_3-50G_4 and not in (2,1) also?- Why is in field (2, 2) 51*G_4? where does the 51 come from?

author: ebastler
author_rank: Super Contributor
timestamp: February 05, 2017, 02:37:44 pm
content: Hmm, something seems to be missing in the definition of that example.Where are U10, U20 and U30 in the diagram?

author: 97hilfel
author_rank: Regular Contributor
timestamp: February 05, 2017, 02:58:05 pm
content: They represent the voltages from node 1 to 0, 2 to 0 and 3 to 0

author: Andy Watson
author_rank: Super Contributor
timestamp: February 05, 2017, 03:01:26 pm
content: Look at the definition of the third voltage source. It is defined as \$50 U_3\$. Redefine \$U_3\$ as \$U_{20}-U_{10}\$, (as in the diagram) and you should see where the \$-50G_4\$ and \$+51G_4\$ terms come from. (I may have mixed my signs but I'm sure you can cope with that).
problem using lm317 - Page 1
Forum section: electronics / beginners

author: saipavan
author_rank: Contributor
timestamp: February 27, 2014, 03:45:41 pm
content: I used lm317 chip along with smoothing caps to regulate voltage from a transformer rated 12 volts at 500 milli amps.after rectification and smoothing the transformer gave around 17 volts.when i used a 470 ohm resistor between adjust and output pin it gave regulated voltage from 1.28 volts to 15 volts.but when the resistor was changed with the resistor that was prescribed in the data sheet that is 220 ohm the output voltage was not increasing beyond 3 to 4 volts.I would like to know the reason for this behaviour and also its solution.(all the voltage readings were taken without any external load).thanks, in advance.....

author: Stonent
author_rank: Super Contributor
timestamp: February 27, 2014, 03:54:01 pm
content: Quote from: saipavan on February 27, 2014, 03:45:41 pmI would say there might be something wrong with your circuit. But without seeing it we can only guess.Many times people will say they followed the datasheet's example but missed something.

author: mariush
author_rank: Super Contributor
timestamp: February 27, 2014, 03:59:39 pm
content: The output voltage is determined by the ratio between a resistor and the default240 ohmresistor recommended (it can vary a bit but around this value) :Iadj x R2 can usually be ignored, as it doesn't produce much change in the output voltage.So you Vout is 1.25 ( 1 + R2 / R1) where R2 is you potentiometer. At 0 ohm, you'll have 1.25 ( 1 + 0) = 1.25v , to get 15v you'd need R2 = 2640 ohm because Vout = 1.25 ( 1 + 2640/240) = 15vYour potentiometer is probably too small - I would guess you use a 1 kOhm resistor ?

author: echen1024
author_rank: Super Contributor
timestamp: February 27, 2014, 04:44:58 pm
content: The LM317 uses a resistive divider between OUT and ADJ to form a 1.25Vref. Therefore, when you adjust the pot, you are changing the ratio by which it divides, and the output voltage changes.

author: AG6QR
author_rank: Frequent Contributor
timestamp: February 27, 2014, 11:08:52 pm
content: In addition to the previous comments...You have to read the data sheet carefully, and pay attention to the minimum load current to maintain regulation. Its max value is 12mA on the Fairchild data sheet I found (http://www.fairchildsemi.com/ds/LM/LM317.pdf) . A 240 ohm value for R1 will give 1.25V/240ohm = 5.2 mA load current, assuming nothing else is connected to the output. That won't always be enough to keep the regulator regulating. Using a value of 120, or even 100 ohms for R1 is a safer bet than 240 ohms, if it's important to maintain full regulation at an open circuit output.Once you've got the value of R1 set to get the right minimum load current, then you choose R2 to give you the output voltage range you desire.
Problem while programming ESP8266 - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: May 01, 2025, 08:38:46 pm
content: I have ESP8266 soldered on a custom pcb and trying to program it through ESP8266 Adapter board (image attached for ref) if I install ESP module on adapter and program it, everything works good.but if I connect my custom PCB board to adapter, it could not find the module on serial port.I also used my custom PCB with USB to serial converter it was able to program the ESP (but there is some issue with driver of USB to serial module sometime my computer does not detect it) that's why i wan to use ESP adapter. Here are the wire connectionsESP Module -> AdapterVCC -> VCCGND -> GNDTX -> RXRX -> TXGPIO0 -> GPIO0RST -> GPIO2 (also tried with RST pin)If i check these pins on logic analyzer i can see GPIO0 gets low for about 450msif i manually (with hand) connect GPIO0 programming works but i have to remove it to switch back to run modeI checked this source for connections and everything looks goodhttps://hackaday.io/project/186620-programming-esp8266-using-arduino-ideis there anything im missing?

author: tooki
author_rank: Super Contributor
timestamp: May 01, 2025, 08:47:56 pm
content: Does your custom board connect anything to the bootstrap pins?This would be a whole lot easier if you just share your custom design schematic and PCB. We aren’t mind-readers, after all!

author: sairfan1
author_rank: Frequent Contributor
timestamp: May 02, 2025, 03:29:31 am
content: Schematic is attached PCB is two layer will not explain as good.R2 is R470Remaining all resistors are 10KJ1 is where i connect programing wires, I have explained these connections in my first post.I was also thinking that those pull up/down resistors are also available on Adapter board and becomes in parallel to one on PCB, can it cause any issue?

author: JustMeHere
author_rank: Frequent Contributor
timestamp: May 02, 2025, 04:40:23 am
content: This is for the ESP32, but I think you need the same thing for the 8266. (If I remember correctly) Look at the auto rest block.The DTR and RTS pins are from the serial programmer chip.https://cdn.sparkfun.com/assets/learn_tutorials/5/0/7/esp32-thing-schematic.pdf

author: kripton2035
author_rank: Super Contributor
timestamp: May 02, 2025, 06:47:52 am
content: https://arduino-esp8266.readthedocs.io/en/latest/boards.html#minimal-hardware-setup-for-bootloading-and-usage

author: xvr
author_rank: Frequent Contributor
timestamp: May 02, 2025, 10:32:33 am
content: R1 & R2 forms resistor divider on GPIO0 pin that moves up logic 0 level to 0.15V. Combined with non zero Logic 0 level from programmer it could violate mimimal Logic 0 level of ESP