hybridfree/eevblog-posts huggingface dataset:
Latch ckt not working - Page 1
Forum section: electronics / beginners

author: deepak.midri
author_rank: Newbie
timestamp: May 25, 2020, 10:31:06 am
content: Attached is latch circuit for powering a microcontroller."External Switch" is trigger pressed by user which will turn on the device and wake up MCU.Once its done, MCU will pull ground to right switch and output should turn off.On simutaltion this ckt is not working, whats wrong in it?Even without pressing trigger, I can read output voltage.

author: Benta
author_rank: Super Contributor
timestamp: May 25, 2020, 10:48:40 am
content: 1 M is far too high. MOSFETs have significant leakage current.

author: deepak.midri
author_rank: Newbie
timestamp: May 26, 2020, 12:27:28 pm
content: I am simulating with 12V input dc at the moment for testing.Since 3.6V mosfets are not available in simulation software.I think its leakage current issue. Can it be solved by using Bjt instead of mosfets?

author: Renate
author_rank: Super Contributor
timestamp: May 26, 2020, 01:21:10 pm
content: Put a load resistor on your simulator.

author: deepak.midri
author_rank: Newbie
timestamp: May 27, 2020, 12:40:54 pm
content: This seems to be working. Instead of N mosfet, NPN is added.Whenever latch is pressed, output will be seen, and MCU is powered up. Now MCU pin is made inout high impedence.When need to turn off, this MCU pin is made output low. This will eventually cut off the latch.Will this work as intended?We need to make as low power as it can be.

author: deepak.midri
author_rank: Newbie
timestamp: May 28, 2020, 11:26:37 am
content: Ok will the circuit work as intended?1. Input dc range is 2V-3V. Will the selected fet work for this range?2. Whenever latch is pressed, output will be seen, and MCU is powered up. Now MCU pin is made inout high impedence.When need to turn off, this MCU pin is made output low. This will eventually cut off the latch.Will this work as intended?3. Load current is only 100mA so 36ohm resistor is connected.

author: Wimberleytech
author_rank: Super Contributor
timestamp: May 28, 2020, 01:27:25 pm
content: Quote from: deepak.midri on May 28, 2020, 11:26:37 amSeems to me, U1B should be a PMOS transistor.>>LOL...I need better glasses...it is a PCH device<<

author: deepak.midri
author_rank: Newbie
timestamp: May 30, 2020, 04:52:20 am
content: Another doubt is in schematic load is shown as R5=36 for simplicity.In actual its "Boost + MCU", boost have input/output capacitors of 47uF each, can they can any issue?Since they will charge in their time constant, and power will go MCU which will then wake up and put MCU pin in high impedecne?During this time it may happen pin of MCU may behave weird?

author: Benta
author_rank: Super Contributor
timestamp: May 30, 2020, 05:02:21 pm
content: It will work with a load, without load it will be marginal.In that case, the leakage current through U1B will flow into the base of Q1 and turn the circuit on.
Latching circuit - Page 1
Forum section: electronics / beginners

author: LarsT
author_rank: Contributor
timestamp: July 05, 2015, 10:27:16 pm
content: Ok, so I've tried making a latching circuit (seen in eevblog #262) using two complementary transistors and two switches for setting and releasing the latch (see attachment). When connecting power to the circuit it does (most of the time) turn itself on automatically unless I've closed the releasing switch right before. I've also tried adding a 10k pull up on the PNP as well as a 10k pull down on the NPN, as well as a capacitor (0.1uF) in parallell to the releasing switch in order to short this when I connect power. None of these measures have been 100% successful. What am I doing wrong here?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 06, 2015, 01:40:40 am
content: Try 1k B-E resistors.Tim

author: LarsT
author_rank: Contributor
timestamp: July 06, 2015, 09:05:26 pm
content: Quote from: T3sl4co1l on July 06, 2015, 01:40:40 amI tried, but with same result as before. I tried a 0.1uF cap on release switch in combination with a 10k pull down on the NPN and that seem to work reliably.I have modified the curcuit to cut the power when supply voltage drops below a set voltage by comparing a defined fraction of the supply voltage to a fixed voltage reference of 3.30V. This circuit does seem to work, but is there anything I should be aware of?
Latching Continuity Tester with Auto Reset Design Critique - Page 1
Forum section: electronics / beginners

author: bitshift
author_rank: Regular Contributor
timestamp: April 06, 2015, 12:31:47 pm
content: Hey Guys,I've been building a latching continuity tester with an auto reset for my bench. I'm still relatively new to electronics and this is the first "complete" circuit I've designed for actual use in the real world.I've attached a fairly detailed schematic:I've breadboarded this circuit and it seems to work fairly nicely. The goal is to run it off 2xAA batteries. I haven't completely optimised the power consumption of the tester but I would like to spend some time on that soon.I would greatly appreciate any constructive criticism or ideas on better ways to build such a circuit.
Latching on off circuit with momentary switch - Page 1
Forum section: electronics / beginners

author: silviasol
author_rank: Regular Contributor
timestamp: August 12, 2017, 10:33:30 pm
content: I have a gameboy advance that I did a backlight mod on. There is a wire that I connect to 3.3v and it makes the screen brighter. Removing the cables will put it in low brightness mod. So I want to make a circuit that uses a momentary switch that will latch on/off due to space restrictions of installing a normal latching switch. Is this possible with 3.3v? I see many guides and dave made a video.

author: Zero999
author_rank: Super Contributor
timestamp: August 13, 2017, 09:14:52 am
content: It will work, as long as the MOSFET is a 3.3V logic level type but this circuit isn't what you need. It's designed to switch relatively high current loads, rather than a tiny logic signal. You need a flip-flop IC. To save space, you can buy single flip-flop ICs in SMT packages.Check out the 74LVC1G74 and 74LVC1G175. Connect the D input to the Q output and CP to +V, via your switch, with a 100nF capacitor in parallel and a 100k pull-down to 0V and all other inputs to 0V. The Q signal will then toggle on and off, when the switch is pressed.http://docs-europe.electrocomponents.com/webdocs/0b49/0900766b80b49d8b.pdfhttps://assets.nexperia.com/documents/data-sheet/74LVC1G175.pdf

author: silviasol
author_rank: Regular Contributor
timestamp: August 13, 2017, 01:22:47 pm
content: Thanks alot for the advice. I searched flip flop ic and found this for a few dollars.http://www.ebay.com/itm/282381541189I guess china has all the answers.Next I have been researching using a lithium rechargeable battery with it. There is a boost regulator to keep the voltage at 3.3v with the voltage range of the AA batteries. I understand that a buck regulator is inefficient using along with the boost regulator so there is not much advantage with lithium ion. I am wondering if I use a lifepo4 4/5AA size is it possible to regulate the power to 3.3v. When it reaches the 3.3v which should be quickly, will the buck regulator still be drawing extra power making it inefficient?.
Latching power circuit - Page 1
Forum section: electronics / beginners

author: TomV
author_rank: Newbie
timestamp: May 05, 2020, 05:00:28 pm
content: Hi,Im building a power switch latching circuit for a project powered by a 3.7v LI-PO. Ive based the circuit on those by mosaic-industries. The circuit turns on and off fine, a hold of the button shuts the system down as expected. However when the MCU pin "SHUTDOWN PIN" is used to turn off the power, by switching to a LOW output signal as soon as the MCU shuts down the circuit is latching back on again and therefore "SHUTDOWN" pin goes high to maintain the latch until the next shutdown is requested, this behaviour loops.The label here that says PWR_BUTTON connects through a momentary switch to GND. Battery is a 3.7v Li-Po pack. I've also tried the IRF7317PBF. Any advice would be great. Thanks.

author: Peabody
author_rank: Super Contributor
timestamp: May 06, 2020, 02:53:35 pm
content: I don't really understand how the pushbutton part works. A short press turns power on, and a long press turns it off? Can you explain how it works?I suspect what's happening with the pin turnoff is that as Vcc decreases it reaches the point where the processor shuts down and the low on the pin is released, but there's still enough voltage to turn the N-channel mosfet back on through the resistors, and the processor reboots. But that's just a guess. I'm not sure how you would fix that without messing up the pushbutton part.
Latching relay is causing Arduino reset - Page 1
Forum section: electronics / beginners

author: aurmer
author_rank: Regular Contributor
timestamp: September 26, 2018, 06:09:42 pm
content: Each time I latchthis 12V relay, my Arduino Uno r3 restarts.Allow me to illustrate.- Arduino with aRelay Shield- One of the 4 shield relays is switching the low side of my 12V relay.- But in testing I realize that when there is no current flowing through the 12V relay, there is 12V on NET 1 (see illustration).When the shield relay latches, for an instant, it connects 12V to GND and I think it is the cause of my restarting issue. (When I remove the 12V relay from the circuit, there is no restarting.)Can someone suggest an additional component or a redesign to help solve this? I am inexperienced with relays, so I am not sure if there is an alternate type of relay that would suit me better.

author: Fleetz
author_rank: Regular Contributor
timestamp: September 26, 2018, 06:20:34 pm
content: Try putting a back EMF diode across the relay coil to supress the large back EMF generated when it is switched on and off. It is mostly causing a spike on the Arduino supply line causing the reset.Also make sure the supply feeding the relay is adequately decoupled.

author: macboy
author_rank: Super Contributor
timestamp: September 26, 2018, 07:23:07 pm
content: +1 on the back EMF diode, or an RC snubber (diode is easier).+1 on decoupling on the relay supply (add an electrolytic cap near the relay).Keep the relay's 12 V supply and return wires close together, preferably twisted together. This prevents them from becoming a big loop antenna to transmit EMF pulses during switching the relay on and off. The same goes for whatever high current load that relay is controlling.You should not need to use a small relay to drive a larger relay, even if the larger relay is driven from a higher voltage, 12 V in your case. You can create a simple open-collector relay driver with any jelly bean NPN transistor (2N2222, 2N3904, etc) and one resistor.
Latching relays - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: July 06, 2020, 12:55:36 pm
content: Hi,It's a solar transfer switch (Latronics SATS), I basically have to connect two terminals (2 & 6) together, this switches my solar panels to a different output, it will probably be done once a day and terminals 2 & 6 will be connected continuously for many hours at a time.I'm thinking I want to use a latching relay, I want to drive it from an MCU I already own (Olimex ESP32-POE), reading some of the 5v latching relay specs you need at least 1A to switch them, my MCU has just over half that at 600mA @ 5V.So am I barking up the wrong tree with latching, my thinking is terminals 2 & 6 might be connected 50% of the day in summer and so latching makes sense?If latching makes sense whats the easiest way to get my 1A to switch it, I only need to switch very infrequently, one or two times a day, my MCU also has a LiPo battery charger.What would you use?Thanks.Richard

author: Psi
author_rank: Super Contributor
timestamp: July 06, 2020, 01:00:36 pm
content: Avoid the style of latching relay where you only have 2 connections and have to change the polarity to change the latch direction, they're annoying to drive. The latching relays with separate coils for each direction are easier to deal with.Also consider if your system needs to detect what the current position of the latching relay is?When you use latching relays you don't know what state the system is going to be starting up in after a power failure. Sometimes that's fine, sometimes not.I've seen many small latching relays that don't need anywhere near 1A to switch.The latch current will depend on how big the contacts are, which will depend on their rated current and the overall relay size.I'm not sure if your latching relay is switching high current solar panel power feeds or just some logic signals. You can get tiny logic signal latching relays which draw maybe 100mA to latch.If you need large latching relays that draw 1A you could have a small supercap in the circuit to buffer the current pulse.
Latching ? - Page 1
Forum section: electronics / beginners

author: Russ
author_rank: Regular Contributor
timestamp: December 11, 2017, 01:40:37 am
content: HelloPlease excuse my naivety on this. But when the word “latching” is used, are they referring to how quickly the meter responds?ThanksRuss

author: danadak
author_rank: Super Contributor
timestamp: December 11, 2017, 02:03:31 am
content: Its a generic term used with more than one meaning.For example a latching relay operates, think of a push buttonto power the coil, one press and release the relay mechanicallylatches on to hold the contacts closed. Another press and releasethe relay latches off.Or its a reference to flip flop operation, like a toggle F-F, wherea clock edge toggles the input into memory element and it is heldthere until the next clock cycle, or latched.Regards, Dana.

author: Russ
author_rank: Regular Contributor
timestamp: December 11, 2017, 02:44:06 am
content: Quote from: danadak on December 11, 2017, 02:03:31 am

author: ataradov
author_rank: Super Contributor
timestamp: December 11, 2017, 03:06:38 am
content: And in context of multimeters is it often used to describe continuity buzzer behavior. Some multimeters buzz when continuity is detected and stop immediately when leads are disconnected. This creates a scratching noise on unreliable connections.Better meters will detect continuity and latch its state for a few ms, and reset the latch every time it is re-detected. This way you get a clear sound, that may be extended a bit after the contact is gone, but it does not matter.This does not affect any measurements, it is just a cosmetic thing. And I'm not sure if I personally like one way or the other. I may like scratching more in some cases.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 11, 2017, 03:14:09 am
content: As I've understood it, a latching continuity buzzer has the benefit of allowing you to detect very short lived events. A directly wired buzzer might not produce a humanly discernible beep, while a latching continuity buzzer will make sure you catch that event by extending the beep duration to a specific minimum.
Latest software/firmware for TL866A - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: February 11, 2023, 05:21:20 pm
content: I am running minipro v6.85 and it identifies my unit as TL866A V03.2.26. Is there anything to update to or is it at the latest already for what it is?

author: alank2
author_rank: Super Contributor
timestamp: February 13, 2023, 02:53:58 pm
content: Maybe this is the latest? I'm surprised no one knows this.

author: DavidKo
author_rank: Frequent Contributor
timestamp: February 15, 2023, 07:31:42 am
content: My experience with XGecu (I have TL866II Plus) is, that the updates are regularly available through theirweb site.
Lathe electronic leadscrew  - Page 1
Forum section: electronics / beginners

author: Dell
author_rank: Contributor
timestamp: May 03, 2023, 08:52:08 pm
content: Hi all I am hoping to search the collective brains on here, I am a bit confused regarding some wiring on the ELS I am installing to my lathe , the stepper driver to ELS control has a red wire piggybacked from pul+, dir +, and ena + but it also said that alternative connections can be made using Rj45 adapter I have adapter with six pins on but it doesn’t explain what way round to fit , so I am going to wire direct do I have to add the red piggyback?.Thanks Dell

author: langwadt
author_rank: Super Contributor
timestamp: May 03, 2023, 09:08:44 pm
content: the -/+ are the cathodes anodes of optocouplers so, yes you need to wire it as shown if you don't use the RJ45

author: Dell
author_rank: Contributor
timestamp: May 04, 2023, 04:35:27 pm
content: Thanks for replying according to Rocketronics the benefit with Rj45 is shielded cable and as I am using shielded cables anyway I can’t see the point.Dell
LATHE SWITCH - Page 1
Forum section: electronics / beginners

author: gedes
author_rank: Newbie
timestamp: March 07, 2022, 06:07:26 pm
content: Good evening,I have bought a mini lathe recently and after using it 3 times the switch brake. Is there any chance that it can be repaired? I was thinking to cut the wire white and black and connect them together and use turn it on and off by the power socket switch, will this work?Thank you and have a nice evening all.Regards

author: richnormand
author_rank: Unknown
timestamp: March 07, 2022, 06:13:49 pm
content: Odds are that the rectangular cutout is a standard dimention and that several other generic switch would fit.While you are in there, in addition to the main switch, I wired a foot swith to my lathe (and also the drill press) so that they operate only when I press the switch.If anything bad happens and have to step away the lathe immediately shuts down, much like a "deadman" switch would.

author: perdrix
author_rank: Frequent Contributor
timestamp: March 08, 2022, 01:38:09 am
content: For safety you should also use a switch that drops out if power is lost, so that the lathe doesn't start turning again when power is restored.David

author: SmallCog
author_rank: Frequent Contributor
timestamp: March 08, 2022, 03:00:37 am
content: Your presumption that you could join the wires is correct - that's what the switch is doing in one position and breaking (disconecting) them in the other.Switch looks pretty standard. Also looks like there's some space around it on the panel.Head along to whatever the go-to local electronics retailer is in the UK with that in your hand and try and find one the same size or slightly bigger. If it's bigger just (carefully) file the cutout a little larger.Ideally your new switch needs to have voltage/current ratings the same or higher as the existing one UNLESS you have the skill to verify the actual parameters (not uncommon for a switch to be over spec'd)

author: Muttley Snickers
author_rank: Unknown
timestamp: March 08, 2022, 06:35:16 am
content: Quote from: gedes on March 07, 2022, 06:07:26 pmIf you bought the lathe recently and only used it 3 times why are you even trying to fix it?, did it not come with some type of guarantee or warranty?You should contact the supplier, distributor or manufacturer and notify them of the problem otherwise you risk voiding any warranty should something else fail.

author: Zero999
author_rank: Super Contributor
timestamp: March 08, 2022, 10:03:18 pm
content: Quote from: Muttley Snickers on March 08, 2022, 06:35:16 amAgreed, but now he's clearly taken it to bits, it's going to be difficult for him to prove he didn't break it. In future, never try to repair new things, unless you've obviously broken it through misuse. Always return it for a replacement/repair/refund. I suppose it's still worth trying to return it.
Lattice Diamond. Can't create a project - Page 1
Forum section: electronics / beginners

author: dudeperfect
author_rank: Newbie
timestamp: February 04, 2015, 04:58:41 pm
content: I'm using Lattice Diamond 3.4.0.80 version.I use these details:Code:• Family – LatticeXP2,• Device – LFXP2-5E,• Package type – TQFP144,• Performance grade – 6• Operating conditions – CommercialWhen I try to create a project, console says:Code:prj_project new -name "FirstProject" -impl "FirstProject" -dev LFXP2-5E-6TN144I -synthesis "synplify"Failed to create projectIt is my first time I use this software on my personal computer. The error message doesn't give me a lot of information, I have no idea what is wrong. (For example same project would work in my university's computer class). I also can't open projects, created in other computer.
Lattice iCEcube2 pains - Page 1
Forum section: electronics / beginners

author: dabell-cc
author_rank: Newbie
timestamp: October 14, 2014, 10:39:49 pm
content: Hi all,I'm here because this forum had the only discussion I could find on using Lattice iCE40 FPGAs.https://www.eevblog.com/forum/microcontrollers/anyone-used-lattice-ice40-fpgas/Reviving such an old thread seemed bad form so I'm here hoping someone else has been playing with these things recently.Basically I'm used to Xilinx ISE and having a hard time with iCEcube2.mrflibble said "The pin constraints editor is not exactly great, but once you know it's "features" it's quite usable."Well I'd like to know where to find said features. The only thing on pcf files I could find was the appendix of the iCEcube2 User Guide, a one-pager that did not make anything clearer.Currently I'm coding in VHDL (examples all seem to be in verilog), and once I've added my pre-made .vhd file and synthesized I've forced the Pin Constraints Editor to save me a .pcf file. Something I noticed right away is that my input clock is NOT in the Pin Constraints list. It shows up in the Package View with a friendly "Access denied"-style red-circle-with-bar-through-it.It would seem (after some poking around) that from the vhdl entity declaration only outputs are automatically picked up for the constraints list. I experimented with another input in the list, and also an inout, only when I labelled it output was the constraints list updated.Code:entity led_fade isport(i_clk : in std_logic; -- Not in constraints listo_leds : out std_logic_vector(3 downto 0); -- all four in constraints listo_something : out std_logic; -- shows up in listio_something : inout std_logic; -- doesn't show upi_something : in std_logc -- doesn't show up);end led_fade;The supporting documentation has not been very useful, I feel like I'm looking for my lost car keys in someone else's house.Any guidance is certainly appreciated.tl;dr : how to use iCEcube2 with vhdl, and what is pcf syntax?Many thanks,dabell-cc
Lattice ispDesign ispDesignExpert Software - Page 1
Forum section: electronics / beginners

author: bgm
author_rank: Unknown
timestamp: September 03, 2015, 10:00:56 pm
content: To all and sundry ... this is a general help call. What I'm after is the Lattice ispDesignExpert (and ispDesign) software. This stuff is "supposedly" available from Lattice but as you can see from the following case that I've raised with them - they no longer have it.The reason for chasing this software is that I need to target some really early devices that ispLever just doesn't support.If anyone has it, can you *please* get in contact with me.Here is the case details from Lattice, so have a read and a giggle.---> CUT HERE <---Dear **********,Your support case #C140646-081915 regarding "ispDesignExpert software download" has been updated.The new notes are updated below:____________________________________________________________________________Hi Brendon,We tried checking the availability of the ispDesign Expert software at our factory and unfortunately we were not able to locate any other version of the software that can help you currently.I regret for the inconvenience this has caused you.We are working on adding a list of software which are no longer supported and not available with Lattice, so future customer do not face similar problem and may get the information initially. Thank you for your suggestion on this point. Lattice provides PCN when the devices are getting Obsolete but, will also start working on upgrading website with old software information.---> END CUT <---

author: smorris11
author_rank: Newbie
timestamp: May 13, 2016, 03:16:32 pm
content: Hello,Did you ever track down a copy of the ispDesignExpert software? We're looking for it as well and can't seem to find it anywhere.Thanks

author: balcol
author_rank: Newbie
timestamp: August 27, 2022, 05:27:30 am
content: I've been going around this issue for a few days now trying to recreate a design I worked on in 2005ish.I found the installation copy of the software version 8.2 but it requires a licence which obviously can't be gotten!It won't install on Windows 10 but I did manage to install it onto an XP VM running in VirtualBox with no obvious issues besides the licence. If you know anyone good at working around the locks..............I have a Galep III which still works on the parallel port and can read the code in the chips but would really like to get this working somehow.. any ideas?

author: balcol
author_rank: Newbie
timestamp: August 28, 2022, 12:11:32 am
content: Software is athttps://www.dropbox.com/sh/5kjsmrig895mq5j/AAAUjkOD-AGnITD-qS8ZvQbOa?dl=0
Lavolta BPS305 (PS305D) bench power supply wiring question - Page 1
Forum section: electronics / beginners

author: neo2001
author_rank: Contributor
timestamp: February 25, 2018, 12:02:09 pm
content: I got this power supply unit a few days ago, did a short test (seems to be ok) and then - of course - opened it up to check it out. After finding a few more or less issues and "imperfections" (like a broken solder pad, bad solder joints, bad/no earthing of the case etc.) I ended up taking it apart completely.Here are some pictures:https://imgur.com/a/t8QIGI also attached the schematics which I found here on the board. Unfortunately the display PCB seems to be of a different origin.There is no problem putting it back together like it was before, but there is one thing about that I do not understand, but would really like to:On the attached image, on the left side you see the PCB for the output terminals going to the front side of the unit. On the right side is the display board containing the display drivers. This board seems to be getting its own power from the transformer (white/black lines in the upper right). There are also some diodes, a voltage regulator etc..Back on the left side there are the larger wires coming from the OUT+ and OUT- from the main PCB (blue and black). And there are two pairs of smaller wires which are also connected to OUT+ and OUT- respectively. One pair goes to the display board and the smallest ones go back to the main PCB (plug in CN102).Now what I don't get is, why they are both connected in reverse? OUT+ is connected to V-, OUT- connected to V+. Also the small wires going back to the main board seem to be connected "wrong" (in the schematic it says "from OUT+", but actually its the OUT- line its coming from and vice versa). Only the main OUT+/OUT- lines are actually connected to the positive/negative output terminals like it's also marked on the PCB.I'm pretty sure there is a reason for that (no smoke or explosions while testing it), but I would like to know/understand why they could have done it this way? I know that voltage is always a difference between two potentials, so maybe it is enough to just get the "difference" - still it feels wrong to connect it this way.Also: What is the purpose of the wires going back to the main PCB? Some kind of feedback loop? Any ideas? If you like, you can see much more details on the other pictures I put a link to, above.
laying out my own pcb for the modella desktop miller Eagle 6.1.  - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: April 13, 2012, 08:36:57 pm
content: Hi I'm going to Fab Lab Manchester to use their desktop miller to mill my pcb. The technician there forwarded on a tutorial he used when he used it.It saysQuoteSo does that mean I should click on the finest button next to the size and not the one at the bottom? What is the Alt setting for?

author: free_electron
author_rank: Super Contributor
timestamp: April 13, 2012, 11:40:16 pm
content: sorry, crystal ball is broken.. What layout software are you using ?

author: amateur_25
author_rank: Regular Contributor
timestamp: April 14, 2012, 12:33:34 am
content: oh crap very sorry for wasting ppl valuable time! I'm using Eagle 6.

author: LEECH666
author_rank: Frequent Contributor
timestamp: April 14, 2012, 05:51:23 am
content: I think you should read Dave Jones exellent tutorial on PCB design first, and then a genereal Eagle (video) tutorial.http://www.alternatezone.com/electronics/files/PCBDesignTutorialRevA.pdfFor very small projects it may be ok to just place the parts on the board without using a corresponding schematic file, however I advise you to do it the right way from the start. That means you draw a schematic first, if you haven't done that already.Then while you route your board you should take the minimum trace widths your milling machine can handle into consideration.The alt grid setting lets you easily switch between the default grid and the alt gird.The alt grid gets activated when you push down the alt-key on your keyboard.Cheers from Germany,FlorianCheers,Florian
Lazyboy Calculator for gain and offset - Page 1
Forum section: electronics / beginners

author: Terry Bites
author_rank: Super Contributor
timestamp: March 03, 2022, 02:45:46 pm
content: I had to work out some gains and offsets to rescale disparate sensors for a an ADC.So rather than working them out one by one I made this little tool.I hope its self explanatory.

author: Zero999
author_rank: Super Contributor
timestamp: March 07, 2022, 10:37:26 pm
content: There are also calculator sits, but it is nice to have the option to do it offline.http://earmark.net/gesr/opamp/
LBO-514A Disassemble  - Page 1
Forum section: electronics / beginners

author: frrobert
author_rank: Contributor
timestamp: February 28, 2016, 03:35:25 pm
content: I was gifted a LBO-514A. It looks in good shape but the when when I move the volts/div knobs I get erratic behavior. The height may or may not change. So I am thinking it may need a good cleaning on the inside and hopefully some contact cleaner may solve the issue.The problem I do not have and manual and I am unable to find one online.I want to take the cover off but I am unsure how to take it off. The scope has screws in the top cover, the bottom, and the front panel.I assume you just take the screws off the top cover but before I do am I want to make sure I am on the right track. I would hate to loosen something I shouldn't but maybe I am just over cautious.Thanks for your help in advance.

author: mstoer
author_rank: Contributor
timestamp: February 28, 2016, 04:35:44 pm
content: Here is the service manual:http://elektrotanya.com/leader_lbo_514.pdf/download.htmlIt downloaded for me just fine. It does not tell you how to open the case or maintain it, just gives you a functional block diagram and schematics.

author: frrobert
author_rank: Contributor
timestamp: February 29, 2016, 12:31:53 am
content: Figured it out.To get inside remove the top cover screws on the top and side and the cover slips right off.

author: mstoer
author_rank: Contributor
timestamp: February 29, 2016, 02:33:45 am
content: This may seem obvious to you, but take photos as you go just to be sure you know how to put it all back later on. I once took a scope apart that had a kind of a spring underneath a ground braid that was jammed into a groove of the front bezel to maintain good electrical contact. It popped all of it out after the bezel was sitting aside and we weren't looking. Took a while to figure out what went where ...
Lc filter after regulator? - Page 1
Forum section: electronics / beginners

author: XaeroDemon
author_rank: Contributor
timestamp: July 20, 2016, 08:10:38 am
content: Can somebody proof the schematics please....Is this even correct ?? I am not sure.I know people use lC filter before Regulator(??)but can u use a lc filter after a regulator? IS THERE A reason not to do it? thanks!!!

author: SeanB
author_rank: Super Contributor
timestamp: July 20, 2016, 08:30:59 am
content: You need a capacitor as well directly on the regulator output, otherwise you will have an oscillator. The LDO regulator is not stable without an output capacitor, the datasheet tells you a recommended value and also min/max limits on ESR of the capacitor as well. Otherwise it will work and reduce noise slightly.

author: TrickyNekro
author_rank: Frequent Contributor
timestamp: July 20, 2016, 08:38:44 am
content: Best way is to go with common mode choke if it´s a must.You should put a schottky between the regulator and the inductor and from the other side connectedto the ground and pointing to the first connection.You should use dampening, rule of thumb, parallel to your existing capacitor you connect a snubber circuit,snubber capacitor 10 x the filter cap and a resistor equal to the minimum impedance of the filter at resonance.You will be much better off to just use a regulator with less noise and / or depending on what you need better CMRR figure.If not go for a RC, which yeah I know it´s going to be big on the PCB but, LC is really overkill.Regards,Lefteris

author: KE5FX
author_rank: Super Contributor
timestamp: July 20, 2016, 10:56:40 am
content: ... and the amplitude of said ringing may be quite a bit higher than you (or your load) expect.Probably the easiest way to improve the situation is to add a low-value series resistor -- maybe 5 ohms or so, depending on the current and acceptable voltage drop. But there goes your load regulation.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 20, 2016, 05:08:26 pm
content: Good way to make an oscillator:http://www.qsl.net/qrp/tx/317-tx.htmTim

author: XaeroDemon
author_rank: Contributor
timestamp: July 21, 2016, 06:30:49 am
content: Thanks Every body for replying ... I am Not gonna go RC bcus voltage drop is not acceptable for and the load.I am using a ULN reg(20uVrms 10hz-100khz) for 3.3V in series so I guess I don't "Need" a LC filter.But the source is pretty noisy so I am gonna use a LC filter anyway.@TrickyNekro I cannot use a snubber,schottky bcus the board space is kinda limited.Thanks again Guys

author: VK5RC
author_rank: Unknown
timestamp: July 21, 2016, 08:21:34 am
content: For a laugh one of my radio mates got a LM317 up to 5MHz.
LC Filter: cutoff frequency vs. ripple reduction? - Page 1
Forum section: electronics / beginners

author: hirada
author_rank: Regular Contributor
timestamp: March 12, 2021, 11:26:03 am
content: Hi,I am trying to get my head around a simple LC filter for slightly added ripple reduction. Fo assistance, I've found a calculator, whos output is a bit hard to comprehend for me, as I does not comply with the cutoff frequency formula I am aware of: 1/(6.28*sqrt(LC)).The online calculator:https://www.ampbooks.com/mobile/amplifier-calculators/LC-ripple-filter/calculator/If we assume 12mF capacitance and 220uH inductance, the cutoff frequency should be around 100Hz. In other words: 6dB down at ripple frequency.However, when using above calculator, ripple reduction is claimed to have a peak at 11.5mF capacitance of proclaimed -60dB. While at 11mF and 12mF straight I am already down to -27dB. But still way higher than the calculated 6dB. GIven the narrow range, this sounds a bit like resonance? But if that should hold true, why is not reflected in the formula?Further, according to the formula, when raising the capacitace to 20mF, the cutoff frequency goes down to ~75Hz, as expected, but according to the calculator, I am only down to -2.7dB. So a completely opposite develeopement.So, there must be some kind of fundamental oversight on my side, but what am I missing? What should I look into?Thanks

author: mvs
author_rank: Frequent Contributor
timestamp: March 12, 2021, 12:20:18 pm
content: Quote from: hirada on March 12, 2021, 11:26:03 amThis calc is made for a rectified voltage and not 100Hz sine wave. If you add a bulk cap and load to output of a rectifier, voltage ripple would have higher frequency content, then just 100Hz.In simple terms:A full bride rectifier is able to charge bulk cap, but can not discharge it. In case of no load, bulk cap would be charged to amplitude voltage and ripple would be 0.A sine wave will do both, charge and discharge a cap. Ripple is then not a function of load.

author: Andree Henkel
author_rank: Regular Contributor
timestamp: March 12, 2021, 03:36:09 pm
content: trap: enter henries and µF.I did .00022h (220µH) and 12000µF (120mF). got 6dB.

author: hirada
author_rank: Regular Contributor
timestamp: March 12, 2021, 06:12:06 pm
content: Quote from: mvs on March 12, 2021, 12:20:18 pmThanks for your explanation. My Idea has been, the ripple is a (not sine any more) wave, overlayed on top of dc. And the lc filter is taking care of only that. More or less. Plus some voltage drop over the caps and the coil.But why whould ripple rise in frequency when a load is attached? In amplitude, yes, but frequency? Howevr, I am not exactly sure I understand what you mean by bulk capacitor.Anyway, is there a way to manually calculate the ripple attenuation, if it is not the same as for ordinay ac?QuoteSo then what have I entered to get -27dB?Thanks for your replies
LC filter for noisy power: diode needed? - Page 1
Forum section: electronics / beginners

author: PeteAU
author_rank: Contributor
timestamp: April 11, 2016, 11:53:03 am
content: Hi,I want to add a little LC filter to a noisy power supply (car!) and am wondering if I need a flyback diode?Is D2 necessary or superfluous?

author: uncle_bob
author_rank: Unknown
timestamp: April 11, 2016, 12:17:32 pm
content: Quote from: PeteAU on April 11, 2016, 11:53:03 amHiSimply for noise, both diodes are technically "superfluous". They are there to take care of fairly normal spike events. I would include both of them, but a lot depends on exactly what the problem is. I also would put a fuse in front of the diodes that is rated at much less than the diode's current rating.Bob

author: danadak
author_rank: Super Contributor
timestamp: April 11, 2016, 12:18:12 pm
content: Its dependent on load and value of L. Basically when you disconnectan active load the catch diode will prevent high V transients. So for thepennies a diode costs I would add it. Also consider a zener on outputto catch load disconnect transients.Regards, Dana.

author: PeteAU
author_rank: Contributor
timestamp: April 11, 2016, 12:20:26 pm
content: Yep, that's what I figured. But, should I put the diode in parallel with the inductor instead of going down to GND?

author: uncle_bob
author_rank: Unknown
timestamp: April 11, 2016, 12:22:23 pm
content: Quote from: PeteAU on April 11, 2016, 12:20:26 pmHiThey are fine as shown.Bob
LC Filter that seems not to work - Page 1
Forum section: electronics / beginners

author: ruscoff
author_rank: Newbie
timestamp: November 23, 2015, 03:54:45 pm
content: Hi all,i'm trying to filter the output of charge pumps (TPS60150, step up from 3.7V to 5V) with LC pi filter. The load use about 1mA.L = 100nH (http://www.farnell.com/datasheets/1910214.pdf)C = 10uF X5R 16V 0805The cut frequency are around 160Khz.Into the PCB the components are very near (1,75mm between them) and ground return paths are clear.As you can see from the attachments there aren't any attenuations, and filter add some noise.So, why the filter doesn't work correctly? i'm expected -40db around 1,5/2MHz

author: Zero999
author_rank: Super Contributor
timestamp: November 23, 2015, 04:08:31 pm
content: The Q is too low. The impedance of the inductor is only 100m Ohm at 160kHz and the DC resistance is 260 mOhm plus the capacitor's ESR.

author: ruscoff
author_rank: Newbie
timestamp: November 23, 2015, 05:47:40 pm
content: I suspect something similar..but i can't understand where is the problem, i didn't find any guide on google.I think, If is only a problem of dc resistance the filter cut frequency should move up but i think i should view anyway the -40db slope.Could you explaing why it won't work?Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 23, 2015, 08:24:55 pm
content: Can't really tell what the horizontal axis is... MHz??dBu is a rather strange unit to pick for the vertical axis. dBuV or dBm is more common. What load impedance is this at?Datasheet says 1.5MHz switching frequency, so there should be a peak at 1.5. But it also has a pulse skipping mode, so your noise output will depend very much on load. A no-load test is inappropriate here.What does your layout and measuring setup look like? These are critical for this measurement.Tim

author: ruscoff
author_rank: Newbie
timestamp: November 23, 2015, 10:41:03 pm
content: X axis is in MHz, it is write but maybe to small.Yes, you have right it is in a skip mode because the load is large, it should sink 10uA with a peak 100mA when works but for very short time < 1ms. Oscilloscope has 1Mohm of input impedance. By the way, the output waveform is a sawtooth with superimposed high frequency ripple, i think the peak at 2MHz. The filter have to attenuate that ripple because the load is pratically ideal.I try to reduce the probe ground wire lenght put it around the probe. The same peak are measurable on the air with the probe like an antenna but if i connect it to circuit peaks increase of 20/40db.I don't know why the software use dbuV.

author: Zero999
author_rank: Super Contributor
timestamp: November 24, 2015, 08:55:45 am
content: Try using L = 100µH and C = 10nF
LC in Tank Configuration Confusion - Page 1
Forum section: electronics / beginners

author: dkggpeters
author_rank: Contributor
timestamp: March 24, 2019, 02:45:52 pm
content: I setup an LC in a tank configuration using a 51uH Inductor and if I use I higher value capacitor the frequency cutoff range comes out to what I calc but when I use a lower value capacitor it is about 1/2.Inductor 51 uHCapacitor 330 pfCalc Freq 1.226 MhzActual Test 1.19 MhzInductor 51 uHCapacitor 20 pfCalc Freq 4.983 MhzActual Test 2.64 MhzI have used different types of capacitors and even different values of Inductors and see the same thing. I calced using a Bode plot and also observing sine wave amplification by manually adjusting frequency and finding the highest amplitude and get the same results.What in the world am I doing wrong?

author: Benta
author_rank: Super Contributor
timestamp: March 24, 2019, 03:44:22 pm
content: With inductor and capacitor values that low, there are lots of parasitic effects: inter-winding capacitance, lead inductance etc.

author: Stray Electron
author_rank: Super Contributor
timestamp: March 24, 2019, 03:53:57 pm
content: Where did you get your parts? If they're Chinese these they usually aren't anywhere near the specified value. If old parts, they could have drifted out of spec. Running too much power through a lot of devices will also cause them change value.This is why things like a GOOD LCR meter is so valuable, they let you check your parts for the proper value before you build the circuit. Then if you built the circuit and it is out of spec then you know the problem is in the construction or operation and not in the components.

author: dkggpeters
author_rank: Contributor
timestamp: March 24, 2019, 05:32:23 pm
content: Quote from: Stray Electron on March 24, 2019, 03:53:57 pmI have a DE-5000 so and used measured values which were close to reported. They are not old parts as well. I believe that the previous post answered my question well. I will test high higher values and wider ranges to see how they respond.

author: dkggpeters
author_rank: Contributor
timestamp: March 24, 2019, 07:38:54 pm
content: Since the capacitance levels are so low, can it be the capacitance of the scope probes and breadboard? I believe that this is driving the majority of the change. Since the capacitance levels were so low, it doesn't take much to double their values. The scope states 15 pf on inputs and when I run the circuit not on a breadboard I get higher frequency values as well. The combination of the two has a huge impact on low capacitance values.

author: Benta
author_rank: Super Contributor
timestamp: March 24, 2019, 08:09:25 pm
content: Then solder a 100k resistor in series with you probe. For determining the resonant frequency it doesn't matter if the amplitude is not quite right.
LC or RC LPF for Class D Audio Amplifier - Page 1
Forum section: electronics / beginners

author: hussamaldean
author_rank: Unknown
timestamp: July 24, 2018, 05:13:13 pm
content: Hi all,I have a question, which one to use for class D audio amplifier ?RC or LC and what the advantage and disadvantage of each one ?Fc is 40KhzI googled and come up inclusiveregards

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 24, 2018, 05:15:57 pm
content: RC filters are lossy. Generally, you don't want to burn half your output power as heat; that defeats the purpose of choosing class D.Tim

author: hamster_nz
author_rank: Super Contributor
timestamp: July 24, 2018, 07:52:44 pm
content: On the input (e.g. for a sub crossover), or on the output?

author: hussamaldean
author_rank: Unknown
timestamp: July 25, 2018, 03:49:15 am
content: Quote from: hamster_nz on July 24, 2018, 07:52:44 pmoutput for the speaker
LC Oscillator - Page 1
Forum section: electronics / beginners

author: amelia
author_rank: Newbie
timestamp: April 26, 2021, 04:50:39 pm
content: Is it possible to design the LC oscillator with negative capacitance and inductance

author: Jwillis
author_rank: Super Contributor
timestamp: April 26, 2021, 06:07:43 pm
content: In a sense it already is.Now assume you had a power supply with a split rail Positive , common , negative and had an LC circuit on each rail . They would oscillate inversly propotional to each other .

author: TimFox
author_rank: Super Contributor
timestamp: April 26, 2021, 07:11:39 pm
content: Negative resistance oscillators are common—for example, the transitron. Negative capacitance in passive devices has been seen in ferroelectric structures, but is not available in standard passive components. The negative resistance circuits involve powered active devices.

author: Zero999
author_rank: Super Contributor
timestamp: April 26, 2021, 08:34:04 pm
content: I thought inductance is negative capacitance and capacitance is negative inductance.The original poster is banned. I wonder why?

author: TimFox
author_rank: Super Contributor
timestamp: April 26, 2021, 11:12:10 pm
content: Capacitance is charge per volt. A non-linear capacitance is defined by C = dQ/dV , and the derivative is normally (almost always) positive. Inductance is defined differently: L = -V/(dI/dt) = -d(phi)/dt, where phi is the magnetic flux linking the coil. For a capacitor, the reactance magnitude falls with frequency, but for an inductor it rises with frequency.