hybridfree/eevblog-posts huggingface dataset:
Im back!!!!!!! - Page 1
Forum section: electronics / beginners

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: March 03, 2015, 07:08:43 pm
content: though i may have a slightly different username i am back!the westminster radio still isnt fixed, i now have 88 of the buggers!

author: SeanB
author_rank: Super Contributor
timestamp: March 03, 2015, 07:46:31 pm
content: Did you get a pair and leave them alone in a cupboard? Or did you have an e*ay blowout.......

author: c4757p
author_rank: Super Contributor
timestamp: March 03, 2015, 07:56:22 pm
content: Quote from: SeanB on March 03, 2015, 07:46:31 pm

author: SeanB
author_rank: Super Contributor
timestamp: March 03, 2015, 08:17:37 pm
content: Quote from: c4757p on March 03, 2015, 07:56:22 pmI took some stuff apart that is made for Pipedream, they actually put some interesting electronics in there. Sanded the part numbers off the PIC micro though, and probably protected it as well. Must take the talking one apart though. Might give Dave palpitations though if I send him one, though JT is having good business in Aus.

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 05, 2015, 08:09:52 pm
content: Quote from: SeanB on March 03, 2015, 07:46:31 pmnope, i just bought lots, i now have 97!

author: Greorge
author_rank: Regular Contributor
timestamp: June 06, 2015, 11:50:14 am
content: What are your plans?

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 06, 2015, 03:14:34 pm
content: Quote from: Greorge on June 06, 2015, 11:50:14 amplans for what? the radios? well i want to reach 100 and get a round ekco.

author: Greorge
author_rank: Regular Contributor
timestamp: June 08, 2015, 06:07:24 am
content: You are very close to your target.All the best!

author: Arlen Moulton2
author_rank: Regular Contributor
timestamp: June 09, 2015, 07:34:37 pm
content: Quote from: Greorge on June 08, 2015, 06:07:24 ami know right! thankyou. it only took 5 years to get 97! i really cant afford a round ekco though, they are just a fantasy for me. O0
Im dumb, tell me what to do with my ESD grounding mat - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: April 23, 2018, 05:32:52 am
content: I have a big velleman ESD mat.I don't have any exposed copper wiring, the radiators and any exposed piping are painted over (building hundreds of year old), best guess is an old metal intercom boxIt came with one alligator clip that snaps to the pad, and it has multiple points to snap something to.I have some grounding wrist straps.Ok now please help me decide what to do with it?Put a wire between the metal frame and metal screw of the intercom box built into the wall, which might not be connected to anything anymore on the other side of the wall, and connect that to one of the grounding points on the matGet an extension cable and connect the mats grounding point to the AC ground prong.Connect the ground on the mat to the device i'm working on and one of the aboveLet's not discuss the degrees of ESD protection but please help me decide how to best use the pad i have. I read a lot on Google and youtube but there seems to be no definitive answer.

author: MosherIV
author_rank: Super Contributor
timestamp: April 23, 2018, 06:39:21 am
content: HiQuoteCheck the resistance between one of the metal studs on the mat and earth is around 1MJust put your work on the mat.Connect wrist strap to the mat and wear it.

author: james_s
author_rank: Super Contributor
timestamp: April 25, 2018, 05:40:43 am
content: Get a grounded plug, connect the wire from the mat to the ground screw in the plug, plug it into the wall.

author: Mp3
author_rank: Frequent Contributor
timestamp: April 27, 2018, 09:13:43 pm
content: I have done this and i get 1Mresistance but i also get about 1.5-2 volts AC power across the metal studs on the mat.is this safe to work on? that seems worryingThanks in advance.

author: MosherIV
author_rank: Super Contributor
timestamp: April 27, 2018, 09:37:12 pm
content: When you touch the mat, do you get that tinggley feeling?If so, something is wrong.If not everything is fine.

author: Electro Detective
author_rank: Super Contributor
timestamp: April 27, 2018, 10:22:56 pm
content: Quote from: Mp3 on April 27, 2018, 09:13:43 pmI would use any affordable multimeter that has the Low-Z function to confirm whether it's merely a stray 'ghost' voltage..or -old wiring- issues waiting to biteFWIW, any direct 'continuous' connection to the mains ground/earth wire which is usually bonded to the Live Neutral at the switchboard, is waiting for trouble...especially in an older property which may have dodgy 'compliance' work done with a mix of shared earths and neutrals to fool the electrical inspectori.e. make sure the ESD routine works as it should or lose it to avoid the possibility of 'can't happen' zaps

author: Mp3
author_rank: Frequent Contributor
timestamp: April 28, 2018, 07:43:58 am
content: Quote from: Electro Detective on April 27, 2018, 10:22:56 pmNo tingley feeling, but i live in a very old building with bad wiring, all running off a 60 amp breakerso maybe i will search harder for somewhere to mount a grounding screw...
I'm having trouble post pictures. - Page 1
Forum section: electronics / beginners

author: Qmavam
author_rank: Regular Contributor
timestamp: April 19, 2020, 07:04:21 pm
content: I browse, pick my picture, it appears next to cancel button, I select inline full size imageand this appears in the post.What am I doing wrong?Mikek

author: DrG
author_rank: Super Contributor
timestamp: April 19, 2020, 10:46:02 pm
content: Not sure what you think is wrong.I browse, pick my picture, it appears next to cancel button, I select inline full size image...(now I hit return twice and do the attachment)and that's it. BTW, that is a penguin at a zoo that I have been watching when bored...he is a bit of an instigator...a trouble-maker...I like that in a penguinEdit. Notice that if you go to modify the post, you will see "attachimg=1" (with brackets where the quotes are) hit cr before and after to keep your text on new lines - is that what you mean?

author: MarkF
author_rank: Super Contributor
timestamp: April 19, 2020, 11:45:35 pm
content: When you select "Inline full-size image", "attachimg=1" will be added at the current location of your cursor.A carriage returnbeforeandafterwill make it look much better. The picture will be on a line by itself.You can also move "attachimg=1" to a different location in the text.You can size the inline picture by adding "attachimg=1 width=200".If you add more than one picture you will also have "attachimg=2, attachimg=3, etc." which you can also place and size.

author: dcac
author_rank: Frequent Contributor
timestamp: July 10, 2020, 03:08:34 pm
content: Lately with picture posting the forum seems to be making fun of me, I attach the file(s) and select how I want it shown - and "Attach=#" or i.e. "Attachimg-#" appear in my post - sometime I move them to get a better layout - then hit post. Review the post and it seems fine on the PC I made the post from. But then I view it from a different PC and the wrong picture appear.What's really strange is posting them like inline expandable thumbnails - the thumbnail looks correct but clicking it the wrong picture appear.I going to test post some pictures here as this is a different PC from the one I first noticed the problem on.

author: dcac
author_rank: Frequent Contributor
timestamp: July 10, 2020, 03:14:52 pm
content: More tests...N/A - getting attachment not available - upload is really slow too.

author: dcac
author_rank: Frequent Contributor
timestamp: July 10, 2020, 03:18:27 pm
content: The first test the two koala pictures uploaded fine and appear correct on this PC.I'm going to check later from another PC if it's ok there too.

author: StillTrying
author_rank: Super Contributor
timestamp: July 10, 2020, 03:31:00 pm
content: "I'm going to check later from another PC if it's ok there too."There's no need, it's a known server problem.https://www.eevblog.com/forum/chat/website-error-reports/225/
im looking for a chip in a particular size - Page 1
Forum section: electronics / beginners

author: xxx888
author_rank: Newbie
timestamp: April 28, 2022, 01:31:39 pm
content: i ordered a cy62128ev30l l-45sxa (2.3cm x 1.3cm) but it is too big for my pcb board. the size of it is the same as a hm62256alfp-10t (2cm x 1cm) and has 44 pins. ive tried looking for it in google shopping to no avail, it just comes up with the large size. any ideas what this chip is? so frustrating...

author: rstofer
author_rank: Super Contributor
timestamp: April 28, 2022, 03:02:41 pm
content: The datasheet will give you the sizes that are actually manufactured and then you can go to Digikey and find out which packages are readily available.https://www.infineon.com/dgdl/Infineon-CY62128EV30_MoBL_Automotive_1-Mbit_(128_K_8)_Static_RAM-DataSheet-v06_00-EN.pdf?fileId=8ac78c8c7d0d8da4017d0ecc205045e5

author: xxx888
author_rank: Newbie
timestamp: April 28, 2022, 03:09:02 pm
content: its 44 pin i need, thats 32 pin

author: xxx888
author_rank: Newbie
timestamp: April 28, 2022, 03:33:06 pm
content: sorry i meant what im looking for is a CY62158E-TSOP44 that is 1cm x 2cm

author: hpmaxim
author_rank: Regular Contributor
timestamp: April 28, 2022, 03:43:49 pm
content: Integrated circuits aren't made in random sizes. Unless there is something particularly special about a particular chip, the chip designers go and find a standard off the shelf package and use that. If it's truly a CY62158E-TSOP44 it's size is whatever the exact size of a TSOP44 is. You're not going to find one in a non-standard size unless someone paid a lot extra just to make sure you couldn't get a replacement part.

author: jpanhalt
author_rank: Super Contributor
timestamp: April 28, 2022, 06:28:55 pm
content: This is what Mouser has:https://www.mouser.com/c/semiconductors/memory-ics/sram/?q=CY62158E&package%20%2F%20case=TSOP-44Long waits for availability are common today.
I’m on the fence on which meter to buy? - Page 1
Forum section: electronics / beginners

author: keithpitts
author_rank: Newbie
timestamp: March 08, 2015, 05:15:51 pm
content: 1 I do some hobby electronics2 work on some A/C units3 some home electric projectsI was looking for a good meter that will work for all (this will be the last meter I will ever buy)I want a good one.I know to work on ac units will need a current adapter ( no problem).So far it’s a toss between an Agilent U1253b and an Agilent U1273AX I love the screen on both meters.Can you please give me the pros and cons on both?Thank YouKeith Pitts

author: picandmix
author_rank: Frequent Contributor
timestamp: March 08, 2015, 08:26:04 pm
content: I would repost your question in the 'Test Equipment' section where those guys should soon help you.Posted in this Beginners section with so many entries each day it may get overlooked.
Im using a pic24f and im trying to decouple the analog and the digital power - Page 1
Forum section: electronics / beginners

author: becoolnike
author_rank: Newbie
timestamp: December 05, 2016, 02:08:20 am
content: Im using a pic24f and im trying to decouple the analog and the digital power supplies so I can avoid the mostnoise when doing an ADC convertion. My pic24f has two pins that says VDD and another one that says VDD/AVDD.is this the correct way to decouple the analog and digital power supplies? Im using a ferrite bead and two caps for each VDD and AVDD. can I connect both VDD pins together and use only one ferrite bead and two caps, since the have the same name?This is the way im doing it:

author: danadak
author_rank: Super Contributor
timestamp: December 05, 2016, 11:38:07 am
content: You are trying to do a 12 bit conversion, if using a 2V reference, gives you 1/2 mVLSB. Use a DSO on infinite persistence, look at supply rail, you will see how challengingit is. There is probably something like 200 LSBs of noise on Vdd logic rail, or worse.So keep the rails split, and only joined the Vss's where power enters the board. Usea polymer tant on each supply rail for best ESR, and a ceramic disk in parallel .1 uFor so.https://www.dropbox.com/s/ruaf9booe17jk8n/PCB%20Layout.zip?dl=0Regards, Dana.
Image Sensor AFE ac coupling capacitor choice - Page 1
Forum section: electronics / beginners

author: bmxsesh
author_rank: Regular Contributor
timestamp: February 09, 2025, 06:28:57 am
content: Hello,I am reading TI VSP2562PT datasheet. Apparently the CCD pixel signal is ac coupled through a capacitor to the Correlated Double Sampling Block.So it makes a high-pass filter with the internal resistance of the CCDIN pin to GNDThe only thing the datasheet mentions is the "Clamp on-resistance" of 400 ohm - is that the R to GND that I am looking for the high-pass filter?My signal is 29.5MHz and the capacitor value C seems to be important to not attenuate the signal but resistance also matters: f=1/(2*pi*R*C)I haven't found any IBIS models for this part either, if anyone can help with that I'd appreciate it-bmxsesh

author: ahsrabrifat
author_rank: Regular Contributor
timestamp: February 09, 2025, 03:41:16 pm
content: To avoid attenuation at your signal frequency of 29.5 MHz, you want the cutoff frequency to be well below that. For example, if you want a cutoff frequency of around 10 MHz, you can solve for C using the formula that you mentioned above.
Image Sensor with Autofocus - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: July 26, 2020, 10:57:42 am
content: Image sensors like OV5640 / OV 5642 had embedded autofocus control via an embedded microcontroller and an internal autofocus engine + autofocus control GPIO.However these sensor- are marked for obsolescence. Are there any alternative methods for implementing autofocus on chips that don't have embedded processors.I believe that an external DSP would be needed that would read the digital data from the image sensor and then run a focus algorithm on it and output a control signal to a VCM (Voice Coil Motor).Are there any single chip solutions that can do this, without need to use multiple chips and needing to implement the autofocus algorithm.Best I could find are autofocus driver solutions from ADI and On semi, however these are only VCM drivers but they don't have the autofocus algorithm within them.TIA

author: Siwastaja
author_rank: Super Contributor
timestamp: July 26, 2020, 12:26:31 pm
content: Sounds like a strange requirement, what are you doing with the image data? Usually you would process it with something, and that something can do the autofocus algorithm, so that you don't need to split the data path to insert an extra IC just to do it.Is the problem that you are using some fixed processing unit you have no control over which doesn't have autofocus logic, or do you just want to avoid developing the autofocus algorithm?

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: July 26, 2020, 12:40:55 pm
content: Quote from: Siwastaja on July 26, 2020, 12:26:31 pmI need to just stream the data over USB like a webcam.Quote from: Siwastaja on July 26, 2020, 12:26:31 pmI would have preferred the image sensor, to have done the autofocus part, since sensors like OV5640 were available which used to do it internally, I'm just wondering why this part has been removed from the newer image sensors. If there is no way out, I may have to do it myself, but considering that autofocus is such an important part in camera's these days I thought that the technology would be mature enough for someone to made an embedded solution out of it.Also I have no idea how much effect it would have on the frame rate in case I decide to process it and run the autofocus algorithm on an external processor (the same processor that is fetching data from the image sensor).
Imax B6 (fake) - suddenly different discharge mode - Page 1
Forum section: electronics / beginners

author: asymcon
author_rank: Contributor
timestamp: July 07, 2018, 03:21:25 pm
content: Hi,I have 210 18650 batteries to test so in addition to my older fake B6 I purchased two more. However the discharge mode is completely different. The old one discharges the cell with steady current (1A) and when cut-off voltage is reached the current drops by 100mA increments until the cell is fully discharged. This is useful for testing capacity.However my new B6s do it all wrong, if I set 1A as discharging current, once the cutoff voltage is reached (3.00V) it'll stop charging,I went through the user manual several times and can't find the right settingto gradually decrease discharging current once cut-off voltage is reached.Apparently there is a host of alternative firmwares, but I lack the cable for it (and the 6pin header)Is this a known problem?
Imax B6 charger, Li ion monitoring - Page 1
Forum section: electronics / beginners

author: Kranthi
author_rank: Newbie
timestamp: September 24, 2017, 03:15:51 pm
content: Hello everyone,I want to know why these small resistor are placed in the circuit and that too different values for the differential amplifiers and what role does 0ohm resistor play in this circuit. Please help me in understanding this.

author: AlessandroAU
author_rank: Regular Contributor
timestamp: September 24, 2017, 07:42:56 pm
content: I would guess just so that the gain of each stage can be tweaked easily. Since the balc voltages will be 4.2, 8.4, 12.6 you need a different gain for each the opamps such that each balance tap can map nicely to the 0-5V input of the micro.Easy to just leave the footprint on the pcb and put a 0 ohm jumper if you don't need it.
IMC - Relays or how does a polarized relay work? - Page 1
Forum section: electronics / beginners

author: Tif
author_rank: Contributor
timestamp: August 05, 2018, 04:52:06 pm
content: Hi,I recently usedIMC03TS relaysand have been trapped with its polarity. I never thought monostable relay could be polarized, but apparently it can...So I was just wondering how it works? I've heard some relays can have an internal diode, but in the datasheet of this one, there is no mention of any diode of this kind...

author: Zero999
author_rank: Super Contributor
timestamp: August 05, 2018, 05:07:18 pm
content: They probably have a permanent magnet armature, which will be more sensitive to the magnetic field, but it means they only work wit the current flowing in one direction.

author: Benta
author_rank: Super Contributor
timestamp: August 05, 2018, 05:27:24 pm
content: I made the same experience with some miniature relays where I didn't observe the polarity of the coil. My conclusion was also that there's some magnetic bias in the relay.

author: SeanB
author_rank: Super Contributor
timestamp: August 05, 2018, 07:25:59 pm
content: To get a high sensitivity many relays use a polarising magnet, so that the core is almost at the point where it will pull in, and the extra current in the coil drives it to the point where it pulls in. Remove the current and there is just not enough remnant magnetism to keep it closed, and it opens. Have a slightly stronger magnet and then you have a bistable relay, the little extra current on the coil in one direction either adds or removes from the field in the magnetic circuit, and the armature then will move to either the open or closed state, and will be stable there providing there is low enough vibration and mechanical shock.Others have 2 coils, wound on the same, or opposite sides of the armature, and use a small high remnance magnet (so that it does not lose field strength with time and the coil being powered for long periods) to provide the latching action needed.There is a further bistable relay that has no magnet, using instead a mechanical switch arrangement that rotates a small pawl around on a shaft, and the pawl drives the contacts so that a pulse will make it change state. A variant has a separate reset, and a pawl with 3 detents, so that you have a brief contact open on energising the coil, and after 3 such the contacts stay open, needing a mechanical reset to release them. These are generally used on power lines, so that a brief overcurrent event ( branch falls on line and shorts it out while being fried off, or your furry rodent bites the cable) disconnects power to stop any arcing, but if there is a permanent fault it will stay open and not power the line till reset by a maintenance crew.

author: Tif
author_rank: Contributor
timestamp: August 05, 2018, 07:37:26 pm
content: Thanks for all your answers. It's all clear now
Impact of high ESR on buck converter output filter cap? - Page 1
Forum section: electronics / beginners

author: nsayer
author_rank: Regular Contributor
timestamp: June 07, 2014, 03:31:41 pm
content: I've ordered the boards, so there's kind of not much turning back.I put a footprint in for a tantalum output cap on the 12->5 and 12->-12 switchers on my project.Before I ordered the boards, I got parts from DigiKey and made sure that they fit the footprint.The one thing I didn't check was the ESR of the caps. They're an order of magnitude higher than the calculator recommends.I've got two weeks before the boards come, so I've got some time to ponder what to do about it.I looked into same-footprint low(er) ESR tantalums, but they're just insanely expensive. I found some low ESR aluminum ones that... sort of... fit. I'll be using them for the next version of the board for certain.What's the impact of high ESR on the output filter cap? Worse ripple? I probably can put up with that for a prototype.

author: janoc
author_rank: Super Contributor
timestamp: June 07, 2014, 03:38:57 pm
content: High ESR on output caps => the caps get hotter due the ripple current passing through them => more heat = more ESR => caps get even hotter => lather rinse repeat until the cap spills its guts and the device stops working.This is the most common failure mode of switching power supplies.If it is a prototype that won't see much use, it is probably OK if you can make do with increased ripple, but the lifetime of the caps will be poor.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 07, 2014, 03:51:17 pm
content: Well, you can always try to shoe-horn a ceramic on there (a large one might fit on a tantalum footprint edgewise?), or have you looked at polymer types (tant or Al)?Yeah, ESR mainly relates to stability, ripple and capacitor heating.Tim

author: nsayer
author_rank: Regular Contributor
timestamp: June 07, 2014, 03:52:34 pm
content: <sad trombone>I'll have to find some other part that fits that footprint. That's a crappy outcome.This one looks promising:http://www.digikey.com/product-detail/en/RWA1E470MEG/493-13841-1-ND/4694934

author: theatrus
author_rank: Frequent Contributor
timestamp: June 07, 2014, 06:06:06 pm
content: A lot of the polymers have tantalum compatible footprints, but maybe not at the voltage you need.

author: nsayer
author_rank: Regular Contributor
timestamp: June 07, 2014, 06:48:58 pm
content: Quote from: theatrus on June 07, 2014, 06:06:06 pmThe one I found (post above yours) is 25V for a 12v supply. Should be fine.
Impedance calculation double sided board - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: August 15, 2019, 12:36:05 am
content: Hi I have tried to calculate track impedance, using a online calculator but I do not know how to calculate my board.It has a track on one side and a fill layer on the other side, both connected by vias.How do I calculate the total impedance?

author: Illusionist
author_rank: Regular Contributor
timestamp: August 15, 2019, 10:16:21 pm
content: There's a really useful, free tool you can download here:http://www.saturnpcb.com/pcb_toolkit/The impedance is calculated on: PCB (dielectric) material, thickness, copper thickness and track width. Note that board thicknesses are often given as copper+dielectric thickness, so if it's double sided 1.6mm, the dielectric is 1.6mm minus 2* the copper thickness.The tool above is really handy because it does some of the conversions for you (for instance converts oz of copper layer to mm/mils etc). It can do a lot - have a play and get used to it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 15, 2019, 10:24:17 pm
content: So the track is connected to the fill with a via? And you need to know the impedance of this effective transmission line stub..?Tim
Impedance matching pad compatibility  - Page 1
Forum section: electronics / beginners

author: billuanand
author_rank: Newbie
timestamp: November 19, 2015, 11:39:47 am
content: HelloNormal 50 ohms receiver like spectrum analyzer is also useful in 75 ohms system with help of matching pads on its input.In case of transmitter like signal generator is it possible to use same i.e. to feed signal from 50 ohms generator to 75 ohms system under test (receiver).For these two applications required same pad or different pad?Thank you.

author: Shock
author_rank: Super Contributor
timestamp: November 19, 2015, 02:21:41 pm
content: Passive attenuators and impedance matching pads should be bidirectional.

author: KJDS
author_rank: Super Contributor
timestamp: November 19, 2015, 02:35:12 pm
content: A sufficiency of information on minimum loss padshttp://www.microwaves101.com/encyclopedias/l-pads

author: billuanand
author_rank: Newbie
timestamp: November 20, 2015, 07:06:52 am
content: thank you allplease can you suggest any product, that suitable for bi-directional operationI know it is available in mini-circuits but this information is not available in datasheet

author: Shock
author_rank: Super Contributor
timestamp: November 20, 2015, 08:06:19 am
content: Quote from: billuanand on November 20, 2015, 07:06:52 amKey information missing is the specs/frequency, connectors, kit options and price range you want. If the datasheet doesn't specify it's unidirectional or bidirectional you can email the manufacturer and ask. You might also want to get the standard pad that comes as an option for the equipment you're using. Since you know all this information and we don't I suggest you do some quick research yourself and ask if you get stuck.
Impedance mismatch between speakers and amp - Page 1
Forum section: electronics / beginners

author: Legion
author_rank: Frequent Contributor
timestamp: March 25, 2015, 05:28:53 pm
content: What effect does an impedance mismatch have on the actual sound coming out of speakers? If I hook up 4 ohm speakers to an amp expecting 8 ohms, other than overdriving the amp, what effect does it have on the sound?

author: katzohki
author_rank: Frequent Contributor
timestamp: March 25, 2015, 05:51:10 pm
content: Difference in loudness. Maybe a bit of distortion depending on how hard your amplifier is working.

author: TimFox
author_rank: Super Contributor
timestamp: March 25, 2015, 06:12:51 pm
content: Impedance mismatch, as that for coaxial cables and terminations at radio frequency or fast pulses, is not relevant normally to audio, where the signal wavelengths are much longer than the cables.Power amplifiers (either vacuum-tube with an output transformer or solid-state with a direct connection) are normally designed to supply a constant voltage to the load, over a reasonable range of load impedance. Solid-state amplifiers usually have an extremely low source impedance, much lower than the nominal load impedance. The source impedance from a typical tube amplifier is higher, but still lower than the load impedance.Lower impedance loads will draw more current than higher impedance loads. The actual load impedance seen by vacuum tubes is somewhat critical to low distortion operation: therefore, the output transformer usually has taps for different popular speaker impedances (4, 8, 16 ohms). With solid-state, the most important question is the power dissipated by the output transistors at higher current than the original design. A solid-state amplifier designed for a 4 ohm load will be safe with an 8 ohm load, but will deliver less power than into a 4 ohm load.

author: Synthetase
author_rank: Regular Contributor
timestamp: March 26, 2015, 12:39:56 pm
content: Another consideration would be power supply collapse. If the amp was designed to drive 8R loads, the supply may not be able to handle the additional current requirements of a 4R load and will collapse sooner, which will limit power output and could give you clipping (with the associated distortion products) much earlier, depending on how hard you're driving it.

author: TimFox
author_rank: Super Contributor
timestamp: March 26, 2015, 12:56:40 pm
content: Yes, the output is limited by clipping, where the amplifier cannot supply more voltage to the load. For a high-Z load, this is probably determined by the power supply voltage, but for a low-Z load the power supply maximum current may cause clipping at a lower voltage. Also, amplifier protection circuitry may limit the current to protect the transistors.
Impedance visualized (video) - Page 1
Forum section: electronics / beginners

author: Mecanix
author_rank: Frequent Contributor
timestamp: September 12, 2020, 11:17:03 pm
content: All those tech talks from modern technicians & other engineers when asked "what is impedance", I have yet came across anyone who explained/shown it better.

author: hamster_nz
author_rank: Super Contributor
timestamp: September 13, 2020, 07:55:49 am
content: I was thinking about this the other day while pushing the boy on a swing.Once moving it is far less effort to swing by pushing high up on the chain than by short shoves.Must be due to the harmonics of the energy being moved from arms to swing.You can also push at twice the frequency if you pull push up and down, rather than front to back...

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 13, 2020, 09:34:30 am
content: That is one of my favorite videos! Funny how this keeps coming back on the forum since 2012 (Hint: search 'entire forum' for DovunOxlY1k )

author: Mecanix
author_rank: Frequent Contributor
timestamp: September 13, 2020, 12:06:05 pm
content: Quote from: PA0PBZ on September 13, 2020, 09:34:30 amMy god lol Was passed to me on StackExchange yesterday by someone who have a great talent in explaining things. Thought it was a creative way, if not the best, to visually represent the concept and dared to be the first to share The Exclusive! Yea that vid/demonstration/contrib is gold, kudos Shive
implement power saving feature in an esp32 project - Page 1
Forum section: electronics / beginners

author: Rishles69@
author_rank: Regular Contributor
timestamp: January 09, 2024, 03:53:34 pm
content: So in my project im using one esp32c3xiao and many modules like 5 or 6. Even though the modules use consume under 1mAh, I want my project to last longer than 6 days without charge. So i decided to turn of the modules which are not used. So,in the modules i purchased, each of the modules have an LDO regulator ic and their EN pin are connected to 3.3v. So i was wondering if i can connect the EN pins to the gpios of the esp32 and control whichever modules should be turned on. Any ideas?
Implementing a proper guard ring  - Page 1
Forum section: electronics / beginners

author: LoveLaika
author_rank: Frequent Contributor
timestamp: September 23, 2020, 02:44:06 am
content: I'm trying to design a transimpedance amplifier, and one of the recommended design guidelines suggest to use a guard ring. Now, i gave it a shot and came up with this below. I laid out a no fill zone in my copper plane, and I ran a guard ring with vias around my high impedance input, at the inverting node of my op-amp. The ring is tied to the non-inverting input, which is itself tied to the ground plane through traces extending from the ring and connecting to the ground plane. You can see the results below. Is this the proper way to implement a guard ring? Datasheet and guides say that the ring should be tied to the reference potential, and i did that with the op-amp input and tracks to the ground plane, but is that correct?

author: wraper
author_rank: Unknown
timestamp: September 23, 2020, 02:54:31 am
content: Simply exposing GND is not a guard ring. In your case it simply does not make any positive difference. From leakage to what does it guard, to GND input signal is surrounded with anyway? And what is that supposed to do on the bottom side where is surrounds no signal?In this case exposing GND would help only if there was some other voltage nearby but there is none. Only a short section where it separates -VCC it makes some sense.

author: LoveLaika
author_rank: Frequent Contributor
timestamp: September 23, 2020, 03:52:16 am
content: My guard ring is supposed to protect the op-amp inverting input node from leakage current. I've posted my schematic below. Following the guidelines of the AD795, my op-amp, Figure 34 on the datasheet has a guard ring that's tied to the non-inverting terminal, which is connected to ground. That's what I'm trying to accomplish in my schematic. For all intents and purposes, in my schematic, Io is the reference/bias voltage to which all other voltages are referenced to. That is what i refer to as ground.I've also included some other links of guard ring notes that I tried to incorporate. You can see in link 2 (figure 6) the same idea. Link 3 is an op-ap reference that I also drew from. I included it on the bottom side as well in order to help strengthen the ring by covering both sides of the PCB. If what I have now doesn't do anything, what am I doing wrong, and what can I do to prevent leakage currents, if not by following what the datasheet says?Link 1:https://www.analog.com/media/en/technical-documentation/data-sheets/ad795.pdfLink 2:https://www.analog.com/en/technical-articles/layout-for-precision-op-amps.htmlLink 3:https://www.analog.com/media/en/technical-documentation/user-guides/ADA4530-1R-EBZ_UG-865.pdf
implementing Power saving features on esp32 with multiple modules - Page 1
Forum section: electronics / beginners

author: Rishles69@
author_rank: Regular Contributor
timestamp: January 03, 2024, 07:11:59 am
content: So i was making a watch using Esp32c3 and many sensors. I wanted to save the power consumption so that the watch can last for 5-7 days without powering of the entire watch project. So i looked up the modules which are mostly tiny inorder to fit it all up inside the watch body i got from a old g-shock. So for the battery, i used a 3.7 400mah battery. But im dissatisfied from the results. The entire project only lasted for 2 days. or 1½ days in sleep and 9 hrs in full time use. So to come over it i decided to use low power modules, and came a list of the each modules with their average power consumption.GY-271 HMC5883L 3-Axis Electronic Compass Module Magnetic Field Sensor - 100μAMPU6050 Accelerometer and Gyroscope Module - 3.6mAh (during readings), 5μA (idle)MAX30102 Heart Rate Sensor Module Puls Detection Blood Oxygen - 600μA (during readings), 0.7μA (standby mode)BMP180 Digital Barometric Pressure Sensor Board - 12μAATGM336h-5n-31 GPS module - <25 mahSSD1327 oled 1.5 inch - 35mahEsp32c3 xiao - 200mah (active), 44 µA (sleep)5630 smd led - 150mahvibration motor- 60mahso these are the list of the components used with 400/450 mah battery.my first plan:- (the display should be on when the esp32 works and the display should turn off when in sleep mode)I don't wanted to turn on these modules at the same time. that means, If i made a weather option, the pressure sensor should only turn on. Or, i made a workout option. the heartrate and gyroscope should be turned on. That means I should be able to turn on by choosing which module can be turned on at which time. So that a lot of power can be saved.i have posted the diagram. i left 5 pins for the vibration motor and 4 switches.

author: bookaboo
author_rank: Frequent Contributor
timestamp: January 03, 2024, 07:24:53 am
content: As a starting point I've used TPS27081ADDCR for similar peripheral power control. I'd only worry about he higher current components so one TPS27081ADDCR for each, either leave the low uA sensors running or group them to the same TPS27081ADDCR.There may be a more optimal component, search "high side switch".

author: Rishles69@
author_rank: Regular Contributor
timestamp: January 03, 2024, 07:29:11 am
content: ok, so how would i implement it? can you show me a diagram?

author: bookaboo
author_rank: Frequent Contributor
timestamp: January 03, 2024, 07:41:16 am
content: Something like this, check the datasheet carefully that your requirements are met.

author: Rishles69@
author_rank: Regular Contributor
timestamp: January 03, 2024, 08:13:03 am
content: ok, i got it. but i wanted to switch b/w these modules in program by using this ic in each modules
Implementing user selectable led driving current with an XL4015 CC/CV module - Page 1
Forum section: electronics / beginners

author: Barkuti
author_rank: Contributor
timestamp: August 03, 2017, 08:34:01 pm
content: 0K fellows, I believe I have this more or less rounded up, but I'd like to ask anyway.This is the sort of module:0K, in my module the diode is an SK54 and the inductor is a bit less beefy, nothing major.It'll be driving a 2S2P XHP70 emitter at a bit above 2A max, as 13-14W is about the maximum amount of power an old CPU heatsink I'm sticking it over can handle without fan, I believe.Of course, my intention is to use a potentiometer with a knob to regulate the driving current at will, but I don't want to be able to go overboard.It uses an onboard 1KOhm trimpot, by about half value or close is the maximum I'd like to go, but of course I believe that if I were to change it for a 470Ohm potentiometer it may not end up working as intended.So, I've decided to change the trimpot with a 1KOhm logarithmic taper potentiometer, as light output assessment works sorta like volume. In order to limit the maximum current, I'll first adjust the CC pot until maximum driving current is set, to then leave the emitter directly connected alone at the output, and upon elapsement of a reasonable emitter warming up period, measure the output voltage and then set this value for the CV trimpot.Does this sounds good enough?Thanks in advance.
Implication of Using current Sensor for ADC - Page 1
Forum section: electronics / beginners

author: Wize93
author_rank: Newbie
timestamp: March 28, 2022, 03:29:29 pm
content: Hello, I'm planning on using 4-20mA current sensor with a resistor to measure voltage change. However, in the datasheet on my motor controller, it states the following.. should I be concerned or does this not apply to me since I'm using a current source converted into a voltage source?I have attached Figure 3-9 belowFigure 3-9.The potentiometer value is limited at the low end by the current that will flow through itand which should ideally not exceed 5 or 10mA. If the potentiometer value is too high,the analog voltage at the pot’s middle point will be distorted by the input’s resistance toground of 53K. A high value potentiometer also makes the input sensitive to noise, particularly if wiring is long. Potentiometers of 1K or 5K are recommended values"

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 28, 2022, 03:48:39 pm
content: They are talking that ADC input resistance is not too high. If you use a current shunt to measure 5-20 mA current - its rated resistance won't be too large (<100 R) so there won't be a problem.

author: Renate
author_rank: Super Contributor
timestamp: March 28, 2022, 04:09:19 pm
content: "4-20 mA"? You speak in the words of the ancients.

author: Wize93
author_rank: Newbie
timestamp: March 28, 2022, 05:34:04 pm
content: Quote from: Vovk_Z on March 28, 2022, 03:48:39 pmI'm planning to use <250 which shouldn't be an issue?

author: BeBuLamar
author_rank: Super Contributor
timestamp: March 28, 2022, 07:11:06 pm
content: Quote from: Renate on March 28, 2022, 04:09:19 pmYou mean that 4-20mA are not used any more?

author: Benta
author_rank: Super Contributor
timestamp: March 28, 2022, 07:26:33 pm
content: Quote from: BeBuLamar on March 28, 2022, 07:11:06 pmThe user is apparently completely remote from industry and production environments. A "hammer" would probably blow her/his/diverse mind.

author: Vovk_Z
author_rank: Super Contributor
timestamp: March 28, 2022, 09:00:31 pm
content: Quote from: Wize93 on March 28, 2022, 05:34:04 pm250 R is 53000/250 >= 200 times larger so it has to be ok..The larger problem can be EMS and all other kinds of protections.
Important charactristics of high speed diodes - Page 1
Forum section: electronics / beginners

author: sean87
author_rank: Regular Contributor
timestamp: February 09, 2012, 12:32:38 pm
content: I am wondering if an application requires high speed diodes, what charactristic I should look for in datasheets?For example, between 1N4448 and 1N914 and 1N3595 who is the winner?My guess will be forward and/or reverse recovery time...But I am not sure if that is the only important factor to consider.Also I see that some people call 1N914 n small signal diode while they call 1N4448 a high-speed diode! Why?

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 09, 2012, 12:57:30 pm
content: Bob Pease devoted an entire chapter to discussing practical diode considerations in hisfamous book. I highly recommend looking into it.

author: sean87
author_rank: Regular Contributor
timestamp: February 09, 2012, 01:02:22 pm
content: I appriciate referencing the books, but I need some atleast some clues about my question until I can afford getting my hands on a book

author: ejeffrey
author_rank: Super Contributor
timestamp: February 09, 2012, 01:23:10 pm
content: It all depends on your application. Forward and reverse recovery are two big things. Shunt capacitance is another big one.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 09, 2012, 01:29:48 pm
content: Quote from: sean87 on February 09, 2012, 01:02:22 pmSome clues can be found here...in particular, the 1st, 2nd and 4th links are rather spot on.

author: olsenn
author_rank: Frequent Contributor
timestamp: February 09, 2012, 01:57:04 pm
content: In general, some (but not all) things to consider when it comes to diodes are forward voltage drop, reverse (breakdown) voltage drop, recovery times (and generally how fast the darned thing can switch), and... not to be neglected... the amount of current that can be passed through it (or maximum power dissipation if you wish).Other than that, just in case you aren't already aware, keep in mind that different diodes with different characteristsics are often classified differently as well... Zener diodes can safely be operated in the reverse (breakdown) region, Schottky diodes have a low forward voltage drop, power rectifiers can dissipate a lot of power (but are usually quite slow to switch) etc.

author: olsenn
author_rank: Frequent Contributor
timestamp: February 09, 2012, 02:00:56 pm
content: I forgot to mention perhaps the most important thing... COST! A 1N4148 won't break the bank anytime soon and it's a very popular component so it won't be discontinued any time soon either, but keep these things in mind when designing a device you want to mass produce.
Imposed Biasing - Page 1
Forum section: electronics / beginners

author: Gilster
author_rank: Newbie
timestamp: March 22, 2014, 05:20:14 am
content: Hi,I've been stuck for hours and I was hoping anyone can help. I'm not even sure how to start the problem (picture attached). Am I supposed to find the value of the resistor R or find different w/l values for the mosfets? How do I approach the problem? Any help is greatly appreciated. Thanks.

author: fcb
author_rank: Super Contributor
timestamp: March 22, 2014, 07:59:21 am
content: 1. Treat M1,2,3 as seperate circuits and find the common gate voltage required.2. Treat Mx as an independent circuit and solve for the common gate voltage above (ohms law).3. If they have the same mosfets, then there is a mistake also with the blue currents?
Impossible Closed Ring Ferrite Transformer has No Visible Gap - Page 1
Forum section: electronics / beginners

author: jonovid
author_rank: Super Contributor
timestamp: December 03, 2020, 06:27:45 am
content: just recently i have been re-using ferrite transformers by rewinding them for joule thief circuit testing.rewinding ferrite transformers this requires splitting the two ferrite E and reassembling them with a new winding.I came across this closed ring ferrite choke transformer! it has No gap in its ferrite ringsee for yourself! many switch mode power supply's have this type of closed ring ferrite choke transformeron the AC input as an inductor used to block higher-frequency. sohow is this type of transformer assembled?their is no gap in the ferrite ring. and no band of tape to hold the transformer together.most ferrite transformers have two ferrite E with a gap, a band of tape holds the transformer together.

author: bob91343
author_rank: Super Contributor
timestamp: December 03, 2020, 06:42:27 am
content: The wire is threaded through by means of a toroid winder. The bobbin the same. I can't tell much from your pictures.

author: jonovid
author_rank: Super Contributor
timestamp: December 03, 2020, 07:11:04 am
content: Quote from: bob91343 on December 03, 2020, 06:42:27 amok more pictures the bobbin is a single unit and I tried to find a gap by scrapping and then breaking one to see how it was assembledbut no

author: BravoV
author_rank: Super Contributor
timestamp: December 03, 2020, 07:27:32 am
content: If you observe carefully the plastic bobbin, its actually 2 pieces, and it has gear where to hook into powering gear to spin it for winding the wire, after it was clamped into solid piece of non gapped ferrite.

author: jonovid
author_rank: Super Contributor
timestamp: December 03, 2020, 02:31:20 pm
content: Quote from: BravoV on December 03, 2020, 07:27:32 amthank you for help .I now know a little more about this component.I did a little more disassembly. with a lot more care not to break the ferrite.thank you