hybridfree/eevblog-posts huggingface dataset:
Question about those analog scope clocks - Page 1
Forum section: electronics / beginners

author: alank2
author_rank: Super Contributor
timestamp: November 09, 2015, 10:04:59 pm
content: How do they blank between parts without a z-axis? Do they go really slow on the changes for the visible parts and really fast on non visible parts and the intensity is turned lower?

author: w2aew
author_rank: Super Contributor
timestamp: November 09, 2015, 10:36:31 pm
content: Quote from: alank2 on November 09, 2015, 10:04:59 pmIf there is no z-axis used, then yes, they move the beam very quickly or may even move it beyond the bounds of the screen quickly.
Question about transformer - Page 1
Forum section: electronics / beginners

author: little_carlos
author_rank: Regular Contributor
timestamp: April 28, 2016, 04:14:50 am
content: Hi, so i made a 3 amp 30 volt psu, every thing was fine, was able to handle 2.8 amps at 30 volts no problem, but these days something weird is happening, when i put a load bigger than 1.8 amps the transformer starts to make a hum, didnt used to do it before, its weird, can some one explain me what is happening? should i replace it?

author: Kappes Buur
author_rank: Regular Contributor
timestamp: April 28, 2016, 05:13:04 am
content: A transformer is not a solid block of iron. Instead it is made of several thin, preshaped pieces called laminations., which means that there is always an airgap between those laminations. As the load increases, the transformer has to 'work' harder and the laminations begin to vibrate, producing this hum.Good transformers are dunked into shellac, which penetrates, or at least should do so, these airgaps which in principle should dampen these vibrations and thusly the hum.As long as the transformer stays warm, there is no concern. However, if the transformer gets hot you should be thinking of replacing it.

author: orolo
author_rank: Frequent Contributor
timestamp: April 28, 2016, 08:50:23 am
content: Excessive hum can be a sign of saturation. Check your power supply for shorts or overloads. There could be a bad solder joint, failing cap, whatever. Check for current draw at the secondary side, with all due cautions.

author: Ian.M
author_rank: Super Contributor
timestamp: April 28, 2016, 09:13:44 am
content: Check the rectifier diodes. If one has gone O/C, you'd only be getting half-wave rectification, drawing pulsed DC from the secondary which would cause saturation and hum at a significantly lower current than the normal full-wave rectification which draws a balanced AC current.
Question about transformer ? - Page 1
Forum section: electronics / beginners

author: Nhan95
author_rank: Contributor
timestamp: May 16, 2015, 02:31:53 am
content: I see that some transformer have the ratio between primary and secondary coil in 1:1. According to theory, I think they won't produce these transformer. But in practical, They still using this type of transformer. Can you explain me why, and its application ? Thanks

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: May 16, 2015, 02:35:31 am
content: This is an isolation transformer.

author: 10101
author_rank: Contributor
timestamp: May 16, 2015, 02:37:33 am
content: http://electronics.stackexchange.com/questions/17496/how-is-using-a-transformer-for-isolation-safer-than-directly-connecting-to-the-phttp://en.wikipedia.org/wiki/Isolation_transformer

author: tautech
author_rank: Super Contributor
timestamp: May 16, 2015, 02:40:50 am
content: Sometimes used "inter-stage" for de-coupling too.And for pulse transformers too.Yes they provide isolation in many applications.

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: May 16, 2015, 10:59:48 am
content: thats called an isolation transformerhttp://en.wikipedia.org/wiki/Isolation_transformerhope that helps
Question about transistor in forward-active mode ? - Page 1
Forum section: electronics / beginners

author: Nhan95
author_rank: Contributor
timestamp: April 09, 2015, 02:48:52 pm
content: I have question about transistor biasing. Between picture 1 and 2, what's difference, why we add the resistor RE in pic 2 ? what's it effect to circuit ? Similarity for pics 3 and 4, instead of connecting RB to Vcc, why do they connect RB to the collector of BJT ? And which is the better way to bias a BJT among 4 pics ? thanks very much

author: Zero999
author_rank: Super Contributor
timestamp: April 09, 2015, 02:54:48 pm
content: 2 & 4 are correct.1 & 3 are wrong.

author: Nhan95
author_rank: Contributor
timestamp: April 09, 2015, 02:57:27 pm
content: Why wrong and why correct ?

author: Odysseus
author_rank: Regular Contributor
timestamp: April 09, 2015, 03:04:36 pm
content: The resulting quiescent operating point of circuits 1 and 3 will depend heavily on the current gain and base-emitter voltage of the transistor, which can vary quite a lot between different transistors and with temperature, to the point of causing the circuit to no longer be in the forward active region. The operating point of circuits 2 and 4, however, largely depend only on the external resistors, which are easily controlled and are relatively temperature insensitive.Actually, circuit 4, depending on it's intended operation, may need an extra resistor from the base to ground/input. Otherwise, the current through RB, and thus the voltage across it, depends directly on the current gain of the transistor.

author: Grapsus
author_rank: Regular Contributor
timestamp: April 09, 2015, 03:12:03 pm
content: Is this some kind of homework ? You have extensive explanations in The Art of Electronics, chapter 2.

author: Simon
author_rank: Unknown
timestamp: April 09, 2015, 03:33:53 pm
content: Quote from: Grapsus on April 09, 2015, 03:12:03 pmwhich is not a book everyone automatically has

author: bobcat
author_rank: Regular Contributor
timestamp: April 09, 2015, 05:26:12 pm
content: w2aew has a good video about transistor biasing:

author: w2aew
author_rank: Super Contributor
timestamp: April 09, 2015, 05:44:31 pm
content: Examples 1 and 3 will create bias conditions that are tricky to get setup properly, because they will be highly dependent upon the transistor's Bete (Hfe), temperature, and power supply variation. They are examples of poor design practice if you want to operate in the active region, class A.Examples 2 and 4 are different examples of applying feedback to stabilize the operating point against transistor parameter and supply variations - at the expense of gain. Feedback also generally improves linearity / reduces distortion.
Question about triple output power supplies - Page 1
Forum section: electronics / beginners

author: laplacepwn
author_rank: Newbie
timestamp: April 03, 2015, 07:05:19 am
content: Hi everyone,I currently use a GW Instek triple output power in my practical classes at university, shown below. 3 outputs, each having their own +ve and -ve terminals.I am curious to know if other triple output supplies that have say ±25v and a +6v channel, like the Rigol unit shown below, can use the negative supply output as a 3rd positive output? I mean, because the + and - channels both share a common port, can you power something with the positive rail, using the common as a common connection and then power something else with the negative terminal being used as a common connection and taking the reverse polarity so that the common output (with respect to the negative terminal) can power something else with a positive voltage (that is greater than 6v so using the +6v channel is not an answer I'm looking for)?Sorry if that was confusing. Hopefully you all can understand what I am asking.

author: ivaylo
author_rank: Frequent Contributor
timestamp: April 03, 2015, 07:28:17 am
content: Depends on the PSU. With some you can do what you are asking, with others you can't. Say the Rigol you are showing can not be used with three independent channels like the GW Instek. If you aren't sure about a specific model just check the manual.
Question about turn ratios - Page 1
Forum section: electronics / beginners

author: Enron
author_rank: Contributor
timestamp: February 02, 2015, 04:48:31 am
content: I'm about to make my first attempt on building an inductor. I was going to do a step up 1:2 transformer using 10 turns on one side and 20 on the other. Then I was thinking why not 5 on one side and 10 on the other or even 2/4.Can someone explain what the difference in turns is. Is it the amount of current it can handle? Because I thought that would be determined by the gauge of the wire. Thanks!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 02, 2015, 12:48:08 pm
content: You need enough inductance to match to the circuit. This depends wildly on what the circuit does, but a few typical examples might be:- A switching power inductor, which needs a certain inductance to satisfy the converter's frequency, voltage and current requirements- An RF choke (RFC), which needs to have at least X inductance at the lowest frequency of interest (against a source resistance R, thus forming an R-L highpass filter, which needs to pass at least the signal frequency of interest)- A resonant coil, where the inductance is very critical in that it sets the resonant frequency of the circuit (the particular value depending on capacitance, since F = 1 / (2*pi*sqrt(L*C)), and the general value being dependent on source resistance R as with the RFC, but also depending on Q (selectivity).For a given geometry, inductance is proportional to turns squared.That means, if your turns are in the exact same diameter, length and position every time, and there's just more or less of them: then it's always as N^2.If any of those dimensions change (like you use the same thickness wire, closely spaced, and put on more turns = longer winding), then the factors change in a complicated way.If you have a magnetic core, things are less complicated because most of the flux is flowing in the core, and inductivity (the amount of inductance you get per squared turn) is much more stable as you vary turns and shape.There's also the matter of core material: ungapped (ferrite and laminated iron, usually) cores have very high permeability, and are intended specifically NOT to store energy (inductance is very high, saturation current is very low). Lower permeability cores (gapped cores, powdered iron toroids, rod and bobbin cores, and good old fashioned air cored inductors) are intended to store energy.Tim

author: w2aew
author_rank: Super Contributor
timestamp: February 02, 2015, 01:37:07 pm
content: Quote from: T3sl4co1l on February 02, 2015, 12:48:08 pmTim gave you a great answer. One more point I'll add. If you are doing an RF transformer (for impedance matching, etc.) then it is common to make the winding's inductive reactance (at the frequency of interest) about 4x higher than the impedance of the circuit it's being used in.
Question about Usable power increase number? - Page 1
Forum section: electronics / beginners

author: ApplePi
author_rank: Contributor
timestamp: September 30, 2013, 06:15:44 pm
content: My datacenter gave me a usable power increase number of 1.78 for switching from single phase to three phase. What does this mean? Is it e.g. 1.78 times as much usable power to end machines?What is the basis of this 1.78 that they gave me?

author: Fsck
author_rank: Super Contributor
timestamp: September 30, 2013, 06:22:23 pm
content: Could be a function of cooling capacity or if it was power delivery limited, then an increase in power delivery capacity.
Question about use of Differential using scope USB port - Page 1
Forum section: electronics / beginners

author: watchmaker
author_rank: Unknown
timestamp: April 28, 2024, 01:16:22 am
content: The MicSig probes use the USB port of your scope for the power supply.Excluding operator error (ignorance? stupidity?) such as putting both hands on the work or working in an electrically unsafe environment, does this mean that the things discussed here about grounding out the scope are avoided?And for those who missed it in Test Equip, Amazon has a coupon for the Micsic DP10013 which drives the price to $150 USD. This price is only marginally higher than a store bought isolation transformer.

author: RJSV
author_rank: Super Contributor
timestamp: April 28, 2024, 02:26:31 am
content: It's a good question, when caring about safety, but maybe too general. Perhaps focus on one thing and associated question, rather than a vague, general 'things that were discussed'.Grounding ties, and related safety should be specific to one instance, (and I don't claim to have that comprehensive).Certainly a 'one handed' rule should specify maybe a rubber mat / shoes also, while explaining the ground paths that are to be avoided...Metal shop chair ? Ditto, as something like metal chair, with rubber feet, and in a mat, could be, cautiously, tolerated.See how detailed and specific that was ?But I'm not expert. Perhaps there is (or should be) a National Electrical Code unit, in D.C. that could answer / respond to the subject on Oscilloscope grounds and related recommended practice(s).Wouldn't be surprised, if (any) agency would be 20 years behind the times, but that's normal in large agencies.

author: watchmaker
author_rank: Unknown
timestamp: April 28, 2024, 11:58:46 am
content: Perhaps you are right. I assumed (never a good thing, especially here) that people looking at Differential Probes have researched good practices, earthing and isolation transformers. At any rate, that is what drove me to consider the expense. (I grew up with non polarized plugs and isolation transformers).But yes, since many Differential Probes were battery operated, I am interested in the impact of the use of a USB port on the scope for power. Especailly given all the attention to the issues regarding working around USB ports.FWIW, I did check my 120 vac with it, with no ill effects. But......

author: David Hess
author_rank: Super Contributor
timestamp: April 28, 2024, 11:41:03 pm
content: A differential probe *must* be grounded to the oscilloscope to control its common mode input voltage. If it was isolated, then its common mode voltage could drift out of range and present a safety hazard itself. So the connection to the USB port is not a concern because the probe will be grounded through the BNC connection anyway.Manufacturers who make oscilloscopes that have galvanically isolated inputs warn about using differential probes with them unless they can be separately grounded to the oscilloscope.

author: watchmaker
author_rank: Unknown
timestamp: April 29, 2024, 12:27:35 am
content: THANK YOU David.
Question about using a couple DC-DC converters together - Page 1
Forum section: electronics / beginners

author: taste_tester
author_rank: Regular Contributor
timestamp: June 23, 2022, 05:18:47 am
content: Need to make a substitute for this totally ruined PSU, needs 2A of 5V for the logic & microprocessor and has a separated +/-12V supply (only 250ma each rail) to power some audio op-amps.The power board is completely ruined - picture attached.I decided my original plan is too inefficient, which would have had me replace the AC input with a 19V DC input and then feed three LM2596 PCB by that.Now i've decided to simply use an encapsulated 5V supply that can output a bit over what I need so I can also power a nifty buck-boost converter which was inexpensive and already set to put out ~200ma of +/-12V - exactly what I need and it will be easier to keep using the original power switch this way as well.The drawing is from before I realized pre-existing buck boost converters with bipolar outputs exist and are pretty cheap, so ignore my crappy dual-LM2596 idea, I attached a picture of one a dd1718pa i'll use.
Question about using a Meanwell psu with buck regulators. - Page 1
Forum section: electronics / beginners

author: IY3775
author_rank: Newbie
timestamp: January 24, 2019, 04:18:46 am
content: Hi, with a 48V 8.4A meanwell psu (EPP-400), will I be able to draw 15-20A @12V with a buck converter like DPS 5020 or similar?EPP-400-48 datasheet:https://www.meanwell.com/webapp/product/search.aspx?prod=EPP-400&mws=3373F963E7D2D4F7#1Sent from my Mi A1 using Tapatalk

author: Gregg
author_rank: Super Contributor
timestamp: January 24, 2019, 04:57:48 am
content: You should be OKThe Meanwell EPP 400 is capable of 400 watts (on paper). From experience with cheap Chinese electronic modules, I usually de rate them 50%; however Meanwell is well established as a reliable supplier and assuming you have a genuine Meanwell power supply you can probably get 75% of the 400 watts from in continuously with peaks of the full 400 watts for a few minutes at a time. Cooling is the big issue with pushing the limits of either the power source or the DPS.The DPS 5020 is rated for 1000 watts and I definitely would de rate it 50% for long term loads but even so you are not pushing it with the EPP 400. In any case, I would not leave the setup unattended and keep an eye out for hot spots.
Question about using a switching regulator with a very low load - Page 1
Forum section: electronics / beginners

author: Razor512
author_rank: Regular Contributor
timestamp: April 16, 2013, 03:53:25 am
content: I was thinking about using a switching regulator to power a thermostat using an old 5.4V DC power adapter. The only problem is that the device pulls less than 1ma when idle (using 2 AA batteries).The low battery warning sucks where once the low battery warning is displayed, it will no longer switch and thus the furnace will not turn on, and the end result is waking up in the morning and the house is 45F (7C), so basically the low battery is only useful for storing the settings and not much else.It is close to an outlet so I would just like to power it from something other than battery power.I was thinking of using an old 5.4V power adapter that went to the charging dock of an old PDA, and a PTH08080W to power the thermostat.http://www.ti.com/product/pth08080wI looked through the datasheet and it does not really talk about having the power source constantly on but connected to a very low load.It is difficult to get the load when it is not idle because it only uses extra power for a short time and my crappy multimeter cannot really detect the change.Will it be a big mistake to to use the switching regulator in this situation (from a safety standpoint, and not having the regulator break after a few minutes) to use it on a device with such a low load?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 16, 2013, 04:07:07 am
content: Hi,Have a look at the LT8610. This has very low quiescent current of 2.5 uA, that means the output is up in regulation, but with no load.You can find the part here:http://www.linear.com/product/LT8610Jay_Diddy_B

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 16, 2013, 04:12:29 am
content: It should work fine, but a linear regulator is a better fit for your application.

author: David_AVD
author_rank: Super Contributor
timestamp: April 16, 2013, 04:13:18 am
content: Why not simply add a resistor to the output to draw the extra current?

author: Razor512
author_rank: Regular Contributor
timestamp: April 16, 2013, 05:00:19 am
content: I will have to see if a resistor can work. I will basically be taking the output from a 5.4V (2.41 amp) DC power source, and getting a output of anything from 2.5-3V (anything in that range should work fine to power the thermostat (it may use around 1ma or less 95% of the time, and probably around 50-70ma when the display backlight is on and you are changing settings)

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 16, 2013, 11:10:53 am
content: Hi,With a thermostat you need to get the circuit as efficient as possible. Any heating inside the enclosure will heat the temperature sensor and make it difficult to read the temperature accurately.If the maximum power consumption is less than a 500mA another part worth considering is the LTC3630.http://www.linear.com/product/LTC3630Jay_Diddy_B
Question about vcc at IC wine cooler psu - Page 1
Forum section: electronics / beginners

author: billbyrd1945
author_rank: Regular Contributor
timestamp: November 25, 2018, 06:52:46 pm
content: I'm working on two identical 12.5v power supply boards for a dual Peltier wine cooler. One seems to be working while the other one doesn't. I barely know enough to ask a good question, but here goes: The voltage at vcc on the IC is a little over 5vdc on the working one and a little over 12vdc on the sick one. But I don't know if that condemns the IC, or if the problem exists before the IC. Is there some way to determine this without desoldering it? (I have oscope and multimeters) Thank you.link to data sheet:https://www.mouser.com/datasheet/2/115/AZ494A_C-271601.pdf

author: hermit
author_rank: Frequent Contributor
timestamp: November 25, 2018, 09:04:25 pm
content: It looks like that chip can use a voltage up to 40V at VCC so my question would be, "Are you absolutely certain that those boards are identical?" Look for revision numbers, etc.

author: billbyrd1945
author_rank: Regular Contributor
timestamp: November 26, 2018, 12:44:00 am
content: Yes. Both boards are PCB90829F1. Since my last post I've been checking the two power transistors on the non-working board. They are 13005D. In searching for tests, I find seemingly credible sources with two conflicting methods. One school is testing diodes B to C and back, and testing B to E and back. My transistors pass that test. But the other school is to do the same tests with one additional test from C to E and back. That test shows my computers to be bad. Maybe we can settle it here on the forum.

author: billbyrd1945
author_rank: Regular Contributor
timestamp: November 26, 2018, 02:05:54 am
content: Here's a drawing that shows how I understand the test to be done. Several videos show it done this way. Conflicting videos show that the last transistor in the drawing should be OL so that the middle and right pins would pass no voltage in either direction. One method condemns my transistors while the other says they're good. What do you guys say? I have no schematic. The markings are all I have.
Question about voltage - Page 1
Forum section: electronics / beginners

author: DoorVb
author_rank: Newbie
timestamp: October 11, 2018, 04:28:35 pm
content: The formula for voltage is V(volt) = J(joule) / C(coulomb)Does this mean that if I have a resistor that is dropping one volt, every coulomb of charge that passes trough it generates one joule of heat?Or am I getting the formula wrong?Any help is appreciated,Van Beveren

author: Paul Rose
author_rank: Regular Contributor
timestamp: October 11, 2018, 04:56:25 pm
content: Sounds right to me.I used to thinking of it in terms of power and current.P = I * V1 Ampere dropping 1 Volt = 1 Watt of powerThat 1 Ampere is just 1 Coulomb of charge per second. And that 1 watt is just 1 Joule per second.Substitute power with charge per time, substitute current with charge per second. Same story.
Question about weird EA power supply - Page 1
Forum section: electronics / beginners

author: greenjazzer
author_rank: Newbie
timestamp: August 18, 2015, 12:33:35 am
content: Hi,I got a Elektro-Automatik EA-PS 8065-05 T laboratory power supply, long storry.It's switched mode adjustable microprocessor controlled voltage (0-65V)/current (0-5A) power supply (325W), very good build quality (Made in Germany), adjustable high voltage protection, analogue remote control interface and "sense" for compensation of voltage drop in conductor. It's priced a bit over 800€. It's doing good job with my hobby electronics (definite overkill) but it seems to me that it basically does the same thing as some much less expensive ps. There is limiting information on internet. I don't have oscilloscope so I can't check the output but specified ripple is not sensational. Am I missing something? I am curious because price seems to be high.Here is more data:Output voltage DCAccuracy <0.2%Stability at 0-100% load <0.05%Stability at ±10% ?Uin <0.02%Regulation 10-100% load <2msRise time 10-90% Max. 30msOutput currentAccuracy <0.2%Stability at 0-100% ?Uout <0.15%Stability at ±10% ?Uin <0.05%Efficiency 92%Ripple U max.* 150mV PP / 20mV RMSRipple I max. 12mA PP / 3mA RMSU (Programmable resolution without device error) 18mVI (Programmable resolution without device error) 2mA*RMS value: measures at LF with BWL 300kHz, PP value: measured at HF with BWL 20MHz

author: eilize
author_rank: Contributor
timestamp: August 18, 2015, 01:12:32 am
content: i guess it's 150mv at 65v ~0.1or 0.2%same for the current ripplei lack experience too, but it seem okmy old atx psu has more like 1-2% ripple, cost me something like 50$ 10years agoyou pay the ripple

author: Chris C
author_rank: Frequent Contributor
timestamp: August 19, 2015, 06:55:59 pm
content: Every technique that I know of to reduce ripple has a downside.You can increase the frequency of the switching power supply, but that reduces efficiency.Or you could attach a filter to the output, like a Pi filter, which is good at reducing ripple. But if you have a stepped load (for example one that goes from 0-3A quickly, or the reverse), the filter slows the response time, causing the voltage to dip or spike. In some cases even a small spike might not be acceptable.So it's probably best not to go overboard with ripple reduction built into the PSU. The user can add external filtering if needed and appropriate.
Question: Customer End-User Certificate while ordering from outside the USA - Page 1
Forum section: electronics / beginners

author: Asim
author_rank: Regular Contributor
timestamp: November 11, 2016, 09:43:58 pm
content: Hey guys,I live in Dubai, United Arab emirates. I have been using mouser for time now. I use a drop and ship service from Aramex.Meaning, Mouser will drop the package in Aramex warehouse /building in USA and then Aramex will ship it to Dubai.It is wayyyyyyyyy cheaper. This time though I received the attached form from Mouser right after checking out.How should I fill it giving my explained situation above?!The components ordered are for personal use ( hobby project) and has nothing to do with my job.I don't have a SSN and never visited USA

author: rsjsouza
author_rank: Super Contributor
timestamp: November 11, 2016, 10:00:28 pm
content: Given they have a field named "Country", they can't expect that everyone will have a US document. In this case, I would simply supply an ID number/type of a Dubai document. Also, check the lists on the links mentioned in the letter and answer accordingly.Similar for the other questions: if military or civilian use, if the components will be re-exported, etc.Just answer truthfully. It will go long way in getting their approval.Just a disclaimer: I am not a lawyer or an expert in foreign commerce. I am a foreign national in US and had to fill zillions of these types documents throughout the years for various reasons.
Question flash NOR memory chip - Page 1
Forum section: electronics / beginners

author: aranvaryt
author_rank: Newbie
timestamp: April 04, 2025, 04:06:15 pm
content: A NOR flash memory chip example: ST M29W640FT 706 H can retain all data for how many years stored at 35-36C temperature? (A maximum of 10 writes and erases were used on this chip)

author: hexreader
author_rank: Frequent Contributor
timestamp: April 04, 2025, 04:34:17 pm
content: You already asked the same question 4 years ago when you were tiago1986 and received good answers.Are you really from New York? - or are you still living in Brazil?Currently 69 user names and 69 forums that I know of.
Question for all trackball switch aficionados - Page 1
Forum section: electronics / beginners

author: fabiodl
author_rank: Frequent Contributor
timestamp: February 11, 2021, 01:54:07 pm
content: The first comment ofthis blogreports that the logitech M570 uses Alps SKHHAJA010. In mine, however, I found the switch in the picture. I never seen a similar red/white top switch.Do you know what switch it is? It reports tk24 on the bottom.

author: drvtech
author_rank: Regular Contributor
timestamp: February 11, 2021, 05:47:11 pm
content: If you check the datasheethttp://www.farnell.com/datasheets/1685516.pdfyou'll see that the colour of the actuator indicates the operating force. Black = 0.98N, red = 2.55N

author: fabiodl
author_rank: Frequent Contributor
timestamp: February 12, 2021, 02:52:46 am
content: Thank you.Are you sure the switch is an alps one? the SKHHAJA010 has a clear alps logo on the bottom, the one I removed from the trackball doesn't.The SKHHAJA010 has a metallic top, the one from the trackball is white (probably plastic?)

author: msat
author_rank: Regular Contributor
timestamp: February 12, 2021, 03:50:54 am
content: I suspect Logi decided to save some pennies by switching (heh) to a cheaper part and then passing on the savings to theircustomersshareholders.
Question for anyone who has used Mechanic brand soldering paste. - Page 1
Forum section: electronics / beginners

author: wade7575
author_rank: Contributor
timestamp: September 27, 2018, 05:05:53 am
content: I was looking at solder paste's with a friend because I want to try some of the cheaper brands because I'm more of a hobbyist and would rather save a bit of money where I can.When we looked at the Mechanic brand tuff I found something odd that I could not figure out and neither could my friend,when you look at the picture in the first link that has the 4 bottle's of it and if you look at the bottle in the upper right hand corner it say's it's Model XG-50 and is 20-38 microns and the XG-80 beside it say's it's a 25-45 microns.https://www.banggood.com/MECHANIC-Soldering-Solder-Welding-Paste-Flux-SMD-SMT-Sn63Pb37-Tool-Soldering-Iron-Flux-Repair-Tool-p-1328894.html?rmmds=search&cur_warehouse=CNIf you look in this second link the XG-50 say's it 25-45 and all of the other listing on ebay with the XG-50 stuff listed are also a 25-45,I was wanting to get a finer micron size solder paste to avoid bridging when solder certain part's.https://www.ebay.com/itm/MECHANIC-Reparing-Solder-Soldering-Paste-XG-50-XG-500-42g-Sn63-Pb37-25-45um/232935616586?hash=item363c0b704aCan anyone tell me if Mechanic brand stopped making the finer stuff or what the deal is because I would have thought that XG-40 50 and 80 would have referred more to the micron size of the solder paste.
Question for Voltage On Amplifier - Page 1
Forum section: electronics / beginners

author: rentner
author_rank: Regular Contributor
timestamp: February 04, 2013, 10:06:03 pm
content: I came over a Circuit, I am pretty interested in, that says, that it cannot handle over 90V.It is the following link.http://hobbyelectronicsdri.blogspot.de/2011/06/600-watt-quasi-amplifier-with-mosfet.htmlI see no reason, why anything over 90V can destroy parts, if capacitors are choosen correct. I want to make a few Changes on that circuit, to get an RMS Power of 1kW into 8 Ohms load. But 1kW into 8 Ohms means VRMS=90 -> Vpk=127 and additional it is good to have a few extra volts, to lower distortion. So I want to put 135VDC+/- to the Amplifier. Well, I am affrait, that it might not handle that Voltage, because the Circuit says, it only works for 90VDC+/-Do I have to change anything else than the output mosfets and Capacitors? (Yeah, I want to change them to another type, which won't be a problem)Thanks for Reply!

author: Psi
author_rank: Super Contributor
timestamp: February 04, 2013, 11:26:56 pm
content: I cant see anywhere that he specifically says it wont work over 90V.All i can see is the voltage range on the schematic 60-90V.It's likely that's just the range it was designed it for.Make sure you use mosfets that can handle both the peak currentandthe heat generated.Also, depending on your new mosfet specs, you may have to adjust the 0.33R source resistors a little to keep the fets balanced.

author: rentner
author_rank: Regular Contributor
timestamp: February 05, 2013, 02:55:20 pm
content: So I hope, it will work for that Voltage...What the hell do I need that crap for? Well...I want to make a HiFi 7.1 reciever with 100WRMS max for each channel at 8 Ohms and 1kW into 8 Ohms for the sub. This will be definitely enough for me.The fun will be a Regulated Power Supply with 35V 1kW for the surround and 1.5kW +135V +10V / -135V.. When I start and make progress I definitely will post something on that in that Forum. I promise.Hope I get that done under 300€. Good, that I already have a few parts.It will, by the way, be a 100% analog Reciever.
Question: HP power supplies - Page 1
Forum section: electronics / beginners

author: djf123
author_rank: Newbie
timestamp: April 26, 2017, 08:47:42 pm
content: I've been reading about which power supply to get, and all the recommendations I've been seeing have suggested that one should get a cheap old HP power supply and not one of those cheap new Chinese ones. I am looking to get a cheap linear power supply that has a small ripple. My question is though are all of the old hp power supplies more or less the same? For example I've been looking at the HP 6200B and the 6286A, but I know so little about power supplies to know what the difference is between them. Is there a big difference? And can someone recommend a particular model for me?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 26, 2017, 09:02:40 pm
content: I have worked with quite a few of that age power supply and they all seem to be nearly bulletproof. Selection should be based on what you want to do.Is current limiting important to you? Crowbar action? How many volts? How many amps? How precise? Tracking? Remote control? Voltage sense? Noise? Bandwidth?If those questions don't make sense it is probably time to do some Googling before you buy any supply, new or old. Or, buy just about any supply and keep playing until you find that it limits you. Both answers are good in their own way.

author: rdl
author_rank: Super Contributor
timestamp: April 26, 2017, 09:10:10 pm
content: This is what I use:Caveats are that the buttons sometimes tend to develop cracks and fall apart and the earlier HP models had some "issues" that were later fixed in the Agilent versions. All of which can be dealt with. For example, the Agilent at the bottom has had two of the buttons replaced (89 cents each + some spray paint).Another power supply that I like is the "Tektronix" CPS250. Not a lot of amps but versatile and covers all the basics.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: April 26, 2017, 09:19:25 pm
content: I have one of each. A programmable high current (5A) Chinese power supply and an old HP similar to the 6200B. I like having both as one's features often covers the other's limitations and if I need two voltages I have them.Expanding a bit on what CatalinaWOW said, you absolutely want current limiting on at least one supply. This helps keep things going up in smoke if you make a mistake.
Question LCD LED display - Page 1
Forum section: electronics / beginners

author: tiago1986
author_rank: Regular Contributor
timestamp: April 25, 2021, 10:31:03 pm
content: is possibly preserve conserve display LCD of the portateis electronics stored long term storage? not loose pression of LCD

author: Renate
author_rank: Super Contributor
timestamp: April 26, 2021, 12:21:42 am
content: Are you asking about a persistent display with low power?How about eInk?https://www.eink.com/(The black and white ones are the most available.)

author: amyk
author_rank: Super Contributor
timestamp: April 26, 2021, 02:27:44 am
content: That posting style looks familiar...https://www.eevblog.com/forum/chat/electronic-device-stored-for-decades-without-corrosion/https://www.eevblog.com/forum/general-computing/question-hdd-control-badblocks/https://www.eevblog.com/forum/chat/question-electrostatic-discharge-microsd/https://www.eevblog.com/forum/chat/question-hygrometer/https://www.eevblog.com/forum/chat/question-remove-battery-smartphone/https://www.eevblog.com/forum/chat/question-charger-universal-battery-movel/https://www.eevblog.com/forum/chat/question-conector-cartridge-and-microsd-contacts-electrical/https://www.eevblog.com/forum/chat/question-scratches-crt-tv/
Question: making a bidirectional TVS - Page 1
Forum section: electronics / beginners

author: Circuitous
author_rank: Unknown
timestamp: August 30, 2012, 12:42:41 am
content: I need to repair a circuit that had a damaged transorb (1n6281C). The new components arrived today, and I realized that I didn't quite order the correct component (1n6281A). The difference is that the original is a bidirectional TVS, but what I have are a bunch of unidirectional TVS diodes.Question: can I just replace the original bidirectional with a pair of unidirectional diodes, in reverse series?Wikipedia (that often not-quite-right source) states that this is how a bidirectional TVS works. Is this correct?The device in question needs to be re-installed on Friday on a radio tower, so I don't have time to order something else.http://corgitronics.com/2012/08/26/radio-tower-navigation-lights/

author: Short Circuit
author_rank: Frequent Contributor
timestamp: August 30, 2012, 01:03:33 am
content: Use just one, and add a regular powerdiode anti-parallel.sorry,uni and bi's got mixed up somewhere between screen and keyboardReverse series config is to make a bidirectional TVS out of two unidirectionals, so yes, WP is correct.

author: Psi
author_rank: Super Contributor
timestamp: August 30, 2012, 01:19:35 am
content: A bidirectional TVS (or two unidirectionals in series) will protect against high voltage spikes in both positive and negative directions, eg for 20V TVS it will clip at above 20V or below -20V. So it's good for protecting an AC line.If its for a DC power line then any negative voltage is unwanted.So, as said above, you can use a regular diode to clip the negative at -0.8V and a TVS to clip the positive at +20 (or whatever)

author: Circuitous
author_rank: Unknown
timestamp: August 30, 2012, 01:47:31 am
content: QuoteYes, the original bi-directional TVS was installed across the low voltage side of a transformer, about 14.5VAC RMS.Thanks for the responses. I'll keep the other approach in mind for DC protection.I appreciate the quick responses, as we need to get the lights flashing at the top of the 400ft. tower.
Question mini LEDs and backlight - Page 1
Forum section: electronics / beginners

author: aranvaryt
author_rank: Newbie
timestamp: March 23, 2025, 05:57:33 pm
content: The LEDs + backlight in portable devices with 3.5" LCD IPS degrade and lose brightness during storage without use. From what temperature or any temperature does it degrade them?

author: abeyer
author_rank: Frequent Contributor
timestamp: March 23, 2025, 07:33:49 pm
content: Please don't start a new thread on the same subject just because you're not getting the answers you want on the first one.Also, if you spent some time making your posts more readable, you might get more engagement. If english isn't your native language, then maybe take advantage of the vastly better translation tools that are available free now. If it is... then use it, please.https://www.eevblog.com/forum/beginners/why-writing-style-and-grammar-matters-in-posts/msg5444555/

author: Zero999
author_rank: Super Contributor
timestamp: March 23, 2025, 08:02:26 pm
content: Quote from: aranvaryt on March 23, 2025, 05:57:33 pmThat sounds like a load of nonsense.There is no reason why backlight will lose efficiency in storage.
Question on a Comparator in a Schematic - Page 1
Forum section: electronics / beginners

author: eev_carl
author_rank: Regular Contributor
timestamp: July 27, 2018, 01:23:27 pm
content: Hi,What's the purpose of the comparator in this schematic? Is it possible to put the gate directly into R5 for demonstration purposes?https://synthnerd.wordpress.com/2016/04/06/envelope-circuits-a-simple-ar-design-using-op-amps/Thanks,Carl

author: madires
author_rank: Super Contributor
timestamp: July 27, 2018, 02:30:19 pm
content: The opamp set up as comparator triggers the attack-release. If the input voltage is higher than the reference (voltage divider with R3 and R4) the opamp's output goes high, and vice versa. If you connect R5 directly to "Gate In" you'd get a different functionality.

author: eev_carl
author_rank: Regular Contributor
timestamp: July 27, 2018, 03:07:02 pm
content: What would the different functionality be? If the gate w/o the compartor went high but was below the reference voltage the capacitor wouldn't charge?

author: bsfeechannel
author_rank: Super Contributor
timestamp: July 27, 2018, 03:54:39 pm
content: The two op amps in this circuit act as buffers. The first, the comparator, is a digital buffer. The second plays the role of an analog buffer.It is always a good idea to buffer the input and output of your circuits, especially when you do not know what is going to be connected to them in terms of loads and impedances.That's why any half decent guitar pedal must have buffers on their inputs and outputs.Of course you can dispense with buffers if you know what you're doing. For instance, if you know that the output buffer of the gate is capable of driving the current necessary to charge C1 besides driving other circuits, you don't need the comparator. If you know that the input of the VCA or VCF is not going to unnecessary discharge C1, then off with the output buffer.But I personally would not recommend it. The cool thing about analog synths is that you can patch together the various modules without having to worry about loads or impedance matching.Good luck with your project.

author: eev_carl
author_rank: Regular Contributor
timestamp: July 27, 2018, 04:20:40 pm
content: Thanks! I'll definitely buffer when I actually build something. Today I'm looking for the minimal amount of components to better understand the diode / capacitor charging with my scope.
Question on adjusting DC offset - Page 1
Forum section: electronics / beginners

author: Pasky
author_rank: Regular Contributor
timestamp: August 26, 2015, 08:43:42 am
content: Got a question about adjusting the DC offset of a signal that fluctuates between 0-3V. I was looking for a method to adjust the dc offset on an analog video signal and was given advice by a peer to use this:This works fine and I can adjust the signal lower or higher, however it doesn't give me much range and I'm unsure if there is a better way to do this.So I guess my question is, is there an efficient and easier way to adjust the DC offset of an analog video signal that could perhaps have a bit more range or is this a preferred method? Thanks.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 26, 2015, 10:57:28 am
content: Yes,there is,& has been,for around seventy years------it is called a "keyed clamper".It turns "on" during the line blanking interval's "front porch",switching that point in the signal to reference level.It is commonly used to clamp to zero volts,but it can clamp to other voltages if required.A keyed clamper uses a "clamp pulse" derived from a delayed version of the line sync pulse to turn the clamp on.You need to research Television equipment to get the complete story of its operation.(Try Googling "keyed clamper")The ones I have worked with usually were discrete component circuits,but there are ICs which do the whole job.

author: Delta
author_rank: Super Contributor
timestamp: August 26, 2015, 12:46:08 pm
content: use an emitter follower with adjustable bias.
Question on Allegro a1308 output filter - Page 1
Forum section: electronics / beginners

author: trilerian
author_rank: Regular Contributor
timestamp: August 26, 2023, 02:54:54 pm
content: Hello, as the title states, I have a question on the Allegro a1308 hall effect sensor output rc filter. In the data sheet it call for a pulldown resistor on the output followed by a cap.They label these as RL and CL. CL can have a max value of 10nf and RL needs to min of 4.7kΩ. I have defaulted these in my schematic to 10kΩ and 4.7nf. But how do I calculate the filter -3db with a pulldown resistor instead of a series resistor? I realize this is a very beginner question, and I am sorry, but my searches have evaded me.

author: srb1954
author_rank: Super Contributor
timestamp: August 26, 2023, 09:13:14 pm
content: Quote from: trilerian on August 26, 2023, 02:54:54 pmThe pulldown resistor is not relevant to calculating the -3dB point as it is the internal O/P resistance of the A1308 driver stage that should be used to calculate the roll-off frequency. The O/P resistance is listed in the datasheet as 3typical so the filtering obtained with the 4n7 capacitor is pretty minimal. If you need filtering it would be better to add a suitable series resistor rather than relying on the not very well controlled internal O/P resistance.The minimum value for RLand the maximum value for CLspecified in the datasheet are there to ensure that excessive load is not put on the output driver; you don't need to use these specified values to make the chip function.
Question on batteries - Page 1
Forum section: electronics / beginners

author: AtLarge
author_rank: Contributor
timestamp: March 13, 2019, 11:26:47 pm
content: Can someone explain to me what the significance of the white wire is on this battery? As best I can find it is some type of "detect" line but I'd like to know more or how I can use it for testing purposes. I know there is charging circuitry on a PCB before the cells but, wouldn't detection be measured right off the positive terminal when voltage is applied there?

author: tooki
author_rank: Super Contributor
timestamp: March 14, 2019, 02:04:52 am
content: Either a data line to a battery IC or a temperature sensor.

author: Jwillis
author_rank: Super Contributor
timestamp: March 14, 2019, 02:41:02 am
content: tooki is correct. Its a communication data bus for the BMS (Battery Management System). This type should only be charged by a smart charger.
Question on Brymen BM235 & Fluke 17B+ - Page 1
Forum section: electronics / beginners

author: Sammickk
author_rank: Newbie
timestamp: February 24, 2020, 03:50:19 pm
content: I know this may be a dumb question from a newbie on DMM's but I've narrowed down my new DMM to two choices.Fluke 17B+ , and the brymen BM235I'm kinda leaning towards the Brymen (EEVblog rebrand) because I've seen people saying the Fluke has no warranty, and no English manual.So my questions are, If I buy the brymen, will these tips work on the probes that come with it?https://www.amazon.com/dp/B000VRFL10/?coliid=I35MEMH6V2TRVS&colid=1C5RQ0A596HZV&psc=1&ref_=lv_ov_lig_dp_itIf not can i get some fluke probes for the brymen? are probes a universal fit between DMM's? At that point should i just go with the Fluke? I need those tips because I do work on some VERY small smd components and these would be GREAT to have. I've already found myself needing them a few times over now and I have a cheap radio shack DMM at the moment so its time to upgrade.