hybridfree/eevblog-posts huggingface dataset:
15 % reduction on Newark, doing my shopping list - Page 1
Forum section: electronics / beginners

author: asgard20032
author_rank: Regular Contributor
timestamp: May 20, 2015, 09:27:59 pm
content: Hi, for those who don't know, there is a 15% reduction on Newark until 31 may. Meanwhile, i need to make a shopping list.Any nice suggestion? Any nice op amp, transistor, mcu, development board, regulator, li-ion charger, whatever interesting IC... (Already have a solder iron and oscilloscope and resistor and capacitor).- J-link edu- Freedom board 2x

author: kolonelkadat
author_rank: Regular Contributor
timestamp: May 21, 2015, 12:56:56 am
content: solder, solder wick, some of those switching 7805s from murata, some mosfets (mtp3055, irfp150n), some jfets, some LM324s, some pushbutton encoders (EVE-UPCAH516B), some voltage references(LM4040D41, MAX6126A), some DACs (MCP4921)these are some things i'd like to keep handy. It really depends on what all you want to make though. It would be best to think about what you would like to make and what it will take to make it, then order extras.

author: Cliff Matthews
author_rank: Unknown
timestamp: May 21, 2015, 03:05:33 am
content: Quote from: asgard20032 on May 20, 2015, 09:27:59 pmWait for the 20% sales.. my inbox says they've become regular
STPS5L60 versus SR560 - Page 1
Forum section: electronics / beginners

author: paul18fr
author_rank: Contributor
timestamp: September 08, 2014, 11:53:25 am
content: Dear AllCan I replace a STPS5L60 Schottky diode by a SR560 one in any application ?Thankspaul

author: Simon
author_rank: Unknown
timestamp: September 08, 2014, 12:29:20 pm
content: the cautious answer and without knowing what your doing is NO!tell us what your trying to do. The reason why there are thousands of diodes on the market is partly because they all have functions they are better at. Nothing is a one size fits all.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 08, 2014, 11:06:28 pm
content: http://www.eicsemi.com/datasheet/SR520_6.pdfthis thing?One thing I note, there's no avalanche or breakdown rating, so if it's in a harsh environment, it's your own problem if it doesn't work...If it's only ever being used as a diode diode, within ratings, I doubt you will find a change.Tim
Can i use cpu's thermal compund to heatsink transistors? - Page 1
Forum section: electronics / beginners

author: little_carlos
author_rank: Regular Contributor
timestamp: April 13, 2014, 04:36:31 pm
content: Hi, i need to heatskink some transistors, and i have some manhattan cpu thermal paste, can i use it for heatsinking transistors as well?

author: Holograph
author_rank: Regular Contributor
timestamp: April 13, 2014, 04:46:21 pm
content: You can't count on it to provide electrical isolation, so if you need that I wouldn't use it without an additional insulator.However I am not familiar with that brand, and I have my doubts that it's of good quality. Poor quality thermal grease dries out over time far more than high-quality stuff does. Arctic Silver 5 is often recommended not because it is the best in performance (it's good in performance, but there are several better) but also because it has a longer shelf/service life than most other thermal greases. Still not for insulating purposes though.

author: David Hess
author_rank: Super Contributor
timestamp: April 13, 2014, 06:35:18 pm
content: It will work fine however it is only about 30% better than zinc oxide thermal paste and not an insulator so cleanup will be important. I would not use it with TO-3 and similar packages because of the possibility of shorting the leads to the case.As far as lifetime, zinc oxide thermal paste as a shelf life but no real operating life and I expect the same for Manhattan cpu thermal paste.

author: free_electron
author_rank: Super Contributor
timestamp: April 13, 2014, 06:44:23 pm
content: alumina oxide is the proper paste as it isolates.shelf life is blabla. the problem is the alumina 'sinks' in the liquifying agent. if you stir it before use there is no problem.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 13, 2014, 06:48:31 pm
content: You asked only about heat-sinking, and the answer to that question is: YES.However, the other issue of isolation is a different story. You didn't mention anything about isolation, so we don't know (and maybe you don't know either?) whether that is important in your situation.I would NEVER rely on "paste" heat-sink compound for ISOLATION. Nowadays, those little silicon "washers" are so dirt-cheap, they do BOTH jobs, of heat-sinking, AND isolation. And, of course, whatever you use, always double-check the isolation before applying power to anything!

author: Fsck
author_rank: Super Contributor
timestamp: April 13, 2014, 06:58:50 pm
content: Quote from: free_electron on April 13, 2014, 06:44:23 pmwhy not go with something like IC7 or any other diamond based paste that's an extremely poor conductor.or you could just use those fujipoly thermal pads.

author: fake-name
author_rank: Regular Contributor
timestamp: April 14, 2014, 02:38:25 am
content: Quote from: free_electron on April 13, 2014, 06:44:23 pmI sure as hell wouldn't trustanyheatsink paste to completely isolate. If you need electrical isolation, use a silpad, a mica shim and any paste, or just swap to a part that has an insulated tab.
op amp spitting out input voltage instead of amplifing signal ? - Page 1
Forum section: electronics / beginners

author: Dantali0n
author_rank: Contributor
timestamp: March 27, 2014, 03:52:02 pm
content: Hey all so I have an op amp an mc4558d dual op amp to be precise. And i hooked it up but it dosent actualy amplify the signal it just spits out a slightly lower voltage then is on the vcc.Ive included an image of my setup. now my question is did my op amp die, certainly can't image that this is normal behaviour.The input is an 1 volt source so with times 2 amplification i expect a 2 volt signal however its 11.4 ?

author: Andy Watson
author_rank: Super Contributor
timestamp: March 27, 2014, 04:16:55 pm
content: Quote from: Dantali0n on March 27, 2014, 03:52:02 pmI make it a gain of 1.5.The 4558 is an old design and it does not operate rail-to-rail. The datasheet seems to suggest that the input (and output) operating range is typically 1 volt above -Vee to 1 volt below +Vcc, (although it could be as much as 3 volts above and below). If you have another power supply available try adding a negative supply to Vee, or else try moving the input voltage range to 1/2 of your power supply voltage.

author: cravenhaven
author_rank: Contributor
timestamp: March 28, 2014, 02:57:13 am
content: Isnt that OpAmp designed to run from a split power supply?. Try biasing the inputs to a virtual earth at half the Vcc voltage.

author: Dantali0n
author_rank: Contributor
timestamp: March 29, 2014, 12:55:33 pm
content: Thanks for all the support, ive tried both suggestions. sadly neither worked and now I think the op amps death. ( it gets very hot )Im just gonna try using another op amp, any suggestion on a op amp that can amplify a one volt signal to 5 volts. its for audio but dosen't need be anything of high power since it will be used as signal input for a transmitter.

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2014, 07:38:25 pm
content: The virtual earth should work but you need to know what you're doing.Use a single supply op-amp such as the LM358.
Oscilloscope Vertical Bar Width - Page 1
Forum section: electronics / beginners

author: CBP
author_rank: Contributor
timestamp: March 20, 2014, 09:45:45 pm
content: A couple of years ago I was given a Beckman 20MHz oscilloscope from a college who were throwing tens of them into a skip, not having a scope I couldn't resist the price of free. The age is unknown but it last shows it was calibrated in 1988 so it is fairly old I guess, running various DC voltages through it still show that it is roughly in calibration but I am not that worried about having a high accuracy.I've never really had cause to use it (and only know the basics) that much but one thing that has been bugging me with it is the vertical bar width is virtually non existent, as you can hopefully see on the photos I get the horizontal but not the vertical. Some times I can very faintly see the vertical traces but for the most it is not there. I don't know what this is called to really find out if I can fix it, is there anyone here that can advise me what might be up? I'm not even sure if this is something that can typically be adjusted or it is likely to be some sort of slow failure in the video circuit?Thanks!

author: pickle9000
author_rank: Super Contributor
timestamp: March 20, 2014, 09:49:36 pm
content: Try adjusting the brightness (to max).

author: Nerull
author_rank: Frequent Contributor
timestamp: March 20, 2014, 09:54:51 pm
content: It's normal for the vertical portion of a square wave to be quite a bit dimmer than the horizontal, that's where the beam has the highest sweep speed and thus spends less time on the phosphor.

author: w2aew
author_rank: Super Contributor
timestamp: March 20, 2014, 10:27:01 pm
content: Quote from: Nerull on March 20, 2014, 09:54:51 pmAgreed - this is normal on a cathode ray tube type oscilloscope. The trace intensity is a function of the speed at which the beam is moving. With a fast rising and falling edge, the trace will be dimmer - sometimes by quite a bit.

author: CBP
author_rank: Contributor
timestamp: March 20, 2014, 10:30:46 pm
content: Thanks for all the replies, can't remember if I messed with the brightness now (embarrassing if that sorts it out) but the reasons behind why that you have helpfully explained make sense, perhaps I will try a sawtooth wave through it and see what that shows.
F-RAM - Page 1
Forum section: electronics / beginners

author: selkathguy
author_rank: Unknown
timestamp: June 04, 2013, 07:47:01 pm
content: http://www.digikey.com/product-highlights/us/en/cypress-serial-f-ram-nonvolatile-memory/3661Seems like this stuff would be great for storing program state data say from a BOD interrupt, as it just writes it so fast and it's persistent immediately.Is there any real downside to using this stuff over EEPROM other than price?What pitfalls await a 'young player' when using devices like this?

author: Neilm
author_rank: Super Contributor
timestamp: June 04, 2013, 08:09:23 pm
content: I looked at putting this into a commercial product I was designing a few years ago. Price is obviously a big factor, but also there were not very many manufacturers. This was a concern as we want to manufacture the product for quite a few years and we don't want to have to redesign the PCB or firmware if we are forced to change manufacturer. Even now, most of the chips are manufactured in only a couple of places then re-badged.Neil

author: marshallh
author_rank: Unknown
timestamp: June 04, 2013, 08:57:40 pm
content: Price, availability, lead times, dependence on a nonstandard part that cant be exchanged easily.If you're buying low quantities through a distributor then you won't have to worry as much about that.Usually if you can approach your design differently you can remove the dependence on this uncommon technology.
Coupled inductors from LCSC/JLCParts - Page 1
Forum section: electronics / projects

author: sleemanj
author_rank: Super Contributor
timestamp: August 12, 2025, 04:10:45 am
content: Does anybody have any tips for finding coupled SMD 1:1 power inductors at LCSC / JLC Parts?For a nascent idea to make a compact general purpose SEPIC, something that seems to be missing in cheap-chinese-dc-dc converters.The only thing I have found is an ad blog post on LCSC about inductors from some company, but they don't seem to actually have any at LCSC.I know it's a bit of a niche thing but you'd think they would have at least one or two.Already tried feeding AI the results of a fairly broad parametric search for power inductors in the area I'm looking to see if any of the results might be coupled, but Gemini said it couldn't find any, and ChatGPT just made some incorrect guesses.

author: sleemanj
author_rank: Super Contributor
timestamp: August 12, 2025, 05:12:24 am
content: Did a search on Taobao for coupled inductors and that led me to find these MPN prefixes. So they are there, just well hidden, the LCSC database doesn't make any mention of them being coupled other than looking at the photos to check their feetm so annoying.https://www.lcsc.com/search?q=SRF0703https://www.lcsc.com/search?q=SRF1280https://www.lcsc.com/search?q=SRF1260https://www.lcsc.com/search?q=LPD5030https://www.lcsc.com/search?q=LPD3015https://www.lcsc.com/search?q=MSD1260https://www.lcsc.com/search?q=MSD7342https://www.lcsc.com/search?q=MSD1278

author: Whales
author_rank: Super Contributor
timestamp: August 12, 2025, 07:12:11 am
content: I did find some a while ago, they were hiding inside the common mode filters category. (As you can imagine I found that frustrating)EDIT: Looked through my history, can't find them sorry. I also don't remember how I picked them out from the intentionally lossy common mode chokes. I think I might have lucked across them accidentally whilst reading datasheets for CMCs.
Polarad Signal Generator 1108 M4 7-11GHz mecanical spline calibration - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: January 28, 2025, 02:28:38 pm
content: you just got to see this patented mecanical frequency set and calibration system from about 1968frequency setting and mecanical calibrate the setpoints in a "spline" type of mecanical way,in a 7-11GHz signal generator i play with at the moment.video linkhttps://youtu.be/rpi7lpAeBlY
IBIS File pin Matching - Page 1
Forum section: electronics / projects

author: electronx
author_rank: Regular Contributor
timestamp: July 05, 2024, 04:46:43 pm
content: I will make pin mapping for ibis LPDDR2 CK enable pin for STM32MP153CAA3.Which one should I choose among the model selector options? Does anyone have experience with ibs files before?So which characteristic impance should I choose for this lpddr2 cke pin? So how do we determine this? Can this be selected in the RAM initialization sequence?
Two way circuit breaking capability for ideal diode controllers - Page 1
Forum section: electronics / projects

author: kellogs
author_rank: Regular Contributor
timestamp: August 08, 2023, 08:51:54 pm
content: ThieLM5069IC - its datasheet does not mention a second anti-series MOSFET at all. Among the dozen features or so supported by LM5069 there is also "Circuit breaker function for severe overcurrent events". Could I add in a second mosfet, placed back-to-back with the mosfet in their example diagrams, controlled by the same GATE pin, and get the circuit breaking feature - this time in both ways ? Would other features fail / be impacted if I did that ?

author: kellogs
author_rank: Regular Contributor
timestamp: August 13, 2023, 04:06:06 pm
content: bump
Need help in identifying SMD part - Page 1
Forum section: electronics / projects

author: rfdes
author_rank: Regular Contributor
timestamp: January 22, 2023, 12:30:37 am
content: I pulled a part from a laptop TFT panel that is either a fuse or PTC resettable fuse. However, the panel is a Hitachi unit from the mid to late '90s so I am thinking it is likely a simple SMD fuse. I believe the mfg is MCC (Micro Commercial Components) but not totally sure as I didn't think MCC manufactured fuses.My photo isn't the best but hopefully someone will be able to identify this part.Thanks -Jim
Help ID 2 chips and find datasheets:  CS4968AM and ALi M5819P - Page 1
Forum section: electronics / projects

author: Nexxen
author_rank: Regular Contributor
timestamp: March 12, 2024, 02:07:55 pm
content: Hello!!While I was repairing a motherboard I came to the conclusion that probably one of these two is responsible for the no POST.They CS4968AM and ALi M5819P. Itried looking for datasheets but I couldn't locate any.CS4968 should be some clock generator, ALi is a RTC, I'm not sure how to proceed without a pinout.See pics attached.The issues I have are stuck Reset and no CLK to cpu (it should read 66MHz but is 0).Thanks for any help!!

author: coromonadalix
author_rank: Super Contributor
timestamp: March 12, 2024, 02:14:42 pm
content: the CS4968AM seems to be the clock generator for the motherboard, this one normally generate many signalsand i see you posted elsewhere too loll you give more details there than here .....

author: Nexxen
author_rank: Regular Contributor
timestamp: March 12, 2024, 02:54:09 pm
content: Quote from: coromonadalix on March 12, 2024, 02:14:42 pmYes, here I just look for another thing.I use Duckduckgo, but with google I found way more. Not the first time.I probably have to switch to G...Posting in multiple places is normal to allow more visibility.http://biossrc.chat.ru/files/5819pb01.PDF
Current sense amplifiers with negative common mode voltage range - Page 1
Forum section: electronics / projects

author: HwAoRrDk
author_rank: Super Contributor
timestamp: June 11, 2021, 05:11:43 pm
content: Does anyone know of any current sense amplifiers apart from the Texas Instruments INA series (e.g.INA197) that have a common-mode voltage range that includes negative? Something that handles at least -14V.I'm thinking about a current-sensing application on a -12V rail, but I can't find anything apart from the TI parts. The usual vendors aren't helpful in their parametric filtering - only Digikey actually has a filter parameter for input voltage range.Or can you use more common current sense amp to monitor negative rails? I found thisMaxim app note, but I am struggling to understand what they're doing there.

author: Ian.M
author_rank: Super Contributor
timestamp: June 11, 2021, 05:29:10 pm
content: Maxim's appnote is a variation on the common OPAMP + MOSFET current sink used to level shift the sense output, by passing the resulting proportional current through a resistor 'hanging off' the ADC Vcc rail to provide a negative going output referenced to Vcc. Instead of using an OPAMP the MOSFET and source resistor are inserted in the feedback loop of the MAX4460, in place of the feedback divider normally used to set its gain.I attach a LTspice sim of the same concept using any OPAMP with a common mode input range including its negative supply. The ratio of sense current to load current is:Is = Iload*R1/R2thus the voltage to the ADC is:ADC = Vcc - Iload*R3*R1/R2The extra parts R4-R6 and C1 are for stability and to protect the OPAMP from transients.

author: MasterT
author_rank: Frequent Contributor
timestamp: June 11, 2021, 10:10:30 pm
content: TSC2010, TSC2011, TSC2012https://www.st.com/content/st_com/en/products/amplifiers-and-comparators/current-sensing/tsc2010.htmlhttps://www.arrow.com/en/products/search?cat=&q=tsc201&r=true

author: ocset
author_rank: Super Contributor
timestamp: June 11, 2021, 11:34:39 pm
content: The Allegromicro hall effect current sensor chips may be of some use to you?
30 meters of Cat5 cable inductance / back emf ? - Page 1
Forum section: electronics / projects

author: TwinScroll
author_rank: Contributor
timestamp: June 21, 2020, 09:58:31 am
content: Hello.I been requested to get 4 LEDs to be displayed about 30 Meters away from a control box (pre designed).The LED interface PCB within the control box is also already designed. Normally these LEDs are on the front panel of the box.There are constant current 20mA drivers fitted for each of the LEDs and the supply voltage to the constant current diodes is 5VDC.I’m probably over thinking this, I know it’s low current but....Q) In principle if driving a 20mA load (LED in this case) by using the pairs within a Cat5 cable, If the length to the LED is long, say 30 Meters, would the total inductance of the cable length create any significant back EMF when the load switched off ?I’d need to use Cat5 cable due to the control box connectors available (there is a spare coupler).I recall from many years back the cable properties will be distributed inductance / resistance and capacitance between the pairs.I can’t recall if assuming a total inductance for the overall cable length is the correct thing to do here ( the use that in the normal di/dt calculations).I try and avoid long leads to loads etc, it’s always a recipe for headaches, though I’m a bit stuck on this one !Best regardsTS

author: mikerj
author_rank: Super Contributor
timestamp: June 21, 2020, 12:54:03 pm
content: Provided you use one of the twisted pairs in the CAT5 cable then inductance should be pretty small, from memory it's of the order of 500nH/meter. A fast diode across the driven end of the pair, connected so it's reverse biased should provide adequate protection.

author: ogden
author_rank: Super Contributor
timestamp: June 21, 2020, 01:10:54 pm
content: Quote from: mikerj on June 21, 2020, 12:54:03 pmRight. Introducing protection in this case is good idea anyway - even if you do not expect back EMF. There could be other kind of surges.

author: TwinScroll
author_rank: Contributor
timestamp: June 21, 2020, 03:14:25 pm
content: Hi, thanks for the input, just to clarify, where you mention ‘driven’ end - is this the end of the line ‘sending’ power out?Each of the 4 LEDs will be making use of the twisted pairs available.

author: mikerj
author_rank: Super Contributor
timestamp: June 21, 2020, 04:45:55 pm
content: Quote from: TwinScroll on June 21, 2020, 03:14:25 pmYes
makinig a rigol scope more portable - Page 1
Forum section: electronics / projects

author: m3vuv
author_rank: Super Contributor
timestamp: April 29, 2022, 11:51:51 am
content: hi all i have a rigol ds 1052d scope its powered from the mains,is there a way to power it from a 12v battery?,or has anyone a schematic of the psu?

author: Zero999
author_rank: Super Contributor
timestamp: April 29, 2022, 12:11:49 pm
content: https://www.eevblog.com/forum/testgear/battery-pack-for-rigol-ds1054z/
Li Ion coin cell battery datasheet explain - Page 1
Forum section: electronics / projects

author: Nikos A.
author_rank: Regular Contributor
timestamp: May 18, 2021, 03:39:30 pm
content: Hi everyone,I read this datasheethttps://biz.maxell.com/en/rechargeable_batteries/CLB_20e.pdfIn the following table notes *3 and *4- What are theItA&E.Vnotations?- What does is means :Discharge: 0.2ItA/E.V. = 3.0V?- Charge: 0.5ItA/4.2V -> This is like charge at 4.2V with charging current 0.5C ?- Discharge: 1mA/E.V. = 3.0V -> This is like discharging with a contant 1mA current and cut-off voltage at 3V ?It is very strange the way that they have denoted information and I am struggling to understandNick

author: Daixiwen
author_rank: Frequent Contributor
timestamp: May 19, 2021, 06:37:44 am
content: E.V. is end voltage. From the look of it it seems that ItA means C, as the values they used are pretty standard for nominal capacity measurement. But it's the first time I see it written that way in a datasheet.For the charge they limit the current at 0.5C and the voltage at 4.2V. They stop the charge when the current gets below 0.03C.For the discharge they limit the current at 0.2C and stop the discharge when the voltage gets below 3.0V.

author: tszaboo
author_rank: Super Contributor
timestamp: May 19, 2021, 06:51:49 am
content: It -> nominal capacity per hour. So for a 70mAh it is 70mA.EV is end voltage, where you are supposed to end the charge or discharge.0.5ItA, for a 70mAh battery just means to charge it with 35mA constant current and 4.2V constant voltage, terminate the charge when it drops to 2.1mA, this will be around 2 hours.

author: Nikos A.
author_rank: Regular Contributor
timestamp: May 19, 2021, 07:45:47 am
content: Thank you guys!! Everything is clear now!!

author: amishasingh
author_rank: Contributor
timestamp: May 20, 2021, 12:25:53 pm
content: Cool information 😎👌
Reduce thermal resistnace on Board - Page 1
Forum section: electronics / projects

author: rakeshm55
author_rank: Regular Contributor
timestamp: December 09, 2019, 03:48:44 pm
content: Hi,I am using LTM4613 SMPS in one of my board. The device has a low thermal resistance from Junction to Board (2.3^C/W).Effective thermal resistance is mentioned as 8^C/Wfrom junction to ambient for BGA heat sink operation. It also come with a suggested application note AN110 for Heat sink or Metal plate.Here what worries me is that the solutions offered for head dissipation are to remove the heat from top. But as I understand device dumps down all the heat to Board/bottom.In the recommended layout no thermal vias are suggested. If that being the case what are the options available to remove heat off the PCB . If I add thermal vias then i guess heat will pass to GND planes quickly, from there what are the options available, removing heat via screws for mounting PCB are they good methods.Please suggest some techniques to remove off heat from PCB. Should i expose pads to bottom layer so that I can connect unmasked area to shield using thermal padsMy aim is to reduce the thermal resistance from board to ambient.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 09, 2019, 07:19:48 pm
content: Note that the ambient spec is as given in the notes, whatever board and copper they used for the test.0. Do you know that you need improved thermals? Typically, if you need higher ambient temperature operation, you would. Or maybe operating at (or beyond?) ratings, if it's derated a bit to begin with.1. Typical builds on multilayer boards have good thermal performance already, given you've used inner layer planes, which spread the heat out. Heat conducts reasonably well between top and inner layers, where the laminate is thin (a typical proto board has 5-10 mils of prepreg here).2. Thermal vias are fine, and can also be filled with solder to approximately double the thermal conductivity; beware of solderability issues with the BGA/LGA device however. You don't want the vias thieving solder from the pads. Place them between pads if possible, and tent with soldermask.3. Screws? Even with copper screws (which you probably can't get -- aluminum, brass and bronze, yes, but they also conduct significantly worse than pure copper), you have the problem of getting heat over to them; lateral heat spreading is not very good in PCBs. Consider using a heat spreader at least, but even better, a thermal pad or something.4. Don't worry about soldermask, by the way. It's thin, a tiny fraction of the total thermal resistance. It hardly matters, even if you're using a thermal pad to sink heat out directly by conduction. It likelyimprovesperformance in a passive convection scenario (the slight edge coming from the higher IR emissivity of the coating).Tim
Limits of a meanwell supply trim? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: November 24, 2018, 04:09:00 pm
content: I got one that goes from 27 to 19V.Can you change the resistor bias network to go even lower, i would like it to be 12V, its working at reduced amperage.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 24, 2018, 05:28:45 pm
content: Stability cannot be guaranteed with such heavy modification, even with reduced load, unless you analyze the complete design. These supplies are basically designed as fixed-voltage supplies and the trim range is quite large already. One way to find out is to try, but it's wise to ramp through zero to full output current and try capacitive loads as well just to be sure.

author: coppercone2
author_rank: Super Contributor
timestamp: November 24, 2018, 05:49:29 pm
content: no guts no glorymaybe it will oscillate in a way that it will power LEDs at the right voltage still? :p

author: wraper
author_rank: Unknown
timestamp: November 24, 2018, 06:21:35 pm
content: Most likely it will just shut down due to undervoltage protection on PWM controller power pin. Hint: usually it's powered from auxiliary transformer winding. Basically it would work only if PWM controller has independent power supply for it.

author: coppercone2
author_rank: Super Contributor
timestamp: November 25, 2018, 11:52:49 pm
content: I tried adding series resistance to the pot (it goes down when the pot resistance goes up) but I think its limited to like 19V some how in the chip itself, maybe a ratio detector or something? It's just a trimpot to ground with a series resistor and a PCB jumper where the trimpot is used as a rheostat to ground. Other end goes to a AP4310not sure if its worth investigating further unless someone has a success story because it looks like it will get complicated to even attempt this.edit: more complicated, missed a trace may have put resistor in wrong place in signal chainedit2: yes I think I just changed the entire impedance of the voltage control and OVP circuits, small trace comming out of a unassuming decoupling capacitor. Need to try again......
Help needed with multiplexers - Page 1
Forum section: electronics / projects

author: void_error
author_rank: Frequent Contributor
timestamp: November 27, 2017, 06:27:34 pm
content: I need to select 1 of 4 logic inputs, all using 3.3V logic levels and I'm a bit doubtful about how to go about this. The maximum frequency they're going to see is a 20MHz square wave.One of the selectable inputs is going to be fed a 10MHz reference clock from a TCXO, another one will be from an external reference, while third one is going to be the frequency to be measured.My question here is what can I get away with using?Will a 74HC153 or 74HC253 do the job or do I need something faster like the LVC series?Another idea was to use half a 74HC139 with a 74HC125 (or LVC version if needed).Suggestions very much appreciated.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: November 27, 2017, 06:57:20 pm
content: First take your 20MHz period - 50ns. Now look in the 74HC153 datasheet at the transition time (Tt). To see what "Tt" means, follow the "Tt = TtHL and TtLH" in the NXP datasheet footnote. If you're looking at the TI datasheet you can just keep wondering since they don't explain it. Looking further down at the diagram and you'll see that TtHL and TtLH are the time it takes for the output to go from high all the way to low or from low all the way to high. Your 20MHz signal will have two transitions in 50nS.Going back to the Tt specification, you can see that this will work "Typically" at 4.5V supply and maybe good enough at 2.0V 25C. Conservative designers don't want their circuits to only work "Typically" so they choose the "Max" values and consider the temperature range. Note that once you increase the temperature range and start talking about "Max" values, the output doesn't transition nearly fast enough.So this is one of those situations where HC may work just fine depending on the part you have and the temperature you're operating at. But maybe not!

author: void_error
author_rank: Frequent Contributor
timestamp: November 27, 2017, 07:57:40 pm
content: Thanks for the tips!Not going to try my luck and use a different approach. 'Might work' won't cut it here.The reason why I mentioned the 74HC139 line selector is that I already use it in several places and I was thinking it could be used to select which tri-state buffer should pass the signal in case I'm pairing it with a 74HC125 or 74LVC125A. Looking at the enable/disable times, there might be a problem if one of them switches on before another switches off and their output levels aren't the same.Would it be a better idea if I used some gates to build a multiplexer along with the 74HC139 instead of the tri-state buffers?
SIMPLE ZIGZAG EDGE STRIP FOR MY DEV BOARDS. - Page 1
Forum section: electronics / projects

author: rickey1990
author_rank: Regular Contributor
timestamp: December 02, 2015, 11:32:04 pm
content: Well iv been thinking of a way of keeping things cheap for some dev boards im designing and building, I want one smallish board to fit my needs, which will be retro computing, iv got some space on the side and was thinking of something like this. if i want 2 serial ports then iv got 2 serial ports, if i want a joystick port and a vga iv got one two. Obverlsy the two big wholes arnt drilled, but that can be easily done after, or the prongs can be snipped off and glued. the pictures not great but its simple.Your forts?

author: matseng
author_rank: Frequent Contributor
timestamp: December 03, 2015, 12:53:25 am
content: Quote

author: mariush
author_rank: Super Contributor
timestamp: December 03, 2015, 06:37:29 am
content: My advice would be to not complicate yourself with that and just stick with regular edge strip.If the space on your board is a concern, you can go to finer pitch (1.27mm / 0.05" instead of the classic 2.54 / 0.1") or even down to 1mm , it would still leave you space between the pins to route traces to each pin.May want to check out flex strip connectors, which would allow you to route each trace directly to the pin instead of going through holes... of course, it's smd and the pitch would be tiny at around 0.5mm but still easy to solder with just dragging soldering iron over traces.then use a flex strip to connect your header to an "extension board" which gives you the regular 2.54 mm / 0.1" headers for each connector you want.
Phone USB stick - Page 1
Forum section: electronics / projects

author: akis
author_rank: Frequent Contributor
timestamp: October 17, 2015, 09:05:03 pm
content: Does anyone know of a USB stick that accepts a SIM, just like those data dongles/sticks, but to allow telephony and SMS ?Currently I am using a 10.5" tablet, with bluetooth keyboard and mouse, which is LTE and I can make and receive calls and messages. It is the Galaxy Tab S 10.5" LTE.It is fantastic for this but unfortunately it runs Android and anything else I want to do is terribly slow and terribly awkward.So I was thinking of buying a small Windows 7 laptop (say up to 11") and plug the usb dongle on it so I have mobile LTE as well as phone calls and messages.

author: amyk
author_rank: Super Contributor
timestamp: October 17, 2015, 11:42:11 pm
content: The term you are looking for is "USB GSM modem". Huawei apparently makes quite a lot of them.

author: akis
author_rank: Frequent Contributor
timestamp: October 18, 2015, 07:44:24 am
content: thank you
Bizarre Thermostat - Page 1
Forum section: electronics / projects

author: calzap
author_rank: Frequent Contributor
timestamp: December 30, 2014, 05:15:21 am
content: I have a Honeywell thermostat in my house that controls the gas furnace and AC. Model is T8112C1023; made 40th week of 1998 and still sold today. Its program and display are maintained by a couple of AA batteries. We normally heat with wood and haven't used the gas furnace this season. We were going away for a while and wanted to use the gas furnace to keep the house from getting too cold. The display was showing a few, dim garbage characters; so I replaced the batteries. Display became quite legible and showed "BATT LO". I checked the batteries, which were new, and they tested at 1.5+ V. Put them back, still no joy. Unplugged and re-plugged furnace, still no joy. Pressed various buttons, rotated batteries, sill nothing. Finally, I was reduced to reading the manual. Way in the back, it says for display problems, insert the batteries backward for at least 5 seconds to reset the thermostat, then replace them in the correct direction.I did it; it worked. What kind of design is this? Is reversing the batteries discharging a cap than is retaining some screwed-up settings in memory?Mike in California

author: Paul Moir
author_rank: Frequent Contributor
timestamp: December 30, 2014, 07:17:46 am
content: You got it, I make it a 1000uF@6.3v. Looks like they geared it up with a resistor so if you put the batteries in backwards you don't run much current through the capacitor, which would harm it.How do I know? I have a board sitting here... From the late 90s. So I guess if you need some spare parts?
Vintage voltage reference - Page 1
Forum section: electronics / projects

author: hpbo
author_rank: Newbie
timestamp: December 09, 2014, 03:26:25 pm
content: Hi everybodyI've just got a vintage voltage reference from ebay.I'm looking for specifications.How can I test the sucker without releasing the magic smoke?RegardshpboVOLT-REFVOLTAGE REFERENCEMODEL 200-19IBM Part 2163444DYNAGE, INC.HARTFORD, CONN.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: December 09, 2014, 05:44:41 pm
content: It appears Dynage is still in business. Maybe an email to them might be your best bet?

author: hpbo
author_rank: Newbie
timestamp: December 11, 2014, 03:43:44 pm
content: I've sent a email to Philip Dooley most likely the last mohican there, as Dynage was dissolved in 2010!QuoteMeanwhile I found a interesting article from the famous Jim Williams lab notes, where a Dynage module is used in the ultra stable voltage source of a high performance differential voltmeter.http://www.introni.it/pdf/Williams%2002%20-%201974-1981%20-%20Electronics.pdfJim Williams Lab Notes:http://www.introni.it/riviste_jim_williams.htmlWow what a gold-mine!
BQ2057WTS battery reverse and short connection protection - Page 1
Forum section: electronics / projects

author: Prayer
author_rank: Contributor
timestamp: May 09, 2014, 08:03:35 am
content: I designed a battery charger for 2 cell Li-po with BQ2057WTS as you can see "bq2057wts" picture attached. I have to short circuit protection and reverse connection protection for battery connection. I added a schottky diode as you can see "bq2057wts revised" picture attached but it didn't solve reverse connection. When I connected battery reverse, the IC burned.I thinked to use P or N channel mosfet but I didn't realise that. Could you suggest a solution for this project ?

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 11, 2014, 07:40:16 am
content: Hi Prayer,The attached circuit should work for short circuit and reverse protection of the chargers output connections. The only thing is R3’s value which protects U1 pin 2 (BAT) from reverse voltage. I cannot find the input current required for this pin under normal operation so there could be a voltage drop across R3 which may change the charging voltage. If the chargers output connections are shorted M2 will turn off followed by M1 disconnecting the output. The same with battery connected in reverse to the charger M2 will turn off followed by M1. The led D1 will light in ether condition. If D1 is not required a 10k resistor across the PMOS is required.HalfSpace

author: Prayer
author_rank: Contributor
timestamp: May 13, 2014, 06:25:36 am
content: Hi HalfspaceFirst of all thanks for your attention. I did a circuit like your suggest circuit. The difference is I controlled this circuit via microcontroller. I have to ask a question. I don't need D1 but I didn't understand where I have to put 10 k resistor. Is it PMOS's S and D pins like D1 and R4 ?

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 13, 2014, 11:22:41 pm
content: Hi Prayer,The 10k resistor replaces D1 and R4 (see circuit attached).HalfSpace

author: Prayer
author_rank: Contributor
timestamp: May 14, 2014, 06:29:19 am
content: Yes, I understand well but I want to know why it is there ?

author: HalfSpace
author_rank: Regular Contributor
timestamp: May 14, 2014, 09:58:05 pm
content: Hi Prayer,The 10k resistor is to make sure the PMOS turns on when no battery is connected. Pin 2 (BAT) should follow the output of Q1 like on the original circuit.HalfSpace

author: Prayer
author_rank: Contributor
timestamp: May 15, 2014, 05:50:41 am
content: Hi HalfSpaceThanks for your explanation and helps for this project.

author: macboy
author_rank: Super Contributor
timestamp: May 15, 2014, 03:09:37 pm
content: Very simple reverse protection can be done with a fuse followed by the reverse-biased rectifier diode. If the battery is connected backwards, the diode basically shorts it out across the fuse, which blows. This is crude but effective. It is designed to save the charger, not the battery, and will stress the battery a little until the fuse opens.
trying to indentify this socket and find the mating half - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: February 05, 2014, 06:44:11 pm
content: http://www.wanapart.co.uk/product_info.php?products_id=41093234&gclid=CKXCnvKUtbwCFQKWtAodCBUAoAused widely on automotive sensors, but what is it and can i readily get the mating half.

author: sdg
author_rank: Regular Contributor
timestamp: February 05, 2014, 09:12:47 pm
content: AMP Junior Power Timer.I bought some here :http://www.autoelectricsupplies.fr/product/680/category/7but I think Farnell or Mouser carry them too.

author: Simon
author_rank: Unknown
timestamp: February 06, 2014, 08:27:05 am
content: excellent, thank you
EA Jun 1991 Quad DI Box P/S - Page 1
Forum section: electronics / projects

author: harveyradar
author_rank: Contributor
timestamp: January 11, 2014, 09:32:23 am
content: I am cleaning up an old ELECTRONICS AUSTRALIA June 1991 Quad DI (direct injection)Box but have no schematic. Is there anyone who has that magazine & can kindly tell what are its power supply requirements please?much thanks (in advance)Harvey

author: aargee
author_rank: Frequent Contributor
timestamp: January 14, 2014, 07:58:52 am
content: Here's a scan... followed by the rest...

author: aargee
author_rank: Frequent Contributor
timestamp: January 14, 2014, 08:00:14 am
content: here's the rest..Enjoy!

author: codeboy2k
author_rank: Super Contributor
timestamp: January 14, 2014, 12:47:33 pm
content: I read that too, thanks!looks similar to Popular Electronics that I read as a kid....I am off the opinion that these old magazines should all be scanned, indexed and searchable online, as from a library.

author: rdl
author_rank: Super Contributor
timestamp: January 14, 2014, 04:04:11 pm
content: QuoteNot indexed or searchable online, but it's a start.Radio-Electronics Magazine at Internet Archive:http://archive.org/search.php?query=collection%3Aradioelectronicsmagazine&sort=-publicdateI have not checked lately for any of the other magazines of that era, they may be there also.

author: codeboy2k
author_rank: Super Contributor
timestamp: January 14, 2014, 05:34:02 pm
content: Nice. Thanks for the link.
DC PSU - Page 1
Forum section: electronics / projects

author: echen1024
author_rank: Super Contributor
timestamp: September 01, 2013, 03:51:28 pm
content: I currently have a LM317 set up in the method TI has it in the datasheet, with a rectifier, and then 2 1000uf filter caps, then the regulator. I was wondering if there is anyway to, for example, use op-amps, to further reduce the ripple voltage. Any help would be appreciated, and please, put the part numbers in.Thanks.

author: rdl
author_rank: Super Contributor
timestamp: September 01, 2013, 04:26:16 pm
content: Do you have the bypass cap on the adjust pin? Do you have sufficient load current?

author: echen1024
author_rank: Super Contributor
timestamp: September 01, 2013, 04:29:20 pm
content: Measurements are done with 0.5A of load current, and a bypass cap.

author: mmagin
author_rank: Frequent Contributor
timestamp: September 01, 2013, 04:50:47 pm
content: I am assuming you have this set up as in Figure 1 in the datasheet.How much ripple are you seeing on the output?What are the input and output voltages? The datasheet specifies a minimum differential of 3 volts between the input and output, and of course, that's going to have to be true under the expected load and the lowest points in the waveform seen on the input filter cap.

author: echen1024
author_rank: Super Contributor
timestamp: September 01, 2013, 04:55:29 pm
content: Quote from: mmagin on September 01, 2013, 04:50:47 pmInput is around 20 volts, and output is 5. I am seeing around 400mv p-p of ripple, though that could be the scope noise as well.

author: mmagin
author_rank: Frequent Contributor
timestamp: September 01, 2013, 05:10:22 pm
content: Quote from: echen1024 on September 01, 2013, 04:55:29 pmWow, that is a lot. You have input and output capacitors, and a capacitor on the adjust pin? What values (besides the 2000 uF you already mentioned on the input)?

author: hlavac
author_rank: Frequent Contributor
timestamp: September 01, 2013, 05:13:09 pm
content: What is the shape of the ripple waveform?And more importantly, do you have a largish heatsink on the regulator? 7.5W is enough to fry it...

author: echen1024
author_rank: Super Contributor
timestamp: September 01, 2013, 06:45:30 pm
content: Quote from: hlavac on September 01, 2013, 05:13:09 pmI have a heatsink used for the Intel 486, with a large, brushless DC fan on the back. And I have a 10uf, 0.1uf, and a 1uf capacitor.

author: rdl
author_rank: Super Contributor
timestamp: September 01, 2013, 07:44:02 pm
content: It's probably time for you to post the actual schematic you built and/or a decent photo, because 400mV of ripple is way more than you should ever get out of an LM317. Maybe the chip is actually not working?

author: echen1024
author_rank: Super Contributor
timestamp: September 01, 2013, 11:39:40 pm
content: Quote from: rdl on September 01, 2013, 07:44:02 pmI investigated, and I think that most of the noise is the oscilloscope probe crap.
Mifare Classic / ISO-14443A memory access - Page 1
Forum section: electronics / projects

author: mc
author_rank: Regular Contributor
timestamp: January 02, 2014, 08:43:41 pm
content: Is it possible to access all memory blocks without having to re-authenticate for each sector?I'm pretty sure the answer is no, given that each sector has a block with access keys, however I just wanted to check in case I'm missing something.

author: casper.bang
author_rank: Frequent Contributor
timestamp: January 02, 2014, 08:54:01 pm
content: Nope. Are you concerned with speed?

author: mc
author_rank: Regular Contributor
timestamp: January 02, 2014, 09:29:15 pm
content: Thanks for confirming that.I'm not too bothered about speed, as the system I'm aiming to replace isn't exactly fast (probably averages 0.5-1sec for the whole process)When 'in use' I only ever need to deal with two blocks.The basic process will be-1) read sector 0/block 1 which stores a pointer to the last block that had information successfully stored2) write information to the next available block (which could be in any sector)3) update the S0B1 with the latest pointerso looking at dealing with 3 sector authentications in total.I'm still trying to decide on if I could update the pointer immediately eliminating step 3, or if I should add a last attempted storage location in addition to the last block, so when the card is read the last read/write cycle can be checked to see if it was fully successful. All the information will also be getting stored on an EEPROM for validation purposes, it's just I need to ensure that if one cycle fails, the next cycle is still guaranteed to work.After use, all stored data then needs to be downloaded which is likely to involve 3-4 sectors worth of data, however provided it takes less than a second, I'll be happy.

author: digsys
author_rank: Unknown
timestamp: January 02, 2014, 11:08:54 pm
content: Are you using a "commercial" development / programming kit / software, or your own?

author: mc
author_rank: Regular Contributor
timestamp: January 02, 2014, 11:49:28 pm
content: Currently an arduino and an Elechouse PN532 based RFID board, just so I can get a couple working prototypes built with minimal hassle and get some real data for writing/testing the required computer software.My ultimate aim is a custom board with an ARM processor and PN532 (or possibly one of the read/write only chips) as I'm dealing with quite alot of u32's, however I'm using quite a bit of code from a previous arduino based project so avoiding the ARM option until I've got the software side dealt with.
Synth Terminology for A.P.C. - Page 1
Forum section: electronics / projects

author: scruffy.mogwai
author_rank: Newbie
timestamp: May 29, 2013, 01:52:22 am
content: Just out of curiosity, I am building an Atari Punk Console (similar to the one from Kaustic Machineshttp://compiler.kaustic.net/machines/apc.html) and was just wondering about terminology.Am I correct in saying one knob alters the Freq. and the other alters the Envelope?Thanks!

author: oPossum
author_rank: Super Contributor
timestamp: May 29, 2013, 02:35:19 am
content: Controls are for frequency (oscillator period) and monostable period.Detailed explanation here:http://www.magicmess.co.uk/electronics/apc.php

author: scruffy.mogwai
author_rank: Newbie
timestamp: May 29, 2013, 07:31:42 am
content: Thanks. I'll have a look at that.