hybridfree/eevblog-posts huggingface dataset:
Is it possible to make flat flex cable at home? - Page 1
Forum section: electronics / projects

author: hlavac
author_rank: Frequent Contributor
timestamp: March 25, 2016, 06:41:17 pm
content: Do you guys think it is possible to make custom shaped flat flex cabling at home in a similar way pcbs can be made?I was thinking copper foil on kapton tape, etch it, glue some plastic tabs under the ends that go into the connector to give it required rigidness and thickness there, more kapton tape to cover the thing, maybe plate something on the end pins (tin? zinc?) to stop corrosion...Or maybe some form of lamination?Ideas?

author: SeanB
author_rank: Super Contributor
timestamp: March 25, 2016, 07:05:21 pm
content: Doable, though you might want to look at getting a cheap vinyl cutter instead and using some self adhesive thin copper film as the trace instead. A pot of instant tin plate ( or a simple electrochemical cell to plate on a thin layer of nickel onto the connector ends) and you are away.

author: Fungus
author_rank: Super Contributor
timestamp: March 25, 2016, 07:24:41 pm
content: It might be better to just make the connectors and use ordinary ribbon cable in between.

author: hlavac
author_rank: Frequent Contributor
timestamp: March 25, 2016, 07:27:25 pm
content: Like, make a pcb, and sand off the bottom to fit the connector?

author: NickAmes
author_rank: Contributor
timestamp: March 27, 2016, 07:29:03 am
content: Instead of sticking copper foil to kapton tape, you could use Pyralux (or another kapton-copper laminate). Pieces turn up on Ebay fairly often and it also looks like Adafruit sells it:https://www.adafruit.com/products/1894?gclid=CMSi3ZWr4MsCFdKIfgod4NsCAg.Also, it should be possible to run Pyralux through a laser printer directly, simplifying etching. I've never done it, but I have printed on Aluminum foil, and that worked OK.

author: Apollyon25_
author_rank: Regular Contributor
timestamp: April 01, 2016, 03:09:00 am
content: In the early days of my previous company, we did exactly this for a demo for HP.It subsequently won the contract and we ended up shipping over 7 million systems.(Though by that stage we used proper flex PCB's and custom silicon, wire bonding, encapsulation etc...)

author: mjkuwp
author_rank: Unknown
timestamp: April 02, 2016, 12:24:29 pm
content: Pyraluxtoner transfer medialaser printeretchant such as ferric chlorideacetoneclothes iron or laminatorparchment paperkapton tape, for reinforcementscotch brite padsnitrile glovesmiscellaneous shop supplies...yes this can be done!
Is it possible to mod a DMM buzzer to behave as a good latched one? - Page 1
Forum section: electronics / projects

author: opablo
author_rank: Regular Contributor
timestamp: October 11, 2012, 06:20:41 am
content: Is it possible to mod a DMM buzzer to behave as a good latched one? Like the kind of sound a good DMM does?I have a DMM which I love and has only one flaw: A highly responsive but not latched continuity test.Could the circuit be generic enough so many of us can apply the same mod on our meters?I'm asking this before making my own just because maybe someone over there already did it and has a story to tell

author: benemorius
author_rank: Regular Contributor
timestamp: October 12, 2012, 01:04:52 pm
content: If the response is quick enough already and you only want to extend the duration of the sound, that can easily be done assuming it uses a piezo buzzer and not an actual speaker. All you'd need to do is drive the buzzer from a bipolar transistor with a base resistor and capacitor to set the duration. You might also need a diode to prevent the capacitor discharging immediately if the buzzer output is push-pull.
Is it possible to reprogram a bluetoothh speaker's broadcast name? - Page 1
Forum section: electronics / projects

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: April 24, 2016, 03:32:25 am
content: Either using software or hardware? I made a bluetooth speaker from the guts of an S113BT speaker, which also happens to be what its broadcast name is.Is there a way I can change this? I want to change it to "The Electric Triangle" as that is what I call it when I show it to friends or talk about it. I figured it would be neat to have a custom name for it.If I have to use some sort of IC reader and programmer, what would I be looking for here?Its not very clear in the second pic but I know that the two ICs in the top middle are analog switches for the 3.5mm/bluetooth switching. So we can rule that out.Full album of teardown pics:http://imgur.com/a/MJ8pA(ignore the last one, its a comparison of my old portable speaker)If I were to use software, what software and how?Is something like this even possible?

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: April 24, 2016, 03:57:37 am
content: Quote from: blueskull on April 24, 2016, 03:51:33 amInteresting! Seems like a lot of work though! Contemplating another bluetooth solution as I plan to beef up the amp to a pam8610 anyway... Hobby electronics are so complicated now!Also it seems that the forums now have a Thanks button!
Is it possible to use an Android cellphone board to control devices via UART/I2 - Page 1
Forum section: electronics / projects

author: Gabrowsk
author_rank: Newbie
timestamp: September 29, 2023, 12:47:33 pm
content: Hello everyone,I am working on a project and would like to get some insights. I am keen to know if it’s possible to use an Android cellphone board to control devices via UART/I2C/SPI. The aim is to receive information from various sensors and modules, such as GNSS, manage this data, and send it to a server in the cloud using mobile internet.The reason why I am considering using a cellphone board is that it already comes equipped with Wi-Fi systems, mobile internet, and a charging system, potentially simplifying the implementation process, and then I would need to create a app to get the data and send it to the server. Is it possible?
Is Lower FET VGS (off) Better ? - Page 1
Forum section: electronics / projects

author: radiotek
author_rank: Contributor
timestamp: January 16, 2021, 11:19:40 pm
content: Lower FET VGS (off) Better ?Is it better to choose a JFET that has a lower VGS off spec when operating a FET with a low voltage supply between 4.5 to 6 volts ?Appreciate any help.Frank

author: Benta
author_rank: Super Contributor
timestamp: January 16, 2021, 11:41:04 pm
content: I think you need to phrase your question more precisely.
Is MCP2221A a preprogrammed PIC16F1455? - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: December 25, 2017, 02:12:53 pm
content: IsMCP2221Aa preprogrammedPIC16F1455? Pins does match one for one.Also, why does chip manufacturers like Microchip do this? Yield?

author: Scrts
author_rank: Frequent Contributor
timestamp: December 25, 2017, 10:49:38 pm
content: What's the price difference? I guess it's just business to offer a full solution.

author: technix
author_rank: Super Contributor
timestamp: December 26, 2017, 04:58:43 am
content: Quote from: Scrts on December 25, 2017, 10:49:38 pmMCP2221A is slightly more expensive. (Look more and more like a software license on top of PIC16F1455 now.)
Is my ESP32 restarting due to spikes?  - Page 1
Forum section: electronics / projects

author: crgarcia
author_rank: Regular Contributor
timestamp: August 02, 2022, 01:32:38 pm
content: I am (still) designing a PCB with a 5V relay that controls an external DIN mounted latching relay (red line with the "1."):The problem I have, is that the ESP32 often restarts after turning the latching relay on/off.This only happens if the latching relay is connected. I don't have any problems when the 5V relay triggers without being connected to anything.When I connect the oscilloscope to the 3.3V rail, I can see a spikes from-40V to 50V (Vpp ~ 90V)This is my schematic for the Power Supply and relays:RAC PS datasheet:https://recom-power.com/pdf/Powerline_AC-DC/RAC05-K.pdfRelay PCN-105D:https://www.mouser.ch/datasheet/2/418/5/ENG_DS_PCN_series_relay_data_sheet_E_0820-1265050.pdfProject full schematic, layout, etc:https://github.com/crgarcia12/electronics-homeassistant-lightscontrollCan those spikes be the responsible of the ESP32 restarting?What can I do to fix that?Thanks!

author: TimFox
author_rank: Super Contributor
timestamp: August 02, 2022, 04:27:05 pm
content: I don't see diodes across the 5 V relay coils. Are they included inside the relays?I have destroyed ICs connected to the relay power supply when there were no coil diodes.

author: kripton2035
author_rank: Super Contributor
timestamp: August 02, 2022, 05:12:35 pm
content: I would add some big capacitor (220uF) on the +5v rail.

author: HwAoRrDk
author_rank: Super Contributor
timestamp: August 02, 2022, 09:58:52 pm
content: Yes, you have no bulk capacitance on the 5V rail.Quote from: TimFox on August 02, 2022, 04:27:05 pmOP is driving the relays with a ULN2003, which has integrated flyback diodes.

author: TimFox
author_rank: Super Contributor
timestamp: August 02, 2022, 10:04:13 pm
content: Yes, but are those diodes directly across the relay coil?

author: crgarcia
author_rank: Regular Contributor
timestamp: August 03, 2022, 01:11:30 pm
content: Quote from: TimFox on August 02, 2022, 10:04:13 pmI think so. As far as I know ULN2003A replaces the transistor and diode needed for the relay. This is the internal schematics of the ICQuote from: kripton2035 on August 02, 2022, 05:12:35 pmMake sense. I have added now 1000uF and it did not solve the problem, but I will add them anyways into my design.Thank you!!

author: mclute0
author_rank: Regular Contributor
timestamp: August 04, 2022, 03:34:13 am
content: I like this guy's series on decupling capacitors, he does a good job explaining.also, you might want to take a look athttps://www.ti.com/lit/pdf/tidrnq4it might give you some ideas on isolating transients in switching circuits driven by a UNL2003a.My guess would be that the 3.3v regulator is dropping out.

author: mikerj
author_rank: Super Contributor
timestamp: August 04, 2022, 01:01:19 pm
content: Quote from: crgarcia on August 03, 2022, 01:11:30 pmA potential problem with using the diodes built into the ULN2003A is the inductance of the interconnects between the relay and the driver, which could be exacerbating the ringing. Idealy you want the diode as close as possible to the relay coils.
Is my jitter measurement method correct? - Page 1
Forum section: electronics / projects

author: drummerdimitri
author_rank: Frequent Contributor
timestamp: March 26, 2019, 05:09:26 pm
content: I would like to compare the jitter measurement of my dac on TOSLINK vs USB input using my oscilloscope.Played a 20 KHz sine wave and hooked up my scope probes to the output XLR pins and got the pure signal.I then adjusted my vertical scale to the lowest possible value, set the display to infinite persistence and measured the signal's horizontal sway and got about 40 ns of jitter.Not sure if this is the right approach but the measurment seems to be in the realm of expectation.Any way I could improve this measurement?

author: David Hess
author_rank: Super Contributor
timestamp: March 26, 2019, 06:47:00 pm
content: I think you are just measuring the jitter of the oscilloscope's trigger which should be zero. I am not sure why it is not.Jitter measurements assume trigger points on two different signals or two points on the same signal. I think what you want to do is trigger in the audio output, and then use the oscilloscope's delay function to measure the jitter in an edge later in the signal. If that is the next edge, then it is cycle-to-cycle jitter which is a rather demanding measurement and I think it will be more relevant to measure a later edge which is produced from a separate USB packet of data.

author: ogden
author_rank: Super Contributor
timestamp: March 26, 2019, 06:51:17 pm
content: Sorry, not even close. Scope with it's 8bit ADC is useless for audio signal quality measurements.20KHz is way too high freq. You shall use 10KHz or 12KHz, hi-end ADC, spectrum analyzer oraudio analyzeroranother audio analyzer. Example of jitter estimation in audio domain:https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-cypher-labs-theorem-720-and-fiio-q1-dac-and-headphone-amp.3324/With scope you may try to catch DAC clock jitter - by probing digital clock signal and using jitter analysis function of scope (if any). More about jitter measurements:http://literature.cdn.keysight.com/litweb/pdf/5991-4000EN.pdfQuote from: David Hess on March 26, 2019, 06:47:00 pmIt's noise. Pay attention to vertical resolution which is 500uV/div.

author: bson
author_rank: Unknown
timestamp: March 27, 2019, 08:55:35 am
content: RMS stochastic jitter is the standard deviation of the period. So set the scope to measure the period and collect statistics for the measurement.
Is my Step Up Voltage circuit alright?  - Page 1
Forum section: electronics / projects

author: EdimarDigital
author_rank: Contributor
timestamp: January 26, 2017, 11:59:36 pm
content: Hello everyone, I'm new to electronics and i want to create a digital watch just like the ChronodeVFDhttp://www.johngineer.com/blog/?p=1595.I will be using a AA battery as my source but we all know micro-controllers need at least 3.3V or more to work and a single cell just delivers 1.5V which is not enough. So i selected a NCP1400Ahttps://www.sparkfun.com/datasheets/Prototyping/Batteries/Voltage_Switcher-NCP1400A-D.pdfto deliver the 5V. I created a schematic which i believe should output 5V according to the datasheets, but being the total amateur i am to this (since I'm only 17 years old with barely any experience) i need a professional to take a look at the schematic and point out the flaws and what can i do to make work efficiently.

author: danadak
author_rank: Super Contributor
timestamp: January 27, 2017, 02:34:33 am
content: Per the datasheet looks like its a go. Note the design recommendationthat output cap be low esr, tantalum or better.Regards, Dana.
Is on the market some ferrite alternative with zero magnetostriction? - Page 1
Forum section: electronics / projects

author: Miyuki
author_rank: Frequent Contributor
timestamp: October 18, 2021, 07:37:04 am
content: Hi, just wonder if it exists and I just cannot find it or it does not exist.With low permeability materials, it is easy, there are Sendust and more modern variants of it without this issue.But when it comes to high permeability matterials I don't know any. Do you?

author: moffy
author_rank: Super Contributor
timestamp: October 18, 2021, 07:57:35 am
content: Mu metal is high permeability and low magnetostriction, but not zero:https://en.wikipedia.org/wiki/Mu-metal

author: Kleinstein
author_rank: Super Contributor
timestamp: October 18, 2021, 08:05:11 am
content: There is also some nano-crystalline material with low magnetostriction. One finds this is some high performance common mode chokes.https://vacuumschmelze.com/Nanocrystalline-Material

author: daniel10351035
author_rank: Newbie
timestamp: January 13, 2022, 04:06:03 am
content: well vacuumschmelze has some materials with very high permeability (cobalt-based i believe). we used to source it from some chinese suppliers. pm me if you need contacts

author: Miyuki
author_rank: Frequent Contributor
timestamp: February 18, 2022, 09:30:23 pm
content: Quote from: daniel10351035 on January 13, 2022, 04:06:03 amI'm trying to avoid Chinese suppliers

author: uer166
author_rank: Super Contributor
timestamp: February 18, 2022, 09:32:43 pm
content: Quote from: Miyuki on February 18, 2022, 09:30:23 pmWhy? Where do you think Vacuumschmelze and other make their stuff? I actually would like to have some contacts for nano-crystalline/amorphous materials for fluxgates.
Is protection needed for the enable pin? - Page 1
Forum section: electronics / projects

author: mrburnzie
author_rank: Regular Contributor
timestamp: March 13, 2023, 05:04:21 pm
content: I'm using this (https://www.digikey.com/en/products/detail/c-k/JS202011JAQN/6137629) switch to control an ideal diode controllers enable pin (https://www.analog.com/media/en/technical-documentation/data-sheets/max16171.pdf)Is there a need to protect that enable pin with a TVS? My first answer would be yes, as the switch can discharge and leads directly into the enable pin.

author: wraper
author_rank: Unknown
timestamp: March 13, 2023, 05:12:02 pm
content: Depends on if it's directly accessible from the outside or there is some sort of plastic knob which makes it almost impossible for ESD to find a path inside the switch. Then what level of protection/reliability is needed. IMHO no ESD protection is needed in 95% of cases. But strange part is why would you need to control EN pin directly from the switch.

author: mrburnzie
author_rank: Regular Contributor
timestamp: March 13, 2023, 08:45:41 pm
content: I don't want a beefy big switch for the powersupply, but more of a simple power button. Thus, disabling the ideal diode of conducting.Is it just easier to do a beefy switch? The powersupply is at 12V around 4A ~50W.

author: mrburnzie
author_rank: Regular Contributor
timestamp: March 13, 2023, 08:51:24 pm
content: Maybe I would actually go for some solutions, where it is a push button and it uses a flip flop or a similar circuit to turn on/off the powersupply (ideal diode)

author: wraper
author_rank: Unknown
timestamp: March 13, 2023, 09:33:59 pm
content: I don't see this switch as a decent power button, it very tiny and not easy to use. It usually used for things with constrained space and rarely used, like power or mode switch on underside of a computer mouse.
Are PTC Fuses for MOSFET gates a good idea? - Page 1
Forum section: electronics / projects

author: LDMattei
author_rank: Newbie
timestamp: March 22, 2021, 05:40:16 pm
content: Hello,I wanted to make a circuit in order to control some indutive loads in a automotive envioroment, so I was thinking if it would be a good idea to add a PTC fuse to protect the MOSFET gate. I do know that it won't act fast enough in order to save the MOSFET, but I thought it was a good ideia to prevent a fire or anything like that, thus I designed it in other to trigger at the maximum current my LVS diode can handle before thermal shutdown.So I wanted some feedback to know if this is actually a good ideia.My circuit diagram is attached below (sorry for my ugly writting). F1 is the PTC fuse of 30mA, R1 is 1KΩ, R2 is 10kΩ and the the LVS triggers at 16.7V,everything is powered by a car battery.

author: ajb
author_rank: Super Contributor
timestamp: March 22, 2021, 08:46:20 pm
content: What are you protecting against? The only real hazard to the gate is an overvoltage event on the input signal here, so the level of protection depends on the sorts of faults that may occur on that node. As drawn, the MOSFET gate is not actually protected by the fuse--it's protected by the TVS diode, and the TVS diode is protected by the fuse and the resistor. This is a fairly sensible arrangement, but the additional 1k resistor in series is also limiting current, so a 30mA PTC is only going to kick in if the input voltage hits 30V above the TVS voltage--so something like 47V, but it depends on the clamping characteristics of the diode. It may not be necessary to have both the PTC and the resistor, since both are effectively doing the same thing. A PTC may be better if you expect DC faults, which would otherwise cause the TVS diode or resistor to cook itself, but for transients the resistor on its own may be fine or even preferable. The lower initial resistance of the PTC would be an advantage if you need to drive the gate hard for faster switching, but if you need fast switching then you need local gate drive with a tight loop and therefore you wouldn't need this kind of protection in the first place.As an aside, TVS diodes begin to conduct at a particular voltage, but as the current increases the diode voltage can rise several volts above that. So a 16.5V TVS diode may clamp at something like 20V with a sufficiently energetic fault, which is into the territory of Vgs(max) for a lot of MOSFETs. So worth considering that you may need a lower voltage TVS diode to adequately protect the transistor depending on the specific parts and the fault conditions you're designing for.Anyway, if the input to this circuit is coming from the outside world, then a PTC and/or resistor in combination with the TVS diode is a good idea, but if it's generated by some other circuitry on board it's likely not necessary, or can be better protected using other methods like not driving the gate directly from the upper voltage rail.
Is QSKL/OSKL a manufacturer? - Page 1
Forum section: electronics / projects

author: analogo
author_rank: Regular Contributor
timestamp: March 23, 2017, 08:02:31 pm
content: There are plenty of cheap converters around labelled QSKL (or is it OSKL). Is it the name of the manufacturer?Other businesses are selling them as their own all over the world, for example this USB step up converter from DROK at <https://www.amazon.com/gp/product/B00C93Z8JY> but also plenty of smaller shops on Aliexpress or eBay.In other cases, for example Adafruits' small boards, those sellers would sell clones without the name. Why don't they do that with QSKL?
Is safe this circuit? - Page 1
Forum section: electronics / projects

author: xorsch
author_rank: Newbie
timestamp: February 19, 2021, 03:30:16 pm
content: I want to make a circuit like that:Is safer if a use an ATX 12v/5 PSU?Will it work properly to hotter quartz resistor?https://tinyurl.com/y3kq8d5p

author: Ian.M
author_rank: Super Contributor
timestamp: February 19, 2021, 03:46:27 pm
content: Looks unsafe. An ATX PSU is *NOT* suitable as its output is ground referenced. You'd need an isolated floating 12V supply with its negative side connected to the MOSFET drains, and the gate pulldowns returned to the drains, not to ground. There should be *NO* ground connection anywhere round the MOSFETs.

author: dmills
author_rank: Super Contributor
timestamp: February 19, 2021, 04:09:04 pm
content: SiLabs do an opto isolator replacement intended exactly for building mosfet based SSRs, that will get you what you want with no need for an isolated 12V rail.Look at the Si8752.

author: wraper
author_rank: Unknown
timestamp: February 19, 2021, 04:14:55 pm
content: Unless you need MOSFETs, use triac + optotriac optocoupler.
Is Software Defined Radio(SDR) Patented ? - Page 1
Forum section: electronics / projects

author: SDRbiCurious
author_rank: Newbie
timestamp: March 03, 2019, 11:13:06 pm
content: Hi There;I want to design and maybe sell a software defined radio.However, I don't know whether it is patented or not.There is a lot of SDRs in the market LimeSDR, BladeRF, HackRF, AirSpy, etc ...Are they paying license fee? Or what would happen if you accidentally violate a patent ?

author: DaJMasta
author_rank: Super Contributor
timestamp: March 03, 2019, 11:39:07 pm
content: A specific SDR may be, SDRs as a whole are far to vague to be patented, and many (including some of those mentioned) are fully open source, open hardware. Edit: Don't know if airspy is open hardware, but it is open source. Otherwise, you can get source design files/firmware/software for free for all of those mentioned.So no.

author: radiolistener
author_rank: Super Contributor
timestamp: March 04, 2019, 02:05:38 am
content: SDR means that the main design is defined in software.So, if you based your software on other software (for example used some code from some project), it may leads to license problems.But if you developed your own software from scratch (with no using other modules or some code) then it's your and you can do whatever you want.

author: magic
author_rank: Super Contributor
timestamp: March 04, 2019, 05:00:01 am
content: So naive. Software patents totally are a thing in America and you would be surprised by what can be patented there.https://arstechnica.com/tech-policy/2013/01/how-newegg-crushed-the-shopping-cart-patent-and-saved-online-retail/So okay, these guys had their patents invalidated, but only when they got greedy and went after too big of a player. They successfully extorted loyalties from others before and the same can happen to you if you do your business in America.Just because something is open source doesn't mean it isn't patent encumbered. The FAT filesystem is (was?) partly patented and yet free implementations abound. Ditto for many media codecs. Open source implementations of such things exist because no one outside America gives a damn and American Linux vendors tend to remove problematic parts from their systems or get some deals or violate the patent hoping that the owner won't come after them because they have their own patents to wield against them.That being said, I have no idea what patents may apply to SDR techniques or the idea of SDR itself, if any. I suspect a patent on "SDR itself" would be ruled invalid as too obvious or too broad, like that shopping cart thing, but patents on particular techniques may be enforceable. Of course IANAL.
Is t_CAC delay in SDRAM due to signal propagation delay? - Page 1
Forum section: electronics / projects

author: Axk
author_rank: Regular Contributor
timestamp: September 09, 2018, 06:16:05 pm
content: This question is out of curiosity, I'm not solving any problem here, I'm sure one can successfully control SDRAM without this knowledge.The question is why t_CAC (the time between the CAS pin going low and valid data available on the data pins, where CAS*t_clk >= t_CAC) is not measured as a constant number of clock cycles independent of the clock frequency, but is a fixed time constant independent of the clock frequency)I understand that the activation phase is asynchronous with the time taken by charge transfer between row capcitors and bitlines and apmplification, but once a row is active it should be just a matter of clocking out the values from the outputs of the amplifiers.Then does it mean that t_CAC is purely due to the signal propagation delay through all the combinational logic between the outputs of the sense amplifiers and the data pins?
Is that a good idea or am I forgetting something obvious? - Page 1
Forum section: electronics / projects

author: poorchava
author_rank: Super Contributor
timestamp: September 23, 2013, 03:41:59 pm
content: Is that a valid way to create artificial ground from single 12V supply? Or am I forgetting something obvious?I need to power a few opamps in a simple device powered by a wall-wart. Signals will partially be DC, so no capacitive coupling. I need the virtual ground to be able to both sink and source a few tens of miliamps (actually, to maintain the virtual ground in the middle between GND and +12V). Technically the vrtual ground will be 6V above wall-wart DC potential, but wall-warts are isolated (at least hope so...) so it should not onterfere with oscilloscope for example.

author: free_electron
author_rank: Super Contributor
timestamp: September 23, 2013, 03:49:03 pm
content: you dont need the extra transistors for a few milliamps.opamp in unity gain woll work. they can handle 10 to 15 mA without problems if you use something like a TS921 they can do 50 to 80 mA

author: BravoV
author_rank: Super Contributor
timestamp: September 23, 2013, 03:50:51 pm
content: Made a similar thread while ago here ->Question on op-amp current capability for making V-Ground circuitIt just works using jelly bean LM358 without transistors, and also I used the quad LM324 parallel for beefier current, there is a link in there about using multiple op-amps as well.

author: poorchava
author_rank: Super Contributor
timestamp: September 23, 2013, 04:19:23 pm
content: What are the 1n4148 for?

author: ConKbot
author_rank: Super Contributor
timestamp: September 23, 2013, 04:58:50 pm
content: http://www.ti.com/product/tle2426-q1If you dont mind the non-jellybean part, its a 1 and done solution. Good for 20mA, 40V input, stable over the whole current range with 1uF on the output.

author: TerminalJack505
author_rank: Super Contributor
timestamp: September 23, 2013, 05:19:40 pm
content: Quote from: poorchava on September 23, 2013, 04:19:23 pmI'm sure they are there to provide a discharge path for the caps into +5V when the circuit is powered down.

author: dannyf
author_rank: Super Contributor
timestamp: September 23, 2013, 11:37:54 pm
content: QuoteSure, but with room for improvement.I would simply use an audio opamp (TDA2030) configured as a follower.

author: BravoV
author_rank: Super Contributor
timestamp: September 24, 2013, 12:48:49 am
content: Quote from: TerminalJack505 on September 23, 2013, 05:19:40 pmYep, thats correct and also quoting ciccio's post regarding those diodes.Quote from: ciccio on February 23, 2012, 07:48:35 am

author: JackOfVA
author_rank: Unknown
timestamp: September 24, 2013, 12:52:11 am
content: Or one could use a TI TLE2426 rail splitter. Rated to +/- 20 mA.
Is that FAN an adequate replacement for Agilent E3633A PSU ? - Page 1
Forum section: electronics / projects

author: subliti
author_rank: Contributor
timestamp: June 30, 2021, 12:49:26 pm
content: HeyI have an Agilent E3633A PSU which can deliver up to 20A and the stock fan is quite noisy and runs all the time. I want to replace it with a "Noctua NF-A8 PWM" but i dont know if the Noctua fan is up to the task since the stock fan is a bit more powerfull, so i wanted your opinion.Specs:NoctuaRPM: 2200Airflow: 55.5 m³/hourStatic Pressure: 2.37mm H2OStock FanRPM: 2950Airflow: 67.2 m³/hourStatic Pressure: 3.55mm H2OSo what do you think, will it burst into flames at 20A with the Noctua fan ?
Is the awm730p1 airflow sensor a hot wire type or a differential pressure type? - Page 1
Forum section: electronics / projects

author: daisizhou
author_rank: Super Contributor
timestamp: September 14, 2024, 12:41:23 am
content: Hi everyoneI checked the Awm730p1 airflow sensor data sheet.However, Honeywell did not specify the type of sensor.If anyone knows please tell me, thankshttps://automation.honeywell.com/us/en/search-results?docType=Product&search=awm730p1

author: moffy
author_rank: Super Contributor
timestamp: September 14, 2024, 06:28:25 am
content: the following quote from:https://prod-edam.honeywell.com/content/dam/honeywell-edam/sps/siot/en-us/products/sensors/airflow-sensors/amplified/awm700/documents/sps-siot-awm700-series-airflow-sensors-install-pk80150-2-en-ciid-50056.pdf"Installation Instructions for the AWM700 Series Airflow SensorsISSUE 2PK 80150Sensing and ControlGENERAL INFORMATIONAWM700 Series airflow sensors operate on the theory of heattransfer due to mass gas flow across the surface of thesensing element. The sensing element consists of a resistorbridge heater circuit and dual temperature-sensing resistorbridges. This configuration senses mass flow rates and flowdirection. "says what it is.

author: daisizhou
author_rank: Super Contributor
timestamp: September 14, 2024, 09:04:46 am
content: Quote from: moffy on September 14, 2024, 06:28:25 amThe text description seems more like a hot wire type, and it may not use alloy docking wire, but a resistor-like material.
Is the built-in watchdog in the chip reliable? - Page 1
Forum section: electronics / projects

author: tilblackout
author_rank: Contributor
timestamp: December 20, 2023, 05:36:53 am
content: We hope that the system can be reset promptly when the program crashes, so we use a watchdog to detect these situations.However, I vaguely heard some people say that the built-in watchdog in the chip may not be reliable.But I think those big chip manufacturers are not that foolish,could the program freezing also cause the internal watchdog of the chip to crash?In some products I have developed, hardware engineers deliberately connected a TPL5010 watchdog chip(TPL5010 chip reference manual:https://www.ti.com/lit/ds/symlink/tpl5010.pdf) to the reset pin of the MCU (such as STM32, I.MX RT1170, Kinetis MK64).I don't believe that the internal watchdogs of these chips are unreliable. What is your opinion? Otherwise, what are the application scenarios for watchdog chips like TPL5010?

author: RoGeorge
author_rank: Super Contributor
timestamp: December 20, 2023, 11:02:26 am
content: What products are you saying about? You have to be more specific, or else we can only speculate.My guess is that that design choice is not because an external watchdog would be more reliable than the internal one. An external watchdog might be more reliable, for example if the external watchdog is rad-hard while the microcontroller is not. But I don't think that was the case here.Some other times, there are design requests based on laws, or based on regulations that are mandatory. To give an example, some industrial installations in power plants and energy distribution must be redundant. And for a better resilience against unknown future pitfalls, the redundancy must be implemented with different brands.Or, maybe the external watchdog was added mostly to lower the power consumption, and that would be the most reasonable guess. The external timer chip is supposed to be even lower power than the standby consumption of the MCU with its internal watchdog still running. So, the external watchdog-timer here is rather used like a wake-up timer, and not like a watchdog that resets the MCU from a malfunction.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: December 20, 2023, 10:12:21 pm
content: Quote from: tilblackout on December 20, 2023, 05:36:53 amThere are many terms in play.Watchdog oscillatorsare very reliable, but properwatchdog operationis certainly non-trivial. It should involve testing by forcing erratic operation.Many novices start the watchdog, and start an interrupt to service the watchdog.Job Done ?Some industry sectors have preference for a power removal watchdog. That gives afull power cycle restart, as there are many failure cases where hitting the MCU-RST alone is not enough.Complex operating system watchdogs often have dual or multiple timeouts. They allow a longer boot-up time, before they apply a shorter service time.The TI part is interesting, it is very low power and has surprising accuracy for such a low power, but it also has a power-up phase, where it measures the set-point.
Is the CRSDV signal required for RMII ethernet? - Page 1
Forum section: electronics / projects

author: sswift
author_rank: Contributor
timestamp: September 29, 2017, 07:19:45 pm
content: Nevermind! It appears the SAMD51 doesn't support ethernet at all. The datasheet in question covers both SAMD and SAME and the SAME is the ethernet model that only comes in larger packages.
Is the datasheet wrong or am I confused? - Page 1
Forum section: electronics / projects

author: LaryPant
author_rank: Contributor
timestamp: June 23, 2021, 10:11:14 pm
content: Hi there,I have several L78L05 voltage regulators from ST in the TO-92 package:https://www.st.com/en/power-management/l78l.html#overview.The pin out can be seen on page 3 in the datasheet, but I am pretty sure that it is wrong. The pin order should be reversed.The attached picture shows a breadboard test of the part and the coloured wires are connected to:Red -> Lab power supplyBlack -> GroundBlue -> 5 V outputThis leads to the interpretation that the pin out provided in the datasheet is wrong, would somebody mind confirming this from my picture or am I just confused?If this is indeed an error, how would I go about getting the attention of ST? Or would it be easier to contact Mouser and they can then contact ST in order to update the datasheet?Thanks in advance,LaryPS: When I connect the device as specified in the datasheet, the quiescent current is almost twice the max rating and the so called output voltage is about one diode drop below the input voltage.

author: hexreader
author_rank: Frequent Contributor
timestamp: June 23, 2021, 10:30:21 pm
content: Datasheet looks correct to me.Did you perhaps miss the text at the top of third page?"Figure 2. Pin connection (top view, bottom view for TO-92)"

author: LaryPant
author_rank: Contributor
timestamp: June 23, 2021, 10:34:38 pm
content: Yes of course, thank you!I just assumed that it was the top view because that is what it usually is - I guess I was confused - but I hopefully wont make that mistake again.Although I do not understand why they did not make all of them top view, that would have made things easier, I think.Lary

author: Ian.M
author_rank: Super Contributor
timestamp: June 23, 2021, 10:39:25 pm
content: 'Back in the day' it was the convention for through hole transistors and devices in similar packages to give the 'pin' view not the top view. Some manufacturers now use a perspective view for such packages to avoid confusion.

author: phil from seattle
author_rank: Super Contributor
timestamp: June 24, 2021, 02:55:46 am
content: Many of us have been bitten by the bottom vs top view thing. It only takes once though...

author: Whales
author_rank: Super Contributor
timestamp: June 24, 2021, 03:09:00 am
content: I've come across datasheets that don't explicitly say whether it's top view or bottom viewLuckily itseemsthat all SMD parts are pictured from above (so the footprint matches what you need to put on the board), so this problem should not continue to get worse.For simple through-hole chips (3 pin BJTs, FETs, etc) I've found a transistor tester to be very useful.
Is the efficiency of single supply amplifier higher than split supply?  - Page 1
Forum section: electronics / projects

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: November 25, 2022, 07:10:11 am
content: Bellow are two identical amps with 25v and +/- 25v supplied, with 0-20v input in one and +/-10v in the second. The current of the positive rail is measured superposed on the output voltage load 10 ohms.In single supply, the peak current is 1A on positive cycle and non in the other, the charged capacitor at the first cycle, powers the negative cycle.Next is the split supply, I have exactly the same current on the positive cycle and of course a negative current from the negative supply on the negative cycle for exactly the same output power. That is, I doubled my supply power to get the same output, where my reasoning is wrong?

author: Kokoriantz
author_rank: Frequent Contributor
timestamp: November 25, 2022, 08:08:53 am
content: I understood the error. If I reduce the split supply to +/-12.5v I get the same result with the same supply power.

author: CaptDon
author_rank: Super Contributor
timestamp: November 26, 2022, 03:17:17 pm
content: Run your simulation for several cycles and understand the difference. With the single supply the coupling capacitor starts at mid-point at idle. There is your first clue, it took energy to charge the capacitor to idle state. You can pull the capacitor to the + rail and most of the current will be supplied to the load AND the capacitor will lose some charge energy. When the signal goes to the return rail the reverse current will also go through the load AND the capacitor will lose more energy. Now when you pull that capacitor back to the + rail again the load will be moving current through the return rail (as it did the first time the signal went positive) and you will be replacing energy that was consumed from the capacitor and needing to supply energy to the load. The power consumption is the same in either single or split rail. The single rail may be slightly less efficient due to energy lost in the capacitor as ESR heat and dielectric losses. In simple terms, over several cycles the current in a single supply will be equal to the pair of currents (when added together as two separate powers) in the split supply. A single supply amplifier may show 1 amp at 20vdc where a dual supply may show +/- .5 amps. This is 'AVERAGE' current. The PEAK current will be very different if you look at current draw vs. time with an oscilloscope. My explanation may not be exactly clear however.
Is the LM399 a good choice for a 4.096V reference? - Page 1
Forum section: electronics / projects

author: ivonenand
author_rank: Contributor
timestamp: December 12, 2016, 10:12:02 pm
content: Hi Guys,I'm looking for a good stable reference for my 24-bit percision ADC. I need a reference voltage of 4.096V, or at least something in the 4 - 4.2V range. I see that LM399 is used often with 6 or even 7 digit DMMs so It seems like a good choice. The problem I see is that the LM399 puts out a voltage of 7V, so I would need to divide that down to 4V. I'm worried that that divider (and extra buffer) would introduce more ppm/C than I would like. So my question is, is the LM399 a good choice for a 4V-ish reference, or am I better of using one of the SOIC type reference voltages from Maxim or AD that have 1 - 2 ppm/C and an already made 4.096V output?On a side note, I saw allot of reference designs with LM399 (and LTZ1000) that use 15V for power supply. I only have an (unstable) 12V available. I would put a LDO on that to 10V, for which I don't know if it's enough for s LM399 and it's heater.Thanks for any advice in advance,Regards,Ivo

author: rob77
author_rank: Super Contributor
timestamp: December 12, 2016, 10:35:03 pm
content: you can use the LTC1043 to divide the reference by 2 . so if you make your lm399 reference output 8.2V (e.g. the standard 10V reference circuit scaled down to 8.2V) and then divide it by 2 and you'll end up with a fairly good reference voltage coming from a overly complicated circuiti would just use a 4.096V reference with a low(-ish) tempco instead.btw... 4.096V is not the best reference for 24bit4.194304V would make more sense for 24bit... but the point is you can use whatever voltage you want or use a ref voltage at which your ADC gives the best results... because you'll have to do calculations in software anyway

author: David Hess
author_rank: Super Contributor
timestamp: December 13, 2016, 06:58:54 am
content: If the ADC is a sampling instead of integrating type, then beware of broadband noise from the reference. Filtering reference noise can be difficult if low DC drift is still required.I like the idea of dividing an LM399 reference output by 2 using an LTC1043.Matched resistors networks with good TC tracking are available which may make the LM399 more favorable.
Is ther ean easy Way to Level Shift logic down by 5 volts using D-Mode N-Channe - Page 1
Forum section: electronics / projects

author: TheRuler8510
author_rank: Regular Contributor
timestamp: September 19, 2015, 01:02:51 am
content: Is there an easy Way to Level Shift logic down by 5 volts using D-Mode N-Channel JFETS only?The only thing I came up with is to use seven diode drops and a current sink. Or a source follower with 7 diode drops. Both will have terrible temperature sensitivity.Is there an easier way using a few simple devices?Thanks for any brain storming!

author: TheRuler8510
author_rank: Regular Contributor
timestamp: September 21, 2015, 12:24:54 pm
content: Quote from: evb149 on September 19, 2015, 03:30:58 amYes it is challenging, but BJTs NPNs PNPs Zeners and logic chips are not an option, only discreet N-channel depletion JFETs and Schottky diodes can be used. Can it be done? This is because of an IC process that is limited.Anyhow, Logic levels are -1.5V and 0.0V and need to shift down to -6V and -4.5V.This is the challenge.Regards,

author: rfeecs
author_rank: Frequent Contributor
timestamp: September 21, 2015, 09:10:19 pm
content: Make a constant current sink and drop the voltage through a resistor?The constant current sink could be just a DFET with gate connected to source.

author: Marco
author_rank: Super Contributor
timestamp: September 21, 2015, 10:11:01 pm
content: Does that work if his "resistors" are also just FETs with shorted gate-source?Not exactly easier or with few devices, but capacitive coupling can provide a temperature independent solution.

author: rfeecs
author_rank: Frequent Contributor
timestamp: September 21, 2015, 11:52:48 pm
content: Quote from: Marco on September 21, 2015, 10:11:01 pmNo.An example would be to size a FET so that it sinks 1mA (Idss=1mA). Then you drop 4.5V through a 4.5k resistor. This is going to vary some with temperature because Idss will vary some with temperature. You will also lose some voltage swing because of the finite output impedance of the current sink.If you try to replace the resistor with another FET, the voltage it drops with be very sensitive to the shape of it's IV curve. If the FET had a very flat saturation characteristic, then a small change in current would result in a big change in the voltage drop. You are sort of putting two current sources in series, which doesn't work well for this application.
Is there a 6 pin version of the SRD-05VDC-SL-C relay??? - Page 1
Forum section: electronics / projects

author: ledtester
author_rank: Super Contributor
timestamp: May 18, 2023, 03:28:53 pm
content: On this WiFi relay board:https://www.amazon.com/gp/product/B09PG1M3M4there are four SRD-05VDC-SL-C relays. However, looking at the bottom on the PCB those relays appear to have 6 pins whereas all the info I can find on the web suggests that model only has 5 pins. The extra pin is a an addition COM pin on the coil side of the relay.E.g. a datasheet:https://www.circuitbasics.com/wp-content/uploads/2015/11/SRD-05VDC-SL-C-Datasheet.pdfIs the board using genuine Songle relays?

author: jm_araujo
author_rank: Regular Contributor
timestamp: May 18, 2023, 03:36:05 pm
content: I can only count 5 pins in each relay (+3 for screw terminals).Where are you counting the 6th pin?

author: ledtester
author_rank: Super Contributor
timestamp: May 19, 2023, 09:56:06 pm
content: Thanks!
Is there a better logic part for this than CD74HC73E - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: March 08, 2019, 05:21:43 pm
content: I want to automatically assert the /WAIT line on a Z80 when it asserts the /IORQ line. I only want it to assert on the high to low TRANSITION of /IORQ - I want to be able to reset it and release the /WAIT even while /IORQ may still be low. Is there a better, more common part to use than CD74HC73E, preferrably in AHC ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 08, 2019, 06:50:02 pm
content: Invert IORQ into type D ('74)'s CLK, D = 0, CLR = 1, PRE = release wait?D f/fs are pretty standard, always been my impression that JKs are archaic?Tim

author: Benta
author_rank: Super Contributor
timestamp: March 08, 2019, 07:32:45 pm
content: Quote from: T3sl4co1l on March 08, 2019, 06:50:02 pmCertainly not!The JK FF is one of the most powerful logic building blocks available.If you have JK-FFs and D-FFs (plus gates of course) in your toolbox, you can doeverything. Really everything.But you do need both.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 08, 2019, 07:40:16 pm
content: Off the top of my head, it should be possible to achieve the same with (clever use) of a 74AHC123, which are readily available (whereas the 73 is not). To be checked though.

author: Benta
author_rank: Super Contributor
timestamp: March 08, 2019, 07:43:37 pm
content: How on earth could a monostable multivibrator replace a JK FF?

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 08, 2019, 08:14:16 pm
content: With the following arrangement maybe?/IORQ line to pin /Apull-up to pin Bpull-down to pin REXT/CEXT(signal to reset output) to pin /RD/WAIT line to pin /Q

author: Benta
author_rank: Super Contributor
timestamp: March 08, 2019, 08:18:26 pm
content: Quote from: SiliconWizard on March 08, 2019, 08:14:16 pmLove it! Asynchronous design like in the ´70s/sarcasm.