hybridfree/eevblog-posts huggingface dataset:
Best Price for Siglent 1104X-E - Page 1
Forum section: electronics / beginners

author: Tech77997
author_rank: Contributor
timestamp: May 20, 2020, 04:07:10 pm
content: Thank you all for your input. I have decided to go ahead and purchase the Siglent 1104X-E. I see the price is $456 on Amazon; is this the best price I can get it for? Are there are any student discounts available anywhere, or EEVBLog discounts available? Thank you.

author: MarkF
author_rank: Super Contributor
timestamp: May 20, 2020, 04:30:53 pm
content: Answer here!https://www.eevblog.com/forum/beginners/which-of-these-rigol-oscilloscopes-or-pay-more-for-sigilent-1104x-e/msg3076648/#msg3076648

author: Old Printer
author_rank: Frequent Contributor
timestamp: May 21, 2020, 02:36:39 pm
content: I bought mine from Saelig last year. Regular price was $499 but between the free shipping, lack of sales tax because I am not in NY state, and the EEVblog discount it was the best deal around. Be advised, they do not list stock status online, so-call them before you order if you want to know if the have stock for immediate shipment. It is the one negative, to me, with them. Otherwise a good company and an excellent scope.
Best process/practices for integrating an IC into a design - Page 1
Forum section: electronics / beginners

author: Tim51
author_rank: Contributor
timestamp: March 07, 2021, 04:12:25 am
content: Hi Guys,When putting a schematic together, what is the best process/practices for integrating a new IC into a design? I'm just curious what other peoples approach is to the subject. Lets just say for example an IC is already selected (not an MCU), you don't know much about it, you've got the data sheet and a user guide. What do you do next?My approach is as follows:Create a google doc where I can write notes from reading the data sheet, user guide, test cases and any other info along with way. I embed links to referencesas well.Understand the general function of the IC.Understand the functions behind each pin on the IC.Determine what the power requirements. Use the reference design as a template. Does it need a buck, LDO, etc?Determine how it will this interface with any other ICs in the design. I2C, SPI, etc?Determine test points or jumper points that could be useful during testing/bring up.Determine test cases with pass/fail parameters for validation.Complete the schematic.Cheers,T
Best program to test a circuit? - Page 1
Forum section: electronics / beginners

author: noahsdev
author_rank: Newbie
timestamp: October 10, 2013, 05:43:28 am
content: I want a program in which I can test my circuit and make sure it actually does exactly what I want it to do before I build it.I would prefer for it to be free but don't mind paying as long as it does what I need.

author: filip_cro
author_rank: Regular Contributor
timestamp: October 10, 2013, 05:52:37 am
content: LT Spice. Pain-in-ass to learn but when you know how to use it, you will have fun with it

author: free_electron
author_rank: Super Contributor
timestamp: October 10, 2013, 12:01:46 pm
content: Solderingiron 1.0It has been around for a very long time. The never released upgrades as it works perfectly fine and is bug-free. The results are 100% accurate.Runner up would be Eldo or Ultrasim. All the rest are wannabe's.

author: tehmeme
author_rank: Regular Contributor
timestamp: October 10, 2013, 12:11:50 pm
content: Quote from: free_electron on October 10, 2013, 12:01:46 pmI had already typed Sold.. in google before getting it... my brain seems to be under-clocked today

author: E
author_rank: Contributor
timestamp: October 10, 2013, 01:15:24 pm
content: I like falstads circuit simulator, it's a quick solution to test some ideas, but it's not always accurate.www.falstad.com/circuit/
Best RF book 2015 - Page 1
Forum section: electronics / beginners

author: asgard20032
author_rank: Regular Contributor
timestamp: September 22, 2015, 01:29:41 am
content: Hi, its been one year that i got interested in radio frequency, but just interested. By that, i mean i didn't made any project yet, or made more serious study. But i want to learn more about it. I already have the radio amateur official certification book for my country, Canada. I already know some basic electronic stuff, although i am more in digital and firmware. I don't need a book about ohm law and resistor/capacitor or dummy book, but something that is beginner/intermediate/maybe a little bit advance, but not in the dummy nor kamikaze too much extreme range.Every subject has its bible, or many bible. For example, there is k&r C, Art of computer programming, CLRS(programming), AoE(general electronics)... But what about RF?I already own AoE, and i am looking for practical electronic for inventor 3rd as a companion of AoE.Looking for theory, and some schematic/building block about common circuit/operation, like modulator, amplifier.Book about power electronics and op amp are also welcome.

author: retrolefty
author_rank: Super Contributor
timestamp: September 22, 2015, 01:39:26 am
content: Not sure any one book can cover all of RF, it's a rather wide field. I would start simple with the ARRL Handbook. They have been published yearly for what like 8 decades? Small changes every year and you should be able to pick up a used one from a past years pretty cheap. That will give basic background on many aspects of RF and a good launching point for further study.

author: ez24
author_rank: Super Contributor
timestamp: September 22, 2015, 01:43:44 am
content: Have you looked through this posthttps://www.eevblog.com/forum/beginners/electronics-primers-course-material-and-books/I do not know if there is any RF stuff there

author: DimitriP
author_rank: Super Contributor
timestamp: September 22, 2015, 02:04:27 am
content: Don't know about best, but these below deserve to be on the "deserted island list" along with a couple of editions of the ARRL Handbook ...http://www.amazon.com/Solid-State-Design-Radio-Amateur/dp/0872590402http://www.amazon.com/Radio-Handbook-Twenty-Third-Edition/dp/0750699477/ref=pd_sim_14_8?ie=UTF8&refRID=1ME6DDPX2JEZ65GC1AJVhttp://www.arrl.org/shop/Experimental-Methods-in-RF-Design

author: Bud
author_rank: Super Contributor
timestamp: September 22, 2015, 05:13:14 pm
content: Yes any ARRL Handbook from the last 20 years.
best software for craft projects - Page 1
Forum section: electronics / beginners

author: new to all this
author_rank: Newbie
timestamp: October 04, 2015, 08:49:12 pm
content: i am new to this and would like to know the best software ! I am wanting something that does letters in different fonts/and something that you can transfer a pic over to it.. say i need a certain pumpkin beings it the season.. all i have to do is send the pumpkin i want over to the machine and it can make it... Again i am new to this and this all may sound crazy so please be patient with me... i need HELP.... i should add i have a new 6040 cnc router engraver that came with the mach3 demo... its not very user friendly

author: singapol
author_rank: Frequent Contributor
timestamp: October 05, 2015, 04:23:41 am
content: First, this is not the best place to ask this question.It would be better if you ask this in a dedicated forum that is about cnc machining, cnc wood carving/router, 3D printing. To point you in the right direction The answer to your question of best software...there is NO bestbut whatever that works and fulfil your needs given your budget.In most cases free software is the way of which sourceforge is the place to look or the various forums mentioned.The truth of the matter is you need more than Mach3 although it's not a paid/licenced version but a hacked one, usable nonetheless.Mach3 only takes the machine readable 3D ( gcode ) data to translate into the movements of the 3 or more axis of the router.Just like creating a pcb, first a 2D schematic drawing and then a pcb translation of the schematic into pcb plus a host of other functions like rules checking, auto routing, etc.Similarly for your purpose of 3D machining/ carving/3D printing:1. Creation of 3D drawing from 2D representation likeFreeCad.2. and then and or a separate function of translating the 3Dcoordinates togcode which Mach3 translate into 3D machine coordinates (gcode )( imagine GPS).See a all-in-one software likePyCad.3. which a 3 axis router can make use of likeMach3.4. Setting up your raw material/blank on the router like clamping,setting machine home/zero origin positionwhence it starts it's linear distance measurement andcutter position/zero.5. Watch the magic.Lastly for cutting fonts although basic software has fonts or rather basic function it's best to look for a deicated font software. Hope this helps. There are many tutorials to set up Mach3..it's not complicated.

author: new to all this
author_rank: Newbie
timestamp: October 05, 2015, 10:14:58 am
content: like i said i am new to this... could you please point me in the right direction and place to ask this ?

author: Cliff Matthews
author_rank: Unknown
timestamp: October 05, 2015, 10:58:52 am
content: Welcome! Pumpkins?This is an electronics forum. YouTube is your friend.https://www.youtube.com/results?search_query=FreeCadandhttps://www.youtube.com/results?search_query=gcode+CNCandhttps://www.youtube.com/results?search_query=Mach3+CNCandhttps://www.youtube.com/results?search_query=Mach3+zero+originBTW: Singapol gracefully typed a lot just for you, please re-read it.
Best textbooks for RF systems engineering - Page 1
Forum section: electronics / beginners

author: adaptivefilter
author_rank: Newbie
timestamp: March 21, 2021, 10:42:59 am
content: I would like to know what books do you consider to be the best books for learning RF system design, in your personal opinion of course.Hope I posted in the right place.

author: bob91343
author_rank: Super Contributor
timestamp: March 21, 2021, 06:40:16 pm
content: There is no best. RF is no different from any other frequency range. Learn the basics. For instance, Terman's Radio Engineering or his handbook. Books on transmission lines. Do some experimentation, as there is nothing as informative as watching things work.RF is such a wide discipline that you need to narrow it a bit to zero in on what it is you want to learn.A random example: I wanted to measure the flatness of a signal generator so I connected an oscilloscope to it via a piece of coaxial line. I was amazed to see the signal rise in amplitude whan I got much beyond 5 or 10 MHz. That showed me that I needed to terminate the cable, not just read it on a high impedance scope. Otherwise this effect would have remained in the domain of theory.

author: Grandchuck
author_rank: Super Contributor
timestamp: March 21, 2021, 07:04:54 pm
content: The ARRL Handbook is an excellent and affordable start in RF:http://www.arrl.org/shop/ARRL-Handbook-2020-Six-Volume-Set/

author: bob91343
author_rank: Super Contributor
timestamp: March 22, 2021, 04:03:59 am
content: The ARRL Radio Amateur's Handbook is a time honored, traditional source. Having said that, I have found recent editions lacking in coherence and accuracy. If you can find an old one, say before the 1960s, I would recommend it. Of course much has elapsed since then so you don't get up to date info, but they haven't repealed Ohm's law as far as I know.The newer ones seem more to be trying to fulfill an obligation to publish yearly rather than an attempt to provide a solid source of technical information. I will say the same for the Antenna Handbook. ARRL isn't what it once was, and to quote Will Rogers, it probably never was.
Best Transistor/Mosfet option for a PIC controlled motor help, please ^_^ - Page 1
Forum section: electronics / beginners

author: Mellowed
author_rank: Newbie
timestamp: July 10, 2011, 06:32:45 pm
content: Hi guys, (First Time posting)I'm trying to build a pic controlled Fish feeder.So far everything works fine except i'm not sure what my best options would be for controlling the motor.At the moment it only needs to run in one direction, on off (figured no need for PWM). The motor is a 1.5V-3V motor and i'v been using a power transistor but it seems to not always run.I' Found a 75N08 Mosfet which i figured could work but would like some input and i'm not to sure if i'v set my circuit up correctly for it.I'v attached a schematic diagram of the circuit.Any help or suggestion would be greatly appreciated.Regards

author: Simon
author_rank: Unknown
timestamp: July 10, 2011, 06:50:15 pm
content: why not use an N channel logic level mosfet like the IRL540(N) ?

author: Mellowed
author_rank: Newbie
timestamp: July 10, 2011, 07:32:30 pm
content: hmm thanks!, never knew such a component existed ^_^Would i still need to use a resistor between it and the PIC?

author: Simon
author_rank: Unknown
timestamp: July 10, 2011, 07:43:12 pm
content: that depends on the frequency, if your turning it on and off as a switch then you could not worry although some people will tell you to. You should have a resistor in parallel with the gate from gate to source

author: Zero999
author_rank: Super Contributor
timestamp: July 10, 2011, 08:00:00 pm
content: I've just Googled for the datasheet for the 75N08 and it should be fine with a VGSof 5V.How much current does the motor use?

author: Mellowed
author_rank: Newbie
timestamp: July 10, 2011, 08:49:09 pm
content: Well it say's 0.3Amps at No Load and 1.05Amps @ MAX Eff.Do you rate the layout i'm using in the schematic for the motor is correct, and should i add a Diode over the motor's ports? (I'v never worked with motors before)

author: Zero999
author_rank: Super Contributor
timestamp: July 10, 2011, 09:13:24 pm
content: Yes, a diode is good practise, although it's very unlikely a 3V motor is going to generate enough back-EMF to kill a 75V MOSFET.The current is low and well within the capabilities of the MOSFET.How are you assembling this? Have you made a proper PCB or are you just using a breadboard?

author: Mellowed
author_rank: Newbie
timestamp: July 10, 2011, 09:41:16 pm
content: It was originally made on Veroboard but i'll be making a PCB tomorrow using the Mosfet and begin testing.Thanks for the help!
Best type of insulator pad for a to-220 LM317 power supply? - Page 1
Forum section: electronics / beginners

author: george graves
author_rank: Super Contributor
timestamp: February 17, 2012, 08:36:27 am
content: I'm thinking of building a power supply using a lm-317. The tab is connected to the output pin. So I'm assuming it would be a good idea to insulate that from the heat sink that will be sticking out of the case?I see there are silicon( or "silica") pads, and "Mica" pads. What performs better? What should I use?

author: Rerouter
author_rank: Super Contributor
timestamp: February 17, 2012, 08:43:13 am
content: Mica is generally better under significant heat,

author: ejeffrey
author_rank: Super Contributor
timestamp: February 17, 2012, 08:59:17 am
content: Silpads are the easiest to use and the most repeatable. Mica is good but suffers from poor thickness and flatness control, and its performance depends on how well you apply the thermal grease. I would generally use a sil-pad unless I was really pushing the edge. In that case I would probably go straight to an aluminum heat spreader insulated from the main heat sink by kapton film.

author: LukeW
author_rank: Frequent Contributor
timestamp: February 17, 2012, 09:42:36 am
content: Silicone is easier, it doesn't require separate thermal interface grease, whilst mica does.

author: Zero999
author_rank: Super Contributor
timestamp: February 18, 2012, 03:32:14 pm
content: When I built an LM317 PSU, I soldered the heat sink directly to a piece of copper bar which was fixed to the metal case, for insulation I used plain old Sellotape which worked perfectly.

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 18, 2012, 09:55:24 pm
content: Quoteif you talking about that transparent plastic shiny sellotape, extreme heat will screw it up, electrical tape is better heat resistant. if the op dont have a screw and nut to stick to the heatsink, my way is silicone that people used to seal aquarium (in tube) in between any insulation used. or the "elephant" glue, not sure what its called, but usually it has elephant picture on the bottle and if you put one drop between your fingers and put together, the fingers will stick each other within seconds.

author: Rerouter
author_rank: Super Contributor
timestamp: February 18, 2012, 10:19:49 pm
content: elephant glue sounds like superglue, and really, you never want to heat superglue over 75 degrees, parts of it vapourises, and it burns your eyes and nose even hours later :/

author: Zero999
author_rank: Super Contributor
timestamp: February 19, 2012, 02:42:14 am
content: Quote from: Mechatrommer on February 18, 2012, 09:55:24 pmI never had a problem, partly because the LM317 was already soldered to a piece of copper bar which spread the heat more evenly. Oh and electrical tape will be worse because it's normally made of PVC which has a lower melting point than cellophane or polypropylene which is what Sellotape is made from.
Best Typs of DIL IC Socket to Use on Vintage PCB - Page 1
Forum section: electronics / beginners

author: Bionic-bean
author_rank: Newbie
timestamp: June 12, 2022, 06:27:47 am
content: Hi Guys,Big hello to everyone on here as this is my first post since registering.Long story short... Ive just started to unbox my vintage computers from storage and currently repairing an old Nascom 1 ( Z80 CPU ) board. The board was populated with old tarnished single wipe I.C. sockets and they had to be removed. Removed all 59 Sockets with only one pad lifting (). Woohooo..So the question is what to replace them with - Turn Pin sockets or double wipe sockets. ? Once I place new sockets in, the board would not survive another desoldering attempt, so what goes in has to stay and work.Standard DIL chips going back into the sockets. 74LS04 adn 2708 Eeproms and Z80 cpu. ect, ect. As some of the menory chips are fairly fragile I suspect the memory chips will need to be inserted and removed multuple times so I'm leaning towards a double wipe socket rather than turn pin.Any thoughts or recomendations much appreacted.Dave'O

author: CJay
author_rank: Super Contributor
timestamp: June 12, 2022, 08:24:09 am
content: If it were my board, I'd install quality double wipe sockets from a name brand.

author: Benta
author_rank: Super Contributor
timestamp: June 12, 2022, 06:52:22 pm
content: Preci DIP machined sockets. Best you can get.https://www.precidip.com/No affiliation.

author: jpanhalt
author_rank: Super Contributor
timestamp: June 12, 2022, 07:01:00 pm
content: Machined pin are the best. As for brands? Mill-Max is well known for its machined pin sockets, including individual DIP pins on a carrier (very low height). Samtec is my other choice for both double wipe and machined pin.https://www.samtec.com/products/ico
Best way to boost 6v to 9v (variable) at highish currents? - Page 1
Forum section: electronics / beginners

author: revilo951
author_rank: Newbie
timestamp: October 01, 2014, 10:27:07 pm
content: Hello,I have a 6v 10A Power Supply that I want to use to run some high power LED's (overdriven). They are MT-G2's so the nominal voltage is 6v, and I would like to drive them up to 8.5v when I need extra brightness. At 8.4v, they take about 2.5A each.Can anyone point me in the right direction?Any more information you need, just let me know!Thanks!

author: sacherjj
author_rank: Frequent Contributor
timestamp: October 02, 2014, 01:40:27 am
content: Do a search for LED driver chips There are many out there for LED backlights and for camera "flash" LEDs. They are usually done as a current control, rather than voltage control. Then the boost circuitry take the voltage up to where is needed to provide the current set.

author: Teledog
author_rank: Regular Contributor
timestamp: October 02, 2014, 03:28:00 am
content: eBay has buck-boost boards for dirt cheap, do a search. ( Step up /step down power supply)It's not worth making them yourself.I buy shitloads ;-)PS: might want to stick with the same voltage, just slowly increment the current (with suitable heat-sinks)

author: revilo951
author_rank: Newbie
timestamp: October 08, 2014, 04:44:46 am
content: OK, I was hoping there would be something that would be a nice project for me to DIY.I'm not a stranger to eBay.If anyone has any suggestions for one in the right voltage range that will do 90W+, I'll be glad to hear.Also, regards:Quote from: Teledog on October 02, 2014, 03:28:00 amDo you care to explain a little? ('scuse my noob question here) Doesn't ohms law come into play? Or do you mean just adjust the current and let the voltage look after itself (adjusting the current rather than the voltage)? From your comment, if I didn't know better, I'd be asking how to increase the current using a heatsink!

author: Psi
author_rank: Super Contributor
timestamp: October 08, 2014, 06:44:01 am
content: Trying to boost convert 90W from 6V will result in terrible efficiency. Its bad enough at 12VYou'll probably lose half a volt just in the wiring. which is 0.5 * 15A = 7.5W.And that's before the switchmode conversion has even started.

author: mzzj
author_rank: Super Contributor
timestamp: October 08, 2014, 07:08:32 am
content: Quote from: Psi on October 08, 2014, 06:44:01 amBetter than 90% effiency is possible but it wont be easy like slapping wires to cheap ebay module.

author: revilo951
author_rank: Newbie
timestamp: October 08, 2014, 09:01:03 pm
content: Efficiency is not a major concern here...I have a power supply that I would like to use, and will work to do what I want at lower efficiencies, even down to 70%
best way to charge 3piece 4v lead acid from 9v 3w panel? - Page 1
Forum section: electronics / beginners

author: dave_j_fan
author_rank: Regular Contributor
timestamp: February 10, 2018, 09:26:54 pm
content: i am planning to charge 3no 4v cells keepin in parallel9v solar panel 3w is the source sourceconnection to cells gives 300mA . I am thinking 100mA per cell is okjust voltage in is 10Vwill it make problemi will add 7 piece 1N4007 as voltage clamper diodes with some reosotor that will eat away once voltagecrosses 4.7vany better alternative ?

author: dave_j_fan
author_rank: Regular Contributor
timestamp: February 11, 2018, 10:09:35 am
content: no reply ?? Anyone

author: paulca
author_rank: Super Contributor
timestamp: February 11, 2018, 10:39:56 am
content: When it's asked, "Can I just connect a panel to a battery?" the answer is almost always, No. It will work, but it will not do what you think it will.If the cells are charged and not pulling current the panel voltage will rise and overcharge them.If the cells are undercharged they will pull a load of current pulling the panel voltage down to the cell voltage resulting in less watts and less charging.I don't think clamp or dropper diodes will work either. Panels are not linear, the voltage will vary a lot.Take a look here. He has other videos on his channel where he demonstrates what happens if you try and do what you are intending. It doesn't work very well is the short of it. You can use a charge pump and PWM with an arduino (Check also Adam Welch videos where he shrinks it to an ATTiny chip)... or you can go full MPPT which is probably overkill for your use case.

author: danadak
author_rank: Super Contributor
timestamp: February 11, 2018, 03:09:43 pm
content: Some ref material -https://www.onsemi.com/pub/Collateral/AND8490-D.PDFhttp://www.vxipower.com/downloads/application-notes/d54467f7b4001657e989f884d1608fd7f1aafd58.pdfftp://ftp.efo.ru/pub/cypress/psoc/PSOC_APP/charger/power_management___a_multi_chemistry_battery_charger___an2107_12.pdfhttps://www.princeton.edu/ssp/workshop/batteries/battery_workshop.pdfGoogle "Handbook of Batteries", good book on topic.Regards, Dana.

author: dave_j_fan
author_rank: Regular Contributor
timestamp: February 11, 2018, 07:21:05 pm
content: paulca,I have been using 4v cell pair in series with a diode on that 9v solar . always charges wellI am using one lantern but it is a bit dim.the unit LED brightness to be increased but not cost by many factorso i decided to go by parallel cell method , adding one cell adds 20cents and possible ( it will be a product )I have read 3w panels cant overcharge cells if nearby voltage .. coz max current 270mAif i add a diode clamp as shown i can prevent overchargedanadak, task has to be done with lowest cost
Best way to connect a switching fet to another chip - Page 1
Forum section: electronics / beginners

author: Moriambar
author_rank: Unknown
timestamp: June 09, 2024, 04:25:20 pm
content: Hi there,I'm wondering: when connecting a fet to an MCU/cmos logic chip/other IC, which configuration is better and why?I put just simple resistors as a load example, but it can be something more complex, but let's assume that it doesn't require a "special" treatment (eg: fast switching or fast pwm), just an on-off for a load.I can think of these three circuits, I usually hook up #2, but I'm wondering if it can be done better. For example I see some circuits without resistors between mcu pins and fets…Can you help please?Cheers

author: globoy
author_rank: Frequent Contributor
timestamp: June 09, 2024, 04:45:53 pm
content: They all have their uses. Which one (or combo) that you select depends on other aspects of your circuit.Circuit 1 protects the MCU for the case that the FET fails with a D-G short and VCC > MCU operating voltage. The series resistor limits the current being sunk by the IO port ESD protection diode array.Circuit 2 ensures the FET is turned off in the case the MCU IO is an input (which often occurs during and after reset before the MCU has a chance to initialize the port as an output and set an initial low level).Circuit 3 can be used if VCC <= MCU operating voltage and the load resistance will sufficiently limit current in the condition of a shorted FET (or you need to save every penny and you don't care what happens if the FET shorts).

author: Moriambar
author_rank: Unknown
timestamp: June 09, 2024, 06:18:43 pm
content: Quote from: globoy on June 09, 2024, 04:45:53 pmthanks, very well explained.

author: Manul
author_rank: Super Contributor
timestamp: June 09, 2024, 07:07:11 pm
content: It is good practice to always add series resistor, like in circuit 1. The only exception is if you drive very small fets with very low gate capacitance. Calculate series resistor based on maximum permissible pin current. For example, if voltage is 5V and maximum pin current is 20mA, use at least 250 Ohms series resistor.For logic ICs, MCUs and other fast switching ICs, capacitive load presents almost a short circuit to ground during fast transitions. So for a brief moment current might hugely exceed maximum limits. Although it's very short and usually does not present significantly increased thermal dissipation, high current peaks might cause momentary sag of supply voltage, either for the whole IC or some section of the IC. Especially if IC does not have very good bypassing. And in general stresses the ouput of IC without reason. If you want to drive a mosfet gate fast, you use some sort of dedicated driver.FYI, power mosfets typically have 1-10nF gate capacitance, that is significant.The need of gate pull-down resistor depends on the application. It is good practice to add it, except if you are sure that driving pin can never be high-z, aka floating.
best way to convert unipolar DAC to bipolar? - Page 1
Forum section: electronics / beginners

author: FrankBuss
author_rank: Unknown
timestamp: July 27, 2018, 12:46:51 pm
content: I have a DAC with an internal 2.44 V reference, with an output range from 0 V to 2.44 V, and I want to convert it to the range -10 V to 10 V. I found 4 circuits for it:- one opamp and 3 resistors:http://www.ti.com/lit/ug/slau525/slau525.pdf- one opamp and 2 resistors:https://www.maximintegrated.com/en/app-notes/index.mvp/id/5581- one opamp and 4 resistors:https://masteringelectronicsdesign.com/design-a-unipolar-to-bipolar-converter-for-a-unipolar-voltage-output-dac/- two opamps and 2 resistors (application note of the DAC I'm using, page 18) :https://datasheets.maximintegrated.com/en/ds/MAX5134-MAX5137.pdfWhat are the advantages and disadvantages of the 4 circuits and which one should I use? Would be nice if I wouldn't need exact matched resistors, like R and 4 x R, but it doesn't need to be exact, could be like +/-10.5 V, or even shifted zero point, and I can calibrate it then in software (if it is stable). But I wouldn't like it, if there are different gain factors for the positive and negative voltages, which I guess could happen with the solutions with more than 2 resistors?

author: mikerj
author_rank: Super Contributor
timestamp: July 27, 2018, 02:15:37 pm
content: The second, third and fourth links are effectively the same solution (two resistors) and only useful when you want the output range to be +-Vref. No good for you, so use the TI app-note in the first link.In your third link the author starts with a conventional diff-amp (4 resistors) and derives the same two resistor solution from it.In your fourth link the extra op-amp is used to buffer the Vref output to prevent loading by the resistors in the amplifier/level shifting stage. The reference on that device has a typical output impedance is only 1 ohm, so providing you keep the resistor values reasonably high you can probably get away without the buffer amp.

author: FrankBuss
author_rank: Unknown
timestamp: July 27, 2018, 02:29:41 pm
content: Thanks. I simulated it in LTSpice and looks like the gain is always constant, the resistors just move the zero and change the whole gain:The datasheet of the DAC says that the REF output is stable up to 100 uA, so I changed the resistors to higher values to be in the safe region. I built the full circuit diagram on a breadboard, with a OPA4188 with very low offset voltage and "zero drift":Looks like it works. I guess C2 is to compensate for higher frequencies and I have to try it out for best compensation, but what is the purpose of C7 and R4? Somewhere I've read you shouldn't connect a capacitor to an op-amp output.
Best way to correct load cell output with large offset? - Page 1
Forum section: electronics / beginners

author: Ahrenp
author_rank: Contributor
timestamp: March 08, 2017, 04:33:42 pm
content: I have a load cell with a 1.785mV/V output that I would like to amplify and connect to a data acquisition system. The load cell may have been damaged and now has a very large (relative to the output level, at least) offset at zero load, of around 135mV. Assuming that the load cell still has a linear output of 1.785mV/V above this 135mV offset (itappearsto in my limited testing) what is the best way for me to subtract the offset prior to amplification? The load cell uses a standard bridge:I built a test circuit (Crude schematic attached) that feeds the bridge output into a unity gain differential amplifier, which is then fed into an inverting summing amplifier along with a trimmable (and op-amp buffered) DC voltage that cancels the offset and has a gain of 100. This works and gives me the expected (inverted) output.Is there a simpler/better way to achieve the same result?P.S. In reality I can probably feed the signal directly (with no amplification) into my DAQ system and correct the offset in software, and my load cell may in fact be NFG, so the circuit design is more of a learning exercise.

author: David Hess
author_rank: Super Contributor
timestamp: March 08, 2017, 05:55:13 pm
content: That is an awful lot of offset so the load cell is probably ruined. Usually shunt resistances added between the excitation and signal pins can be used to bring the zero within range but the shunt resistance drift will contribute to the zero drift.

author: Ahrenp
author_rank: Contributor
timestamp: March 08, 2017, 06:04:29 pm
content: I tend to agree that my load cell is probably no good. If we assume, for the sake of argument, that the load cell is fine aside from the offset, is my approach reasonable? Can shunt resistances be used to trim that much offset?

author: David Hess
author_rank: Super Contributor
timestamp: March 08, 2017, 06:10:22 pm
content: What you are doing should work. The zero correction needs to follow the excitation voltage which is the case with your schematic. The amplifier buffering the offset trim is not needed. The offset trim could also be applied directly to the load cell.

author: Brutte
author_rank: Frequent Contributor
timestamp: March 08, 2017, 07:11:22 pm
content: Bridge is usually wired remotely so the unbalanced sensing wires might cause trouble.I'd try to repair/balance the bridge itself by attaching some fixed resistors on it, keeping the sensing wires loaded with similar currents at all times.
Best way to deliver power to an Internet tower - Page 1
Forum section: electronics / beginners

author: german77
author_rank: Regular Contributor
timestamp: June 25, 2018, 07:41:31 pm
content: Hi, I need help determining what kind of installation for a Internet tower would be the best. Let me explain how everything it's connected.The height of the tower it's 30 meters, most devices work from 20V to 30V others from 30V to 60V. The average power consumption it's 378w.Actual installation: I have two 350w 28.5v PSU connected in parallel one has a 0.05 ohm resistor in the positive terminal with a little higher voltage to ensure that power it's distributed equally. After that it's connected to a 20A solar controller that charges a battery and lowers the voltage to 27V. Then its connected to an AC power bar. This it's located in a cooled room close to the tower. The DC voltage is delivered with 14AWG cable to the devices in the tower. Then each device that work at 50v has it's own step up converter. The tower consumes about 14A and only 23.7V reaches the device. There is 3.3v voltage drop which is unacceptable specially when power goes out because the batteries deliver 24.8v and only 20v arrives to the devices which is to low.Suggested solution: Use a 600w 32v PSU go to the solar charger then put two AC power bars at 24v and a third one with 50v that has an step up converter of 500w. Then deliver each device with the correct voltage with a 10AWG cable.Sounds overkill, but the voltage drop should be less than 0.8v, a single PSU for each voltage should work better and reduce the current in the cable by a half.Solution 2: Deliver 50v to the tower then step down for 24v devices. Problems: Most solar controllers work up to 24 batteries. Not really solving the problem. Making everything more complicated and a new source of problems, specially if the step down fails and delivers 50v to a 24v device.Not a solution: Use a no-break. Put a box in the middle of the tower with a PSU with 24v and other with 50v then deliver to the devices. Problems: Signal noise in the AC supply and Ethernet cables via induction. Overheating in the box, they usually go over 60°C not good for a PSU. And difficult maintenance.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 25, 2018, 07:56:39 pm
content: Quote from: german77 on June 25, 2018, 07:41:31 pm48V is a common DC standard so things like DC-DC converters are readily available ( decent ones that won't fail to 48V out) .You might also consider distributing as mains voltage (110 or 220), as all the conversion you'll need is available easily off the shelf, and you'll save on cable.,
Best way to get a stable negative power rail - Page 1
Forum section: electronics / beginners

author: AMyatt
author_rank: Contributor
timestamp: August 13, 2014, 02:37:08 am
content: I have a 5v supply and need a +-5v supply for a DAC. What is the best way to get a stable -5v supply from the 5v supply I have?Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 13, 2014, 03:24:28 am
content: Current? Ripple? How stable is "stable"?Weak piddly stuff, you'd usually go with a charge pump (ICL7660 or one of those SOT-23-5 devices) and eat the ~1V loss.Tim

author: Richard Crowley
author_rank: Super Contributor
timestamp: August 13, 2014, 03:26:26 am
content: There are chips and circuits that convert +x voltage to -x voltage.But there is no way of answering your question without knowing how much current you need.These kinds of solutions are typically good for only low current.If you need significant current, then you should probably be looking at an additional supply for the - rail.

author: AMyatt
author_rank: Contributor
timestamp: August 13, 2014, 03:27:45 am
content: Hi Tim,Thanks for your reply.I am looking at using one of these DACs (http://www.analog.com/en/audiovideo-products/audio-da-converters/ad1851/products/product.html).The output will basically go to an ADC within another product.

author: Richard Crowley
author_rank: Super Contributor
timestamp: August 13, 2014, 03:37:23 am
content: Quote from: AMyatt on August 13, 2014, 03:27:45 amThe power requirements for that chip are pretty low, so a charge-pump converter would probably work fine.QuoteSo you are converting digital to analog so you can feed it into an analog to digital converter?

author: AMyatt
author_rank: Contributor
timestamp: August 13, 2014, 03:42:58 am
content: Hi Richard,Thank you for your reply.Based on your reply and Tim's it would seem that a charge-pump converter is the way to go.Quote from: Richard Crowley on August 13, 2014, 03:37:23 amYes, I know this sounds stupid and is going to loose some accuracy but unfortunately I don't have control over the input side.The input of the existing product was designed to be connected to a sensor that outputs a varying voltage.I am wanting to emulate this sensor.
Best way to get audio peaks at specific frequencies? - Page 1
Forum section: electronics / beginners

author: botcrusher
author_rank: Regular Contributor
timestamp: March 31, 2016, 05:45:12 pm
content: My end goal is to control lighting via DMX-512, that being said and iut of the way, i have several options at my disposal, several of which would work.1. Software: some kind of package or library that i can use with python, cleanest in terms if requiring no additional hardware. (Aside from dmx module)2. ATmega, software. Can i even use the analog pins for audio?3. ATmega, harware. Some kind of low pass filter so i can get a voltage level for a certain frequency?I'm not sure what the best route would be, if you could give me advice on any of these, or any additional ideas which would work, that would be great.At the end of the day, i need to analyse peaks at specific frequencies, then interface with either the ATmega, python, or both (i have code for intercomunication)

author: alexanderbrevig
author_rank: Frequent Contributor
timestamp: March 31, 2016, 08:39:59 pm
content: I guess it depends on what you want (and which frequencies you want to analyze, especially for option 2 as you'll only be able to sample up to 5kHz).Getting something looking good for anything but the bass is more difficult than it sounds. Personally I'd make it quicker with python and one of the FFT libraries out there, but I would do it with option 3 as a cool project. Simply run the input through 1 to 6 band pass filters, then into a envelope follower into one of the analog inputs on the Arduino. Now it's just a matter of figuring out what level you want to see on the analog input (and for how 'long' the value should be read) before sending a DMX value.

author: packetbob
author_rank: Contributor
timestamp: April 01, 2016, 01:33:41 am
content: The Arduino may be a bit under powered to do any reasonable amount of audio processing but you could use an Arduino with a MSGEQ7 chip. I have never used it but it apparently has 7 different filters and gives you a dc output for each band (they are multiplexed out a single pin). Lots of Arduino examples on the net. Might be something with DMX output.

author: LaurentR
author_rank: Frequent Contributor
timestamp: April 01, 2016, 02:01:01 am
content: One Arduino example is here:https://learn.adafruit.com/piccolo/codeIt works reasonably well but is in no way accurate or easy to tune.I was planning on trying out the MSGEQ7 mentioned by packetbob, but I haven't yet.https://www.sparkfun.com/products/10468
Best way to get non-symmetrical voltages? - Page 1
Forum section: electronics / beginners

author: facumedica
author_rank: Contributor
timestamp: March 28, 2014, 02:01:35 am
content: Like -2 +12. For a op amp circuit. Maybe a simple voltage divider, maybe something better?Thanks!

author: David_AVD
author_rank: Super Contributor
timestamp: March 28, 2014, 02:35:31 am
content: Would depend on the original voltage source. (battery, transformer, etc)

author: facumedica
author_rank: Contributor
timestamp: March 28, 2014, 02:28:25 pm
content: From a single supply, battery, wal-wart, whatever.

author: David_AVD
author_rank: Super Contributor
timestamp: March 28, 2014, 09:40:44 pm
content: Off the top of my head a few diodes between the 0V line and the V- line (cathode to V-) should work for a coupe of Volts.I've used an ICL7660 chip to generate a small -ve rail sometimes too.Otherwise an opamp (with a suitable voltage divider at input) as a 0V reference is something I've also seen.

author: AG6QR
author_rank: Frequent Contributor
timestamp: March 28, 2014, 11:37:27 pm
content: Are you planning to draw any current? How much?A voltage divider only works if you draw no significant current from it. As soon as you use it to sink or source current, the two resistors will have non-matching currents, so the voltages across the resistors will no longer be in proportion to the ratio of their resistances.You can use an op amp to buffer the voltage divider, so that it doesn't have to source or sink significant current, and then use the op amp's output to source or sink the required current. There are "rail splitter" ICs which are designed for this purpose, combining the voltage divider with an op-amp in one package, but they usually split the input voltage exactly in half.There are various other possibilities, like zener diodes, linear regulators, switching regulators, charge pump voltage inverters, and more. The "best" solution depends on more detailed description of the requirements.Does your input cover the entire voltage range required? IOW, if you want -2, +12, do you have at least a 14V supply? Is the supply floating? What are your current requirements on each rail? Do you have any particular low noise requirements?

author: facumedica
author_rank: Contributor
timestamp: March 30, 2014, 04:53:19 pm
content: Thanks for your replies! It's for feeding a OpAmp for a PSU, maybe I won't be using this because I found a single supply OpAmp which seems to go to 0v without problems.Otherwise, it will be good to know how to achieve a non symmetrical power. The diodes solution it's quite good and elegant, and "discrete"Other simple circuits? Maybe with an OpAmp and push-pull transistors?Thanks!
Best way to learn about / identify "standard" jellybean parts? - Page 1
Forum section: electronics / beginners

author: xrstf
author_rank: Newbie
timestamp: July 01, 2021, 05:14:23 pm
content: So I am watching a lot of Dave's videos and of course he has oodles and oodles of years of experience. It makes sense that he can look at a board, see a chip marking and can probably tell you within a good ballpark what the chip does.However for me as a beginner (2y tinkering), it's somewhat hard to get a good grasp on the various chip series that get thrown around a lot. "Oh that's a 4000 series chip comparator", "Here's a XYZ123, that classic op-amp!", "it says 1N..., so it must be a diode" etc.So far I managed to read up stuff on Wikipedia regarding "famous" (?) chip series like 74xx, 4000 series and think to know that "78xx" are linear voltage regulators. This is not only relevant to ICs, but also diodes, transistors etc. Is this just the kind of stuff you learn over the years or have I skipped some steps in the selfmade tinkerer playbook?This then affects how I try to find parts for my projects. Even when I know "I need a shift register", I can search for it on my local electronics supplier, but will probably find some exotic chip no one ever heard of. And I might not even have any idea that there is a de-facto standard chip for this purpose that wouldn't necessarily tie me to a random exotic chip from a specific manufacturer.So my question would be, is there some kind of overview or guide to common jellybean parts? The parts that will get you by in 90% of the cases unless you have some very specific requirements, basically. Any tips for searching on digikey/mouser besides "sort by supply", which is currently .... well, yeah. ^^ Should I just bookmark the Wikipedia pages for some series?Sorry if this is kind of rambling, but sometimes I feel like I'm missing part of the "common vocabulary".

author: magic
author_rank: Super Contributor
timestamp: July 01, 2021, 09:23:48 pm
content: Stuff you start to recognize by seeing it used a lot over and over againThere are occasional threads about jellybean parts, like below:https://www.eevblog.com/forum/beginners/jellybean-hobbyist-general-purpose-transistors/https://www.eevblog.com/forum/beginners/classic-chips/For 74 series logic those lists are OK, but you will find that most of the part numbers are obsolete.

author: Jwillis
author_rank: Super Contributor
timestamp: July 02, 2021, 02:45:34 am
content: You can download free PDF's of "Encyclopedia Of Electronic Components volume 1 ,2and 3 ". Or you can buy them , up to you . The three volumes show the most common electronic components , how they work and what can go wrong . Volume 2 has the 7400 series and 4000 series logic gates , flip flops , shift registers and what not .Hope this helps.
Best way to measure current through a PCB trace - Page 1
Forum section: electronics / beginners

author: wardenclyffe
author_rank: Contributor
timestamp: November 01, 2011, 03:28:01 pm
content: I was wondering what is the best way to measure current through a PCB trace. I guess ideally if you were designing your own board you would include test points with jumpers, but what trying to troubleshoot existing consumer products. How can you measure the current without cutting traces? Is there special equipment that exists to do the job or am I missing some obvious way to go about it?

author: Time
author_rank: Frequent Contributor
timestamp: November 01, 2011, 03:33:50 pm
content: http://www.tti-test.com/go/iprober/index.htm

author: IanB
author_rank: Super Contributor
timestamp: November 01, 2011, 03:34:53 pm
content: It's not easy. Must diagnostic tests can be done by measuring voltages or looking at signals at various points on the board without having to break the circuit. The need to measure actual current is quite rare. If it must be done I think you would have to de-solder a component and insert your meter in the circuit at the break. This was easier to do with through-hole components than with SMT components.

author: DaveW
author_rank: Frequent Contributor
timestamp: November 01, 2011, 07:14:19 pm
content: This works brilliantly-I've been playing around with one for the last few days-I can do a quick review if people are interested.There are also other probes that work by using the track itself as a resistor and measuring the voltage drop, using a oddly shaped head, however these are rendered useless by solder resist or similar, and like the TTI, you have to put in the width of the track.The only other method I've used is definitely fiddly-measure the resistance of the track using accurate meter, then place a wire of the same resistance in parallel with the track, measure the current through the wire and multiply by two. Have to careful of the different tempco of the two paths thoughQuote from: Time on November 01, 2011, 03:33:50 pm

author: Psi
author_rank: Super Contributor
timestamp: November 02, 2011, 01:25:21 am
content: There are HALL effect ICs which detect current through any pcb trace that runs under the IC on the boardI doubt they are very accurate in the mA range but might be worth a look.

author: wardenclyffe
author_rank: Contributor
timestamp: November 02, 2011, 05:17:43 pm
content: Quote from: DaveW on November 01, 2011, 07:14:19 pmThanks for all the replies everybody. I would be interested in seeing a review of this product if you are up for it. I am not sure I quite understand how it works.