hybridfree/eevblog-posts huggingface dataset:
Demod on Rigol DSA815 TG - Page 1
Forum section: electronics / beginners

author: geggi1
author_rank: Frequent Contributor
timestamp: October 05, 2014, 01:55:07 am
content: Just got my new toyI have been playing about with it for a few days.Today I tested the demod fonction but can not get any audio form the speaker jack in the fornt.Is there somone here that can cive me some hits.Signal level and impedance ?Stereo or mono jack?Ring center and tip if tereo jack?Regards.Geir

author: Rory
author_rank: Frequent Contributor
timestamp: October 05, 2014, 03:38:41 am
content: Did you remember to turn the earphone ON, in the demodulator menu? It is not turned on by default.

author: Rory
author_rank: Frequent Contributor
timestamp: October 05, 2014, 03:48:24 am
content: This Rigol document will answer your questions.

author: geggi1
author_rank: Frequent Contributor
timestamp: October 05, 2014, 08:34:09 am
content: Tanks that helped a lot.I'll get a mini jack with mono and give it a new try.Do you know anything about the signal levels?Is it enought to drive a speaker directly or will i have to use a speaker with a amp?

author: HighVoltage
author_rank: Super Contributor
timestamp: October 05, 2014, 09:05:01 am
content: I have been using a standard stereo PC headset on the DSA815 and it works well.The sound comes out on both speakers of the headset.As was said already, make sure to turn the Earphone ON and set the Demod Time to a larger than the default 100 ms valueThis way you can very easily listen to all FM stations, at least here in Germany.

author: XFDDesign
author_rank: Frequent Contributor
timestamp: October 06, 2014, 09:31:35 pm
content: The audio output on that jack is designed around a 10kOhm load, not headphones directly, so plug it into your computer instead of headphones.

author: IconicPCB
author_rank: Super Contributor
timestamp: October 07, 2014, 01:28:26 am
content: zero span and tuned in the carrier?Bandwidth wide enough to not reject the signal?
Demux for power selection - Page 1
Forum section: electronics / beginners

author: amangg
author_rank: Newbie
timestamp: January 25, 2018, 12:16:14 pm
content: Hello all,I am designing a multiple solenoid valve control system with each needing 12VDC.I have a single power supply for 12VDC and am thinking of a selector device to switch on and off one solenoid valve or the other. Only one solenoid valve is active at any point of time.Can I use a demux as a selector device ? what should be the criteria for choosing a demux in this case?thank you.aman

author: David Hess
author_rank: Super Contributor
timestamp: January 25, 2018, 03:10:39 pm
content: Demultiplexers are usually logic level devices so they will not drive a solenoid directly. They would require a power transistor on each output.Selecting one output among two more more is usually done by a decoder but demultiplexers can do the same thing and some decoders can be used as demultiplexers. But the same thing about being logic level devices applies.A single pole double throw relay or switch could be considered a 2 line multiplexer/demultiplexor or decoder.

author: danadak
author_rank: Super Contributor
timestamp: January 26, 2018, 09:48:53 pm
content: Google "solenoid drivers", here is one octal example -http://www.st.com/en/automotive-analog-and-power/l9822e.htmlYou have to do thermal calculations to make sure you heatsink it properly.And of course look at specs for current capability.....Regards, Dana.
Denon dra cx3 amplifier - Page 1
Forum section: electronics / beginners

author: sam Kafka
author_rank: Newbie
timestamp: October 17, 2024, 02:35:14 pm
content: Hi to all the members, i am new here and i am searching for some help.A couple of days ago i bought an amplifier from e-bay with a defekt.It is a Denon Dra cx3.The amplifier is not turning on, the power button when pushed is blinking and the screen stays alway off.I know some basic stuff over electronics and i am interested on learning more by practicing on similar projects.I am searching for some guidance and a way to approach this problem in order to learn and spend some good time trying to fix it .So, from where do i start ?Thank you all in advance.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 17, 2024, 04:15:46 pm
content: begin by understanding the service manual for it, check voltageshttps://audiocircuit.dk/downloads/denon/Denon-DRACX3-rec-sm.pdfand sadly this unit use an already made power supply module, find the brand and model ... try to find schematics ...and for sure, i hope you do realize that in this psu, you'll have high voltages ...

author: MathWizard
author_rank: Super Contributor
timestamp: October 19, 2024, 06:48:40 am
content: Being that small, is it a switch-mode PSU ? How heavy is the Denon ? SMPS's are usually a lot lighter.I would remove the PCB's, and check all the voltage rails. Some of them might be deactivated, depending on the problem, maybe only standby power is running, and blinking the light.But everything should power up in a certain order, so it might not get as far as running the display...or maybe the display has the problem. Do you have an oscilloscope ? That can really help, like for watching all the voltage rails on startup.
Depletion mode mosfets in push-pull circuit? - Page 1
Forum section: electronics / beginners

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: June 27, 2018, 01:32:14 pm
content: Is there any reason why, with appropriate biasing, one could not use an enhancement-mode mosfet paired with a depletion-mode mosfet for a push-pull circuit, working with a DC sine-wave (rather than true AC) on the gates?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 27, 2018, 03:29:09 pm
content: "DC sine" is self contradictory."DC" is the part that isn't moving. AC is the part that is moving. These two components are independent. It's not meaningful to make a distinction between "DC", "pulsed DC", "AC" and so on, without supplying further meaning (i.e., "pulsed DC" is usually meant to mean a DC source turning on and off, i.e. the source resistance varying widely, which has different effects on different kinds of loads, hence it's not to be used as a general term).If you mean simply biasing the gates wherever as needed, and you mean using the same polarity (e.g. both N channel), then you must:- Supply complementary polarity AC, because one is a source follower (noninverting) and the other is common source (inverting)- Either supply equal amplitudes to the gates, with isolated drive to the high side gate (effectively turning it into a common source configuration), or setting the drive amplitudes (with respect to ground) inversely proportional to the average gains of each transistor (because gain(source follower) ~= 1, while gain(common source) might be ~20.Solutions to these problems are ancient, because vacuum tubes are only depletion mode N channel. Consider these:- White CF- SEPP (single ended push-pull)- Mu follower- Futterman OTL(and others I've probably forgotten)Tim

author: TheBaconWizard
author_rank: Regular Contributor
timestamp: June 27, 2018, 03:59:44 pm
content: Having briefly researched the things you suggest, it seems at first glance like a Single-ended push-pull kind of idea is going to be ideal, thanks
deploying programms wit mbed studio  - Page 1
Forum section: electronics / beginners

author: benny
author_rank: Newbie
timestamp: March 31, 2020, 06:38:43 pm
content: Dear forum usersI have a little probably verry stupide question regarding mbed studio.How do I upload programms for mbed studio to a mbed enabled dev board.I pressed the play button in build, release and debug build profileand nothing happens on the dev board that i plugged in.So my question is what am I doing wrong?thank you in advance and with best regards Ben

author: rstofer
author_rank: Super Contributor
timestamp: March 31, 2020, 08:31:19 pm
content: I haven't used MBED Studio but the online system compiles and creates a .bin file which is downloaded to the PC by automagic. I assume Studio just creates it in some directory (of your choice). This file is simply dragged and dropped onto the board which should show up as a disk drive in File Manager.Does the board show up as a disk drive in File Manager?Is there a .bin file created by Studio?

author: benny
author_rank: Newbie
timestamp: March 31, 2020, 10:23:45 pm
content: Yes there is and tried the dragging it to the board but notting happens again. And I know this program works in the online edditor.Thanks for the help end with best regards Ben

author: rstofer
author_rank: Super Contributor
timestamp: April 01, 2020, 02:14:24 am
content: Do you see a directory listing for the mbed device in File Manager?

author: benny
author_rank: Newbie
timestamp: April 01, 2020, 01:17:33 pm
content: do you mean the file manager for windows? If so Yes, If you mean in mbed studio no( see included screenshots)

author: benny
author_rank: Newbie
timestamp: April 01, 2020, 01:18:09 pm
content: Sorry if forgot to include the second screenshot

author: rstofer
author_rank: Super Contributor
timestamp: April 01, 2020, 05:23:37 pm
content: Why can't you copy and paste (or drag-drop) test.bin into the directory of the target (E:/) and then press the 'reset' button?
Derating caps for charge pump - Page 1
Forum section: electronics / beginners

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 22, 2015, 03:54:47 am
content: I'm a bit uncertain about capacitor voltage ratings in a charge pump scenario.I don't want to waste space, but I know that ceramic capacitors need to be seriously derated as their capacitance droops as we come close to their rated voltage...So in relation to the voltage output of the charge pump, how should the capacitors be rated? Does the switching frequency affect this choice?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 22, 2015, 07:44:30 am
content: Switching frequency affects value but not voltage.Typically, if you'll be choosing X7R type caps (I wouldn't recommend anything worse e.g. X5R, Z5U), using no more than third or half of rated voltage is recommendable.For a charge pump, you can use excessively large values for the operating frequency (assuming the chip is OK with this) and current flow will be limited by channel resistance of the switches, rather than reactance. The only consequence of using nominal value (or less) capacitances is increased supply resistance.Unless you're severely constrained on cost and space, I should think this isn't a problem; charge pumps are rarely used beyond +/-12V or so, and at low currents (< 10s mA?). A regular 0805 at 50V and 0.1uF should be a good starting point, or up to 1uF in the same size I think. You'd have to compromise on value, voltage or performance to use smaller or cheaper parts.Tim
Derivation of stability criterion for type 3 digital PLL - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: November 23, 2018, 04:32:40 am
content: Could anyone help to derive the following expression (4.23) which is the stability criterion for type 3 digital PLL ?Note: Screenshots are taken from Floyd Gardner's book : Phaselock Techniques 3rd Edition
Derivation of time constant expression - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: July 05, 2024, 03:39:27 pm
content: How to derive the time constant expression (13) inside the paper :High-performance crystal oscillator circuits: theory and application?

author: m k
author_rank: Super Contributor
timestamp: July 14, 2024, 05:38:31 pm
content: https://www.sciencedirect.com/topics/mathematics/rlc-circuit

author: promach
author_rank: Frequent Contributor
timestamp: August 01, 2024, 07:51:10 am
content: Complete step-by-step derivation from gpt4:
Deriving Equations from Chua's 1971 Memristor Paper - Page 1
Forum section: electronics / beginners

author: Mattjd
author_rank: Regular Contributor
timestamp: May 28, 2017, 12:39:43 am
content: I'm going through Chua's 1971 memristor paper. I am stuck on a part that I believe in pretty crucial. It isObserve that the, value of the incremental memristance (memductance) at any time to depends upon the time integral of the memristor current (voltage) from t = - co to t= to. Hence, while the memristor behaves like an ordinary resistor at a given instant of time to, its resistance (conductance) depends on the complete past history of the memristor current (voltage). - Page 511(page 5 of the pdf) top of the right columnhttp://www.cpmt.org/scv/meetings/chua.pdfI'm not seeing the integral from any of the equations 1 through 4 that are presented in the paper.When I read the section in question, this is what comes to mind, but I cannot see the derivation. Am I thinking about this incorrectly?To expand further on what I have triedDoes anyone see anything glaringly wrong with my math? Is it a physics thing possibly? I'm not seeing how current gets into this at all. I realize memristors is a rather newish topic that not many people are aware of or even care about.

author: ironmonkey
author_rank: Contributor
timestamp: May 28, 2017, 01:18:20 am
content: If you look q(t) as a variable of the phi(t) (by composition), you get the first axiom equals M(q(t)) replacing it in 2. If you replace tau by t is right there. Is that ok or am I wrong with your question?Enviado desde mi MotoG3 mediante Tapatalk

author: Mattjd
author_rank: Regular Contributor
timestamp: May 28, 2017, 01:48:44 am
content: Would it be too much to type it up? Please.

author: Mattjd
author_rank: Regular Contributor
timestamp: May 28, 2017, 01:59:52 am
content: The q(t) subscript denotes the with respect to q(t), prime is with respect to t.at this point, if you apply a 2nd iteration of integration by parts, you can go two ways, let the anti derivative be q'(t), in which case you are back to square 1 or you can apply n iterations to v'(t)_q(t)
Deriving equations from the MOSFET Characteristics curve - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: April 13, 2025, 05:03:44 pm
content: Hello Guys,I can't understand some parts of the MOSFET static characteristics curve. Here the equation given for the Triode region for the characteristics curve of the MOSFET is VP≤ VGS ≤ 0 andVDS ≤ VGS-VP. My question is How I can find these two equations by looking at the graph? Or it would be better if someone could explain how to determine these two equations by analyzing the graph shown in the picture.
Deriving formulas for calculating the errors that occur in the measurement circu - Page 1
Forum section: electronics / beginners

author: bibizyana
author_rank: Newbie
timestamp: May 14, 2023, 06:23:09 pm
content: Hello! I need to derive formulas for calculating the errors that occur in the measurement circuit with a two-wire and three-wire resistance thermometer connection scheme. But, unfortunately, I have almost no values except for α (temperature coefficient of the resistance converter), constants A, B and C, the nominal value of resistance R0 at a temperature of 0° C and table values of resistance for certain temperatures. Where can I find some information about it? I will be very grateful for any answer. Thanks in advance.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 14, 2023, 06:38:26 pm
content: Error occurs simply due to wire and connector resistance, so formula is simple, R_indicated = R_true + R_wire. If you have a table of resistances for certain temperatures, just add the wire resistance to those values and directly look up the indicated temperature. 3-wire differs from 2-wire such that you only add thedifferenceof resistances between the two main wires and connectors.The challenge is to know the wire and especially connector resistances. With wires, it's possible to look up to maybe some +/- 20% accuracy if you know the wire gauge, but connectors are worse, manufacturers only give worst case numbers, and connectors age and give different contact resistance on each insertion.If you think about it, if it was easy to calculate the amount of error, there would be no need for 3- or 4-wire measurement - just calculate and remove the error. But 3- and 4-wire measurement is needed exactly because the error is unknown and cannot be calculated because of lack of knowledge into the wires and connectors used.

author: jwet
author_rank: Frequent Contributor
timestamp: May 15, 2023, 07:57:46 pm
content: National Semi (now TI) had good app notes about applying RTD's and related with 2,3 and 4 wire type connections. I think they went through some of this. Its mostly just basic plug and chug kind of DC analysis and algebra taking all the parasitic wiring resistances, etc into account. Sharp pencil, lots of paper and a red bull like sophomore circuits courses. Go out after you finish and get blind drunk, you can relive the whole college experience... Good luck.
Deriving Key Expressions for Optimizing CMOS Buffer Amplifier Design - Page 1
Forum section: electronics / beginners

author: curiousmind
author_rank: Newbie
timestamp: September 12, 2024, 02:09:01 pm
content: Above is the internal circuit of a CMOS buffer. The firs stage is a differential amplifier. The second stage takes the differential output of the first stage and sends a converted single ended signal to the output driver stage which is a source follower. RC and CC are the compensation elements where RC is a resistor and CC is a capacitor. There are some MOS switches: SW1, SW2 and SW3 to ensure proper activation deactivation of the circuit. When NEN=0 the circuit is enabled. I1 is variable current source which controls the tail current of the first stage. The circuit must be capable to drive 1pF capacitive load and a constant current load of 100µA-1mA.Notice the feedback connection from Vout to the input of P2Solve the circuit and create generic expressions which you can use to do hand calculations of the design.Derive expressions for• Gain of the circuit• Minimum common mode input• Maximum common mode input• Output and Dynamic Range• Slew Rate• Expressions for poles and zeroes of the system• Gain BW and Phase MarginAlso try to derive expressions to help you size the compensation network.

author: Benta
author_rank: Super Contributor
timestamp: September 12, 2024, 06:24:16 pm
content: I don't do homework, sorry.
Deriving Op Amp Output Equations - Page 1
Forum section: electronics / beginners

author: TeddyPython
author_rank: Contributor
timestamp: September 15, 2019, 11:19:34 pm
content: I'm learning about the basics of op amps - at the moment looking into using them to remove or add offsets. However I'm struggling with deriving a 'general-case' equation for such a circuit for gain and why it offsets the way it seems to in simulation.Using a standard op amp model I found that, for an inverting amp, applying a voltage, Vx, to the non-inverting input would offset the output by 2Vx without affecting the gain.I tried deriving the gain equation, as shown in my attachment. When the inverting input is 0V, the Vp terms disappear nicely - but in this case they don't... Instead I am juggling Vout by (5) and have no idea where it goes from here...Also, as far as it comes to figuring out why the offset is twice the voltage at the +'ve terminal - I have no idea where to start.Any further explanation would be really appreciated.

author: magic
author_rank: Super Contributor
timestamp: September 16, 2019, 06:41:24 am
content: Firstly, gain is Vout/Vin rather than Vin/Vout, but that doesn't really matter.Secondly, you made the mistake of trying to calculate DC gain. Of course if the input is 1V and the offset is 1000V, the DC "gain" of the whole circuit will be about 1000x. That's not really a useful spec to have at allCalculate the AC gain, which is how much the output varies when Vin varies. This is probably what you want to know.It may be helpful to observe that Vout=Vin+(R1+R2)/R1·(Vp-Vin).
Deriving Transfer for function for Circuit (Impedance Matching) - Page 1
Forum section: electronics / beginners

author: Mattjd
author_rank: Regular Contributor
timestamp: April 26, 2020, 04:06:27 pm
content: Hi, I'm working on impedance matching circuit for RF. I determined using a smith chart a possible topology and what the values of the L matching network are. I am now trying to derive the transfer function so I can plot the frequency response of the circuit.I worked out the first half, but am having trouble determine what impedance 1 should be for the second second voltage divider. I realize impedance 2 is just the load resistor.https://imgur.com/a/iNDb4lC
Descrete Voltage Regulator for microcontroller - Page 1
Forum section: electronics / beginners

author: dutchboy
author_rank: Newbie
timestamp: December 28, 2013, 12:28:01 pm
content: Hi all,Thanks for taking the time to read this.I have an Attiny45 programmed to flash some banks of leds, using transistors as switches, that are running off of a 9v PP3 battery supply and i also want to run the Attiny off of this supply. I had a look round and could use a LM7805 linear regulator but wondered if there was another option. I had a look at zener shunt regulators and that is an option but means i need to go and get another set of zeners(im lazy and always looking for alternatives!).I was playing around in iCircuit on my iPad and came up with the schematic attached, i just wondered if any of you have used similar circuits or any reason why this circuit is a bad idea (i am a noob at electronics). The simulation seems to work well but it is just an iPad app.The 2n2907 PNP is added to allow the regulator circuit more current, its possibly overkill but thought i would add it anyway.I hope i have explained myself well enough.Thanks,Ian.

author: digsys
author_rank: Unknown
timestamp: December 28, 2013, 12:44:36 pm
content: Problem with that circuit is - NO actual regulation. As the 9V battery drops, so too will the output !Don't fool around, use an LM7805 or 7805L (up to 100mA) :-)

author: fcb
author_rank: Super Contributor
timestamp: December 28, 2013, 01:07:04 pm
content: That 2907 looks useful..Where exactly is the regulation?

author: IvoS
author_rank: Frequent Contributor
timestamp: December 28, 2013, 01:10:49 pm
content: I think you could use a zener diode instead of 680 ohm resistor.

author: dutchboy
author_rank: Newbie
timestamp: December 28, 2013, 01:13:06 pm
content: Great thanks for the replys will go with the 7805!! told you i was a noob!!! lol thanks all

author: dutchboy
author_rank: Newbie
timestamp: December 28, 2013, 09:28:18 pm
content: @fcp apologies if I habe offended you in some way. I believed this was in the beginners part of the forum and therefore posted a question as a beginner in the hope of some guidance.
Descriptions of feedback systems-terminology - Page 1
Forum section: electronics / beginners

author: Kirill V.
author_rank: Regular Contributor
timestamp: February 09, 2020, 12:28:24 am
content: Hi friends,Let's discuss different terminologies of the description of amplifiers with feedback. This will help me systematize and refresh my knowledge. I am familiar with both Russian and Western terminology in this area from different eras. And they differ both in epochs and in principle.1) So, the termfeedback depth. It can be expressed in decibels and percentages. How to calculate? What's the point?2)The termfeedback coefficient. Also called thefeedback factor. I think it's the same thing, right? Thefeedback factoris expressed by the formula (1+A*beta). Russian notation (1+K*beta).What these letters mean and what the sign depends on I know, you can not explain it. But for some reason in the earlier literature I find the termcoefficient, and in the newer literature it is afactor. I want to be sure that it's the same thing.

author: Kirill V.
author_rank: Regular Contributor
timestamp: February 09, 2020, 02:35:51 pm
content: The termfeedback depthis used in Western countries? Maybe it's cause you have a misunderstanding?
Design a Basic Circuit - Page 1
Forum section: electronics / beginners

author: grantw34
author_rank: Newbie
timestamp: August 18, 2012, 07:26:15 am
content: Hi thereI am looking for some assistance to design a fairly basic 12v circuit.I have the skills to assemble but not to design itI have a 12v keypad from a car immobiliser kit that I wish to use to operate 2 1v solenoids, to lock and unlock my shed doors.I can post any required drawings, just let me know.Thanks

author: Rerouter
author_rank: Super Contributor
timestamp: August 18, 2012, 08:24:46 am
content: 1V solenoids? that is awefully low, at what current? ,even so a dropping resistor on each should be all you need to adapt it, hook the battery and negative wires up to a 12V battery, being its use it can be a far lower capacity even 2 6V latern batteries in series, and as long as it isnt looking for any other signals it should just be click on click off,

author: TerminalJack505
author_rank: Super Contributor
timestamp: August 18, 2012, 07:27:50 pm
content: You might get more help if you can give people a better idea of your requirements.Can you explain theuse cases? That is, what does the user do when interacting with the system and how does the system react?What kind or electrical requirements do you have? Is this going to run off battery power? Mains power? Both?How many digits for the passcode? Is the passcode programmable? Does entering the passcode when the doors are unlocked, lock the doors or is there a different procedure to lock the doors?Is there going to be some special key(s) to use to start/stop the passcode?More information regarding the keypad will help too. What kind of (electrical) interface does the keypad have? What keys? Why, specifically, is it 12V? Most keypads are just a matrix of switches and aren't voltage specific.

author: TerminalJack505
author_rank: Super Contributor
timestamp: September 06, 2012, 03:55:51 am
content: I thought it would be interesting to see how simple (or not) it would be to design a passcode circuit using just 74HCxx components. Here's what I came up with.It comes to 32 chips, by my count. I breadboarded it and it seems to work fine. I had to use substitutes (4000-series, 74F-series and 74xx-series, for example) for a few of the parts since I didn't have what I used in the schematic, which is pretty much just 74HC-series parts.Naturally, this isn't how such a thing would be done these days. Kids these days would, of course, use a highfalutin microcontroller or CPLD or FPGA. This is how real men would have done it in the 1970s and 1980s. *grunt*

author: TerminalJack505
author_rank: Super Contributor
timestamp: September 23, 2012, 03:09:02 pm
content: In case anyone is interested, here's the latest version of this circuit. I'll probably tear down the project soon since I used practically every breadboard I own to make it and will need them sooner or later.
Design an enclosure for a small DC motor to decrease noise? - Page 1
Forum section: electronics / beginners

author: engineheat
author_rank: Frequent Contributor
timestamp: December 19, 2018, 02:18:48 am
content: This is for a hobby project. A small DC motor is battery powered. The motor is geared and it produces a bit of noise at high speed. The goal is to design an enclosure for it so that the output shaft protrudes out and drives a load but the noise is largely dampened or isolated.Any suggestions? For example, should there be a lot of air surrounding the motor inside the enclosure or it's better to fill it solid with a dampening material?Thanks

author: cdev
author_rank: Super Contributor
timestamp: December 19, 2018, 03:01:19 am
content: Quote from: engineheat on December 19, 2018, 02:18:48 amRigid foam is a good sound dampener. you can put it underneath the supports to prevent vibrations making their way to the floor. (thats the main medium for sound propagation, if something is resting on it)Wood is good too. Another option is hanging motor containing things from chains or bungee cords.
plz tell..design failure modes of TFT - Page 1
Forum section: electronics / beginners

author: d_n
author_rank: Newbie
timestamp: May 15, 2014, 09:24:49 am
content: what could be the design failure modes,effects and preventive measures regarding TFT modules..?

author: matmay
author_rank: Newbie
timestamp: May 21, 2014, 11:42:05 am
content: I don't understand your question.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 21, 2014, 11:32:21 pm
content: Smashy-smashy hammer shatters the glass, for one.Well, you didn't specify WHAT kinds of failure modes you wanted to know about......Also, if you're doing FMEA, shouldn't you, oh I don't know, do your homework somewhere other than an *internet forum*? The pertinent regulatory agencies would love to see *that* particular paper trail I'm sure.Tim

author: Dinsdale
author_rank: Regular Contributor
timestamp: May 22, 2014, 12:17:48 am
content: Designfailure? Did you design one and it didn't work?
Design help required - How to vary output amplitude of a square wave - Page 1
Forum section: electronics / beginners

author: Everton
author_rank: Contributor
timestamp: January 31, 2015, 03:25:55 am
content: Hi,I have a DDS board outputting a sin wave from essentially Dc up to 20Mhz. I want to produce a variable amplitude square wave from this.I am generating the square wave using a comparator, and by changing the reference voltage I can vary the duty cycle. So far so good. Now that I have a square wave of say 5V peak to peak, I want to vary its amplitude from 0 to 10 V (using a microcontroller) and keep the output impedance at 50 ohms.My 1st thought was to setup an amplifier with a fixed gain of say 3 and precede this with a variable pi attenuator. I modeled this in spice and using a JFET in the triode region for the center leg of the T, but I couldn't get the dynamic range I was looking for. (ie. I couldn't get close enough to 0 and 10). Further, my amplifier's bandwidth was nowhere near good enough for the slew rate of a 10V signal at 20MHz!I also thought about simply pulling the comparator up with 50 resistor and calling it a day, but at 10V that 2W through the poor little comparator when it is sinking current!Am I missing something, or is this problem harder than it seems?!Thanks

author: vaualbus
author_rank: Frequent Contributor
timestamp: February 19, 2015, 11:08:48 am
content: I was looking at almost the same last year for a school project. At the end due to time limitation I bot care about amplitude control.by the way i think you could do is use a differential amplfier made by two transistor. Varying the collector current result in a amplitude changing.

author: kizzap
author_rank: Unknown
timestamp: February 19, 2015, 11:56:14 am
content: I would think that a resistor divider to bring the "High" voltage down to your minimum output voltage, then control the amplification of that signal somehow? Alternately, you can amplify the voltage output of the comparator, and then attenuate that signal somehow.You seem to be a few steps ahead of where I am up to in designing a function generator it seems.

author: vaualbus
author_rank: Frequent Contributor
timestamp: February 19, 2015, 01:30:50 pm
content: Ya at the end last year I made somethingh working but it not so finished I have a strange software error that lock the pic I use so you need to restart it. But I have present the project and passed the year.It should be a digital controlled function generator.I was very unluck at the end three days before the exam my pic decide to become a shorted circuit and in the way it have also destroyed the graphical display I was using.

author: ConnorGames
author_rank: Regular Contributor
timestamp: February 19, 2015, 08:39:14 pm
content: A concept schematic is attached. It may or may not work!Using a MOSFET driver is probably overkill unless you want a fair bit of power without the buffer amp, in which case you should also beef up the ADC buffer and buy a large heatsink
Design Question - Page 1
Forum section: electronics / beginners

author: Shale
author_rank: Contributor
timestamp: February 01, 2012, 03:18:34 pm
content: I was looking at Daves power supply design. I have looked at both rev A and rev B and there is something I can not figure out why it was done. If you look at rev B on the ADC, the op amps have different voltage sources. One has the voltage source, while the other also has a cap and a ground. It i the same with the op amps in the PUS area of the schematic as well. Why is this?

author: benemorius
author_rank: Regular Contributor
timestamp: February 02, 2012, 04:51:35 am
content: Those are decoupling (aka bypass) caps. They appear on only one of the two opamp symbols because each pair of opamps is actually contained within the same IC and that IC has only one power pin to be bypassed. Notice how the opamps near the ADC are labeled U12A and U12B rather than U12 and U13. This is to designate that they are two parts of the same package.

author: Psi
author_rank: Super Contributor
timestamp: February 02, 2012, 05:45:41 am
content: Also, if you're trying to understand the circuit then be aware. There was an error in one of the revisions, cant remember which, it was in the video.One of the opamps had its inputs reversed.

author: Rerouter
author_rank: Super Contributor
timestamp: February 02, 2012, 06:23:57 am
content: it was revB, he cut the wrong trace while pretty-ing it up for us

author: Shale
author_rank: Contributor
timestamp: February 02, 2012, 12:24:40 pm
content: Quote from: benemorius on February 02, 2012, 04:51:35 amOk. that makes better sense. Thank you for clarifying that for me.

author: chrome
author_rank: Regular Contributor
timestamp: February 02, 2012, 06:31:00 pm
content: Quote from: benemorius on February 02, 2012, 04:51:35 amWait, did dave forget bypass caps in his original design?

author: amspire
author_rank: Super Contributor
timestamp: February 02, 2012, 11:44:56 pm
content: Quote from: chrome on February 02, 2012, 06:31:00 pmBypass capacitors are not required on every op-amp package, but it is just a good idea. With bypass capacitors, you tend to want to have too many rather then too few.
Design recommendation for solder mask openings for smd devices.  - Page 1
Forum section: electronics / beginners

author: Fflint
author_rank: Frequent Contributor
timestamp: January 02, 2021, 03:55:08 pm
content: Hi,I've been looking online for some materials discussing benefits of using solder mask openings of various sizes, but all I found were few manufacturability guides. What I'm looking for is advice on what is best and when rather than manufacturing capability.Component manufacturers publish documentation for preferred solder mask expansion for individual pads, but I saw boards that use solder mask openings that encompass entire package rather than just pads. For some components like passives I don't have an idea why anyone would prefer to leave a narrow Web between pads vs not (beyond the obvious : if there is a trace there put solder mask over it).What is a good set of rules to follow when designing hobby-level pcbs with solder mask?

author: wraper
author_rank: Unknown
timestamp: January 02, 2021, 04:07:48 pm
content: The best is to have solder mask enclosing the pads as tight as possible. However not every fab can produce solder mask precise enough to place it in between of tightly spaced pads. If you do not use components with <= 0.5 mm pin pitch or 0201 passives, you don't need to bother with removing it between pads. Even cheap fab should be able to produce it.
design  simple amp - Page 1
Forum section: electronics / beginners

author: NASK
author_rank: Contributor
timestamp: July 16, 2018, 03:26:09 am
content: i need to understand basic bjt amplifier concept therefor I design this simple amp but i didn't getting required out put using calculation values. could i know reason for it? (i have attached the calculation & out puts)furthermore, using Cin & Cout calculated value didn't come to at least near to the required output value. but change it to Cin 10uF and Cout 15uF it pass the 1V peak but not come to 2V peak (design value) .Is it not possible to achieve Av=200 from Bc548

author: oPossum
author_rank: Super Contributor
timestamp: July 16, 2018, 04:03:15 am
content: 2N2222 has much lower Hfe than BC548

author: Zero999
author_rank: Super Contributor
timestamp: July 16, 2018, 08:09:56 am
content: Use lower resistor values for the biasing potential divider, if possible, so the Hfe is less of a factor.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 16, 2018, 08:16:08 am
content: For AC the R5 is effectively parallel to R1 and thus the gain is reduced.

author: LvW
author_rank: Frequent Contributor
timestamp: July 16, 2018, 04:03:37 pm
content: Without any external load - and assuming that all capacitors are large enough for coupling the 1kHz - the actual gain isAv=-6k/25=-240.Because I do not see that the load is specified, the remaining task is to find the proper load resistor for reducing the gain to -200.That is a simple task.In case, the load is given the effective gain determining resistor is 6k||10k=3.75 kohms and the gain can never reach the value of -200.(Av=-3.75k/25=-150) .Comment: Modifying the base resistors cannot help at all because it is the transconductance (gm=1/re) that matters only (as far as gain is concerned).

author: NASK
author_rank: Contributor
timestamp: July 17, 2018, 03:51:43 am
content: Thank you all for support.I did a mistake calculating Cin coupling cap & it needs to be correct as 1/zin = (1/R3) + (1/R4) + (1/β*re). Not the 1/zin = (1/R3)+ (1/R4)+ (1/β*(R2+re) now Cin is 75nF.Hi LvWI made a mistake to choose external load thank you for reminding. therefor I use this equation Av=Zout/ (re+Ze) instead of Av=Zout/ (re); because if Zout < R1 voltage gain is reduce by R5 however if R5 >>R1 load make little effect on gain.Therefor I take re+Ze value as 29.5Ω (true value is 30Ω) otherwise R5 become infinity.Av=Zout/ (re+Ze)Zout=5.9kΩR5=Zout*R1/(R1-Zout)R5=354kΩ(proper load )C1=1/2πf Zout = 27nF200mv out is coming @1mv input . when changing to 10mV input output is not symmetrical why is it? .
Design Software - Page 1
Forum section: electronics / beginners

author: Gmm213
author_rank: Contributor
timestamp: January 10, 2018, 06:47:53 am
content: I am wondering if anyone can recommend a simple lightweight program for creating blueprints for projects? I am wanting to use my Asus 2 in 1. I have touchscreen capability and run Windows 10

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 10, 2018, 07:02:21 am
content: When you say "Blueprints", what do you mean? Schematics? PCB Layouts? Mechanical drawings? The program you might want to use will be different for each (and even within the types there will be different choices based on what specificly you want).

author: Gmm213
author_rank: Contributor
timestamp: January 10, 2018, 07:19:46 am
content: Sorry about that. I mean schematics

author: tooki
author_rank: Super Contributor
timestamp: January 10, 2018, 07:45:28 am
content: There’s an entire forum about this, dude...https://www.eevblog.com/forum/eda/
Design your own SMU - Page 1
Forum section: electronics / beginners

author: ggtx
author_rank: Newbie
timestamp: April 25, 2017, 01:21:59 pm
content: Hi all, just discovered this amazing forum :-) pleased to meet you all.Since time I am curious to deep understand how a SMU are done and designed, and I found the video from Dave where is opening the box of the Keithley 2400:In another topic this user aims to build its own SMU:http://www.edaboard.com/thread364430.htmlwith a reply discouraging him :-) Someone knows something like tutorials, thesis, datasheet or something more detailed about the idea?Thank you in advanced. GTx.

author: Avacee
author_rank: Unknown
timestamp: April 25, 2017, 01:25:35 pm
content: Link doesn't work - remove the "," at the end.Without comma:http://www.edaboard.com/thread364430.html

author: helgel
author_rank: Newbie
timestamp: August 21, 2018, 12:55:41 pm
content: I've also played with the idea of designing a SMU. Found that it's way above my competence level... However, a few months ago I started to collect info, links etc. It's just unstructured info, but might be useful for others. At least I learned a lot.https://poormanssmu.wordpress.com/research/

author: schmitt trigger
author_rank: Super Contributor
timestamp: August 21, 2018, 01:10:04 pm
content: Welcome to the forum,any information about SMUs you find, please share it here.

author: exe
author_rank: Unknown
timestamp: August 21, 2018, 05:47:26 pm
content: I'm not building an SMU, but a PSU with some sinking capability and multiple (dual) current range and small output capacitance.I'd say the first step to build an SMU is to define desired specs (voltage/current ranges, set/readback resolution and accuracy, bandwidth, protection, etc). As I see it, you just take a "regular" power supply and "upgrade" it until it meets your specs.I wouldn't go down to microvolts and nanoamps for the first build. Also don't expect it have 5+digit accuracy. Reading voltnuts' articles helps a lot in understanding challenges.

author: David Hess
author_rank: Super Contributor
timestamp: August 21, 2018, 07:35:26 pm
content: Also take a look at old documented curve tracer designs. They faced a lot of the same problems and solved them in the same ways.
designing a 1:1 isolation transformer - Page 1
Forum section: electronics / beginners

author: electronics man
author_rank: Frequent Contributor
timestamp: July 14, 2015, 07:18:30 pm
content: i want to make a 1:1 transformer, i have a 4250nH core, how many turns of wire will i need at approximately 50KHz?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 14, 2015, 09:15:56 pm
content: What are you isolating? Does it carry DC? Sine, square, ... waveform?How big is the core (l_e, A_e, A_w)? How much loss does the material have at that frequency?Ed: mods, suggest merge withhttps://www.eevblog.com/forum/beginners/transformer-core-inductance/?topicseenTim

author: electronics man
author_rank: Frequent Contributor
timestamp: July 14, 2015, 10:30:08 pm
content: http://www.rapidonline.com/Electronic-Components/4250nH-MagDev-RM10-F48-Ferrite-Core-67-1025this core and it will be a 12v square wave with no dc component

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 14, 2015, 11:52:33 pm
content: 3 turns or more.

author: electronics man
author_rank: Frequent Contributor
timestamp: July 15, 2015, 09:16:47 am
content: Quote from: T3sl4co1l on July 14, 2015, 11:52:33 pmhow did you work that out?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 15, 2015, 09:29:59 am
content: N = Vpk / (4 * Bmax * F * Ae)Lots of resources online, e.g.http://seventransistorlabs.com/tmoranwms/Elec_Magnetics.htmlTim
Designing a better multimeter video concern - Page 1
Forum section: electronics / beginners

author: fedimakni
author_rank: Regular Contributor
timestamp: June 22, 2020, 02:18:47 am
content: Hello,I am interested in Designing a better multimeter video link:But i was confused in the part where we need to switch the mosfet on and off.Depending on dave we could switch the mosfet from external uC for example but the 5V or 3.3V logic will have a GND level at the gate different than the source so do that will cause problem in switching the mosfet how we could solve this kind of problem?Thanks

author: tooki
author_rank: Super Contributor
timestamp: June 23, 2020, 03:48:42 pm
content: Others correct me if I’m wrong, but I think that since MOSFETs are voltage controlled devices, the extra resistance to ground doesn’t change the voltage present at the gate. It’ll just limit current, meaning the gate capacitor will charge more slowly, which will make no difference in this application.
Designing a boost converter - Page 1
Forum section: electronics / beginners

author: 0xC6
author_rank: Newbie
timestamp: January 30, 2019, 01:45:04 pm
content: Hey, I'm trying to desgin a boost converter to boost the voltage from 6 18650 cells in parallel to 5v and up to 6,5A out.I'm relatively new to designing electronics but I do know the principle of how a boost converter works, however I'm having a bit of trouble deciding on a regulator for it.I have looked into the MC34063A but I don't know if there are better alternatives for regulators?If you could give me some suggestions/alternatives that'd be greatly appreciated!

author: Buriedcode
author_rank: Super Contributor
timestamp: January 30, 2019, 02:41:14 pm
content: He said parallel, so the input would be 4.2V down to ~3.1V (3.0 cut-off is generally safe). Although givne possible issues with cell balancing I would recommend that the OP does indeed use the cells in series and use a buck converter. Having them in parallel, and for 6.5A out, assuming a 90% efficiency, the input power would be (5V*6.5A)/ 0.9 = ~ 36W. With an average input voltage of 3.7V thats roughly 10A in, which is quite a lot to design a boost converter for.OTOH, as spec assumed/suggested, if you have the cells in series, your input range is from ~18v - 25V. Average 3.7V* 6 = 22.2V. With an input power of 36W, that gives an input of 36/22.2 = ~1.6A which is much easier to deal with, but will beyond the capability of the old MC34063A. Even with an external switch, its efficiency would be pretty poo. There are much "better" devices out there (by better, I mean, more expensive, but higher efficiency, higher switching speed, which means small inductor/caps and more features like protection).Since national semi were taken over by Texas Instruments, you can use their "bench designer"http://www.ti.com/design-tools/overview.htmlI'm not a fan of it myself but it can at least show you options.A 40-50W buck converter designed for 24V in and 5v out could work, but the market is flooded with modules like this, with few actual specs posted, so they could be awful or work jsut fine, I don't know.

author: spec
author_rank: Frequent Contributor
timestamp: January 30, 2019, 02:47:14 pm
content: Quote from: Buriedcode on January 30, 2019, 02:41:14 pmArrraagh. Thanks will delete my post.

author: Buriedcode
author_rank: Super Contributor
timestamp: January 30, 2019, 03:24:26 pm
content: Quote from: spec on January 30, 2019, 02:47:14 pmNo!! As I said, it is far better for series connection, so your post was perfectly valid - I wasn't having a go

author: Kasper
author_rank: Frequent Contributor
timestamp: January 31, 2019, 08:45:00 am
content: Perhaps a little of both would be best. 3P2S (3 parallel 2 series) and a buck converter.

author: hsn93
author_rank: Regular Contributor
timestamp: January 31, 2019, 08:53:52 am
content: Quote from: spec on January 30, 2019, 02:47:14 pmunfortunately, i think its nice to edit it and say this post was wrong or putstrikelineon it.. its very helpful for us to learn from others..