hybridfree/eevblog-posts huggingface dataset:
Communicating with ADS131M04EVM over SPI with EK-TM4C129EXL - Page 1
Forum section: electronics / beginners

author: vivianjoshua
author_rank: Newbie
timestamp: April 21, 2025, 10:08:25 am
content: Hello All,I am very new to embedded environment, so please bear with me.I am trying to read the values at all 4 channels of my ADC (ADS131M04EVM) using the EK-TM4C129EXL board. I am trying to do this over SPI.I found some work from Texas Instruments here:https://github.com/TexasInstruments/precision-adc-examples/tree/main/devices/ads131m08This work was integrated (or at least an effort was made) with the Blinky example that comes with TivaWare.Unfortunately, owing to my limited knowledge in the field, I am a bit stuck and clueless with what to do next.I tried calling the adcStartup function, but I do not know if it even works, and how can I read the values of the ADC in realtime.Can someone please help me? You can find my work on Github here:https://github.com/vivianjoshua/TM4C129WithADS131M04I would immensely appreciate some guidance on this. Looking forward to your responses.Sincerely,Vivian

author: PGPG
author_rank: Frequent Contributor
timestamp: April 21, 2025, 11:03:11 am
content: I have never written even a single line of embedded environment code.Few years ago my brother bought USB - logic state analyzer. Sorry I can't identify it in any way. I only know that is very small box having 8 or 16 input lines and the price was about $10.I think such device is what you probably need to be able to analyze SPI communication down to each byte (or bite) level. When you see what is going on at communication port you have a chance to find the reason of problems.

author: xvr
author_rank: Frequent Contributor
timestamp: April 21, 2025, 04:13:07 pm
content: QuoteUse function readData
Communication Protocols Review - Page 1
Forum section: electronics / beginners

author: pccmd
author_rank: Newbie
timestamp: November 04, 2012, 09:18:03 pm
content: Would appreciate suggestion re: educational materials on USART vs SPI vs I2C.Thanks in advance.

author: Simon
author_rank: Unknown
timestamp: November 04, 2012, 09:33:00 pm
content: erm, as in ? try looking up the protocols on Wikipedia, they will probably have a fairly good breakdown of how the protocol works.
Communications Engineering - Where to start ?  - Page 1
Forum section: electronics / beginners

author: alin_im
author_rank: Regular Contributor
timestamp: June 12, 2015, 11:55:22 pm
content: Hi guys,I am a final year student at Communications Engineering. In my second year I started to communications (AM, FM, PCM, Noise) and i find it very interesting but also very hard (high frequencies, many parameters that can influence the circuit).My questions are: Where to start fromWhat books do you recommend with applicability and practical circuitsAny basic circuits that every "mini electronics lab" should have in this fieldThere are so many topics on this and it is overwhelming. Also keep in mind that my best equipment so far are a 40 MHz oscilloscope, 2 x 1MHz signal generators, 2x DMMs and a decade resistance box and some LM317 and LM337 PSUs. Keep in mind all the equipment is vintage, nothing too fancy.What should I buy / make, where should i start

author: German_EE
author_rank: Super Contributor
timestamp: June 13, 2015, 07:40:59 am
content: Experimental Methods in RF Design - Wes HaywardThe ARRL Handbook - ARRLThe Radio Communications Handbook - RSGBSingle Sideband Circuits & Systems - William SabinSolid State Design For The Radio Amateur - Wes HaywardThe last publication is now out of print but it's well worth trying to borrow a copy from someone. You could also try to find your local Ham Radio club where, hopefully, you will get more ideas.

author: dmills
author_rank: Super Contributor
timestamp: June 13, 2015, 03:09:01 pm
content: Solid state design was IIRC the predecessor to EMRFD, so there is probably little to be gained by hunting both down.Other then that, yea good list.Regards, Dan.

author: alin_im
author_rank: Regular Contributor
timestamp: June 13, 2015, 05:59:36 pm
content: thank you for your recommendations !!! any useful circuits that i can build
Comon or not so common Analogue circuits/tricks - Page 1
Forum section: electronics / beginners

author: AlfBaz
author_rank: Super Contributor
timestamp: February 11, 2014, 02:14:08 pm
content: So most text books have things like rectifiers, filters, discrete amplifiers etc...Does anybody know of good books, websites or other that have collections of the many other "standard" circuit "tricks".You occasionally run into them here and there in appnotes, but I was wondering if there were any informative collections of these circuits.Things like diode switches, adding hysteresis to comparators, compensating for input bias in op-amps, subtracting a voltage from a signal with a transistor and a zener, simple level detectors...I've seen Alan (w2aew) cover some of these "tricks" in his videos, was just wondering if there was some repository of them out there

author: free_electron
author_rank: Super Contributor
timestamp: February 11, 2014, 03:18:16 pm
content: Bob pease. Troubleshooting analog circuits.That is the gold standard

author: AlfBaz
author_rank: Super Contributor
timestamp: February 11, 2014, 04:28:25 pm
content: Thanks Vincent, looks very interesting so I just ordered a copy.I also have "Linear Applications Handbook" by National Semi which is also full of helpful stuff.What I was hoping for, and your suggestion may fit the bill, was an easily searchable collection of discrete circuits that either solves or give ideas to help solve common analogue design problemsFor example, I needed to pull something low when a certain voltage was reached in an already overcrowded circuit. I didn't want to stick a comparator or op-amp in there, dicking around with power supplies, decoupling caps and/or feedback resistors, so I managed get it done with a resistor, zener and transistor.Unfortunately I don't come across these sorts of problems often enough to get good at it and thought some reference cct's would of been handy.

author: w2aew
author_rank: Super Contributor
timestamp: February 11, 2014, 08:37:36 pm
content: Quote from: free_electron on February 11, 2014, 03:18:16 pm+1 on that - great book from a real analog wizard.

author: AlfBaz
author_rank: Super Contributor
timestamp: February 12, 2014, 01:58:39 am
content: Thanks for tip guys, much appreciated

author: qno
author_rank: Frequent Contributor
timestamp: February 12, 2014, 07:02:15 pm
content: Look for the books from Jim WilliamsA lot of simple tricks you can find in the books of Forrest Mimms
Compact fluorescent lamp - Ballast? - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: April 25, 2020, 11:09:16 am
content: HelloI don't know if I'm on the right forum and category but I'm not getting any answer anywhere so, let's give it a try hereI need to wire 3 compact fluorescent lamps, 11W each,2G7 Type.Specs of the lamps:I also need electronic ballast to drive them, and I have chosen theOSRAM QT-ECO 2X5-11, it's a 2 lamps ballast. (I ordered 2 of them)No issue to wire it correctly, but how do I wire it correctly with only 1 lamp connected (the third)Can it actually work with only one lamp???I have an opinion about it, but I wanted a confirmationThank you!

author: Ian.M
author_rank: Super Contributor
timestamp: April 25, 2020, 11:28:47 am
content: You don't. Its got both tubes filaments in series at the common end, and no instructions for single tube connections in its datasheet, so odds are, it will overdrive the filaments leading to shortened tube life if you attempt to use it for only one tube.

author: Tantalum
author_rank: Regular Contributor
timestamp: April 25, 2020, 11:46:02 am
content: Thank you very muchOk so I had to choose a different one.Can I take theQT-ECO 1X4-16? (4 to 16W)On the label it's marked as compatible withS/E 11Wlamps (=mine, 2G7 Type @ Osram) but it delivers only0.09Aand my lamps are rated at 0.15A@75V.I don't understand how can they state that they are compatible with S/E 11W and don't delivery the right current??? :-/

author: schmitt trigger
author_rank: Super Contributor
timestamp: April 25, 2020, 12:29:14 pm
content: The lamps will still light up, but they will be dimmer.

author: Tantalum
author_rank: Regular Contributor
timestamp: April 25, 2020, 12:38:50 pm
content: And for the the first ballast (OSRAM QT-ECO 2X5-11), it's rated for S/E 11W at 0.15A, but is it 0.15A for each of the 2 lamps or 0.075A each, in other words the 0.15A stated are for the total current?I have no idea how a ballast actually works :sHow does it know the right voltage and current??? It's a different value from lamp to lamp, so, how does it know?
Company KAWEEI Technology - Page 1
Forum section: electronics / beginners

author: moffe
author_rank: Newbie
timestamp: November 18, 2020, 04:39:41 pm
content: Hi All,Do you know how to get in touch with this company, i need them for for specifc connectorsThank you in advanceKind regardsMorten

author: mairo
author_rank: Unknown
timestamp: May 18, 2021, 10:07:47 pm
content: This is theirs website:http://www.cwe.com.tw/
Comparator and MCU as an Opamp - Page 1
Forum section: electronics / beginners

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 11, 2016, 05:46:59 pm
content: thinking about it its rational, but it just came to me when i was simulating my preregulator circuit using a comparator as so called "novel" SMPS PWM generator, because i trust a comparator somewhat like a logic circuit only producing HI or LO output. but then due to unbehaviour of my simulation (my supposedly SMPS circuit went into linear mode and the mosfet is going to burn like fire) tracing my circuit, i realized the comparator setup is just as similar as a gain opamp and hence went to a stable mid voltage output in the rail, how can this be? its a blasphemy! now i'm adding logic circuit upfront the comparator so i can further ensure only HI or LO is produced, is this a rational move? i dont know, the Tina simulator doesnt have logic part to simulate with.and then googling "comparator as an opamp" gives very very few result, 1 in a million maybe, the rest of 999999 are talking about "opamp as comparator" the vice versa. but one thing special about this 1 link, is the text is talking about using an MCU comparator as a gain voltage opamp, this is justbut reading it its typical using RC filter. but then, unlike MCU's comparator (which can produce only HIGH or LOW, through digital flip flop), analog comparator like 393 is subjected to the opamp behaviour without even the need of RC filter. maybe this MCU opamp setup can be applicable to my next project, just saying.http://electronicdesign.com/analog/get-extra-op-amps-using-spare-comparators

author: uncle_bob
author_rank: Unknown
timestamp: July 11, 2016, 11:49:56 pm
content: Quote from: Mechatrommer on July 11, 2016, 05:46:59 pmHiMost comparators have really awful phase response. If you put them in the linear region, they oscillate. Many MCU comparators have a finite amount of hysteresis built in to tame them that makes them really poor op-amps.Bob

author: Ian.M
author_rank: Super Contributor
timestamp: July 12, 2016, 12:23:42 am
content: The basic idea is to wire the comparator with feedback into a capacitor to generate a PWM then low-pass filter that. The result is a very crappy OPAMP.Prior art: TIP #12 in Microchip'sPICmicro Comparator Tips ‘n Tricks, 2003.As the Microchip example didn't have any explanation, I would assume it was regarded as obvious or a common technique so it probably goes back a lot earlier than that. It may even originate from electromechanical regulator systems predating the transistor.

author: David Hess
author_rank: Super Contributor
timestamp: July 12, 2016, 05:17:18 am
content: Take a look at the design of switching regulators like the popular mc34063 which use pulse frequency modulation. They place a set/reset flip-flop at the output of the comparator so the clock provides a constant off time.
Comparator and oscillationS - Page 1
Forum section: electronics / beginners

author: zanzeoo
author_rank: Contributor
timestamp: November 29, 2016, 07:16:18 pm
content: Hi every !I designed this circuit below , the purpose is to "convert" a signal from +/- 10Vac , 400Hz , into a 0 - 5 Vdc .I used an AD790 powered by a +/- 15 Vdc supply , the particularity of this comparator is the output which can be TTL ( see the datasheet) so Vlogic is 5 VDC .I add a +/- 100 mV hysteresys with external resistors , but it still oscillate a bit .So wonder if i add a feedback capacitor , will it be better ?How do you determine the value of the feed back capacitor ?ThxSorry for my english

author: zanzeoo
author_rank: Contributor
timestamp: December 10, 2016, 02:43:27 pm
content: up

author: danadak
author_rank: Super Contributor
timestamp: December 10, 2016, 03:13:59 pm
content: Looks like you only have a couple mV of hysterisishttp://sim.okawa-denshi.jp/en/compkeisan.htmRegards, Dana.

author: Andy Watson
author_rank: Super Contributor
timestamp: December 10, 2016, 03:34:14 pm
content: Have you applied all the recommendations given in the datasheet, specifically with regard to layout and "Bypassing and Grounding". What/how have you connected the latch input?How do you know it is oscillating? - If you have applied an oscilloscope probe directly to the output of the AD970 the additional capacitance could be making the AD970 unstable - isolate the probe with 100-200\$\Omega\$ at the probe tip.

author: mash107
author_rank: Contributor
timestamp: December 10, 2016, 03:58:51 pm
content: Quote from: zanzeoo on November 29, 2016, 07:16:18 pmAs a rule of thumb, you don't want to limit the bandwidth of the positive feedback. It's not depicted in your schematic.. but say you had a noisy power supply that you're dividing down, and you had to add a large filter capacitor (in parallel with R4). Then you would need a cap like C1 to increase the bandwidth of the hysteresis. Otherwise it would be a large R (R1) charging a large C, and that might be too slow for the AC signal you want to convert. Let me know if that helps out.

author: PChi
author_rank: Frequent Contributor
timestamp: December 10, 2016, 09:13:19 pm
content: My experience of the AD790 is that it likes to oscillate at the transition even when care is taken with the layout and decoupling.Are the decoupling capacitors right by the AD790 and are the connections to the inputs as short as possible to minimise the capacitive feedback?Even with the hysteresis there might be a very short oscillation burst at the transistion.
Comparator problem  - Page 1
Forum section: electronics / beginners

author: NASK
author_rank: Contributor
timestamp: April 03, 2019, 06:49:01 am
content: plz help me to figure it this issue. + input is 12.5 mV & - input is 1.7V then LED is ON. when + input is 12.5 mV & - input is 2.7V LED is off. how this is possible ? is it issue in ic ?

author: not1xor1
author_rank: Frequent Contributor
timestamp: April 03, 2019, 07:16:19 am
content: Quote from: NASK on April 03, 2019, 06:49:01 amLM741cannot work in that circuit because:-1) supply voltage is below the minimum value specified by the datasheet (20V)-2) input voltage range is beyond the limits specified in the datasheet (2-3 volts above/below negative/positive supply)you need either a different operational amplifier (rail-to-rail or so called single supply operational amplifier) or different supply voltage and input voltage valuesBTW while there is no problem in using an operational amplifier as comparator to switch on a LED, there are many cases where one can only use real comparators

author: Zero999
author_rank: Super Contributor
timestamp: April 03, 2019, 08:11:30 am
content: It's a typical comparator application, so you ideally need a comparator, rather than an op-amp.If you replaced the 741 with a comparator, which can work at 5V, such as the the MCP6541 or TLC3702 (note that this has a different pin-out) it would work.If you don't have either of the above, then you could try the LM358, an op-amp designed for use at lower voltages and its inputs work down to the negative rail.The best cheap and commonly available part for your application is the LM393, but it has an open collector output, which means its output can only be pulled down to 0V, so the LED will need to be wired from the output to +V and the inverting and non-inverting inputs exchanged.Shouldn't R2 be 47k?

author: NASK
author_rank: Contributor
timestamp: April 03, 2019, 09:37:56 am
content: thank you both of you , any one can tell me where did you find this information in datasheet because I cant find it.QuoteZero999it a given circuit to me , 47R

author: Zero999
author_rank: Super Contributor
timestamp: April 03, 2019, 10:05:54 am
content: Quote from: NASK on April 03, 2019, 09:37:56 amIt's the common mode or input range specification, page 5. ±12 to ±13, which is specified with a 15V positive and negative supply, a difference of 2V to 3V.QuoteIt doesn't look right. with R2 = 47R, the LED will only turn on, when the potentiometer's wiper is right at the end, which may or may not be the desired effect.
Comparator problem - Page 1
Forum section: electronics / beginners

author: AxleD
author_rank: Regular Contributor
timestamp: April 22, 2015, 12:38:24 pm
content: Hi All,For my first project I was looking at building a simple linear power supply based on the LM317 chip. I built up the circuit yesterday (breadboard) and the voltage, relay and current controls are all working as expected.As discussed in a previous thread, to determine if the supply is in current limiting mode, I am using a differential amplifier to the look at the voltage drop across the first 317 (in the attached circuit) and then compare the output to a reference voltage. If it’s greater than 2V in this case, the comparator lights a LED.The circuit works well but I have a small issue with the current limiting LED turning on briefly whenever the power switch is flipped (on or off). I have rebuilt the circuit without the relays and it still occurs. I also have added a separate voltage regulator for the opamp and comparator but still no luck. I also added some hysteresis to the comparator but I still get the issue.Any ideas on what this could be? Any guidance on what I should look for would be appreciated. I am currently using a cheap plug pack to power the system and I wonder if that could be the issue?Thanks

author: Simon
author_rank: Unknown
timestamp: April 22, 2015, 02:25:04 pm
content: You need to post a diagram of what you have done.

author: AxleD
author_rank: Regular Contributor
timestamp: April 23, 2015, 05:00:33 am
content: Thanks i will try and post a better circuit diagram.

author: Zero999
author_rank: Super Contributor
timestamp: April 23, 2015, 08:09:22 am
content: This is happening because the capacitors on the output provide a short circuit as they charge up, causing it to briefly go into current limiting mode.This can be fixed by reducing the bandwidth of the differential amplifier (bypass one of the feedback resistors with a capacitor) so it no longer responds to brief transients.
Comparator question? - Page 1
Forum section: electronics / beginners

author: etstudent
author_rank: Regular Contributor
timestamp: October 28, 2012, 11:25:55 pm
content: If the signal to the input is larger than the signal to the non-inverting input of the comparator, what is the result?Is it a larger positive or negative output or a small positive or negative output? Any hints will be appreciated? Question is confusing me.

author: PA4TIM
author_rank: Super Contributor
timestamp: October 28, 2012, 11:43:50 pm
content: Most comprators have an open collector output.

author: etstudent
author_rank: Regular Contributor
timestamp: October 29, 2012, 02:33:05 am
content: Got it, thank you. The answer is a small positive output. I found the answer in my book after looking 900 times.With the inverting input larger than the non-inverting input it can't drive the output negative. Am I correct?

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 29, 2012, 03:51:05 am
content: Code:if (non-invert input > inverting input) output = +railelseif (non-invert input < inverting input) output = -railelse output = undefinedconfusing?

author: peter.mitchell
author_rank: Super Contributor
timestamp: October 30, 2012, 06:48:47 am
content: From the wikipedia article on comparators;Quote
Comparator Voltage reference - Page 1
Forum section: electronics / beginners

author: Pariston
author_rank: Contributor
timestamp: June 08, 2021, 04:24:53 am
content: Hi,I have a problem setting up my comparator. Reference voltage is set with Zener diode to the ground, which we want to compare to a voltage across series LEDs. Voltage across these LEDs is controlled by switching LED driver, which is not referenced to our main ground(basically I get 6.8 volt across diodes, and square wave of 33-9volt from led anode to the main ground(which is useless...)) . How do I get that 6.8 volt to the comparator? I feel like there should be a way to mirror that voltage and use it...

author: exe
author_rank: Unknown
timestamp: June 08, 2021, 07:48:29 am
content: Schematic would help to understand the issue, but I'll do a shot in the dark: consider an instrumentation amplifier. Beware that its output reference pin needs a low-impedance source (e.g., ground, or opamp unity-gain buffer). Check the datasheet for common gotchas with inamps, such as input common-mode voltage, and output swing. I suggest simulate your circuit before building it to avoid disappointment.PS a tl431 or something similar might be more stable than zener.

author: Zero999
author_rank: Super Contributor
timestamp: June 08, 2021, 08:56:38 am
content: There are plenty of ICs which integrate the comparator and voltage reference:TSM931, MCP65R41/6, LTC1540 etc. The TL431 can also be used as comparator on its own, in many applications.
Comparator without active V(ref) - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: October 18, 2020, 02:34:41 pm
content: I have looked all around on google for this and i am turning up nothing.Let's say I want to have a comparator that will take my battery voltage and compare it to a desired value of 2.5v. The purpose is to activate a LED when the battery level has dipped below 2.5v. To let me know that the battery level is getting close to empty.I can't seem to find out any way to achieve this without providing 2.5v somehow, and by the time it dips below that point I obviously won't have a way to provide 2.5v.Are there comparators out there which can accept a specific resistance for V(ref) and do the job i need?

author: Siwastaja
author_rank: Super Contributor
timestamp: October 18, 2020, 02:38:02 pm
content: You use a reference voltage significantly lower than the battery voltage will ever be, and divide down the battery measurement using a resistor divider network.For example, you could use a 1.25V reference and compare that to your battery voltage divided by two using a divider consisting of two resistors of the same value. High values like 470 kOhm would be desirable in order to not to drain the battery, but then you need to look at the input bias current spec of the comparator not to cause a significant error. You also want to add a capacitor (say 100nF) in parallel with the lower resistor to filter out any noise and interference which easily couples when you use large value resistors.0.8V to 1.25V are usual reference voltages easily available.There are also ICs that combine a reference and a comparator.

author: Mp3
author_rank: Frequent Contributor
timestamp: October 18, 2020, 02:47:04 pm
content: Quote from: Siwastaja on October 18, 2020, 02:38:02 pmThat's immensely helpful. thank you, I will also seek out those combined IC's you mentioned as i'm sure one is tailored to the purpose i seek.

author: exe
author_rank: Unknown
timestamp: October 18, 2020, 03:24:39 pm
content: Those are called supervisors. There are ready devices that are as as few cents:https://lcsc.com/products/PMIC-Supervisors_934.html. Like this one:https://lcsc.com/product-detail/PMIC-Supervisors_AnaSem-VDD251MNTA_C697875.html. Beware that parametric search on lcsc in this section is unreliable, many cheap parts don't have proper entries, like the one I mentioned. Also, most them accept only voltages as high as 6 or 7V.

author: Electro Fan
author_rank: Super Contributor
timestamp: October 19, 2020, 02:11:19 am
content: might be something in here that is usefulhttps://youtu.be/BRtE_IavUEA
Comparator - Page 1
Forum section: electronics / beginners

author: elki
author_rank: Regular Contributor
timestamp: June 28, 2025, 05:47:14 am
content: Hello, I am trying to understand the performance of the following circuit using a comparator. With the currently set threshold around 1V, I would expect no signal to be present at the output, however, it does appear somehow. Could someone help me understanding this behavior?

author: Whales
author_rank: Super Contributor
timestamp: June 28, 2025, 06:13:44 am
content: Which nodes are the green and red traces? Directly on the + and - inputs of the comparator, or is one of them something else?

author: elki
author_rank: Regular Contributor
timestamp: June 28, 2025, 06:15:39 am
content: Sorry: the green is at the inverting input of the comparator, the red is at the non-inverting input, and blue is the output.

author: Whales
author_rank: Super Contributor
timestamp: June 28, 2025, 06:20:17 am
content: ThankyouThe green (inverting) input voltage looks likes its going outside of the supply voltage (-0.4V is below 0V). The TLV350x datasheet says the common mode range only extends to -0.2V, so perhaps that extra negative signal is causing your problem.

author: Zero999
author_rank: Super Contributor
timestamp: June 29, 2025, 02:52:18 pm
content: Increase R7 to something more sensible, such as 10k. Add a Schottky diode between inverting input to 0V, anode to 0V.You forgot to show the input voltage, before C7.I've noticed you're using TI models. Be warned they do silly things such as defining all of the subcircuits used internally as global, which can cause problems if you use more than one model of a TI device.The TLV3501 model sets its output to half the supply voltage, when either of its inputs exceeds the common mode range, which is the supply voltage. This is not the same as a real TLV3501. Refer to the data sheet.Here's an example, comparing an ideal comparator model, to the TI TLV3501 model, when the input voltage is swept from -1V to 6V, with a 5V power supply. I've modified the TI model so all of the subcircuits it uses are no longer global. I've also removed the shutdown feature, by shorting the SHDN node to 0V, via a zero voltage source. If you want to use it, then delete V0 SHDN 0 0.
comparator's with hysterisis - Page 1
Forum section: electronics / beginners

author: CameronHanson20
author_rank: Contributor
timestamp: March 18, 2015, 07:47:23 pm
content: Hello everybody. I am playing around with comparatorsband hysteresis. I have a circuit built up and have calculated the thresholds and verified them. My question is why do you use a proportion to figure out the feedback voltage and not use the voltage divider. I know the answer is probably simple but I just don't understand why. I've attached my circuit.

author: IanB
author_rank: Super Contributor
timestamp: March 18, 2015, 07:58:50 pm
content: Quote from: CameronHanson20 on March 18, 2015, 07:47:23 pmWhen asking a question it's a good idea to lay out and describe everything you are doing and each step in your calculations, and then ask your question about which step is puzzling you.Otherwise there are probably many things in your mind and many details written down that you have not shown us, and we can only guess at the missing information before attempting to come up with an answer.Here you have said "why do you use a proportion to figure out...?". Well maybeyouuse a proportion, but I do not know what I would use. Maybe I would do things a different way. Do you see the problem?

author: CameronHanson20
author_rank: Contributor
timestamp: March 18, 2015, 08:08:44 pm
content: Yes, I figured this would happen. So I was watching wae2w circuit fun about building a analog control for a rc servo. Link ishttp://m.youtube.com/watch?v=iaGZOO33Z-o.When he goes to the calculations towards the end. He has vth= vref + vref(R1\R2) and Vlh = vref - vref(R1\R2). That's the confusion. Why does he don't he proportion of R1 to R2, instead of the voltage divider rule?

author: IanB
author_rank: Super Contributor
timestamp: March 19, 2015, 03:19:49 am
content: Quote from: CameronHanson20 on March 18, 2015, 08:08:44 pmBut he does use the voltage divider rule!He has:Vth=Vref+Vref(R1/R2)Let's factorize outVrefVth=Vref(1 +R1/R2)Now put over a common denominator:Vth=Vref[(R2+R1) /R2]Finally, rearrange:Vref=Vth[R2/ (R1+R2) ]And there is your voltage divider rule! It was just in disguise.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2015, 10:31:50 am
content: https://www.eevblog.com/forum/beginners/comparator's-with-hysteresis/msg632402/#msg632402Merge threads?
Comparators basics and analysis - Page 1
Forum section: electronics / beginners

author: steamedhams
author_rank: Regular Contributor
timestamp: March 22, 2021, 10:42:13 pm
content: I am investigating comparators using cadence but frustrated because I cannot discuss with other students because we are all studying from home.. but they aren't really into discussing stuff anyways so here I am. (My course is more about using cadence than comparator design.)My tutor asked me the following questions. Any feedback would be appreciated.1. Explain the difference between PSS and TRAN simulations. Why discrete-time circuits should be characterized using a PSS.PSS will display the output after it becomes periodic. TRAN will display the output over a period of time.Discrete-time circuits will produce a sequence of quantities after the initial stage which means PSS should be used.2.What is the periodic steady state transfer function? Which simulation in Cadence could provide you a periodic steady state transfer function?I believe it was Pnoise but after a quick good, it appears I can also use the following tool:Periodic transfer function analysis (PXF).3.What is a PNOISE simulation? Which sources of noise could be taken into account with a PNOISE analysis?The Pnoise computes the effect of the periodically time-varying bias point on the device that generates noise.Which noise sources... thermal, flicker. Any noise that is periodic i am guessing?
Comparing the output of 4 op amps in Wien-Bridge circuit - Page 1
Forum section: electronics / beginners

author: renzoms
author_rank: Regular Contributor
timestamp: December 14, 2021, 12:04:20 am
content: I built a Wien-bridge oscillator and swapped in 4 different op amps to see what happened.I found only one op amp produced something I may expect (the AD820).Two of them didn’t work (the two OPs that aren't precision op amps). I measured an odd-wave measured at the inverting terminal.1. Any ideas why the LT1078 has a small distortion? I wonder if it's because of the probes or something about frequency and the RC circuits.2. Why did two of the op-amps not work/why do you think I got these waveforms from the negative input terminal? And what is that distortion you can see in LF412's output when I wiggle wires.3. What measurements/scope features may I have found valuable besides Pk-Pk and Freq?Thanks.I think I found the AD820 will produce a nice sine wave I can pass through a transistor amplifierwoohoo

author: rstofer
author_rank: Super Contributor
timestamp: December 14, 2021, 12:57:31 am
content: What's the power supply voltage? Is there any chance you are running out of headroom? You generally need to stay a couple of volts away from the rails. There are exceptions for rail-to-rail op amps but even then, 'rail-to-rail' is a marketing term not an engineering reality.ETA: The AD820 does have a nice waveform but the Pk-Pk voltage is a LOT lower than the other 3 examples.

author: renzoms
author_rank: Regular Contributor
timestamp: December 14, 2021, 01:04:10 am
content: It's supposed to be +/- 15V, but it's +/- 9.9V.
Comparing the relative percentage change of two voltage outputs. - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 11, 2016, 11:19:57 pm
content: I have two separate variable voltage signals, 0 to 12V DC. Signal A and signal B. I want to read both signals and if A ever rises more than say 10% higher than B an output goes high (or low, it doesn't really matter). I would much prefer this to be all analogue CMOS the stuff running a single 12 v supply. The circuit creating the voltages must not be unduly loaded. What are my options and please consider I am a real novice. It's to measure the outputs of an SWR bridge and at different operating power levels, and hence different voltages from the bridge, still be able to trip a no TX circuit if reflected power gets too high. Thanks. I can post a schematic of the circuit including the bridge if required.

author: Ian.M
author_rank: Super Contributor
timestamp: December 11, 2016, 11:36:59 pm
content: Assuming they share a common ground, two fairly high resistance potential dividers, with ratios differing by 10% using precision resistors, feeding a CMOS comparator with rail-to-rail inputs. You can easily get the resistive loading on the signal source above 1Meg. If you need hysteresis, use feedback via a resistor from the output to a low resistance tap at the bottom of the +ve input's divider, as that lets you apply a small amount of feedback without needing a multi-meg feedback resistor.

author: Chris Wilson
author_rank: Super Contributor
timestamp: December 12, 2016, 12:01:43 am
content: Hi Ian, thanks for the reply. I attach the schematic below, I have taken signals at the pink starred points to HEF4001's configured as set / rest flip flops, in the case of the first measuring point, which goes Low on loss of drive signal, I have put it through an inverter. This works fine and a separate LED is lit, and stays lit if drive signal is lost, PA current rises too high, or reflected antenna power rises too high. This improves on the shown circuit which just lit the one LED no matter which of the 3 protection circuits was triggered, so you didn't immediately know why it had tripped.The simple reflected volatge measurement shown is OK'ish at full power where a mismatch can return over 5V to the flip flop and it's then triggered, but a t low power, using a reduced PA FET voltage, not enough reflected voltage is seen by the HEF2001 SR flip flops (not shown) to trigger it, even with no antenna connected. Hence the need to compare the percent difference between forward and reflected voltage from the bridge.Complicated to explain concisely, I hope you can follow my rambling?Some hysteresis would be good to stop shuffling. Can you see any issues with your kind suggestion based on the above and the attached schematic? Thanks again Ian!
Comparitor (LM2903) issues - Page 1
Forum section: electronics / beginners

author: uprightsquire
author_rank: Contributor
timestamp: March 20, 2013, 09:31:32 am
content: I have this circuit (attached below) to act as a low battery indicator. Vcc is 5V from a 78L05CD regulator, driven from a battery supply ('9V').Vcc = 4.9VIn - = 1.5VIn + = 2.2VVout = 0.7VI was expecting Vout to be either 0V or 5V.... Obviously this will not be enough to light the led. Thoughts about what is happening? It's driving me nuts.

author: Rerouter
author_rank: Super Contributor
timestamp: March 20, 2013, 09:41:29 am
content: take a good look at the spec sheet for it, the high level output of the device itself is only rated at 1uA yes micro not milli, so its only going to be 0.7V because at that current its only just turning on the LED,you really need to either amplify it using a darlington transistor or find a comparitor with far more current output,

author: Rerouter
author_rank: Super Contributor
timestamp: March 20, 2013, 09:46:56 am
content: upon furthur reading, flip it around, the op amp can sink 6mA when its outputting low, which should be enough to illuminate your led,
Compatible with X9C103 only with 8 bits (256 steps) - Page 1
Forum section: electronics / beginners

author: aless2056
author_rank: Contributor
timestamp: May 03, 2021, 11:01:43 pm
content: Compatible with X9C103 only with 8 bits (256 steps)Personal,I have a little project that I'm using the X9C103 digital potentiometer but it only has 7 bits, 127 steps, does anyone know any other that has 8 bits, 256 steps and is simple like it, only with the UP / Down pin (barred) and Inc ?

author: DrG
author_rank: Super Contributor
timestamp: May 03, 2021, 11:34:09 pm
content: What about MAX5450, MAX5451 [note I am not looking real carefully]
compenent reference query  - Page 1
Forum section: electronics / beginners

author: yalect
author_rank: Regular Contributor
timestamp: July 10, 2017, 11:19:04 pm
content: Hello,I would like to ask you if you can determine what is the compenent appeared on the attached picture, they look like a transistors, mybe the reference printed on the package helps more.thank you

author: macboy
author_rank: Super Contributor
timestamp: July 11, 2017, 02:02:04 am
content: BSS101 is typically marked SS101, so that's a possibility.
compensated amplifier  - Page 1
Forum section: electronics / beginners

author: Skyland
author_rank: Contributor
timestamp: April 28, 2015, 03:12:26 pm
content: From the text book notes attached, the loop gain is given which makes sense but I don't see how I can incorporate the closed loop gain and bandwidth given using this transfer function to satisfy the requirements.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 28, 2015, 05:24:23 pm
content: Solve for T == v_o / i_s = (10V/uA) / [1 + s / (2*pi*(10kHz))] and pole-zero cancellation (if possible given the range of component values allowable). Or instead of a fixed frequency, let it be BW and solve for maxima(BW).Tim

author: Skyland
author_rank: Contributor
timestamp: April 28, 2015, 07:47:40 pm
content: Quote from: T3sl4co1l on April 28, 2015, 05:24:23 pmI see you are scaling the frequency but I am not sure I understand very well all the steps. Could you provide more details please.
Compiling and understanding Hex codes for TI BQ20z80 chipset - Page 1
Forum section: electronics / beginners

author: Davepix
author_rank: Newbie
timestamp: March 02, 2025, 06:23:37 pm
content: I’m trying to understand how to create the hex codes necessary to change parameters as well as understand codes that are reported back by the BMS/chipset.For example, how would I create a hex code to write parameters from the register below, say, to write ZVCHG1 and CHGLED high and all the rest low or is it when bit 3 is low it’s CHGLED and high would be SLEEP?The particular code I need to modify is following and I do wish to modify ZVCHG and SVCHG0 between each of the four choices to see if what they are connected to operats correctly. Operation Cfg A = 1E60 also B and C take hex codes and I’m pretty clueless as to how 1E60 is derived from the below table or parameters.Operation Cfg AThis register is used to enable or disable various functions on the bq20z80. These bits are continued in B.LEDRLEDRCACHGLEDDMODELED1LED0CC1CC0--SLEEPTEMP1TEMP0SLEDZVCHG1ZVCHG0n ZVCHG1,0 [1,0]: These bits are also known as Pre-Charge 1,0. These bits are used to tell the bq20z80 how the Pre-Charge circuit is configured in the application. In other words it tells the bq2z80 what pin on the bq29312A to use for Pre-Charge functions when required.• 1,1 = No action is taken in Pre-Charge functions with this setting.• 1,0 = OD pin is used for Pre-Charge functions.• 0,1 = Charge FET is used for Pre-Charge functions.• 0,0 = ZVCHG FET is being used for Pre-Charge functionsNormal Setting: If using a separate Pre-Charge FET it is highly recommended not to use the OD pin for this function because it does not have good “zero volt charging” capabilities when a battery is completely dead. Therefore the ZVCHG pin should be used because it has excellent clamping abilities. The default is for using the Charge FET pin on the bq29312A.Reference materials used to get this far, Texas Instruments tech docs:slua334b.pdfslua340c.pdfslua342.pdfslua350.pdfslua359.pdfslua364b.pdfslua375.pdfslua379e.pdfslua381.pdfslua382.pdfslua421a.pdfsluaa98.pdfsluu276.pdfsluu313a.pdfsluuc94.pdfslva208b.pdfProgramming BQ20z80 chipset with EV2300 and BQ Evaluation softwareDevice is an Elinchrom Lithium battery for Ranger Quadra Hybrid or ELB flash systems.This chipset is also found on older Apple laptop batteries
Compiling assembly for old CPUs like 6309 / 6809 using lwasm? - Page 1
Forum section: electronics / beginners

author: gmc
author_rank: Regular Contributor
timestamp: September 28, 2025, 07:22:54 am
content: I've started designing a simple SBC for the circuit for the Hitachi HD6309 CPU. When the CPU resets it to reset vector at FFFE and FFFE, loads the 2 bytes there and jumps to that location.I am also using a GAL to do the address decoding for RAM/ROM and a 27C256 ROMand have it mapped out as follows:Code:0x0000 to 0x7FFF = RAM0x8000 to 0x80FF = I/O LEDs0x8800 to 0xFFFF = ROMOn the 27C256 this maps to:0x800 to 0x7FFF and reset vector at 0x7FFE/0x7FFFSo at reset it loads the bytes at FFFE/FFFF (Which will then be the start of ROM, ie 0x8800)Now this is all well and good and I have the following simple program:Code:START EQU $8800RESET EQU $FFFEORG $8800 ; Start of ROM imageLOOP1:NOPNOPJMP LOOP1; Reset VectorORG $FFFEFDB STARTSo far so good, the code all compiles using lwasmhttp://www.lwtools.ca(Assembler for the 6309 CPUs)and it spits outs a BIN file.This is where things go wrong. No amount of Googling seems to be working and ChatGTP is even confused more than me.When compiling the ROM how does it know it's a 27C256 and the code should be at 0x800h and reset vector at 7FFEh? When I compile the asm all the code starts at 0x0000:I've read this needs to be done using padding by not sure how to achieve this? I, incorrectly, thought lwasm would magically take care of this. Unless I'm not using it correctly which is very possible.Code:lwasm --output=main.hex main.asm

author: oPossum
author_rank: Super Contributor
timestamp: September 28, 2025, 09:19:53 am
content: --format=srecor--format=ihex

author: brucehoult
author_rank: Super Contributor
timestamp: September 28, 2025, 09:57:40 am
content: Quote from: gmc on September 28, 2025, 07:22:54 amI assume you actually mean 0x8800 as that's what you said in the memory address decoding section, and in the ORG in the code.The ORG should be all you need.Note that if you output a raw binary or hex file then there is no address information in that at all. It will just be a file suitable for flashing into your ROM at address 0 in the ROM -- which will end up at 0x8800 in the final system.That file will presumably have 0s as any necessary padding between the code and the vectors.30k is a strange size to have as a ROM. You probably should decode the address as having the ROM starting at 0x8000 (bit 15 set) but only actually enable the chip if bits 14:11 of the address are not `0000`.Then you'll want to make your code ORG 0x8000 but write 0s into the first 0x800 bytes before starting your actual code.

author: gmc
author_rank: Regular Contributor
timestamp: September 28, 2025, 11:47:06 am
content: Thanks all. That was easy fix.
Compiling Firmware - Page 1
Forum section: electronics / beginners

author: davidleverett30
author_rank: Contributor
timestamp: May 08, 2017, 10:12:48 am
content: I have bought an inemo-M1 IMU and would like to change part of the firmware (I want to use the SPI external interface on the board).I have the source code (C/C++) and can see the (SPI) driver to use, however, the documentation doesn't explain how I update the code.I can only assume that I need to take the existing code, drop the driver into the correct folder and then compile it.The firmware is in .hex format. C/C++ ---> .hexTo be honest, this is the first time I've done anything like this and it is pretty confusing. Where should I start?

author: Matir
author_rank: Contributor
timestamp: May 08, 2017, 03:05:52 pm
content: Is the code somewhere public? Does it have a Makefile or any build scripts?

author: davidleverett30
author_rank: Contributor
timestamp: May 09, 2017, 03:48:48 am
content: I've made some steps forward.I looked into the source code until I found something called MDK.. googlig... this lead to an ARM-MDK software that can compile the code into a hex.There is a file with the extension .uvproj with a list of everything my hex file should include.I have enabled the SPI stuff and will then compile the code. I'll update the board tonight.This dude was a big help:
Complementary MOSFET Motor Controller - Page 1
Forum section: electronics / beginners

author: hsn93
author_rank: Regular Contributor
timestamp: March 11, 2018, 06:40:27 am
content: hello,i was looking in pmos and while reading post in electronics-tutorial found this page:https://www.electronics-tutorials.ws/transistor/tran_7.htmlthe question is: the Vin has to be ( +vdd for logic 1 ) and ( -vdd for logic 0 ) right ?as if it was for example ( TTL or cmos) the N mosfet will be on even the Vg was ground .. as the voltage at source is negative right ??

author: rstofer
author_rank: Super Contributor
timestamp: March 12, 2018, 09:13:28 pm
content: You got it right.This is a particularly bad way to do the switching because it is going to be difficult to avoid shoot-through. The N channel device turning off will overlap with the P channel device turning on and vice versa.The MOSFET part is ok but the switching signals need to guarantee no overlap.A full H-bridge is a better solution.
complementary switching on ac signals - Page 1
Forum section: electronics / beginners

author: mheruian
author_rank: Contributor
timestamp: July 26, 2018, 06:28:15 am
content: Hi i'm just a starting out hobbyist who knows how to use arduino in switching purposes but there is this switching scheme i want to perform but didn't work out the way i thought it was when i simulate it. Though given i have references provided by guys here told me to follow. I'm not much knowledgeable about the different matters about transistors. All i know about them is these are like switches on saturation.above is the circuit i simulated using this sitehttps://www.falstad.com/circuit/it's a circuit where i want the hi-ac voltage be turned into small value and will act as a small signal analog for input testing. Originally, it doesn't have those complementary mosfets so basically the outputs will be from the two end points where the difference is their phasing only, one is reverse using the inverting op amp configuration (w/c i learn at youtube tutorial only).now i want to create a one end output only where it'll either output the non-reversed phase or reversed phase via 1 switching only (either coming from spdt switch, another transistor, ICs like DMX, i/o expanders, microcontroller, etc.) i even wanted to put a pull down diode and resistor setup on the gates of the complementary mosfets to give state indicator. But this setup doesn't work the way i think because every time i open the switch, it doesn't reverse the phasing - it doesn't even have output (0 volts).in short, i want to create a dpst (double pole single throw) digital switch for my two AC outputs having 180 degree phase difference, i don't want to use ssr or relays.i hope you can help me.my references are below: