hybridfree/eevblog-posts huggingface dataset:
How can this 10-bit ADC getting 16-bit performance? - Page 1
Forum section: electronics / beginners

author: Bootalito
author_rank: Unknown
timestamp: December 30, 2017, 04:51:47 pm
content: I bought this panel meter a while ago:https://www.amazon.com/gp/product/B00BYOL4JM/ref=oh_aui_search_detailpage?ie=UTF8&psc=1I just took it out and started messing with it to see if I wanted to use it in a project, and its accurate from 0.000 - 30.000 down to the 1LSB when compared to my 500,000 count brymen BM867s It has an ST micro STM8S003F3Datasheet from Mouser.comwhich only has a 10-bit ADC. How is it measuring the difference between 30.000 and 30.001 which should only be possible with a 16-bit+ ADC?!

author: Kleinstein
author_rank: Super Contributor
timestamp: December 30, 2017, 05:15:32 pm
content: There is an external ADC in a SOT23-6 package, likely an MCP3421 - this is an 18 Bit ADC with internal reference.

author: Neganur
author_rank: Unknown
timestamp: December 30, 2017, 08:54:19 pm
content: those modules are way cool for how cheap they are.Even though the last digit is a bit iffy, I'd say it's easily within +/-100uV
How can this cap have low ESR yet large Dissipation Factor? - Page 1
Forum section: electronics / beginners

author: humidbeing
author_rank: Regular Contributor
timestamp: November 22, 2023, 07:10:31 pm
content: I'm looking at this Wurth cap part number: 870055673001It's 10uF, 35V, Aluminum Organic PolymerESR is 40 mOhms, DF is 12.According to Digikey, we calculate ESR from DF using this formula:ESR = DF / (2 * PI * Test Freq in HZ * Capacitance)Using that formula, with a 120Hz test Freq, I get 1.6K ohms for the ESR, but the datasheet lists it 40 mOhms. How can that be?

author: Kleinstein
author_rank: Super Contributor
timestamp: November 22, 2023, 07:29:48 pm
content: The formular is not telling the whole story. The DF is usually frequency dependent and the ESR only applies to the higher frequency case.The ESR form is used to decribe the rather high frequency case when the capacitor behaves essentially like a resistor with little effect of the frequency.The DF is mainly used for the range when the capacitor still acts like a capacitor, but with losses. The ESR calculated from the formular would be frequency dependent.Usually the DF is << 1 , so 12 would be more like 1/DF or maybe 12% as more typical values for electrolytic capacitors.

author: bdunham7
author_rank: Super Contributor
timestamp: November 22, 2023, 07:36:03 pm
content: DF = 12 is wrong, it is 12%, so DF = 0.12 and your calculated ESR at 120Hz is ~16R. The 40mR is at a different test frequency of 100kHz.

author: humidbeing
author_rank: Regular Contributor
timestamp: November 22, 2023, 07:44:55 pm
content: Quote from: bdunham7 on November 22, 2023, 07:36:03 pmWhoops. Mouser listed the DF as 12 not as 12%, now that I inspect the full datasheet I see that it's in percentage. Thanks for pointing that out, gang.So, to check my understanding: A lower DF @ 120Hz means the cap will perform better for low freq ripple?

author: Kleinstein
author_rank: Super Contributor
timestamp: November 22, 2023, 08:48:40 pm
content: The DF in the datasheet is about the losses at relatively low frequency, where the capacitor is still behaving like a capacitor. For the capacitor here this could be 120 Hz and maybe 1 kHz.The usual ESR number is for a high frequency where the capacitor is more or less reduced to the parasitic resistance, like 100 kHz for this size capacitor.A lower DF would mainly cause less heating of the capacitor. The ripply voltage would still be about the same, just a little phase shift.The equation to link DF and ESR is questionable - it is a different kind of series resistance the formular uses.
How can this VCO take 20V control input? - Page 1
Forum section: electronics / beginners

author: dbctronic
author_rank: Regular Contributor
timestamp: March 15, 2022, 05:35:09 pm
content: I found this 950 - 2200 MHz VCO circuit. As shown, they specify up to 20V for control input, but D1 (SVM1232 varactor) is rated for 15V absolute maximum. Sure looks to me like D1 is dropping the full control voltage, innit?

author: ledtester
author_rank: Super Contributor
timestamp: March 15, 2022, 06:08:37 pm
content: 15V is when the diode begins to conduct. But in this case there is the 100K resistor limiting current. At 20V only about 50 microamps will flow through the diode.QuoteDon't forget the voltage drop across the resistor.

author: dbctronic
author_rank: Regular Contributor
timestamp: March 15, 2022, 08:25:55 pm
content: Many thanks. This is the first circuit of any kind I've seen in a while for whichallof the listed components are readily available and still cheap!! No scary substitutions needed. And it's just what I need, with no tweaks. Changing times...Next adventures - PCB layout and GaN FET power amplifier. One or two bipolars to drive the gate capacitance without loading the VCO, and hopefully it'll work. I suppose I should keep the VCO and amp in separate metal boxes joined by coax.

author: MathWizard
author_rank: Super Contributor
timestamp: March 15, 2022, 09:22:55 pm
content: I'm not used to seeing diodes w/ such low reverse break down voltage. I bought some jellybean Germanium diodes, and variactor diodes ages ago, I must mind the voltages when using them.

author: idnihus
author_rank: Newbie
timestamp: March 15, 2022, 09:43:33 pm
content: It would be interesting to see how much the frequency changes between 15 volts and 20 volts. Let us know what you find.Check this out, save you a lot of work, -- CVCO55CW-1000-2000

author: dbctronic
author_rank: Regular Contributor
timestamp: March 16, 2022, 01:44:51 am
content: According to the SVM1232 datasheet, capacitance change flattens out quite a bit at around 10V. It starts out at 4.5 pF and goes down to around 0.8, not too much after that. If I cobble this circuit up, I'll stay below 12V.I'm familiar with the CVC series of VCOs. But the datasheets do not specify any modulation slew rates or settling rates, no information at all on it, so Crystek obviously does not intend for the units to be operated as anything but stable, plus or minus a small lock-on swing. I will need fairly rapid slewing. So, I'm shopping for DIY circuits like this one, where I can see what's going on. I'm not a fan of DIY 'buy and try' component spec'ing, or begging manufacturer support for hints. If it ain't specified, it ain't guaranteed. The second one you buy might be very different from the first one. And at $25 - $35 apiece, I'm not a fan of buy and try at all.

author: Extrasolar
author_rank: Contributor
timestamp: July 17, 2022, 10:43:11 pm
content: Here is a Crystek VCO and diagram (take it with a pinch of salt as I'm not to sure whats on the base/gate of the transistor because I had to resolder some knocked off components)
How check function of oscilator  - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: August 14, 2021, 07:16:27 am
content: I have PCB with SMD oscilator that has 4 pins:XTAL_19P2M_OUTGROUNDXTAL_19P2M_INXO_THERMHow can I check ( with osciloscope) that the oscilator works properly?On which pin should I measure the frequency 19.2 MHz?Thank you for help

author: bob91343
author_rank: Super Contributor
timestamp: August 14, 2021, 05:07:26 pm
content: OUT pin

author: Jane
author_rank: Frequent Contributor
timestamp: August 14, 2021, 05:20:05 pm
content: Thank you for your replySo, the (crystal) oscilator has IN and OUT pins connected to an IC.Questions:1. Does it mean that IC provides input voltage for that oscilator (on IN pin)?2. Is that AC or DC voltage (that IC provides on IN pin)?3. On OUT pin isACvoltage of 19.2MHz?Thank you for help

author: Zero999
author_rank: Super Contributor
timestamp: August 14, 2021, 05:56:10 pm
content: The oscillator takes a DC voltage, normally 5V and converts into a squarewave, of the same voltage, minus a small voltage drop.

author: bob91343
author_rank: Super Contributor
timestamp: August 14, 2021, 06:28:57 pm
content: IN is power supplyOUT is outputGND is groundTherm is either a thermistor to test temperature or perhaps an input to adjust. You need the data sheet to find out.

author: Jane
author_rank: Frequent Contributor
timestamp: August 14, 2021, 08:09:13 pm
content: Thank you for your replies.Does it mean I can simply test the oscilator in this way:connect 5V to IN pinground to GROUND pinand on OUT pin Imustmeasure 19.2MHz , if the oscilator is not faulty?Is possible to connect 5V directly or must use a resistor/cappacitor/inductor?

author: Zero999
author_rank: Super Contributor
timestamp: August 14, 2021, 08:32:40 pm
content: Quote from: Jane on August 14, 2021, 08:09:13 pmYes, connect the 5V directly to the oscillator's in pin and 0V to the ground pin. It's also a good idea to connect a 100nF capacitor across the supply, as close to the oscillator as possible, but lots of devices already include some decoupling. The out pin should measure 19.2MHz.

author: fourfathom
author_rank: Super Contributor
timestamp: August 14, 2021, 08:45:00 pm
content: Is this a 5V part? Many SMD oscillators are 3.3V (or possibly some other voltage). You might try using 3.3V and see how that works.

author: ambrosia heart
author_rank: Regular Contributor
timestamp: August 15, 2021, 01:27:05 am
content: How to check see pm

author: bob91343
author_rank: Super Contributor
timestamp: August 15, 2021, 04:32:03 am
content: If you have the part number perhaps someone can find the data sheet.
How to Connect DS1309b to SimmCom 5320 using uart - Page 1
Forum section: electronics / beginners

author: eyeshield21v2
author_rank: Newbie
timestamp: September 12, 2017, 03:29:46 am
content: Hello Electronic Enthusiasts I would like to ask something about how to connect DS1309b to Sim5320 using UART and reading the Data from DS1309b.. the output that I read would in the attached picture.. I have used Putty to see what are the data that DS1309b has. But when I have connected DS1309b to simcom5320 using UART it send nil value or Null value. By the way I am using Lua script on SimmCom 5320, because it is the default application. Please consider my question. I am a newbie.

author: danadak
author_rank: Super Contributor
timestamp: September 14, 2017, 12:28:15 am
content: I assume you are connecting the parts directly so they meet logic levelsof the two chips.Is baudrate, start, stop, parity bits same for both ends of link ?Regards, Dana.

author: eyeshield21v2
author_rank: Newbie
timestamp: September 14, 2017, 01:28:47 am
content: Yes I have connected it correctly and I have set the Baud rate permanently in the program to read the output of the DS1309b. However I have been asking for documentation from the Manufacturer, but they are not responding at the moment. I have search for documentation of the product, but it directs me on the seller site.. Thanks for replying..
How Connect Electronic DC Load to ATX Negative Voltage ? - Page 1
Forum section: electronics / beginners

author: danz
author_rank: Newbie
timestamp: May 29, 2021, 01:36:10 pm
content: Hi Everyone,I Have Electronic DC Load and i want to use it for simple Power Supply Load Testing. For 3.3v , 5v , 12v , and 5VSB i don't have any problem connecting to my DC LOAD. But for -12V (Negative 12V) i don't have idea how i can connect to my DC LOAD.Maybe someone can give direction how i can connect my DC LOAD or maybe i need some other device. I try to search some information in other PC Review web like Tomshardware , Anandtech , etc they can test all PSU Voltage 12V , 5V , 3.3V , 5VSB and -12V using several DC LOAD Tester without any problem but i can not find any information how they connect DC LOAD wire to their ATX Power Supply -12V.Thanks all.

author: Vincenzo
author_rank: Regular Contributor
timestamp: May 29, 2021, 02:26:17 pm
content: the first method you mentioned (-12 to active load -ive and ATX GND to active load +ive) is the right way (notice the reversed black and red wires in the other testers photo). The reason for that is that it is an "Active load" which is basically a MOSFET(s) which are not bilateral like resistors.Notice in their photo, too, that the current of the ATX -12V is about 150 mA which is the least of the other voltages. The -12V ATX output has a very limited current capability, so when you connected constant current, how much that current was. You probably put too much current.

author: danz
author_rank: Newbie
timestamp: May 29, 2021, 02:35:18 pm
content: @vincenzo Thanks for your reply.Yes i also notice they reversed cable color in other web DC LOAD.And yes -12V in ATX Power Supply usually only max 0.3A.I try to set load only 0.05A / 0.1A to -12V and enabled my Constant Current Load my PSU still Power Off suddenly.I will try checking with other ATX PSU again.

author: gamalot
author_rank: Super Contributor
timestamp: May 29, 2021, 03:41:35 pm
content: Have you tested whether the negative input terminal of your electronic load is connected to the mains ground, if so, you will not be able to test the negative voltage out of your ATX power supply unless you use an isolation transformer.

author: Vincenzo
author_rank: Regular Contributor
timestamp: May 29, 2021, 03:51:16 pm
content: Quote from: gamalot on May 29, 2021, 03:41:35 pmThat was exactly what i was thinking about, check negative to ground in both load and power supply

author: danz
author_rank: Newbie
timestamp: May 30, 2021, 12:46:51 am
content: @gamalot @vincenzo Thanks all for help and reply.I have found the problem come from my Breakout board -12V connector. Now All working normally.Problem Solved
How could I implant "gain" in analog circuit ? - Page 1
Forum section: electronics / beginners

author: ammjy
author_rank: Regular Contributor
timestamp: July 11, 2021, 10:13:45 pm
content: Hello, there !Thanks you for your time.when we want divide signal by some number, we can use simply "voltage divider circuit".But, when we want multiply signal with some number, what we could use for it ?The Book I reading now only explaining "voltage divider circuit" case about "Gain".we have to use OP AMP ?Please, let me know,,,

author: Zero999
author_rank: Super Contributor
timestamp: July 11, 2021, 10:40:44 pm
content: The word you're looking for is amplifier. If a circuit has a gain of 2, it means it multiplies the voltage by 2. Amplifiers need a power supply voltage, higher than the maximum output voltage to work properly.An op-amp can be used to build an amplifier with a stable gain.

author: ammjy
author_rank: Regular Contributor
timestamp: July 12, 2021, 01:13:09 am
content: Thanks a lot Zero999 !yes I agree with you,,
How could I increase the power usage on G23 UV Lamp? - Page 1
Forum section: electronics / beginners

author: multifrag
author_rank: Contributor
timestamp: July 09, 2020, 02:41:54 pm
content: I have a nail curing station that uses 4xG23 9w UV lamps. From the power meter it looks like they are only running at 6W each instead of 9W. My guess is that pcb is designed for the lower power bulbs but came with the 9W ones. Would there be a way to increase the power on this board(images below)? From reading around I understand that G23 Bulbs need a ballast as a means of limiting current. My pcb is using 7.4nH inductors. Would changing them out be the solution?
How could I simulate noise injected on voltage rails caused by switching loads? - Page 1
Forum section: electronics / beginners

author: Metatronic_Mods
author_rank: Contributor
timestamp: March 08, 2018, 02:54:39 am
content: On a system I'm working on there are numerous subsystems which share common VDC+ VDC- and GND buses. A few of the subsystems are injecting noise onto the supply buses. They all have a bunch of LEDs being driven by PWM at audio rate (WHY??) and they aren't very well bypassed internally -which can present as a problem for some of the other subsystems (sensors etc.). So my plan is to add passive inline T-filters between the noisy systems and the supply buses.I'd like to be able to simulate a few different designs (different loads & prominent frequencies) but I'm not sure whether I'm on the right track with my model or not.Starting with just one of the subsystems being powered, I was able to measure the DC average current draw, as well as the transient current draw.Am I right to think that I could model the subsystems loading effect as an equivalent load resistance in parallel with an alternating current source?Example: Vbus = +12V, DC load current = ~200mA Transient current = 50mA @ 1000HzPower supply is to the left, the subsystem being powered is to the right, and the boxed area contains the filter I want to add.
how data and power can be sent down the data lines of a poe connection - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: September 12, 2015, 03:42:59 pm
content: HiIf it's a 100mbps connection then you can use the spare pairs to send power to your device then split it up at the device you're powering.But Gigabit Ethernet use all 4 pairs so how can you send data and power at the same time without affecting the integrity of signal?Also does these so call powerline device (ethernet connection over mains wiring) work in the same way

author: Monkeh
author_rank: Super Contributor
timestamp: September 12, 2015, 03:47:25 pm
content: Quote from: amateur_25 on September 12, 2015, 03:42:59 pmAC coupling.QuoteIn the broadest sense.

author: amateur_25
author_rank: Regular Contributor
timestamp: September 12, 2015, 04:07:33 pm
content: oh Ac coupling ah. So basically in newbie speak it the data signal is actually an ac signal.By using capacitors it can then filter out the dc as if it's not there.Then how do home plugs work because mains is AC.Am guessing it knows the difference between whats ac power and the data becausemains electricity in the uk is 50hz and Ethernet has a higher frequency?Similar to how broadband and voice are sent down the phone line yes?

author: Monkeh
author_rank: Super Contributor
timestamp: September 12, 2015, 04:10:09 pm
content: Quote from: amateur_25 on September 12, 2015, 04:07:33 pmBasically, yes. Just filter out the boring low frequency components.QuoteActually, yes. It's very much like DSL.

author: andtfoot
author_rank: Unknown
timestamp: September 12, 2015, 04:30:12 pm
content: Quote from: amateur_25 on September 12, 2015, 04:07:33 pmClose, but in this case it uses centre-tapped transformers (called magnetics) to split the signal from the power.

author: kc8apf
author_rank: Regular Contributor
timestamp: September 12, 2015, 04:44:53 pm
content: Ethernet uses transformer-coupled data lines on both ends. Any DC offset present on the lines is thus removed before it hits the PHY.I'm not up on the latest home powerline standards but there are a few different schemes. As you've already noted, mains power uses AC but at a low frequency (50 or 60Hz). A few of the schemes work by using a higher-frequency modulation scheme that essentially treats the house wiring as an RF connection. Something like QAM1024 at a few hundred MHz will give a lot of data rate. Older systems like X10 (I think it was X10), send high-frequency bursts during the mains-power zero crossing. That makes the receiver simpler (no need to add downconvert) but significantly reduces the data rate as your 1MHz symbol rate can only happen for a few milliseconds per second.
How do (not very) different scope probe coax lengths affect measurement? - Page 1
Forum section: electronics / beginners

author: AndrejaKo
author_rank: Frequent Contributor
timestamp: April 09, 2013, 04:30:21 pm
content: Recently I got two Testec TT-LF312 (150 MHz/15 Mhz 1x/10x) scope probes for my Owon SDS7102 (100 MHz, 1Gs/s or 2x500MS/s) scope. I noticed that the coaxial cables connecting the probes themselves to the scope have different lengths and the difference is about 2-3 cm.Thinking about this, I see that there should be differences in signal attenuation in the cable and phase difference. On the other hand, I'm not sure if I should be worried about this in practice.

author: w2aew
author_rank: Super Contributor
timestamp: April 09, 2013, 04:53:21 pm
content: The difference in attenuation will be negligible. The difference in delay will also be negligible at these frequencies. In typical 50ohm coax, the signal travels about 7.8 inches (about 20cm) in 1ns. Thus, a 2-3cm difference in length will mean about 100ps of delay difference. At 100MHz, or about 4 degrees. (if I did the quick maths right).

author: AndrejaKo
author_rank: Frequent Contributor
timestamp: April 09, 2013, 11:20:15 pm
content: Thank you very much for the answer.

author: codeboy2k
author_rank: Super Contributor
timestamp: April 10, 2013, 06:36:10 am
content: Quote from: w2aew on April 09, 2013, 04:53:21 pmYep. I verified your math :2cm = 100ps, 3.6 degrees; 3cm = 150ps, 5.4 degrees, so that's the range to expect for a 100Mhz signal.

author: Unknown
author_rank: Unknown
timestamp: April 10, 2013, 10:28:22 am
content: If you use two probes in subtract mode as a poor man's differential probe, then the phase shift will screw up your common mode rejection ratio at higher frequencies. Not that it's great with two matching probes.

author: free_electron
author_rank: Super Contributor
timestamp: April 10, 2013, 03:08:58 pm
content: That is why proper oscilloscopes can deskew their inputs.... Hook inputs to to the same signal , then deskew (phase align).

author: Unknown
author_rank: Unknown
timestamp: April 10, 2013, 04:00:45 pm
content: True, although these scopes will usually have more bandwidth, making skew more critical. Skew also tends to be larger with fancy probes, for example one active and one current probe.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 10, 2013, 04:15:58 pm
content: Quote from: free_electron on April 10, 2013, 03:08:58 pmwhat about capacitance and inductance mismatches correction? is "proper oscilloscope" does it too? can you name the scope and the price? something that can work on normal probes?
How do acknowledgments work in a frequency hopping system? - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: May 19, 2017, 07:41:20 am
content: Tried searching on Google without much luck, perhaps because I don't know what key words to search for.Once a transmitter has finished sending a message does it listen for an ack on the same frequency before jumping to the next frequency in the series. Presumably it cannot wait for too long otherwise it'll miss the scheduled transition to the next frequency.Also, what happens if the receiving party is in the middle of sending an ack when the next frequency hop is supposed to happen?Is this solved by effectively having dead zones on either side of a hop where two parties are neither transmitting or receiving? If so does that make it less efficient in terms of bits per second?Mike

author: Benta
author_rank: Super Contributor
timestamp: May 19, 2017, 10:44:13 am
content: I think you are mixing up modulation (frequency hopping) with signalling.The frequency hopping occurs continuously and independently of the data being transmitted. It is quite possible, even likely, that a lot of frequency hops occur during the transmission of a message.The acknowledgement is just another message being sent/received.Systems I've seen are "always on" when active. One could imagine a system where TX/RX are turned off between messages, but then resyncing the hopping is needed before each message, which is time consuming and inefficient.

author: e100
author_rank: Frequent Contributor
timestamp: May 20, 2017, 12:50:22 am
content: OK, thanks that makes things a bit clearer.
How do ADSL modems calculate line attenuation? - Page 1
Forum section: electronics / beginners

author: fubar.gr
author_rank: Unknown
timestamp: February 18, 2015, 05:21:54 pm
content: All ADSL modems have a line attenuation measurement, usually in dB.Obviously the modem can measure the received signal power. But to calculate attenuation the transmitted power is also needed. Does it assume some standard transmitted power?

author: ivan747
author_rank: Super Contributor
timestamp: February 18, 2015, 07:30:59 pm
content: I dunno about ADLS modems, but my GPON fiber modem only reports transmit power in dB. Maybe the ADSL modem is doing that.

author: free_electron
author_rank: Super Contributor
timestamp: February 18, 2015, 08:37:31 pm
content: Very simple : be sweeping it.When the initial contact is made between the modem and the DSLAM ( the central office : Digital Subscriber Line Access Multiplexer) there is a period of training. The modem sends a 'medley'.ADSLl uses a QAM (quadrature modulation : phase and amplitude) signal on individual carriers . This is called DMT : Discrete Multi-ToneYou need to think of the DSL signal as a number of carrier waves that each carry up to 4 bits of information. These are spaced apart in the available bandwidth.The modem sends a pure sinewave carrier by carrier. the DSLAM takes a measurement of the amplitude and distortion and reports a signal back : Up or Down. ( meaning : we get too much power , or not enough power for this 'tone')Once this is established the modem knows what the gain setting needs to be , per tone, in the spectrum. Since a phone line is a static element this will not change for the lifetime of the cable. So it only needs to be done whenever there was a power loss , or you unplugged the modem from the line .And then we start transmitting .If we get bit errors these are cause by temporary disturbances in the spectrum. For example if the neighbours pimply-faced kid takes his , badly dampened, dirt bike out and goes pweeeeeeeee. : that shows up as error in specific channels (base + some harmonics )That is seen as channel errors. Feedback tells the modem : this channel gets a lot of errors : drop from 8 to 4 or 2 bits or stop using this channel and use an alternate ( only 192 of the 256 are in use. the rest are 'spares' to be able to hop around 'bad' channels.Depending on where you live some channels may always be bad due to noise sources. In that case we permanently allocates some of the spares.
How do automotive compute units interface with the sensors? - Page 1
Forum section: electronics / beginners

author: drakejest
author_rank: Regular Contributor
timestamp: October 28, 2023, 08:28:38 pm
content: I am curious on how do automotive grade ECU's interface with its sensors, Im talking about the very simple kind of sensors such as switches. How do the signals from these switches gets to the micro controller of automotive grade ECUs? If we look at industrial equipments (such as PLC) they almost always use an optocoupler to isolate the input(or output) signals to micro-controller. For automotive ECU's though , from the pictures i can see on google i really dont see optocoupler looking ICs in them. Which would make sense because there is really no point for galvanic isolation since they all share the same power source (the vehicle battery). But i also dont believe that there is no some sort of input protection, not to mention that the voltage will still need to be shifted down to lower voltage level for the microcontroller.There also switch debouncing is that done on hardware ? Thats for the input , i assume that the output is another can of worms, although most of the high current devices on an automotive application will have a relay, i would still assume that those output pins are atleast able to tolerate short circuits and reverse voltage.How do automotive grade circuits do it?

author: IanB
author_rank: Super Contributor
timestamp: October 28, 2023, 08:33:23 pm
content: The engine control module of a modern vehicle is a big black box with lots of connections on the outside and lots of electronics on the inside. The MCU is only one component of the whole thing. While I do not know how they work in detail, I am sure that each of the inputs is buffered to protect it from spikes and surges, and each of the outputs is similarly robust.

author: drakejest
author_rank: Regular Contributor
timestamp: October 28, 2023, 08:37:18 pm
content: Quote from: IanB on October 28, 2023, 08:33:23 pmHow it achieves its robustness is the thing i want to know, hoping that i can use it in my designs.

author: ataradov
author_rank: Super Contributor
timestamp: October 28, 2023, 09:00:45 pm
content: There is usually plenty of protection. Usually in a form of clamping diodes with current limiting resistors and ferrite beads.Optocouplers are not that useful in a car. They are good for decoupling things that may be at different potentials and have no solid ground connection. In a car, the whole car body is a ground connection.They also use robust transceivers (CAN/LIN) that are designed to handle a lot of abuse.For the switches and buttons - more and more they are handled locally and use CAN or LIN to communicate the state digitally. It reduces the amount of wiring you need to do and localizes input protection. So, there are not long runs of wires that go to the button on the other side of the car.There is a good reason cars have dozens if not hundreds of microcontrollers all over the place. It is cheaper to do it that way, at least until something happens you can't get MCUs anymore.
how do electrolytic capacitors get to be polarised.    - Page 1
Forum section: electronics / beginners

author: jonovid
author_rank: Super Contributor
timestamp: March 05, 2017, 09:36:52 am
content: just getting a second opinion. here.electrolytic capacitors, how much reverse polarised tolerance is ok?also know of non polarised electrolytic type capacitors used in audio of speaker crossover designs.

author: SeanB
author_rank: Super Contributor
timestamp: March 05, 2017, 01:55:03 pm
content: Generally they are meant to be used with less than 1V of reverse bias, except for some with low breakdown voltage, where it is less. The non polarised ones are made with 2 premade anode foils, instead of the regular one, which has a single anode foil etched and anodised to withstand the operating voltage, and a cathode foil with a much thinner naturally formed oxide film.You have a very large value cathode end capacitor in series with the anode side capacitor, the dominant value is the anode side, the electrolyte is the one electrode, with the cathode being the connection to the other side. Thus reverse voltage damages the anode oxide film, and the breakdown has to be less than the cathode film breakdown voltage.
How do ESD monitors work? - Page 1
Forum section: electronics / beginners

author: zibilytou
author_rank: Newbie
timestamp: April 04, 2020, 11:39:00 am
content: Hi everyone.I want to know how do ESD monitors work, those who detect if someone is wearing the ESD wrist band or not. The problem is that there is only one wire feedback from the wrist band so i don't know how can you measure anything from just one wire.Thank you.
How do i add a chip? - Page 1
Forum section: electronics / beginners

author: ScottG
author_rank: Newbie
timestamp: March 31, 2014, 02:41:36 am
content: I tryed posting this in another topic. Im not an electronics gear head by any chance, but i do know my way around computer hardware, but not design. What i have is an built module that emulates a CD changer for my car, and allows my to plugin my phone to this unit to play music over the cars stereo. while it works, I'd be nice to have bluetooth. I found the Roving Networks RN-52 that is designed for audio/hands free car applications... by research it appears as if the chip has Spker_L+ Out, and Spker_R+ Out, using thoes, you can ground the negative, and have an headphone jack for output.. The unit i built takes input with the headphone jack. I do intend to use the programmible pins on the chip in the future for the steering wheel controls. How would i go about adding an Roving Networks RN-52 to an unit i already built? Heres the text from the other thread i started..... Note i did NOT design the unit but would like to addon to it. I do know how to solder well, just not design... The unit uses an voltage regulator to step down to 5v for the chips, the main chip with the white sticker is from Sparkfun(Its an Atmega328 with the bootloader preinstalled)Text replaced with link to previous post :https://www.eevblog.com/forum/projects/saab-aux-input/msg415428/#msg415428
How do I add a voltage regulator in the falstad circuit simulator? - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: June 04, 2019, 08:01:31 pm
content: Hi I am trying to add a voltage regulator like the LM317 to a circuit in thehttp://www.falstad.com/circuitsimulatore.How do I do that?

author: cur8xgo
author_rank: Regular Contributor
timestamp: June 04, 2019, 08:50:44 pm
content: Never used that simulator but looking at its web page I think you are going to have to build a regulator as it shows here:http://www.falstad.com/circuit/e-opamp-regulator.html

author: FriedMule
author_rank: Frequent Contributor
timestamp: June 05, 2019, 12:34:16 am
content: Quote from: cur8xgo on June 04, 2019, 08:50:44 pmThank you!So there may be no other way?

author: mikerj
author_rank: Super Contributor
timestamp: June 05, 2019, 12:24:37 pm
content: The Falstad simulator is primarily for educational use, using simple circuits with discrete components. There is no support for using third party Spice models and a very limited library of ICs. If you want to simulate a circuit with an LM317 you'll need to use a proper simulator such as PSpice or LTSpice.

author: Zero999
author_rank: Super Contributor
timestamp: June 05, 2019, 12:52:24 pm
content: Just one question: why?If you want a regulated voltage, just use a voltage source.If you want to look at how the LM317 works, then how about simulating the simplified schematic of it?

author: zaniver
author_rank: Newbie
timestamp: April 04, 2020, 10:13:15 am
content: I also faced the same problem. I make a simulation of LM317 with Voltage-Controlled Source with formula 1.25*a/(a-b).A is connected to the input source (pinIN of LM317). B is the midpoint of divider R1/R2 (pinADJ of LM317). V+ is out.Here is the circuit:
How do I backup firmware.  - Page 1
Forum section: electronics / beginners

author: chinoy
author_rank: Regular Contributor
timestamp: April 13, 2022, 07:29:26 pm
content: How do I backup the firmware on my hantek DSO5000 series scope.I would like to take a backup before I upgrade to the latest version.Does anybody have a list of all official firmwares ?.There web site only shares the latest version.I have done the 4 file backup and the 8 file backup does this cover the firmware ?
How do I build a PCB from schematic? - Page 1
Forum section: electronics / beginners

author: redgear
author_rank: Frequent Contributor
timestamp: August 05, 2019, 07:07:22 am
content: I followed few open source projects and duplicated their schematics on KiCad. How do I build PCBs from this? How to decide the wire thickness, amount of copper, etc?Thanks

author: Nusa
author_rank: Super Contributor
timestamp: August 05, 2019, 07:28:52 am
content: If you want something Kicad specific, there are a ton of tutorial videos. Just a matter of searching for them.That should give you some general answers. Lots of stuff you just learn by experience. If you later have a specific question you can't find the answer to, ask again.

author: thinkfat
author_rank: Unknown
timestamp: August 05, 2019, 07:53:15 am
content: Quote from: Nusa on August 05, 2019, 07:28:52 amCovers KiCad 4, but not much difference with 5.

author: redgear
author_rank: Frequent Contributor
timestamp: August 05, 2019, 08:30:27 am
content: Quote from: Nusa on August 05, 2019, 07:28:52 amSure. ThanksQuote from: thinkfat on August 05, 2019, 07:53:15 amThanks

author: JustMeHere
author_rank: Frequent Contributor
timestamp: August 06, 2019, 02:05:09 am
content: Oshpark.com is a good start.Pcbway is a bit more complicated, but if you keep your design small, it's very cheap. 100mmx100mm.
How do I calculate a single resistor value in a parallel circuit? - Page 1
Forum section: electronics / beginners

author: HiGhGuY
author_rank: Newbie
timestamp: November 07, 2012, 02:38:33 pm
content: I don't know the proper formula to figure this out. I have a 3 branch Parallel Circuit. The values I have are:Vt (total voltage)R1 (1st resistor)R2 (2nd resistor)It (total current)I need to calculate:R3 (3rd resistor)I also need to find a bunch of other values, which I know how to do, assuming I have the value of R3 but I don't know how to find R3 in the first place.Would appreciate the help if anyone knows the proper formula, thanks.

author: firewalker
author_rank: Super Contributor
timestamp: November 07, 2012, 02:54:52 pm
content: It=I1+I2+I3I1=Vt/R1, I2=Vt/R2, I3=Vt/R3It=Vt(1/R1 + 1/R2 + 1/R3). Rearrange the formula to R3.Alexander.
how do I calculate the cathode current on this "op amp" tube circuit? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: May 14, 2020, 11:13:06 am
content: there's no cathode resistor. the grid is referenced to ground. how do I draw the cathode load line?[ Attachment Invalid Or Does Not Exist ]

author: gbaddeley
author_rank: Regular Contributor
timestamp: May 14, 2020, 11:31:43 am
content: Do some research on common cathode differential amplifiers. The 110k in the cathodes is essentially a constant current source. The anode currents will always sum to about 1.35mA. So the anodes will sit at about 62.5V below B+. The anode load line is like a normal common cathode voltage gain stage.

author: ivi_yak
author_rank: Regular Contributor
timestamp: May 14, 2020, 11:38:02 am
content: hi looks like 3.2mA

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: May 14, 2020, 12:36:28 pm
content: Quote from: ELS122 on May 14, 2020, 12:04:58 pmFor tubes circuits Fun With Tubeshttp://www.funwithtubes.com/and The Valve Wizardhttp://www.valvewizard.co.uk/cover in great detail almost everything anyone needs to know.As for your particular query this is a good starting point:http://www.valvewizard.co.uk/acltp.html
[SOLVED]How do I calculate the power dissipation for a ULN2003A Darlington array - Page 1
Forum section: electronics / beginners

author: SlowBro
author_rank: Regular Contributor
timestamp: November 05, 2019, 08:58:17 pm
content: How do I calculate the power dissipation for a ULN2003A Darlington array? Is it Vce(sat) * Ic?https://www.seeedstudio.com/document/pdf/ULN2003%20Datasheet.pdf

author: StillTrying
author_rank: Super Contributor
timestamp: November 05, 2019, 09:05:44 pm
content: Is it Vce(sat) * Ic?Yes, assuming they're fully switched on, the data sheet gives the typical saturation voltages 100mA to 350mA, 0.9V to 1.3V....add a few mW for the resistors and 1st transistor.

author: SlowBro
author_rank: Regular Contributor
timestamp: November 05, 2019, 09:11:21 pm
content: So for example I want to using multiple channels drive 20 LEDs at 20mA each for 400mA total. Dissipation = 1.6V (max) Vce * 400mA = 640mW. Did I get that right?

author: StillTrying
author_rank: Super Contributor
timestamp: November 05, 2019, 09:17:35 pm
content: one of these channels drive 20 LEDs at 20mA each for 400mA total.I was going to say it might be a bit higher with 400mA though the one channel, 550 to 600mW, but you've already done it.Don't forget to add the other channels. I can't work out the Max. allowed dissipation from that data sheet.

author: SlowBro
author_rank: Regular Contributor
timestamp: November 05, 2019, 09:26:05 pm
content: Yeah, all channels combined it will be pushing the Rth j-amb max but the on time will be brief so I feel comfortable about it. Thanks!

author: floobydust
author_rank: Super Contributor
timestamp: November 05, 2019, 09:50:23 pm
content: Don't forget the IC has a limit of 500mA total for all channels, and that the SO-16 has about twice the thermal resistance compared to a DIP-16 part, check it won't get too hot...

author: StillTrying
author_rank: Super Contributor
timestamp: November 05, 2019, 10:00:18 pm
content: I don't know how many LEDs or channels there are.These ULNs used to be used to drive the pins in ribbon dot matrix printers, I never came across a blown ULN.

author: SlowBro
author_rank: Regular Contributor
timestamp: November 06, 2019, 12:56:48 am
content: Cool I wondered what they were made for. Anyway at the max current of 500mA and 5V the dissipated watts are 1.6V x 500mA = 800mW. The thermal resistance in the surface mount package is 120C/W and junction max is 150 so that leaves a buffer of 54C of ambient. I won't be driving it this hard and even when I do drive it will be intermittent so I'm comfortable. Thanks everyone!

author: digsys
author_rank: Unknown
timestamp: November 06, 2019, 01:59:56 am
content: I use FET based arrays for higher switching currents and way less losses. Very similar / same packaging and costs
How do I change probe tips? - Page 1
Forum section: electronics / beginners

author: Legion
author_rank: Frequent Contributor
timestamp: February 09, 2014, 02:41:09 pm
content: I've been staring at this for a while now and I can't figure out how to get the hook tip on my oscilloscope probe.It comes like this:I remove the IC cap and it exposes the tip:I slide the hook tip on but it doesn't stay on and it isn't making contact so no signal gets through.Any ideas on what I'm doing wrong?

author: denelec
author_rank: Regular Contributor
timestamp: February 09, 2014, 02:55:54 pm
content: With my Rigol, I have to push the hook tip until it clicks in place.

author: nanofrog
author_rank: Super Contributor
timestamp: February 09, 2014, 06:02:49 pm
content: The witch hat is where near pushed down enough to be fully seated. Hard to tell on the pic, but I'd figure needs to slide another 1"/2.5cm or so yet (you'll feel it bottom out/can't be pushed down any farther).

author: Legion
author_rank: Frequent Contributor
timestamp: February 09, 2014, 06:42:09 pm
content: You guys were right. I just wasn't pushing hard enough. I thought the probe tip would bend if I pushed too hard.Lessons learned: Remove the IC cap before putting on the hook tip. Didn't do that for one of my probes and now the IC cap is jammed up in one of the hook tips. Good thing hooktips and IC caps are only a couple bucks on eBay.
How do I decide what current rating these Zeners need to be? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 29, 2013, 12:41:49 pm
content: OK, the easy way is to ask the guy who designed the circuit. That is quite possible, I am in contact with him, but I won't learn anything much with that approach. Instead, would someone mind giving a quick run through of how I myself should assess this given just the schematic please? I am able to measure relay current draw, and get semiconductor data sheets for the devices used. Thanks.

author: Zero999
author_rank: Super Contributor
timestamp: August 29, 2013, 12:59:16 pm
content: Use Ohm's law to calculate the power, P = VI

author: Andy Watson
author_rank: Super Contributor
timestamp: August 29, 2013, 01:23:49 pm
content: I can only see D8 as taking any appreciable current, and it only does so when the relays turn off. Worst case would be 2 x 35mA. The remaining zeners supply negligible bias currents to control the MOSFETs, except for Q4 which appears to float!Edit: What exactly are RL2 and RL3? It's not clear from the web whether these are solid state, or reed relays. If it's the former, you don't need D8. In either case, are the relays actually needed? They appear to be driving another relay.

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 29, 2013, 02:11:01 pm
content: I too thought there seemed an abundance of relays, but the designer claims it all works. I wasn't going to argue, as he is far more qualified than I with thisRL2 and RL3 are mercury wetted reed relays, the spec sheet is attached. Thanks!
how do i decode the markings on a cement resister - Page 1
Forum section: electronics / beginners

author: mcoenen
author_rank: Newbie
timestamp: May 01, 2015, 08:57:33 pm
content: I’m not sure what value resister I have. I’ve done numerous google searches with no clear answer. It’s a cement wire wound resistor. The marking are K S C 2.7?K 5W It’s from the 70’s. I think it’s a 2.7K ohm 5 watt but with the ohm symbol between the 2.7 and the K I’m not sure. I am converting a PC ATX power supply for use as a bench PS and need a dummy load on the 12V line to stabilize when using small amounts of current. I think this resister is to much for that use. 27ohm 5w was suggested and I’m to impatient to order one so I’m scrounging through a pile of old parts.Any suggestions on what other values may also work?thanks

author: Ian.M
author_rank: Super Contributor
timestamp: May 01, 2015, 08:59:11 pm
content: Why not measure it?

author: SeanB
author_rank: Super Contributor
timestamp: May 01, 2015, 09:03:44 pm
content: 2R7 5% tolerance 5W resistor. The 2.7 omega is the resistance value, the K is the tolerance ( 5%) and the 5W is the rating. KSC is the manufacturer.

author: Cliff Matthews
author_rank: Unknown
timestamp: May 01, 2015, 10:04:13 pm
content: Bathtub resistors... does that mean I'm over the hill?

author: mcoenen
author_rank: Newbie
timestamp: May 01, 2015, 11:40:11 pm
content: thanks guys. that's what i needed to know.
How do I determine what filter capacitors to use (power supply line)? - Page 1
Forum section: electronics / beginners

author: roogadget
author_rank: Contributor
timestamp: October 10, 2018, 06:48:20 am
content: How do I determine what power supply capacitors to use?I am working with a module that has already provided me with with correct capacitors. (attacked)However, I would like to know the reason or rather formula behind their decisions.All of the resources I have found don't go into enough detail. It almost seems like picking these caps just comes from trail and error.I've ask one of my professors and he pretty much told me to keep switching them until I find a cap that filters best...any ideas?

author: David Hess
author_rank: Super Contributor
timestamp: October 10, 2018, 11:22:03 pm
content: Usually just a bulk electrolytic capacitor is combined with a ceramic or film capacitor which provides a lower ESR at higher frequencies. Multiple capacitors of different values might be used where series inductance is more of a problem like with leaded parts.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: October 10, 2018, 11:49:08 pm
content: it all comes to what is acceptable for you're circuit powering, in terms of... ripple :https://en.wikipedia.org/wiki/Ripple_(electrical)

author: german77
author_rank: Regular Contributor
timestamp: October 11, 2018, 12:22:09 am
content: If you want to know exactly witch capacitors to use you need to test them as each brand and type filters different frequencies. This is done with expensive equipment. I think Dave have made some videos about this. Usually using multiple capacitors of an order of magnitude value will give the best results.If you go from 10mF....100uF, 10uf, 1uF, 100nF, 10nF....1pF. you will filter almost anything. But of course in practice having 9+ capacitors to filter a power supply will not be very practical. And will introduce other problems like the initial current spike. So one usually start adding a capacitors one by one looking for the best results. 2 to 4 capacitors will filter the most noise. Adding more will reduce even more but not by a significant amount.