hybridfree/eevblog-posts huggingface dataset:
Fun With Ohm's and Kirchoffs Laws - Page 1
Forum section: electronics / beginners

author: Lance
author_rank: Frequent Contributor
timestamp: March 25, 2011, 07:39:57 am
content: I'm given the following problem:8 bulbs (I'm assuming identical) are connected in parallel by two wires that have a resistance of 1.8 ohms each to a 180V source.If the current through each bulb is 0.180A what is the resistance of each?Well we have 8 identical bulbs, which can be treated as resistors. So by that logic they all have the same resistance, and by Kirchhoff's current law the current should get evenly divided between them all. So I figured that the current through the circuit over all should be the sum of the current through each bulb, therefore:Total Current=.180A*8 = 1.44 A total.To find the resistance of each I did this:V=IR --> R=V/IThe net result of the resistances of the bulbs is their equivalent series resistance is 1/8 of their own resistance(1.8*2+RBulb/8)=180V/1.44AI calculated the Resistance using this to be 971.2 ohms per bulb. Everything worked out alright, and I got about 1000ohms. The automated system that I enter my answers into (my school is lazy) says 990. Am I right, or did I goof up somewhere?Then I need to find the power wasted in the wires, or rather the fraction wasted in the wires. I'm still working on that.EDIT: I got it. And I misinterpreted the problem. The net resistance of the leads is 1.8 ohms. So that difference is why my answer was off.

author: Simon
author_rank: Unknown
timestamp: March 25, 2011, 07:49:20 am
content: Quote from: Lance on March 25, 2011, 07:39:57 amthats the clue that you made a mistake in your first part, you did not account for the wire resistance that will cause a voltage drop so there is not 180V on the bulbs. You need to figure out the total bulb current then work out the voltage drop on the wires so that you get the actual voltage across the bulbs and so get a more acurate resistance.school tests never give extra info just for the fun of itIf the questions states that the wires "are connected to a 180V source" then yes your school is lazy. if both wires are connected to a 180V source there will be no current flow anyhow

author: Lance
author_rank: Frequent Contributor
timestamp: March 25, 2011, 08:21:13 am
content: Well it's not the school in particular, it's the textbook publishers online service. That and that's my own wording. It was clear only one of the wires was connected to the source. I don't know if you saw my edit, but the way the question was worded the resistance of the wires was a bit ambiguous. I thought that it was 1.8 ohms per wire, but it turned out they were 1.8 ohms total. That made the minor difference.After I figured that out solving the power problem was cake.Thanks.

author: deephaven
author_rank: Frequent Contributor
timestamp: March 25, 2011, 08:26:55 am
content: With the phrase "two wires that have a resistance of 1.8 ohms each" it looks like you made a sensible assumption!
Function gen output - TTL vs 50 ohm? - Page 1
Forum section: electronics / beginners

author: george graves
author_rank: Super Contributor
timestamp: September 26, 2012, 04:40:54 am
content: I'm working with a function generator I recently got off of ebay. (FG-8002) I'm playing around with a couple circuits and wanted to use it to test a frequence to voltage converter chip - and also an arduino to measure frequency of a square wave.It has two outputs. 50 ohm, and TTL.When is the right situation to use one or the other? And why?And how much can it drive?Dave? How about a little "how to use a function gen" video?

author: shebu18
author_rank: Frequent Contributor
timestamp: September 26, 2012, 04:58:23 am
content: On the function gen ou can have 10Vpp, so this means a plu 5V and a -5V, this would not work on ttl. On ttl you have 5Vpp and an offset of 2,5V so you get a maximum of 5V and a minimum of 0V on the output.

author: ejeffrey
author_rank: Super Contributor
timestamp: September 26, 2012, 08:43:30 am
content: The "50 ohm" terminal is the main output of the function generator. The TTL terminal is the sync. It is the same frequency and phase of your output signal, but a logic level square wave. You use it to synchronize multiple instruments. You can send it to your scope trigger input or you can use it with a lock-in amplifier to provide a phase reference.
function gen. - Page 1
Forum section: electronics / beginners

author: Cali-Sam
author_rank: Contributor
timestamp: January 01, 2014, 01:24:20 am
content: i found GFG-8219A analog function generator on my local Craigslist for $100.is that a good deal, or is there a better deal out there?

author: nanofrog
author_rank: Super Contributor
timestamp: January 01, 2014, 05:39:20 am
content: The price is about 1/3rd of new (~$313 new on Amazon), so not terrible IMHO.You can find less expensive ones on eBay (cheapest I saw at a quick check is ~$40, but most tend to start ~$60+ incl. shipping). But they may/may not be working (no idea if non-working is an issue for you) or have all the features or BW you want.

author: peter.mitchell
author_rank: Super Contributor
timestamp: January 01, 2014, 10:02:55 am
content: It is an OK budget function gen, but at $100, that makes it a much better deal than at its retail.If you're a beginner and you don't have a function generator, but have most other equip, i'd probably get it. It comes with a few things a kit normally wouldn't, including a case and a decent built in power supply.It doesn't have all the bells and whistles a good function gen has, but the price vs performance is good for a beginner. Also, often, when building u stuff and testing stuff, you need a "reference" to check things with, so you need to somewhat trust the instrument, and this is where i'd have issue with the cheap chinese ones from ebay ect.
function generator - Page 1
Forum section: electronics / beginners

author: jude_elec
author_rank: Newbie
timestamp: December 22, 2018, 12:38:47 am
content: hello everyone, i am new to electronics and have received a lab assignment to evaluate an arbitrary function generator (GW instek mfg-2260 mra )i am trying to evaluate it and see the benefits it has vs what is being used now (holzworth HSM1001A)what i need from this device is to be able to produce a clean sine wave in 160 MHz to a circuiti read the device data sheet and spec and tried to measure using my scope jitter and sine distortion of both of them also attenuation as frequency increases and compered to the spec, i wanted to know there are more thing i should do to compare the performence of this device?i am not sure i fully understand the usage of trigger but i read about the trigger input option of this device and i wanted to know is there a way to use this input as a reference clock for the sine signal?and also if anyone ever used this device before i would like to know how can i remote control with usb because the manual was not so helpful (or where can i read about it)hope you could assist me.thank you.

author: Rerouter
author_rank: Super Contributor
timestamp: December 22, 2018, 12:52:28 am
content: As far as remotly controlling it, have a read on from page 250 in the manual,https://www.gwinstek.com/en-global/products/downloadSeriesDownNew/5080/418The trigger functions of a signal generator is generally used to either turn on or off the output, or change some characteristic of the output when the state changes, e.g. a really basic example would be you want it to generate a frequency whenever a signal goes high, and be off the moment it goes low, the trigger can be used to do that,Then there are more complex things, e.g. giving it an arbitrary waveform that is a malformed packet or transmission of your desired protocol. and firing it off as you vary supply voltage of your device, or change something else.

author: MarkF
author_rank: Super Contributor
timestamp: December 22, 2018, 03:39:06 am
content: One thing you can do to see how clean your sine output is to look at the frequency domain with the FFT function on your scope or spectrum analyser. Look at the harmonics and what their amplitude is.

author: jude_elec
author_rank: Newbie
timestamp: December 22, 2018, 09:31:47 pm
content: thank you for your replyIve measured the harmonic distortion of both of devices in one frequency that i am mostly interested in(156 MHz), and the difference is of less than 1%, does it has any effect?and secondly , should i perform for more frequencies surrounding that specific one? is THD a size you can average on' cause it is frequency dependent?
function generator cable set - Page 1
Forum section: electronics / beginners

author: Chai
author_rank: Regular Contributor
timestamp: April 11, 2016, 04:15:18 am
content: I'm about to order my first (2ch) function generator and I'd like to know which cables and quantity would be a good start to buy alongside. It'll be joining my 4ch oscilloscope.?http://www.saelig.com/product/UCO003.htmhttp://www.saelig.com/product/PSBEA006.htm?

author: jobog
author_rank: Regular Contributor
timestamp: April 11, 2016, 05:11:19 am
content: I would recommend 2 of each, BNC to mini grabber, BNC to BNC, and BNC to alligator clip. This combination serves me well but you can never have enough cables.

author: Blaffetuur
author_rank: Regular Contributor
timestamp: April 11, 2016, 06:58:20 am
content: I have a BNC to BNC to feed the trigger to my scope and a BNC to minigrabber to feed the signal to my circuit

author: MrSlack
author_rank: Frequent Contributor
timestamp: April 11, 2016, 09:42:43 am
content: I wouldn't get any BNC -> minigrabber long cables. They are inflexible and unreliable and if the clips die or the cable dies you lose the whole thing. Best bet is to grab 3-4 BNC RG58 patches and get two pomona 3788 BNC/minigrabbers. They can be stuck on the end of a BNC patch so you can switch your cables around as required. They are relatively expensive but millions of times more reliable than the cheap chinese crap ones which will be nothing but pain for you.Pomona 3788 for reference:

author: Blaffetuur
author_rank: Regular Contributor
timestamp: April 11, 2016, 11:15:14 am
content: Quote from: MrSlack on April 11, 2016, 09:42:43 amI didn't know these even existed

author: vindoline
author_rank: Unknown
timestamp: April 11, 2016, 04:46:07 pm
content: I agree completely with MrSlack. Get a set of nice quality bnc to bnc coax cables and then get various adapters. I also use these all the time:

author: mmagin
author_rank: Frequent Contributor
timestamp: April 11, 2016, 06:41:01 pm
content: Quote from: vindoline on April 11, 2016, 04:46:07 pmMe too. I love having solidly-built BNC to banana/binding post adapters on hand. Just attach a couple wires as you need.

author: Chai
author_rank: Regular Contributor
timestamp: April 11, 2016, 07:16:18 pm
content: how about 3x these?Amphenol-RF CABLE BNC ST PLUG-PLUG RG-58 36"Gender Male to MaleStyle BNC to BNC1st Connector BNC Male Plug2nd Connector BNC Male PlugLength 36.0" (914.4mm)Cable Type RG-58Impedance 50 Ohmhttps://www.digikey.com/product-search/en?keywords=ACX1795-ND

author: LaurentR
author_rank: Frequent Contributor
timestamp: April 11, 2016, 08:37:48 pm
content: BK Precision TLFGNot cheap but has all you need (as has been described above).http://www.tequipment.net/BKTLFG.html
Function generator.  For what does it stand for? - Page 1
Forum section: electronics / beginners

author: CiscERsang
author_rank: Regular Contributor
timestamp: May 14, 2019, 02:42:19 pm
content: Hello everyone,Could anyone explain. For what does function generator stand for.I see some oscilloscopes come with built-in one.Thank you!

author: YaSaRa_N
author_rank: Contributor
timestamp: May 14, 2019, 03:15:45 pm
content: function generator is the same thing as the waveform generator, signal generator. when designing debugging electronic circuits, some times it is needed to feed external voltage signals into the circuit. The function generators (waveform generators ) allows us to create many kinds of voltage signals (waves) such as sine, square, triangle etc. we can set the required frequency, amplitude and dc offset of the signal (within the supported range of the function generator)some oscilloscopes(base model of most high end scopes and upgraded versions of several low end ones) has a built-in function generator. so you don't need to buy a separate one but they may not offer some advance features as expensive standalone function generators.you can find more info on the web.
Function Generator Frequency Range for Calibrating Oscilloscope - Page 1
Forum section: electronics / beginners

author: TinkerGDS
author_rank: Contributor
timestamp: July 31, 2016, 07:36:46 pm
content: I have a very rudimentary question about Function Generators. I do not have one so I can't test anything to know the answer. If I want to calibrate a 400Mhz oscilloscope, do I need a function generator that has a range up to 400Mhz?

author: tggzzz
author_rank: Super Contributor
timestamp: July 31, 2016, 08:07:51 pm
content: No you don't need a function generator. If you think about the duality between time and frequency, you can simply use a voltage step with a sufficiently short rise time. The rule of thumb is that BW = 0.35/tr

author: rstofer
author_rank: Super Contributor
timestamp: July 31, 2016, 10:10:55 pm
content: Quote from: tggzzz on July 31, 2016, 08:07:51 pmWhich presents another problem, where do you find a signal source with less than 1 nS rise time. Not that they aren't available but what do you buy off the shelf?

author: tggzzz
author_rank: Super Contributor
timestamp: July 31, 2016, 10:18:44 pm
content: Quote from: rstofer on July 31, 2016, 10:10:55 pmA 74LVC1G14 has a risetime of that order. Three of them in parallel each with a 130ohm series resistor will drive a 50ohm line with ~650ps (not 650pS, of course) transition time. Make sure they are well decoupled.I use that when calibrating my Tek 485 (which also has a built-in 1ns/1MHz calibrator waveform).
Function Generator Output - Page 1
Forum section: electronics / beginners

author: MapleLeaf
author_rank: Contributor
timestamp: January 16, 2016, 06:12:25 pm
content: I need to inject a 10 MHz signal into a radio.I have a function generator, Siglent SDG 5082. I plan to create a coil of 10 turns of wire off the end of the function generator cable to put next to the radio’s antenna to get the signal into the radio.The function generator has two settings for the output: 50 ohm and high impedance. I know about the 50 ohm watching Dave’s excellent videos on impedance matching for test instrument cables. My question is: what is the high impedance for? Would this be the setting for my 10 turn coil? What other applications should the high impedance setting be used for?I have looked at the Siglent manual and it is worthless. It doen’t even say what the high impedance ohm value is.

author: dadler
author_rank: Unknown
timestamp: January 16, 2016, 07:34:18 pm
content: The choice on the generator allows you to configure the load you are terminatinginto.The generator always has 50 ohm output impedance. The two settings just change the displayed voltage levels on the screen of the generator. It does the math for you.It's a convenience function, in the case you are not terminating the signal into 50 ohms. On the 50 ohm setting, it assumes there is essentially a 50 ohm resistor on the other end of the cable, resulting in a 1/2 voltage divider. In high impedance mode, you are essentially saying there is no load/terminating resistor at the other end of the cable. The voltage displayed on the screen will be twice as high as when 50 ohm is chosen. The actual voltage and output impedance will not change.
Function Generator Rigol DG1022Z - Page 1
Forum section: electronics / beginners

author: stefanvr
author_rank: Newbie
timestamp: July 11, 2017, 09:13:52 am
content: Hi all,I just bought a function generator DG1022Z from Rigol.Is there a way to change the output signal? i connected it on the base of a transistor with a large resistor and i get 250 mv on it. With a 5V pp on the screen. It seems its gives me just 1/10 of the voltage.Stefan

author: ElektronikLabor
author_rank: Regular Contributor
timestamp: July 11, 2017, 10:57:27 am
content: Hello and welcome Stefan!1. Can you confirm, that the output is not loaded? (no current flows out of the output)2. If you measure the voltage with a oscilloscope and a 1:10 passive probe: Can you confirm, that the division rate of 1:10 is adjusted on the scope to compensate the voltage drop?

author: xrunner
author_rank: Super Contributor
timestamp: July 11, 2017, 11:31:54 am
content: Well, have you verified that the DG1022 is outputting properly? Connect it directly to a scope, you should see 5 Vpp on the screen. The only setting that would change the display amplitude to match an expected output level when connected to a circuit (specifically 50 ohms) would be the load setting in the utility menu (50 ohms or high Z). But I don't think that is your issue.
Function Generator software for MacOS & interface question. - Page 1
Forum section: electronics / beginners

author: Jebnor
author_rank: Regular Contributor
timestamp: October 18, 2013, 02:09:31 am
content: Hello all,I'm looking for a Function generator for my Macbook, using the audio output, preferably independent stereo outputs. Can anyone recommend one?Further I am wondering about proper interfacing. I know headphone outputs have a 32ohm impedance, so I will add an appropriate resistor before buffering the signal. Is there anything else I need to do? I will probably add a DC offset and gain stage.Random thoughts:Are L/R channels of an audio output interlaced?
Function generator what is deemed good? - Page 1
Forum section: electronics / beginners

author: MrZwing
author_rank: Regular Contributor
timestamp: February 03, 2015, 12:36:32 pm
content: I'm looking around at different Function generators and well I don't really know what I should be looking at, I'm looking for something decent for audio and testing filters and low noise power supplies. I'm also trying to save as much money as I can since I'm a poor man indeed.saw this on E-bay:http://www.ebay.com/itm/2MHz-Dual-Channel-DDS-Function-Signal-Generator-Sine-Square-Wave-Sweep-Counter-/171382538522?pt=LH_DefaultDomain_0&hash=item27e732011aBut I guess it's a cheapo "stay away" product or have someone tested it and found it decent?

author: Yago
author_rank: Frequent Contributor
timestamp: February 03, 2015, 12:51:30 pm
content: There are some threads on the subject, but the search engine here is not so good (can't find a way to look at all threads created by a user?).Found this thread:https://www.eevblog.com/forum/chat/in-need-for-a-function-generator/msg110590/#msg110590Definitely get advice as there are some junk out there.I ended up getting a used Fluke from Ebay.
Function generators - Page 1
Forum section: electronics / beginners

author: netdudeuk
author_rank: Frequent Contributor
timestamp: October 05, 2014, 11:10:37 am
content: I'm interested in how many amateur electronics enthusiasts use function generators, what the specifications are and for what purpose.Is something like thishttp://www.ebay.co.uk/itm/2MHz-Dual-Channel-DDS-Function-Signal-Generator-Sine-Square-Wave-Sweep-Counter-/291250699525?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item43cfe4fd05or thishttp://www.ebay.co.uk/itm/New-DDS-Function-Signal-Generator-Module-Sine-Square-Sawtooth-Triangle-Wave-/281225637298?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item417a5aadb2any good for anything at all ?

author: abaxas
author_rank: Regular Contributor
timestamp: October 05, 2014, 03:30:11 pm
content: http://www.ebay.co.uk/itm/New-10MHz-Dual-Channel-DDS-Function-Signal-Generator-Source-Frequency-Cymometer-/311104863686Seams liike there is a 10mhz version for 11 quid more..I guess they are just those cheapo dds doodars in a nice box?
Function generators - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: June 02, 2013, 11:08:37 am
content: I seem to be building different types of generator's of late , so far , a pulse generator, also a fast edge pulse generator from W2AEW you tube channel, now I've gotten interested in a sweep generator , which seems to have several uses so looking for a simple effective circuit. which will be the last one I build for a while.The next project after, is a simple pc based simple spectrum analyser by a radio amateur EI9GQ who's Homebrew cookbook I have, so the first part is the noise generator, and I'm wondering if there's a way to connect it to my scope rather than computer, one it's uses are when building filters, for amateur radio to see there cut off frequency, and it uses the computers sound card to display the plot, can't wait to get at it.

author: FrankBuss
author_rank: Unknown
timestamp: June 02, 2013, 01:51:20 pm
content: Sounds interesting. Do you have a website where you publish it? Once I've implemented a simple function generator, too, with a FPGA development board:http://www.frank-buss.de/SignalGenerator/index.html

author: Unknown
author_rank: Unknown
timestamp: June 02, 2013, 02:21:24 pm
content: Quote from: FrankBuss on June 02, 2013, 01:51:20 pmHi Frank, no I do not have a website, I do find these things fascinating though, just getting a good understanding of them before I move on, W2AEW Alan has a good circuit on you tube , of a fast edge pulse generator, and it works really well, a good simple build. I hardly use my bought frequency generator now as I use my own instead, very satisfying.

author: FrankBuss
author_rank: Unknown
timestamp: June 02, 2013, 02:26:53 pm
content: Thanks, I'm now subscribed to his Youtube channel:https://www.youtube.com/user/w2aew/featured

author: Unknown
author_rank: Unknown
timestamp: June 02, 2013, 02:32:10 pm
content: Quote from: FrankBuss on June 02, 2013, 02:26:53 pmOK good this is my version of W2AEW fast edge pulse generator, Alan's video will explain all about it
Function of a little dot on bobbin of a flyback transformer - Page 1
Forum section: electronics / beginners

author: khatus
author_rank: Regular Contributor
timestamp: August 12, 2019, 05:04:41 pm
content: Hello guys i want to know function of this dot on bobbin of a flyback transformer.I guess it is for dot convention of transformerwhen i remove first layer of sticky tape i have found it was wound in clockwise direction.

author: Domagoj T
author_rank: Frequent Contributor
timestamp: August 12, 2019, 05:20:01 pm
content: Marking for pin 1.

author: Ian.M
author_rank: Super Contributor
timestamp: August 12, 2019, 06:49:34 pm
content: It wouldn't need a peg like that just to visually *identify* pin 1, so it must be intended to operate a sensor or engage with a hole in a jig for (semi) automated assembly to ensure the bobbin orientation is correct with respect to the coil winding machine, or for part orientation during (semi) automated board stuffing.
Function of checkered pattern on trace - Page 1
Forum section: electronics / beginners

author: giosif
author_rank: Frequent Contributor
timestamp: February 28, 2022, 07:21:21 pm
content: Hi,I am trying to draw the schematics of a module from a SMPS (power supply P/N A25G1-02M).This module is a PCB on a ceramic substrate and hosts the voltage reference, opto-isolator, switching IC and a bunch of passives (namely capacitors and laser-trimmed resistors).However, I am seeing this checkered patter on one of the traces and I am wondering what purpose it might serve (please see attache photo).Can someone help clarify this, please?Thanks!

author: Benta
author_rank: Super Contributor
timestamp: February 28, 2022, 07:25:32 pm
content: Could be for calibrating the mask positions when producing the substrate. You'll see this on IC die patterns as well.

author: giosif
author_rank: Frequent Contributor
timestamp: February 28, 2022, 08:23:25 pm
content: That makes sense.Thank you for the info!

author: Watth
author_rank: Frequent Contributor
timestamp: March 01, 2022, 10:34:05 am
content: Are the blueish areas an isolating layer between the copper traces that come across?

author: giosif
author_rank: Frequent Contributor
timestamp: March 01, 2022, 03:56:19 pm
content: Yes, they are.
Function of this circuit? - Page 1
Forum section: electronics / beginners

author: WillHuang
author_rank: Contributor
timestamp: January 04, 2017, 02:30:27 am
content: In the image attached, I see a LPF. At the output, there are some additional resistors and capacitors before feeding into an ADC. I was wondering what are these resistors and capcitors for?

author: David Hess
author_rank: Super Contributor
timestamp: January 04, 2017, 03:23:43 am
content: ADCs with sampling inputs can present a dynamic load which is difficult for a operational amplifier to drive. The output RC network isolates the ADC input from the operational amplifier output.

author: orolo
author_rank: Frequent Contributor
timestamp: January 04, 2017, 03:41:06 am
content: What about this?The LPF has a corner frequency of 10Hz. The 10K resistor just after the LPF acts as a load for the op-amp.The 1.5k resitor has two roles:1) protects the op-amp from capacitive loading.2) If the test point TP? is used to inject a testing signal, the 10k/1.5k divider causes the ADC to see a mix of about 0.9 times the op-amp output and 0.1 times the injected signal. In that case, the 1.8n/1MEG RC could work as a LPF (~10kHz) for the injected test signal.I think this could be an explanation, because the 1MEG resistor doesn't seem to be RC filtering the op-amp, the 10K+1.5K take care of that.Edit: No. Of course, a signal injected from the test point will see an RC filter with 1.8n and 1.5k, so the 1MEG resistor does nothing in that respect. What is that 1MEG resistor for?

author: Benta
author_rank: Super Contributor
timestamp: January 04, 2017, 10:26:56 am
content: You have a Sallen-Key active low-pass filter at the input, which is the worst filter topology ever designed.It has several deficits, one being tolerance sensitivity, which is the change of filter characteristics vs. component tolerances.It also turns into a high-pass filter at higher frequencies, the passive LPF at the output is to keep this tendency under control.I suggest you change to an MFB topology instead.

author: Benta
author_rank: Super Contributor
timestamp: January 04, 2017, 11:57:31 am
content: By the way, TI has a very good application note:http://www.ti.com/lit/an/sloa049b/sloa049b.pdfLook at page 13 and you'll see the problem.
Function Opamp - Page 1
Forum section: electronics / beginners

author: nuclear213
author_rank: Newbie
timestamp: October 07, 2019, 08:53:55 pm
content: Hello everyone,after I got such great help the first time I asked, thanks again for that, I have another problem.I wanted to play a bit with wireless power transfer and found a, what I think, great dev kithttps://www.we-online.de/web/de/electronic_components/produkte_pb/demoboards/wireless_power/design_kit_200_w/wireless_power_200wkit_page.phpfrom Würth Elektronik. The coupling and the power transfer is not that difficult to understand however they also include a AM transmitter and receiver. That is where I have my problem.The transmitter side is still ok to understand, they just switch in some extra caps in the resonant circuit, changing the resonance frequency and thus changing the amplitude.The receiver-side is what I do not understand and sadly I can also not find anything relevant on google about it. As far as I understand the Zenner D16 is there just to lower the Voltage by 20V. Then we have an envelope detector with D14, R45 and C56 and an AC-coupling with C54. After that I would guess we have the diodes to limit the voltage to -Vfwd and Vcc-Vfwd.But then I do not understand the function of the first opamp. Does anyone have a pdf or a book recommendation for that? I have not seen such a configuration before.

author: iMo
author_rank: Super Contributor
timestamp: October 08, 2019, 08:29:42 am
content: The C55 R43 R40 form an low-pass with time constant t1 - that creates the floating "reference level".The parts at the inverting input form a "shaper".The opamp will compare the average ref level at the noninverting input with the actual modulation level at the inverting input, thus it recovers the digital signal off the input independent of the signal's amplitude (it compares the "fast modulation changes" against the "average reference level").The "longest period td" of the digital modulation signal (1/0 changes) should be much smaller than the t1.PS: this circuit was pretty popular in 70ties as we were building the DIY radio-control for models. The signal coming from the receiver (with varying amplitude carrying the digital modulation signal) passed that opamp, and the output TTL/CMOS level was then fed into a shift register. The outputs of the shift register were wired to the servo's PWM inputs..

author: nuclear213
author_rank: Newbie
timestamp: October 08, 2019, 01:24:53 pm
content: Thanks for your reply.I am a bit embarrassed that I did not see the RC-filter there. But that helps a lot.However I tried to simulate the same design in LTspice and it just would not work. Even used the same opamps (AD8642). I can see the modulation at TP1 however the opamps do not output anything.I tried 100kHz and 150kHz, as those are the frequencies used in their dev kit for the carrier signal and a simple 5kHz rectangle signal. Lowering or rising the amplitude of the AM signal does not change anything.
Functional 36vdc External Speed Controller Circuit? - Page 1
Forum section: electronics / beginners

author: electromateria
author_rank: Regular Contributor
timestamp: July 16, 2021, 04:22:28 am
content: What's the most basic but also stable and functional ESC circuit floating around? Ideally with voltage protection and any other necessary things. Made from very common components. Has anyone built one and shared?

author: Zero999
author_rank: Super Contributor
timestamp: July 16, 2021, 10:18:36 am
content: There isn't enough information to go on. Your question is akin to asking someone to recommend a car which runs on gasoline.You're making it more difficult by starting so many threads. Just make one thread about your scooter project and stick to it.

author: Faringdon
author_rank: Super Contributor
timestamp: July 17, 2021, 07:46:01 pm
content: QuoteWell, you know they are all basically BLDC inverters....and usually 3 phase....so its a 6 transistor bridge....and you switch them so you make the coil excitation rotate round the stator, and spin the motor like that....so really , the biggest effort is the software if anything. At start-up you have to "tease" the motor to rotate by not rotating the field too fast or too slow. You should really write your software with knowledge of the motors "characteristics"...but in truth you can hack it about without knowing the motor characteristics. Have some fast analog current limitation too, so you dont overcurrent it (the motor windings).

author: Siwastaja
author_rank: Super Contributor
timestamp: July 18, 2021, 01:59:06 pm
content: There are many projects, open source or public otherwise, use Google.There is no acceptable off-the-shelf IC to do it as far as I know, so every project involves a microcontroller. Some STM32 is most typical, and almost any in STM32 series is capable of doing it. In STM32 terms, you need one Advanced Control Timer per motor, and ADC. Even the simplest STM32F0 series devices are good enough for the task.Largest part is the software, but you can try to utilize existing open source code, or learn the whole thing yourself, but it's not completely trivial. You need to understand the concepts of FOC and sensorless rotor angle estimation.In addition to the microcontroller, you need gate drivers, MOSFETs, current shunt resistors and amplifiers, DC link capacitors and decent layout work. Nothing too fancy.

author: Terry Bites
author_rank: Super Contributor
timestamp: July 18, 2021, 02:24:36 pm
content: Floating where. Ebay is awash with them. Pick one and report back your findings to the forum.That'll be one floater less.
Functions generator XR2206 and oscilloscope FNRSI DSO152 - first use - Page 1
Forum section: electronics / beginners

author: kbm
author_rank: Newbie
timestamp: May 09, 2024, 06:37:13 am
content: Functions generator XR2206 is connected to oscilloscope FNRSI DSO152. To functions generator is connected power supply 9V, 1 mA.Oscilloscope shows signal on chart but all time is the same signal. I change jumper from Sine to Triangle but it still shows the same chart. I change jumper responsible for frequency but chart is the same too. I changed AMP, FINE and Coarse adjustment but chart did not change. All time oscilloscope shows the same chart.On oscilloscope I tried in Auto and Normal mode and chart didn't change.Could this mean that the functions generator is faulty?

author: BennoG
author_rank: Frequent Contributor
timestamp: May 09, 2024, 07:26:51 am
content: the output voltage is far to low, so you have the potmeter set to 0V output or your power supply is faulty.if you have soldered it yourselves, then you could have made an error in the soldering.the power supply needs to be at least 10V DCBenno

author: Aldo22
author_rank: Super Contributor
timestamp: May 09, 2024, 07:36:46 am
content: That's probably just 50Hz noise you're seeing.Is the square output (red wire) working?

author: wasedadoc
author_rank: Super Contributor
timestamp: May 09, 2024, 08:53:08 am
content: IIRC the amplitude control (the leftmost) is wired backwards. Fully clockwise is zero amplitude. Set it midway for starters.

author: CaptDon
author_rank: Super Contributor
timestamp: May 09, 2024, 12:40:39 pm
content: What do you mean Power Supply 1 ma.? The connector looks like a wall wart power supply. Is the voltage correct and is the polarity correct and is it D.C. and NOT A.C.?

author: kbm
author_rank: Newbie
timestamp: May 09, 2024, 08:48:27 pm
content: Power supply is 1000mA - sorry for mistake.The output voltage now is 11V DC. Is was DC but too low. I changed power supply. Now it works and shows correct chart. I can change amplitude control and amplitude of wave changes on chart.
Fundamental difference between BC559C and BC557B - Page 1
Forum section: electronics / beginners

author: Dave Turner
author_rank: Frequent Contributor
timestamp: December 10, 2014, 10:29:05 pm
content: I've just come across the specs for the 'Curious C-beeper'. The version I've seen specifies BC559C and BC549C transistors.The closest I have in stock are BC557B & BC547B respectively. At first glance they seem to have similar specs.Clearly I'm missing something fundamental and important. Would someone point out what I'm missing please?

author: madires
author_rank: Super Contributor
timestamp: December 10, 2014, 10:42:46 pm
content: Check out the datasheetV_CEO is 30V for BC549 and 45V for the BC547. That should be fine. But hFE could be an issue since C means 420-800 and B means 200-450. Try to find BC547Bs with an hFE of about 400. The same applies to the BC557B.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: December 10, 2014, 11:18:35 pm
content: Madires - Thanks it's so easy to miss the obvious. If I may, however ask subsequent question; suppose I had BC557Cs with hFE 420 - 800 what is the difference between them and the 559C?I'm going to experiment anyway. but whilst I usually understand the overall picture I'd like to properly comprehend the subtler issues.

author: David_AVD
author_rank: Super Contributor
timestamp: December 10, 2014, 11:45:23 pm
content: BC5x7 and BC5x9 have different Vce specs.

author: Dave Turner
author_rank: Frequent Contributor
timestamp: December 11, 2014, 05:25:10 pm
content: David_AVD - thanks. I finally found the Fairchild data sheets which compare the BC556/7/8/9 & 60. It's a little easier to spot that VCEOand VCBOvaries.

author: Tube_Dude
author_rank: Regular Contributor
timestamp: December 17, 2014, 03:56:48 pm
content: BC559 and BC549 are lower noise versions of the BC557 and BC547 respectively.They are usually used at input stages and where lower noise is determinant.There are some voltage ratings differences, as you can see in the data sheet, and the suffix letter (A,B,C) show the hFE variation interval...

author: Dave Turner
author_rank: Frequent Contributor
timestamp: December 17, 2014, 05:25:18 pm
content: Tube_Dude - cheers. I was wondering whether the 557 would be a suitable substitute for a 559 in a curious c beeper, because that's all I have to hand. I guess the only answer is to breadboard it and check it.
Fundamental understanding 🤷‍♀️ - Page 1
Forum section: electronics / beginners

author: wrx757
author_rank: Newbie
timestamp: June 03, 2024, 03:00:29 pm
content: Why doesn't a solenoid coil melt if the conductor is so thin? Is it because it's so long causing high resistance thus low current flow?

author: Manul
author_rank: Super Contributor
timestamp: June 03, 2024, 03:52:45 pm
content: Every conductor has some current carying capacity orrating, depending on it's material, thickness and ambient temperature.Conductor wound into tight coil has slightly lower current carrying capacity due to worse cooling (heat starts to accumulate).Current depends on cunductor resistance and applied voltage. See Ohms law. In your case, current depends on voltage applied to the solenoid. If you apply too high voltage, it will melt.Heating, orpower dissipationof a resistive load is equal to voltage times current.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 03, 2024, 04:14:00 pm
content: The two equations you need are V = IR, and P = IV. V = voltage (Volts), I = current (Amps), R = Resistance (ohms), P = Power (Watts).Say you have a solenoid, powered by 12V DC rated for 1 Watt. Whilst its indictive and the current in the coil won't change instantly, when the magnetic field is saturated it essentially becomes a resistor. The current flowing in the coild will be I = V/R. Thats I = 12/R. The power dissipated by the coil will be P = I*12. You can use the equations above by rearraging or combining to get P = I2* R.Or P = V2/ R.Since we're using a fixed regulated voltage to power the coil, 12V, thats P = 144 / R. If its rated for 1 Watt we can work out its resistance as R = 144 / P, where P = 1 Watt. So, R = 144 /1 = 144 Ohms.The current flowing in it should be I = V/R = 12 / 144 = 0.0833 = 83.3mA.In terms of heat, that is the power dissipated by the coil, since thats the only real way a coil of wire can "lose" energy - unless its really hot then it will also emit light. As to how hot a coil will get based on its power dissipation (in Watts) depends on its construction, since a smaller coil has less surface area, so can't radiate (or if in contact with a heatsink, conduct) heat as much as a coil with a larger surface area.So the short answer to your question is, yes, higher resistance, for a given fixed voltage means less current will flow. Less current = less power = less energy to dissipate = lower temperature.This is why Mains operated relays and solenoids have very high resistance coils, and since they can't be huge - have to use very thin wire to achieve that resistance in a given volume.

author: RJSV
author_rank: Super Contributor
timestamp: June 03, 2024, 06:40:05 pm
content: The coil inductance is going to limit current, as well as any wire resistance. That's only true, however, for A C. or with brief transients.The rough equivalent parameter is reluctance, which goes up as frequency goes up.
fundamentals friday - Page 1
Forum section: electronics / beginners

author: joejoe317
author_rank: Contributor
timestamp: March 21, 2015, 08:44:06 am
content: Hello, I very much enjoyed some of the fundamentals friday videos that Dave has created. I googled for it and found there was a playlist of about 17 videos for this.Can anyone confirm that this is all he has for fundamentals friday, or am I missing them? The last one I found on youtube was posted in jan 2014.I really wanted to see the fundamentals of how you can use a circuit to read voltages using op amps. I have found some interesting circuits in some of the books I have purchased, but there isn't much detail on how they work.Also, fundamentals friday is just pure awesome! Just watched the video on the dickson doubler, is it possible to boost current with this with a darlington pair?

author: SeanB
author_rank: Super Contributor
timestamp: March 21, 2015, 08:50:25 am
content: Look on YT for W2AEWhttps://www.youtube.com/channel/UCiqd3GLTluk2s_IBt7p_LjAHe also has a lot of explanations done in a very good easy to comprehend way.

author: joejoe317
author_rank: Contributor
timestamp: March 21, 2015, 09:00:28 am
content: Funny you mention that, I just watched his adjustable voltage drop video. Good stuff!

author: atferrari
author_rank: Frequent Contributor
timestamp: March 21, 2015, 11:10:20 am
content: Quote from: joejoe317 on March 21, 2015, 09:00:28 amHola J JWhat number of video is that? Gracias.

author: SeanB
author_rank: Super Contributor
timestamp: March 21, 2015, 12:06:41 pm
content: Adjustable Vbe multiplier.Here is the video list.https://www.youtube.com/user/w2aew/videos

author: atferrari
author_rank: Frequent Contributor
timestamp: March 21, 2015, 12:13:28 pm
content: Quote from: SeanB on March 21, 2015, 12:06:41 pmThesearchfunction in Youtube seems rather poor compared to that of Google.Gracias Sean

author: w2aew
author_rank: Super Contributor
timestamp: March 22, 2015, 01:09:17 am
content: Quote from: atferrari on March 21, 2015, 11:10:20 amSeanB gave you the link, but to answer your question, it is #198.I can't believe I have almost 200 videos on my channel!

author: VK5RC
author_rank: Unknown
timestamp: March 22, 2015, 02:46:48 am
content: The Dave and W2AEW "basics" videos are excellent viewing and learning ( or re-learning !).An interesting point is that at my Amateur radio club once every month or so a "basics" topic is presented and the attendance is fantastic, including some of our serious but retired guys from our local military research organisation.Another classic video I wished I had seen years earlier, Bell Labs (AT&T) re Wave behaviour

author: atferrari
author_rank: Frequent Contributor
timestamp: March 22, 2015, 01:53:55 pm
content: Quote from: w2aew on March 22, 2015, 01:09:17 amShort and to the point, Alan, something I appreciate whether in text or videos.I finally ubscribed to your channel!
Fundamental vs overtone crystal - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: June 08, 2017, 08:52:46 am
content: If I need high frequency,ofcourse I go overtone becose there arent 1GHz fundamental crystals,but at 10MHz fundamental crystals exist.If I can buy a 10MHz fundamental crystal and 10MHz overtone crystal,why should I chose one over another? In various aspects of performance like long term stability,phase noise,output power... what are the pros and cons of each.I want lowest phase noise and high output power,long term freqency stability doesnt matter,what type of crystal should I get?

author: chris_leyson
author_rank: Super Contributor
timestamp: June 08, 2017, 12:16:26 pm
content: Hi fonograph, a lot of design choices depend on your final output frequency and phase noise requirement. If you start at 10MHz for example then go for a fundamental whereas if you start at 100MHz then you need a 3rd or 5th overtone. For low phase noise you need a crystal with a high Q and you need to pick an oscillator architecture that doesn't add phase noise. Avoid oscillators where the active device is saturated or cut-off as this is where most of the additional noise is generated, Collpits is one of the worst architectures in this respect. A Pierce oscillator with fast Schottky clamp diodes on the collector is a good place to start as the transistor is always working in its linear region and you avoid the additional noise generated from saturation and cut-off.Buffer the oscillator output with a low noise tuned buffer amplifier followed by a fast Schmitt buffer, the faster the better as this will reduce phase noise but will depend on the Schmitt buffer used.Blueskull made some very important points about supply noise, you need a very low noise clean supply to avoid AM to FM noise conversion.For multiplying up to higher frequency I would go for a step recovery diode or similar approach rather than a PLL but that's just my personal opinion.Using a Schottky clamped Pierce oscillator, buffer amp and single gate 74LS14 I managed to get about -155dBc/root Hz at 1kHz offset using a good quality 16MHz AT cut crystal.If you want lower phase noise then stress compensated SC cut crystals have a higher Q than AT cut crystals but cost a lot more.Frequency Synthesis, Theory and Design by Vadim Manassewitsch is an excellent book on ultra-stable specrally pure synthesis techniques.

author: TimFox
author_rank: Super Contributor
timestamp: June 08, 2017, 06:30:01 pm
content: Note that all normal crystals have a fundamental frequency and a discrete set of overtone modes. The overtone frequencies are close to (but not exactly equal to) the odd harmonics of the fundamental. The frequency marked on the crystal assumes either fundamental mode or overtone mode, depending on the specification. In general, overtone frequencies are only harmonic (integer multiples of the fundamental) for one-dimensional systems such as a vibrating string or a misterminated length of coax.
Funny behavior from transistors - Page 1
Forum section: electronics / beginners

author: Landrew2390
author_rank: Regular Contributor
timestamp: October 14, 2017, 06:28:34 am
content: I'm trying to build a circuit for a model train club and I can't figure out why the circuit is behaving strangely. The incoming signal will be either DC current or a square-wave AC signal of the same amplitude. As designed, the opto-couplers should discharge their respective capacitor. When the comparator senses the capacitor is below the set threshold, it should pull its output to ground. If both comparator outputs go to ground, the LED should extinguish showing the signal on the track is either absent or a DC voltage instead of a modulated DCC signal.The signal I'm searching for is an 8KHz square wave and I'm pretty sure everything in the circuit up to the comparator is working. The issue I'm having is the output transistors forming an OR gate aren't switching off. They are almost switching off, but the barest trace of light can be seen within the LED. Is this a caused by the comparator not being able to pull the transistor base low enough and if so, is there a practical way to fix it?Two things of note. First, the reference shown in the diagram is actually inside the MAX934 IC and this circuit is built on a breadboard. Thanks in advance for any help rendered.

author: Landrew2390
author_rank: Regular Contributor
timestamp: October 14, 2017, 06:51:14 am
content: Thanks for getting back with me so quickly. I won't be able to change out the parts until tomorrow night and once I test it, I'll post a reply here either way. Luckily, I've got plenty of parts in the bin.

author: eblc1388
author_rank: Frequent Contributor
timestamp: October 14, 2017, 07:46:35 am
content: Blueskull's suggestion requires 4 extra resistors.You can also connect the transistors in the emitter follower fashion without additional resistors to get the same result.Connects the both collector of the Q1 & Q2 to +5V, and emitter of Q1 & Q2 together then 1K and LED to ground.Or, do away with Q1 & 2, just connect 1N4148 (anode) to each of the MAX934 outputs, connects their cathodes together then 1K and LED to Ground.

author: Landrew2390
author_rank: Regular Contributor
timestamp: November 15, 2017, 06:16:46 pm
content: I know it's been a month, but you guys were right on all counts. I tested both designs, but in the end, the club decided they wanted to add some additional logic to the output stages. Now, I've got the comparators driving NOR gates with the transistors on the outputs of those.The important thing is it all works as designed with no undocumented features.Thanks again for all the help.