hybridfree/eevblog-posts huggingface dataset:
Clapp Oscillator with Filter - Page 1
Forum section: electronics / beginners

author: Havass
author_rank: Newbie
timestamp: August 01, 2023, 09:07:07 pm
content: Hello,I have designed a Clapp oscillator with help from others. But now I do not know how exactly this circuit works because the filter is integrated in the LC-oscillator. I dont know what R5 and L2 do and also C10,C11 and R7 work. Normally C11 and R7 would be a CR lowpass-Filter, but C10 is confusing me.I would be very glad if you could help me

author: MathWizard
author_rank: Super Contributor
timestamp: August 02, 2023, 02:18:11 am
content: Why is R6 shorted, and in real life, if those polarized caps' were upside down, they might explode.IDK near enough about this, I'd put R5 and L2, in parallel with L3,C9...that part, and then try to find the poles and zero's of just that part alone, to try and see what LCR values matter the most. IDK how much the poles and zeros of that section would matter, in the full circuit.Maybe you know all this, but R5 would be setting the DC bias voltage, and will get rolled into the AC gain also. Is there coupling between the inductors L2 and 3 ? That's way over the frequencies I should be talking about.

author: Kim Christensen
author_rank: Super Contributor
timestamp: August 02, 2023, 03:04:11 am
content: Hint: Oscillators are amplifiers with positive feedback. So think about the phase shift from the amplifier's input to it's output and then realize that the resonant feedback circuit must shift the phase so it becomes positive feedback.

author: RFDx
author_rank: Regular Contributor
timestamp: August 02, 2023, 07:16:38 am
content: Quote from: Havass on August 01, 2023, 09:07:07 pmThe capacitor in the series resonant tank circuit was split into C9 and C10. C10 is a low impedance tap point that extracts an output voltage with low harmonic content for the 50 Ohm load. The 50 Ohm load (R7orR8, there is only one load) is coupled lightly to the tap point through another, small capacitor (C11). C10 and C11 determine how much power is available at the 50 Ohm load. The goal was ~0dBm/1mW in the original design.R6 is shorted out btw.

author: Havass
author_rank: Newbie
timestamp: August 02, 2023, 09:21:31 am
content: Quote from: RFDx on August 02, 2023, 07:16:38 amThank you, now I understand what C9 and C10 are doing and Ive corrected the short at R6. . R8 is just a load from Harmonic Balance of Keysight ADS. But what exactly are R5 and L2 doing? And are C11 and R7 no Highpass-Filter?

author: RFDx
author_rank: Regular Contributor
timestamp: August 02, 2023, 01:54:49 pm
content: Quote from: Havass on August 02, 2023, 09:21:31 amThere is no need for R7 if R8 is the load (output port) in ADS. R5 and L2 transforms the (low impedance) voltage source into a high impedance current source, at least for AC signals. For DC it's only 100 Ohms. R5 + L2 are "invisible" to the actual oscillator circuit. Yes, C11 and the load R8 (or R7) form a high-pass filter but their purpose is not really to filter.

author: wasedadoc
author_rank: Super Contributor
timestamp: August 02, 2023, 08:28:28 pm
content: Quote from: Havass on August 01, 2023, 09:07:07 pmHigh pass, not low pass.
clarification about oscilloscopes basics  - Page 1
Forum section: electronics / beginners

author: mt007
author_rank: Newbie
timestamp: January 31, 2017, 02:13:59 pm
content: I have never used oscilloscope before, but have been interested in learning how to use so I got the chance to buy, and try it out. after reading about the basic; I tried measuring a 9V battery, and after adjusting the vertical knob ( voltage ) the scale is set to be 1V ( attached screenshot).. it looks like I have a reading of 1V. I tried measuring the voltage via multimeter the result was 8V.screenshot of the oscilloscope ;http://imgur.com/a/zcXsYI was following up basics about oscilloscopes with this fella :https://youtu.be/CzY2abWCVTY?t=12m2sand he was using a 9V battery as an example and he was able to get 7V when adjusting the vertical knob positioner.Could you please clarify this for the newbie ?

author: danadak
author_rank: Super Contributor
timestamp: January 31, 2017, 02:17:18 pm
content: Is your scope probe set to 10x, but scope probe setup setting is set to 1x ? Soscope thinks it is seeing 9V / 10 ~= 1VRegards, Dana.

author: rstofer
author_rank: Super Contributor
timestamp: January 31, 2017, 02:17:35 pm
content: Are you using a 10x probe? On some scopes, you can give the scope a hint and it will use the probe factor when calculating measurements. My analog scope doesn't have this feature so I always have to keep the 10x in mind. My DSO does have a setting for probe factor.

author: mt007
author_rank: Newbie
timestamp: January 31, 2017, 02:26:47 pm
content: thank you, I checked on the scope prob setting is 1X I changed it to 10X the reading was as expected. but then I just noticed since you said it the prob itself has 1X/10X and it was set on 10X so I reset it both on 1X. thank you again.

author: rstofer
author_rank: Super Contributor
timestamp: January 31, 2017, 02:27:51 pm
content: Quote from: rstofer on January 31, 2017, 02:17:35 pmYour Rigol scope has this capability as well as mine. Press CH1 -> Probe -> 10XSee page 1-7 here:http://download.zeitech.de/Documents/DS1000D_E_Manual_EN.pdf

author: rstofer
author_rank: Super Contributor
timestamp: January 31, 2017, 02:31:50 pm
content: Quote from: mt007 on January 31, 2017, 02:26:47 pmYou don't want to do that! The probe should almost always be set at 10X as this provides the maximum bandwidth and the least load to the circuit under test. X1 is hardly ever used. That's not 'never' but very seldom. Scope compensation is only effective on the 10X setting as well.Here's an overview:http://www.syscompdesign.com/assets/Images/AppNotes/probes.pdf

author: w2aew
author_rank: Super Contributor
timestamp: January 31, 2017, 06:06:03 pm
content: If you're serious about learning about oscilloscopes - I have several videos on the topic. This playlist contains most of them:https://www.youtube.com/playlist?list=PL746BF38BC2E068E0
Clarification about step up modules/converters - Page 1
Forum section: electronics / beginners

author: malium
author_rank: Contributor
timestamp: September 15, 2013, 09:54:34 pm
content: Hello,just a quick one. DC step up converter based on LM2577, it trades of A for V, right? If I have 5A input to the converter, and boost from 3,7V to 12V, I am still gonna end with 0,5A on the output, no matter what?Thanks!

author: Dave
author_rank: Super Contributor
timestamp: September 15, 2013, 09:59:51 pm
content: Think of power.You have 3,7V * 5A = 18,5W going in. Your switching converter has a certain efficiency, for example 85%, so output power will be 18,5W * 0,85 = 15,7W. Your output voltage will be 12V, so your maximum output current will be 15,7W / 12V = 1,3A.

author: malium
author_rank: Contributor
timestamp: September 15, 2013, 10:04:44 pm
content: Dear neighbour from Slovenia, many, many thanks! I suspected that, but their datasheets confused me there for the momentThanks again!

author: fcb
author_rank: Super Contributor
timestamp: September 15, 2013, 10:05:01 pm
content: Vout * Iout * Efficiency = Vin * IinSo if you are drawing 5A @ 3.7v you are using 18.5W (watts!), so at 12v (assuming 100% efficiency) your load is drawing 18.5/12 = 1.54AEfficiency is more likely to be around 70-80%.Also, it's more conventional to design for the output current rather than the input current.
Clarification and comments on power supply schematic - Page 1
Forum section: electronics / beginners

author: d4n13l
author_rank: Regular Contributor
timestamp: August 10, 2018, 12:58:15 am
content: Hi,I'm starting with semiconductor and my goal project is to make my own variable power supply and understand how it all works. I've been searching for schematics (without ICs, I attached one schematic). Here the supply's output is taken from the emitter of the power transistor. I think it resembles a common base configuration but in that configuration the emitter is supposed to be the input not the output, so can someone explain how is it working here?Also any comments you may have on this schematic would be appreciated.

author: JS
author_rank: Frequent Contributor
timestamp: August 10, 2018, 01:11:56 am
content: It's a common collector configuration, I think that should help you to continue, feel free to keep asking.JS

author: d4n13l
author_rank: Regular Contributor
timestamp: August 16, 2018, 05:11:11 am
content: I think I understand how the circuit works now, except I don't see why they used a second transformer for the reference voltage? what advantage can it have over setting Vref directly from the main transformer?I reorganize the schematic for clarity, it looked terrible before.

author: glarsson
author_rank: Frequent Contributor
timestamp: August 16, 2018, 08:07:34 am
content: The second transformer is used to create a negative voltage.

author: rstofer
author_rank: Super Contributor
timestamp: August 16, 2018, 01:54:33 pm
content: Quote from: glarsson on August 16, 2018, 08:07:34 amWithout which you can't set the output voltage close to 0V.
Clarification on the Role of capacitor in Supply Switching Circuit - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: May 06, 2025, 07:59:56 am
content: In the supply switching circuit shown below, where an NPN transistor is driven by a microcontroller (MCU) output pin, I would like to clarify the purpose of the 10nF capacitor labeled C144.Could you please elaborate on the function of this capacitor in the circuit? Additionally, I’m evaluating the possibility of removing it to reduce the BOM cost. What potential issues or undesirable behavior might arise from omitting this component?

author: PGPG
author_rank: Frequent Contributor
timestamp: May 06, 2025, 11:01:30 am
content: In my opinion intention of using C144 was to not suddenly connect discharged 10nF on the right to AT1 voltage.You didn't said a word about what AT1 is. What voltage, do have capacitor on it.Depending on AT1 parameters you can know what will happen if discharged 10nF will be connected to it.Thanks to C144 the 10nF on the right will be relatively slowly charged to AT1 voltage before Q112 will be fully switched on.

author: Freshman
author_rank: Regular Contributor
timestamp: May 06, 2025, 11:09:45 am
content: @PGPG, AT1 is 16V. not having a capacitor, will turn ON/OFF the transistor quickly, causing any high frequency noise spikes?any potential problem, If I omit the capacitor going forward with my design? The supply is 16V. And do you think, how fast I turn ON the NPN , would cause me any problem without the C144 capacitor?

author: PGPG
author_rank: Frequent Contributor
timestamp: May 06, 2025, 04:25:08 pm
content: If AT1 has no capacitor at it than rapidly connecting discharged 10nF can cause short AT1 voltage drop down close to 0V.Now everything depends on what AT1 is also used for and if such drop is acceptable to other circuits or not.I would be not expected problems of high frequency noise as switching power on/of rather is done in mHz range than kHz range.

author: David Hess
author_rank: Super Contributor
timestamp: May 06, 2025, 05:50:26 pm
content: C144 slows the switching times. With the resistor values shown, turn-on is faster than turn-off.

author: MathWizard
author_rank: Super Contributor
timestamp: May 08, 2025, 09:10:32 pm
content: Well to reduce cost, why use 2x 1.3k, I doubt that || combo will be critical, so use a 620R or 680R. But if this is for some hobby or 1 off thing, you could 'borrow' a 10nF or 100n cap from just about anything, like a TV, or GPU even, there's plenty of places they wouldn't miss 1.

author: langwadt
author_rank: Super Contributor
timestamp: May 08, 2025, 10:10:20 pm
content: Quote from: MathWizard on May 08, 2025, 09:10:32 pmat 16V it would be close to half a watt ...
Class A Amplifier general Question - Page 1
Forum section: electronics / beginners

author: Amoebius
author_rank: Contributor
timestamp: October 14, 2022, 09:51:40 am
content: Hello,I am new to the forum.I have a question regarding a class a amp. I used the following formulas to calculate it:Vcc = 12VHfe = 200For Rc I chose 200 Ohm,for Vre 1V,Ic max = (Vcc-Vre)/Rc = 55mAIc qpoint =((Vcc-Vre)/2)/Rc = 27,5mAIb = Ic qpoint/Hfe = 137,5 uAIre = Ic qpoint+Ib = 27,6375 uARe = Vre/Ire = 36R1 = (Vcc-(Vre+0,7))/(11*Ib) = 6744 OhmR2 = (Vre+0,7)/(10*Ib) = 1309 OhmCe = 1/(2Pi*f*Xc) = 2199 uFre = 25mV/IeCin = 1/(2Pi*f*Zin) = 52uFCout = 1/(2Pi*f*Zout) = 71uFWhen I simulate this in LTSpice I get an AC output sine with a bigger negative amplitude than the positive.When I remove the Ce, its much more symmetric.Why is that and does that influence the sound?I hope you can understand my writings, english is not my first language.Greetings,DirkP.S.: I used the wrong value for Cin in LTSpice, 47uF instead of 52uF, doesn't seem to change the output sine though.

author: CaptDon
author_rank: Super Contributor
timestamp: October 14, 2022, 01:53:49 pm
content: The sinewave output doesn't look drastically distorted. Since your output (250 ohm) resistor is A.C. coupled I don't know how Spice could possibly show an offset. In the real world the sinewave would tend to center itself when A.C. coupled to the load resistor unless the wave was severely distorted. Try raising and lowering the value of R1. Moving in one direction should show increasing distortion at the top of the wave and the opposite will be true when moving R1 in the other direction. As the wave distorts it should indeed begin to show unusual offsets at the load resistor.

author: TimFox
author_rank: Super Contributor
timestamp: October 14, 2022, 02:25:43 pm
content: You are seeing a small amount of 2nd-harmonic distortion on the output, which is normal for a single-ended amplifier.After the decay of the initial transient on your first few cycles, the mean value of the waveform should be zero, but with slightly wider positive swings than negative swings (in time), the negative peak will be greater than the positive peak in magnitude (voltage).Removing CE gives you negative feedback (by emitter degeneration with the series resistor) that reduces the gain and improves the linearity (reduced distortion).

author: Amoebius
author_rank: Contributor
timestamp: October 14, 2022, 04:35:40 pm
content: Ok, thanks a lot, i couldn't figure out what was going on.
Class AB Amp Power Efficiency - How to calculate? - Page 1
Forum section: electronics / beginners

author: igorbog
author_rank: Contributor
timestamp: January 31, 2012, 01:47:29 pm
content: HiI have a HW question to calculate power efficiency - Please help meQuote

author: grumpydoc
author_rank: Super Contributor
timestamp: January 31, 2012, 02:01:20 pm
content: No idea but the way this is worded sounds like a course work or exam question - if so, although I'm sure there are lots of people here who can answer it for you, you will probably get more benefit by working out the answers yourself.Apologies if this is not the case
Class B Amp - Page 1
Forum section: electronics / beginners

author: Steve1959
author_rank: Newbie
timestamp: April 03, 2019, 02:36:28 am
content: I was taught that a class b amp (transistors) is usually in a push-pull configuration. Therefore requiring two.I have a circuit for a transistor demodulator for AM and it says it is wired for class B. Can a single transistor be wired class B or is it a typo? Find attached a .jpg to see the circuit.My very first post ever.

author: hamster_nz
author_rank: Super Contributor
timestamp: April 03, 2019, 03:23:57 am
content: Looks to be typo. That is a common emitter amplifier.Unless something funny is going on and the transistor is biased to cause non-linear operation.

author: Calvin
author_rank: Regular Contributor
timestamp: April 03, 2019, 06:02:05 am
content: Hi,QuoteA single transistor can be biased in class B (or class A and C) however You wish.The classification only describes over how much part of 360° of a phase the transistor conducts.Class B is defined as 180°, class A as 180° to 360°, class C 0° to 180°.In this case however it seems rather a typo, as it wouldn´t make much sense to bias this amplifier below class AregardsCalvin

author: Gyro
author_rank: Super Contributor
timestamp: April 03, 2019, 08:54:13 am
content: It's hard to tell without component values but the placement of C2 is unusual. In combination with R3 this will form a time constant which will limit the rate of rise of the output when Q1's Base is being driven low by the input waveform. When the Base is driven high, it will form a lower resistance path for charging C2 again.It would be wrong to describe it as Class-B amplifier though as there's always going to besomeC-E current flowing through Q1, even if it varies a lot more than usual for a common emitter stage (again, depending on component values).

author: mikerj
author_rank: Super Contributor
timestamp: April 03, 2019, 12:13:36 pm
content: I suspect this really is class B (or very close to) as the biasing resistors will be set to barely turn on the transistor. It's effectively a half wave rectifier with some gain and close to zero forward voltage due to the biasing.

author: Circlotron
author_rank: Super Contributor
timestamp: April 03, 2019, 12:55:04 pm
content: ^^ And therefore an AM detector. A normal diode detector also has 180 deg conduction angle.

author: Steve1959
author_rank: Newbie
timestamp: April 03, 2019, 10:06:08 pm
content: mikerj, You were correct. I did some more digging. It is biased very low so it will act like a diode. Only positive pulses will be produced. C2 filters out the carrier and the modulation is coupled out at C3. ThanksThanks everyone for the assist.

author: AlanS
author_rank: Unknown
timestamp: April 04, 2019, 12:28:24 am
content: Mmm.With some values we could run it through a simulator! Hell we could make up some values and run it though a simulator.

author: hamster_nz
author_rank: Super Contributor
timestamp: April 04, 2019, 12:52:21 am
content: Quote from: AlanS on April 04, 2019, 12:28:24 amPulling numbers out of thin air...Vcc=5V, 43k Ohm, R1=150k & R2=22k, R3=1k seems to be about right for something like Class B operation....
Class C amplifier - Page 1
Forum section: electronics / beginners

author: promach
author_rank: Frequent Contributor
timestamp: October 03, 2017, 07:19:18 am
content: I have done transient simulation on the following Class C amplifier circuit, and the third picture shows that the transistor is ON for less than half a cycle, which means the conduction angle is less than 180 degrees. This agrees with the concept of class-C amplifier.However, I am quite confused with the AC simulation analysis I got.According tohttp://whites.sdsmt.edu/classes/ee322/class_notes/322Lecture22.pdf#page=9, we cannot use the small signal model of transistor due to non-linearity issue. Is that true ?

author: w2aew
author_rank: Super Contributor
timestamp: October 03, 2017, 03:12:14 pm
content: True - you can't use AC analysis in SPICE for a non-linear circuit like this. The AC analysis in SPICE is performed by first computing the DC operating point, computing a linear transfer function around that operating point, then using that transfer function to compute the AC response. Thus, it is *only* good for small signal analysis, where the signal swings do not dramatically affect the bias conditions of the circuit.A Class C amplifier, by design, turns the transistor on and off - two very different bias conditions. So, a linearized small signal analysis is not appropriate or applicable.You can apply a swept sine source in the TRANsient analysis in SPICE in order to observe the frequency response.

author: promach
author_rank: Frequent Contributor
timestamp: October 04, 2017, 03:21:11 pm
content: QuoteI am confused about the above statement. Would you elaborate on this ?

author: w2aew
author_rank: Super Contributor
timestamp: October 04, 2017, 06:21:02 pm
content: Quote from: promach on October 04, 2017, 03:21:11 pmMany SPICE or other simulators allow you to define a transient source that is a sinewave which sweeps from a starting frequency to an ending frequency over a defined period of time.

author: promach
author_rank: Frequent Contributor
timestamp: October 05, 2017, 05:38:11 am
content: a) For Class C amplifier, how would Periodic Steady-State Analysis in SPICE helps ? For distortion check, harmonic content check ?b) Besides, could anyone explain the following statement for page 2 inhttp://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.22.7143&rep=rep1&type=pdfQuotec) Why does the voltage-across-Cb or v(vin, vbase) varies sinusoidally around 85mV ? Note: i(v_ip1) is the collector current
Class D amp - Page 1
Forum section: electronics / beginners

author: Shinobot2
author_rank: Newbie
timestamp: October 15, 2015, 10:28:12 pm
content: Hi, I tried to build a class D amplifier but I´m having some problems.I see a lot of distortion in the output specially at frequencies above 3kHz.I already changed the filter to see if it was the problem, but not much improvement. The triangular wave is nice and clean, but the frequency is not as I predicted, 420kHz instead of 500kHz.I removed the feedback and it got a lot worst.The pictures bellow are related to the 3 points in the schematic, Vfeed, Verror and Vo, as you can see Vfeed looks good, but Verror doesn´t and it´s similar to the output.I didn´t measured the signal across the load, because of grouding problems, don´t know if it makes a big diference.I connected to my speaker and sounds ok.Thanks

author: NoItAint
author_rank: Contributor
timestamp: October 16, 2015, 01:57:09 am
content: Looks good to meYou should measure with the speaker or load connected.The LC filter is calculated with the load. A lot of the switching noise will filter out when a load is applied.The frequency of the switching can change, just keep in mind it's much higher than the signal your reproducing.

author: Shinobot2
author_rank: Newbie
timestamp: October 16, 2015, 10:28:26 am
content: The load is connected, it´s a 4ohm, but not purely resistive.The amp is a full brige with fixed switching frequency around the 500kHz.I´m not measuring the signal across the load because I dont have an isolated power supply.What I dont understand is why the output looks realy weird and the filtered feedback signal looks like a sinewave (with switching ripple as expected). Is it because I´m not measuring signal across the load?
Class D amplifier - Page 1
Forum section: electronics / beginners

author: nast
author_rank: Newbie
timestamp: May 22, 2020, 03:09:58 pm
content: Hello Maybe someone has simple (the simpler the better) circuit for a low-frequency transistor amplifier with a class D cascade, or can explain how to creat it, I'm going to make it in Microcap? I can only find very complex circuits in internet.

author: Zero999
author_rank: Super Contributor
timestamp: May 22, 2020, 03:38:10 pm
content: You can only find complex circuits because a class D amplifier isn't simple. If you want simple, then use an IC with all of the complex circuitary builr-in. If you want to simulate it, find an IC with a SPICE model, which will work with Microcap.

author: Etesla
author_rank: Regular Contributor
timestamp: May 22, 2020, 05:11:24 pm
content: The operating principle of class D is pretty simple. Just make a PWM signal proportional to your input signals amplitude, make that PWM signal super powerful, then low pass filter it to get a high power output signal.The general way to get a PWM signal proportional to your input is to compare your input signal to a triangle wave.The general way to make the PWM signal super powerful is to use a full bridge of mosfets.The general way to low pass filter that powerful PWM signal is with an LC filter in the middle of the full bridge.If you understand all these words, you understand all you need to know to make a class D amplifier from scratch. Some of the waveforms I was describing are shown in the image linked here:https://www.researchgate.net/figure/Class-D-Amplifier-Waveforms_fig2_303685974All the extra 'complicated' circuitry in the schematics you see online are just different ways of doing these three steps. There is also a lot you can do in the way of feedback and other neat tricks. No doubt a lot of the circuitry also has to do with something called gate drive for the mosfets.I had a good time as a beginner designing and building one of these from discrete components and some simple IC's like 555 timers. Learned a lot. Hopefully you will have a similar experience.
Class D Amplifier Design Help - Page 1
Forum section: electronics / beginners

author: sonnytiger
author_rank: Frequent Contributor
timestamp: February 06, 2013, 03:29:47 pm
content: I'm looking to build an amplifier to power a 4 Ohm 6 Watt Speaker, possible configured as two in series, I'm looking to use one of these chips or possibly others if they are suggested:http://www.ti.com/lit/ds/symlink/tpa3004d2.pdfhttp://www.ti.com/lit/ds/symlink/tpa3117d2.pdfusing this one i would only have to use one chip to power the four speakers i intend to use in the final product:http://www.ti.com/lit/ds/symlink/tpa3110d2.pdfOne problem I can't figure out is the effect of using the 3.5mm (the small headphone style jacks) output from the back of my computer, when the chips all expect differential input. Is this a problem? Will it work? I don't know. Any help appreciated, thanks!

author: c4757p
author_rank: Super Contributor
timestamp: February 06, 2013, 03:33:41 pm
content: Read the whole datasheet, it tells you how to use a single-ended input.

author: sonnytiger
author_rank: Frequent Contributor
timestamp: February 06, 2013, 03:41:57 pm
content: The first one does? or all of them? I skimmed through but i must have missed it.ah okay yes I have found it thank you.

author: c4757p
author_rank: Super Contributor
timestamp: February 06, 2013, 03:51:00 pm
content: I don't mean to be rude (I know nobody really appreciates a cold "RTFM!"), but these are somewhat complicated chips. It's going to bite you in the ass if you don't read the datasheet all the way through.(By the way, I didn't read them all the way through either, I just hit Ctrl-F and typed "single".)

author: sonnytiger
author_rank: Frequent Contributor
timestamp: February 07, 2013, 12:14:14 am
content: No problem, thanks for the help!
Class-D Amplifier Ferrite Bead Selection - Page 1
Forum section: electronics / beginners

author: sparksflying
author_rank: Contributor
timestamp: December 29, 2013, 12:56:52 am
content: I am making a Class D amplifier to replace a Class AB amplifier in a radio I have. I have chosen the TI TPA3117D2 because it seems to be able to drive the 8ohm, 7W speakers in the radio at 12V.http://www.ti.com/lit/ds/slos672/slos672.pdfI requires a filter on the speaker output, the app note on page 20 shows an LC filter or a ferrite chip bead-capacitor filter. I'm not too familiar with ferrite beads, when searching for them they all seem the same, there are no inductance values listed...how do I know which one to choose?I found this one from Panasonic, it lists "digital audio" in it's Recommended Application. It also does up to 2A of current, which I think should be sufficient.http://australia.rs-online.com/web/p/ferrite-beads/2335083/

author: Hideki
author_rank: Frequent Contributor
timestamp: December 29, 2013, 01:41:58 am
content: In a ferrite bead, the inductance falls off and is replaced by resistance as frequency rises, so they are usually specified by the impedance it has at 100 MHz -- like 115 ohm @ 100 MHz for the one you linked to.That alone is helpful information, but there are many types of ferrite material that show rather different impedance curves at various frequencies. If you don't know where your noise is, it can be hard to choose. Check the pdf for more information:http://www.digikey.com/Web%20Export/Supplier%20Content/TDK_445/PDF/TDK_InCompliance_Aug2010.pdf?redirected=1

author: Rufus
author_rank: Super Contributor
timestamp: December 29, 2013, 02:16:54 am
content: Quote from: sparksflying on December 29, 2013, 12:56:52 amThe datasheet offers 3 specific part suggestions for which you can look up the data.Bead data usually gives impedance against frequency plots. Look at the plots for the suggested parts, you want something similar. Also be aware of the current rating. The ferrite will saturate with increasing current and impedance will drop.

author: sparksflying
author_rank: Contributor
timestamp: December 29, 2013, 02:44:09 am
content: Quote from: Rufus on December 29, 2013, 02:16:54 amThanks, I didn't see that. I'll try to find one on RS that matches the graph.
Class D FET amp component function question - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: February 02, 2017, 11:10:00 pm
content: In the attached schematic what is the function of C1 and C2 and their two 15k associated resistors please. Do the add "dead time" by acting as a RC constant in the signal path to the FET driver chip? The amp is fed with a X2 signal of 472kHz and outputs 136kHz.Secondly, in the second schematic of a commercial FET RF (I think...) amp gate driver protection circuit, could someone very briefly tell me the function of all the components associated ith driving the gate and how they protect it please?Thanks
Class III equipement - Page 1
Forum section: electronics / beginners

author: mar.meryem
author_rank: Newbie
timestamp: October 05, 2023, 12:53:38 pm
content: Hello Everyone,I have a very beginner question as I'm a mechanical engineer but do work with Electrical safety standard.For example, i'm reading IEC 61010 standard and a dielectric test is needed after almost each tests (Fault conditions,impact and drop test..) to ensure that the product is safe against electric shock.My question is to know if Dielectric test is applied to my product, that is Class III and opearting under 54.6V (SELV)is dielectric test only applied to class I and II products?Thansk in advance

author: switchabl
author_rank: Frequent Contributor
timestamp: October 05, 2023, 08:37:46 pm
content: It isn't really possible to give a definite answer without a lot more context, so if that is what you are looking for, you will need to talk to the EE in charge of the electrical safety and/or the test house.If you are just interested in gaining a better understanding of the standard, you may want to take a look at section 4.1:QuoteAssuming that there cannot be any hazardous voltages in the circuit by design, you could claim that there can never be any hazardous voltage on accessible parts either and that you would always pass that test. And since you aren't implementing any of the permissible protective measures, like double insulation, to achieve that, there isn't actually any insulation to test.
Classes in EE simulation... - Page 1
Forum section: electronics / beginners

author: westfw
author_rank: Super Contributor
timestamp: October 01, 2019, 02:12:40 am
content: Are there any online classes that specifically focus on using some of the modern analog simulation tools (ltspice or similar.)I sorta missed out on that, since my formal education predated the possibility, and my career was mostly SW oriented.I don't particularly want a "Basic Circuits Theory" class that includes simulation as a visualization tool, because I think I remember most of that, but I guess I could deal with it if I have to.Preferably the class should use multi-platform tools that don't cost a fortune for non-students.

author: rstofer
author_rank: Super Contributor
timestamp: October 01, 2019, 02:24:03 am
content: LTspice is priced right, it's free.There are many books written about simulation with LTspice, check out AmazonThere are also many video tutorials and here is an 8 part series:http://www.simonbramble.co.uk/lt_spice/ltspice_lt_spice.htmThere is a very competent LTspice group on groups.yahoo.com. There are actually two groups, one for discussions and the other as a simulation repository. A couple of the fellows that hang out on the group are VERY knowledgeable and are in tight with the developer.

author: IanB
author_rank: Super Contributor
timestamp: October 01, 2019, 02:53:27 am
content: This is a very interesting topic. I have spent my career using and developing simulation tools in a different branch of engineering. There's a lot to be covered in such a class, especially understanding what the tools can and can't do, about the limitations of different solution techniques used, the limitations of the models, and how to tell whether the answer may be accurate (or not). A big question, if you fail to get an answer, is whether it is your fault or the software's fault, and how to overcome such problems.
Classifying Resistors for Reference Numbering - Page 1
Forum section: electronics / beginners

author: Falcon69
author_rank: Super Contributor
timestamp: November 29, 2014, 10:10:08 pm
content: Well, I know for reference numbering, a Resistor is like R1, R2, R3, etc....A 4.2k Resistor becomes 4K2 for easier understanding.But what if you have a resistor that is 4.02K? Would it read as 4K02? What is the correct way to write that when you are dealing with resistors rated in hundreths?

author: Zero999
author_rank: Super Contributor
timestamp: November 29, 2014, 11:00:15 pm
content: Yes, the k denotes the decimal. 2k005 would also be valid but that sort of precision is rare.I have seen R022 for 22mOhm though.

author: Falcon69
author_rank: Super Contributor
timestamp: November 29, 2014, 11:03:36 pm
content: k, thank you Hero999
Cleaning bnc connetor - Page 1
Forum section: electronics / beginners

author: TorqueRanger
author_rank: Frequent Contributor
timestamp: December 08, 2012, 09:30:13 am
content: I got a B+K PRECISION 20 MHZ MODEL 2120 DUAL CHANNEL and I waiting for my order to come in so I can fix it ... But I notice the BNC connectors are tarnished and I was not not sure if that's going to effect my end results at allIs there anyway of cleaning the tarnish off with out doing damage to the machine and what kind of metal is it madeThanksJAy

author: SeanB
author_rank: Super Contributor
timestamp: December 08, 2012, 10:29:33 am
content: First start with a new toothbrush and scrub with alcohol, that removes most of the gunge. They normally are nickel plated brass, so generally can be cleaned up reasonably. If really green and the alcohol does not remove it then you can use Brasso ( brassware cleaner) with the toothbrush, rinsing it off by scrubbing with a new brush again with the IPA to get the stuff off of all the crevices and the inside. When clean coat with light lubricating oil (3 in 1 works well, I use a synthetic that I use otherwise at work) to protect it. Best is to place a terminator always on it, or a plastic dust cover.

author: M0BSW
author_rank: Frequent Contributor
timestamp: December 08, 2012, 05:26:04 pm
content: Quote from: SeanB on December 08, 2012, 10:29:33 amThats interesting ,as I've some on a function generat that could do with a clean, thank you.
Cleaning Flex Rigid PCB's - Page 1
Forum section: electronics / beginners

author: tronoglock
author_rank: Newbie
timestamp: November 21, 2023, 01:26:27 pm
content: Can flex-rigid PCB assemblies go through an aqueous wash system post assembly?

author: liaifat85
author_rank: Regular Contributor
timestamp: November 23, 2023, 12:55:45 pm
content: Because flexible substrate is easy to deform and bend, it is advisable to use chemical cleaning or electrolytic cleaning. You can find more info regarding flex PCB manufacturing here:https://www.pcbway.com/blog/Flexible_PCB/Simple_Analysis_of_Flex_PCB_Manufacturing_Process.html
cleaning PCBs - Page 1
Forum section: electronics / beginners

author: norf
author_rank: Newbie
timestamp: August 29, 2014, 02:10:27 am
content: What do you usually use to clean dirty (dust, grime, etc.) PCBs that have parts on them? I've read about Deoxit used to clean/lubricate? pots and switches, but it's expensive. Have you used other types of electronic cleaners or some DIY concoctions?

author: IanB
author_rank: Super Contributor
timestamp: August 29, 2014, 02:15:29 am
content: Depends what's on the PCB and why you want to clean it.Deionized or distilled water and a soft brush will work for most boards, followed by a thorough drying.However if water gets inside trim pots or other mechanical parts like DIP switches, you may have to dry in a warm place for several days to let all the water evaporate. Else you might rinse with isopropyl alcohol to speed up the drying process.

author: BillWojo
author_rank: Regular Contributor
timestamp: August 29, 2014, 04:17:49 am
content: I've pulled out PCB's on old CNC machines that were so dirty that you could barely see the components. Oil, coolant and dust mixed into a black overlayer that eventually caused the control to stop working. Some of the boards have trim pots and dip switches but that's about the only thing that water could get into. I use Simple Green and a soft brush along with hot water. Usually takes several applications to get them really clean. Blow dry them with compressed air and place them somewhere warm for a few hours. Reinstall and it almost always fixes the problem.BillWojo

author: David Hess
author_rank: Super Contributor
timestamp: August 29, 2014, 04:40:04 am
content: For general cleaning as oppose to flux removal, I use plain hot water with a little bit of TSP or dish soap in it and then rinse with distilled or deionized water. In some cases I drop the whole board into my ultrasonic cleaner. I dry using an air compressor but be careful not to blow oil on the board and bake it out if necessary at relatively low temperature.Water cleaning solutions are especially effective if a board is suffering from leakage problems.

author: Pedram
author_rank: Regular Contributor
timestamp: August 29, 2014, 05:55:32 am
content: Ultrasound cleaners are useful too.
Cleaning Soldering Iron's Tip - Which Of These Do You Recommend? - Page 1
Forum section: electronics / beginners

author: Boris_yo
author_rank: Frequent Contributor
timestamp: September 01, 2012, 03:11:40 pm
content: As I am beginner in soldering, I don't have any special cleaning equipment and clean soldering iron's tip with damp cloth. So far I am aware of 3 better solutions for this which you can see on attached picture. I initially thought of using thermal sponges but somebody said that they put iron under thermal shock and suggested using soldering removing ball. So I am contemplating between two and if second would be a better choice indeed, I think buying third which is soldering removing ball inside container would be better.Is using damp cloth or damp thermal sponge bad for soldering iron and why? What would you recommend?
Cleaning strip boards - Page 1
Forum section: electronics / beginners

author: dalpets
author_rank: Contributor
timestamp: May 28, 2014, 03:18:31 pm
content: Up until now I have been using standard paper strip board for prototype projects, cleaning them before assembly with Staedtler Mars plastic pencil rubber.I am now reverting to using epoxy resin strip boards for some of my projects. Do I continue to use the Staedtler method or do I need to use another cleaning method pre assembly?Thanks

author: vk6zgo
author_rank: Super Contributor
timestamp: May 29, 2014, 05:12:54 am
content: Go ahead,the copper is still the same,& the epoxy resin won't care,either.I would suggest wiping it over with acohol after you use the eraser to help remove any "rubber" residue.
Cleaning the output of a cheap SMPS? - Page 1
Forum section: electronics / beginners

author: Pack34
author_rank: Frequent Contributor
timestamp: November 06, 2015, 05:24:33 pm
content: These SMPS power supplies are all over ebay and picked one up for some projects. However, the output of the unit is rather noisy and it seems to permeate through the input linear regulators and can be seen super-imposed on some analog signal lines that I'm sampling.Power supply in question:http://www.ebay.com/itm/Mean-Well-RT-65C-AC-to-DC-Power-Supply-Triple-Output-Enclosed-Switching-65-5W-/111702973357?hash=item1a02041bad:g:WA4AAOSw-vlViwGSThe Noise:See the "scope_4.png" attachment to see the noise on the power rail AFTER the input linear regulator.A clean input:See the "scope_5.png" attachment as a reference for the rail using a benchtop power supply.Now, it's not something that's absolutely terrible but it's something that I want to learn how to address.My first plan-of-attack was to add an LC filter between the SMPS and the electronics. It can be seen in the first reply in this thread:https://www.eevblog.com/forum/beginners/lc-filter-basics-for-smps/Unfortunately, it didn't seem to do anything. The most likely culprit could be the values I used (3.9uH inductors and a 470uF cap). However, the cut-off frequency is 1/(2*pi*sqrt(LC)). This should give me a cut-off of about 3.7kHz. If I'm reading it right, the datasheet link below shows a switching frequency of 60 kHz. It's marked as fosc next to the block diagram.http://www.meanwell.com/webapp/product/search.aspx?prod=rt-65Taking some measurements on my scope. The most noticeable peaks are roughly at:244kHz181kHz118kHz116kHz6.82kHzThen a really small peak at around the 120Hz mark (8.3ms period) as seen on the scope screenshot.Considering that all of these are substantially higher (sans the 120Hz) than my input filter I hacked in ( 3.7kHz ), do I just need an inductor with a greater rating? How should I move forward to try to clean up the switching output to mitigate those pulses every 8.3ms?

author: miceuz
author_rank: Frequent Contributor
timestamp: November 06, 2015, 06:07:05 pm
content: both of your attachments are 0 bytes

author: Pack34
author_rank: Frequent Contributor
timestamp: November 06, 2015, 06:17:38 pm
content: Quote from: miceuz on November 06, 2015, 06:07:05 pmFixed. Thank you.EDIT:// Now that's interesting. It appears to be ground noise. I can have the probe attached to ground and probe the ground pin on the input linear regulator and it has the same noise as when I probe the power rails.

author: Pack34
author_rank: Frequent Contributor
timestamp: November 09, 2015, 05:22:13 pm
content: I think I have it all cleaned up.1. Added a small resistor andinductorferrite bead in series with the incoming power and ground lines.2. After the LDO I hacked in an RC low-pass filter targeting 30 Hz.Considering we're only talking a maximum of 200mA on the voltage rail, I think the RC filter will work just fine. an LC filter would probably be better but the necessary inductor would be incredibly large and expensive.
Clean/repair a rotary encoder? - Page 1
Forum section: electronics / beginners

author: Peabody
author_rank: Super Contributor
timestamp: February 14, 2018, 05:38:20 am
content: I've got a little mechanical rotary encoder with one really bouncy switch, and I just wondered if it's possible to take it apart in the hope of fixing it. It looks like you could bend the tabs back and open it up, but I don't want to run into tiny exploding springs or whatever, and be unable to get it back together. I would just replace it, but can't find a match. Anyway, is this a reasonable thing to attempt? Does it ever work?

author: xavier60
author_rank: Super Contributor
timestamp: February 14, 2018, 06:45:06 am
content: Try getting some oil into it. There are all sorts of oils out there, some better than others for the job. And some specifically marketed for that application.I have been using PAO synthetic oil with good success for many years. The stuff I use is sold for use in auto aircon compressors. Synthetic oil for air compressors is usually PAO also.A pair of small capacitors(10nF) across the A and B switches can help also.

author: xavier60
author_rank: Super Contributor
timestamp: February 14, 2018, 07:09:39 am
content: Some products for contact lubrication purposes are PAO oil based,http://www.tecnolubeseal.it/applications/greases-electrical-contacts/?lang=en

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 14, 2018, 08:16:03 am
content: oil into a rotary encoder seems like a bad advice... just open it up, clean and improvise, should be better than live with a dead encoder, you got nothing to lose.. ymmv..

author: xavier60
author_rank: Super Contributor
timestamp: February 14, 2018, 08:50:01 am
content: There is an earlier thread on the same topic,https://www.eevblog.com/forum/beginners/alps-rotary-encoder-gone-crazy/

author: Mechatrommer
author_rank: Super Contributor
timestamp: February 14, 2018, 09:10:52 am
content: damned i always mixed up optical encoder with rotary encoder, this is my problem with threads with no pictures... oil can be one thing, but rotary encoders like mine dont have exploding spring, so its an easy dissassembly reassembly fix...https://www.eevblog.com/forum/reviews/rigol-ds1052e-annual-service-(knob-problem)/msg75048/#msg75048

author: Peabody
author_rank: Super Contributor
timestamp: February 14, 2018, 06:52:02 pm
content: Thanks for the comments. I'll try to muster the courage to give it a go.
Clear lacquer over LED strips - Page 1
Forum section: electronics / beginners

author: iceisfun
author_rank: Regular Contributor
timestamp: November 27, 2016, 10:08:24 am
content: I've made some christmas decorations out of LED strips soldered together and want to know if I can just dunk them into lacquer and let them dry or is the lacquer too conductive?These snowflakes are 22 square in so we wanted to just get enough to submerge them, pull them out and let them dry then repeat a few times.I see there is spray on electrical stuff but I'm worried it would not get all over without a bunch of effort.Suggestions?

author: senso
author_rank: Frequent Contributor
timestamp: November 27, 2016, 04:33:21 pm
content: Canned conformal coating, spray, let dry, done, might have a slight yellow tint.
Clearing out my father's (ex EEV) workshop - what are these ...? - Page 1
Forum section: electronics / beginners

author: Chelmsford321
author_rank: Newbie
timestamp: October 30, 2021, 07:44:11 pm
content: Hi, I would really appreciate help identifying these bits and pieces from my late father's workshop. He was at EEV his entire working life and would never forgive me for just consigning stuff to the dump without trying to find a new home for it first.Any idea of values / offers from interested parties?I will post more photos on another post as I've reached my limit ...

author: TimFox
author_rank: Super Contributor
timestamp: October 30, 2021, 07:56:12 pm
content: 6920-6923: Two 240 V Variacs6925-6926: 240 V, 50 Hz running-time meter6932: another one6936-6940: Various cartridge fuses and holders

author: Benta
author_rank: Super Contributor
timestamp: October 30, 2021, 08:12:16 pm
content: +1 to TimFox' identification.The variacs are valuable and could certainly be of interest to someone. The rest, not so much.

author: johnkenyon
author_rank: Regular Contributor
timestamp: November 09, 2021, 05:18:53 pm
content: With the OP having a name like Chelmsford321, perhaps the kit came from Marconi Radar - probably explains why the variac frontpanel has a "magnetron heater" label.(For the OP's benefit, a magnetron can be used to generate microwaves to feed a radar transmitter)PS - shirley it should be "Chelmsford 123"https://en.wikipedia.org/wiki/Chelmsford_123
CLG-150-36A + LDD+Vero 10 LED - Page 1
Forum section: electronics / beginners

author: KnH
author_rank: Newbie
timestamp: February 14, 2015, 05:00:42 pm
content: If someone could check my wiring to make sure it’s right or if this is the right way to do it.Vero 10 @ 500Ma Fv 24.9-30.5, Typ 27.7, 14 wattsCLG-150-36a, Constsnt Current 27 ~ 36Vm,- Voltage Adjustment Randge 31 ~ 41VLDD500HWI Have a (lo ADJ) and a (Vo ADJ) pot, which one to adjust the voltage to match up with the vero & LDD ?”http://www.meanwell.com/search/CLG-150/CLG-150-spec.pdfhttp://www.bridgelux.com/wp-content/uploads/2014/02/DS30-Bridgelux%C2%A0Vero%C2%A010-LED-Array%C2%A0Data-Sheet%C2%A02014.02.03.pdf