hybridfree/eevblog-posts huggingface dataset:
Help with old radio and electronic equipment  - Page 1
Forum section: electronics / beginners

author: The_Welding_Library_Guy
author_rank: Contributor
timestamp: February 10, 2019, 07:24:25 pm
content: Hey all.I got a great deal on a haul of equipment that a woman a few towns over wants to get rid of. Turns out her dad was a radio engineer. Most of it I knew what it was already what it was such as an O-scope, resistor substitution box, ect. but there are some bits that I could use a little help figuring out what they are and what kind of use I could get out of them. The frist 3 photos I have no clue what they are. Then the other photos i was able to google but I'm not real sure on how to use them or what to use them for. Like the model 970 when i google it people are talking about a built in power supply and signal generator but there calling it a radio annalist rather then a transistor annalist. So they maybe talking about another bit of gear all together.

author: Wimberleytech
author_rank: Super Contributor
timestamp: February 10, 2019, 07:31:11 pm
content: 2054 is a curve tracer. It interfaces to an oscilloscope to trace transistor/FET curves.These appear to have been stored in suboptimal environmental conditions.

author: alex.martinez
author_rank: Contributor
timestamp: February 10, 2019, 07:44:06 pm
content: Quote from: Wimberleytech on February 10, 2019, 07:31:11 pmThe 147A is a signal tracer, a lot of documentation online:<iframe width="560" height="315" src="https://www.youtube.com/embed/A2T7j48FPXA" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

author: The_Welding_Library_Guy
author_rank: Contributor
timestamp: February 10, 2019, 09:02:47 pm
content: Ok so am I wrong in thinking the signal tracer is comparable to a continuity tester?Sent from my VS500PP using Tapatalk

author: alex.martinez
author_rank: Contributor
timestamp: February 10, 2019, 09:33:38 pm
content: Quote from: The_Welding_Library_Guy on February 10, 2019, 09:02:47 pmOne of its applications, think of it as a multimeter for radio (very high frequencies). You can check the signal, probing in the various nodes of the system. It even has a power meter.
Help with old resistor color code. - Page 1
Forum section: electronics / beginners

author: Algojervia
author_rank: Unknown
timestamp: November 02, 2016, 03:47:09 pm
content: I can't decide the color on the last band. I see pink or maybe white but it doesn't add up. Anyone that might have experience in how the colors age on these things?

author: Ian.M
author_rank: Super Contributor
timestamp: November 02, 2016, 04:48:59 pm
content: A fifth 'Salmon pink' band after the tolerance band used to be used to indicate high stability resistors. From the farthest to the nearest 51K 1%, 5.1K 1% and something in the hundreds of ohms range (as we cant see the first two bands), also 1%.

author: Algojervia
author_rank: Unknown
timestamp: November 02, 2016, 05:13:03 pm
content: Thanks, when I google I see some statement that the band only indicate a high grade material but no actually percentage value. Most say that it should be one or two but have a look at the chart close to the top of this page.http://www.mds975.co.uk/Content/components01.htmlWhat's up with that?

author: Ian.M
author_rank: Super Contributor
timestamp: November 02, 2016, 05:18:20 pm
content: Yes. The brown fourth band indicates the 1% tolerance.The page you linked shows pink fourth band as 20% tolerance - that would be extremely rare as it was more usual to have NO fourth band for 20%
Help with oscilloscope readings  - Page 1
Forum section: electronics / beginners

author: aabbcc
author_rank: Regular Contributor
timestamp: February 13, 2018, 02:03:57 pm
content: So I recently got my Rigol DS1054z and wanted to use it straight away to tune a synth I have. I've never really used a scope before so here goes.Going over the service manual for the synth and the manual for the scope I realize I have no idea what I'm looking forWhat values should I be looking at when scoping for the different adjustment points below? Period? Width? Etc.

author: David Hess
author_rank: Super Contributor
timestamp: February 13, 2018, 02:37:44 pm
content: For the first three you are looking for a period measurement. For the last one, you will need to do it by eye or using cursors.

author: newbrain
author_rank: Super Contributor
timestamp: February 13, 2018, 02:42:35 pm
content: A modern scope, even a simple one as the Rigol 1054Z, can be a bit overwhelming for a newcomer.For a general understanding of how scopes works and can be used, you can have a look atW2AEW course.For your specific questions, I'll try to give some brief hints.One channel is enough, let's say you use channel 1 (theyellowone)You should have an idea of the amplitude of the signals, in this case I would think they are ground referenced and some volts peak.So, I would start with 5V per vertical division, making sure that you are using the probe in 10x mode, and the scope is also set for a 10x probe, then go down (2V/div, 1V/div etc.) so as to have the screen optimally filled up.Timebase (horizontal) depends on the specific TP you are checking: to see 2-3 cycles on the screen, this could something like 2ms/div for TP1, 500µs/div for TP2, 500µs/div for VCO (but see below) and 2ms/div for VCF. You can then adjust the timebase to you liking.The trigger can be set to positive edge, about half the peak to peak value of your signal. The last test point might need some care in setting the level to have a stable waveform.About the VCO setting, I've assumed that CL and CH are the C note below and above central A, so about 260 and 520 Hz. The idea is to set the VCO so that an octave is exactly double the frequency of the previous one.The measurements can be done by looking at the grid (the old days way) or using the scope provided measurement as already suggested by David Hess.
Help with parasitic oscillation in cmos logic circuit - Page 1
Forum section: electronics / beginners

author: Victorman222
author_rank: Regular Contributor
timestamp: July 18, 2023, 06:07:38 pm
content: I have been trying to build a stepper motor driver using CD4000A series chips inspired by a schematic i found on the internet where 2 D flip-flops are used to generate a full step drive signal. After testing it in a logic simulator, the logic seems to work out. Using CD4042A quad D flip-flop (schematic below) i keep getting parasitic oscillation (oscilloscope image and video included). Things i tried:- improved bypassing- some combinations of R and C in the feedback path- removing the IC U3 and joining the feedback path straight- trying different clock sourcesI built this circuit 2 times, once on a PCB and another on solder protoboard, the behaivour is unchanged. The output transistors are disconnected, so they arent affecting the IC.video:Thank you!

author: Victorman222
author_rank: Regular Contributor
timestamp: July 19, 2023, 03:35:01 am
content: I just breadboarded this with some CD4013 and 4013A and it worked fine without parasitic oscillations... Maybe the ICs i was using are a bad batch, they were made in 1990 in the USSR after all. Or maybe how the signals are connected internally or the clock polarity defining gates.

author: thermistor-guy
author_rank: Frequent Contributor
timestamp: July 19, 2023, 04:20:17 am
content: Quote from: Victorman222 on July 18, 2023, 06:07:38 pmThe CD4042A has lengthy hold times. See for examplehttps://datasheetspdf.com/pdf-file/1100059/RCA/CD4042A/1"Hold time" equals how long you need to keep the D inputs stable, after the clock edge samples them. Fast logic familieshave guaranteed hold times near zero, making them easy to use for state machines (like your circuit).It's possible that, after each active clock edge, the CD4042A inputs are changing too soon, before the chip's holdtimes are satisfied - that could make the outputs go unstable.

author: Ian.M
author_rank: Super Contributor
timestamp: July 19, 2023, 04:52:29 am
content: If you are continuing with 4000 series logic, one approach to meeting the hold time constraints would be to cascade two CD4042A chips, with their Polarity pins at opposite levels, so at the leading edge of the clock the first one latches the outputs of the feedback gates (inputs driven by the second one), holding the second one's input state stable through the clock falling edge, which finally updates the feedback gate state. Provided the interval between clock edges is greater than the worst case hold time requirement (+ feedback propagation delay) the result should be free from glitches and instability.
Help with PCB routing for nixie tube clock - Page 1
Forum section: electronics / beginners

author: halenthir
author_rank: Newbie
timestamp: December 13, 2020, 09:59:32 pm
content: Hello everyone,I'm new to this forum and I started electronic only months ago, so please don't hesitate to post your remark.For my first project, I want to design a vintage alarm clock using nixie tubes, with 6 IN-14 for the digits and 2 IN-3 for the dots. It is an educational project for me.I choose to design 2 separate boards for this project, the first one is used for nixie tube multiplexing and the second for the alarm logic, the speaker and the RTC. For now I choose to start with the first one (tube multiplexing).I created this post to get some advice concerning the PCB design, but if you want to make comments on the schematic, I will gladly read those too.I never used an EDA software in the past, so I watched some videos and read articles before starting, but I still have questions about PCB design:1) I use 170V DC for the tubes, is there any precaution that I should ensure for a safe design?2) What trace width should I use?I used a trace width of 0.3mm and 0.4mm (arbitrary) for the main power source (+170V).I intend to order the PCB online after finishing my design.The website I wish to use offers 1oz copper weight by default.I checked if this is enough with the first calculator found on google.Given the longest path in my design is 160mm and the low consumption of nixie tubes, it seems okay.3) I had a difficult time routing my PCB, I use a lot of vias.Do you think this will cause an error or lead to interferences?Do you have advice to make it simpler?4) I use a 2-layers PCB, should I use a 4-layers one instead?Also, is it me or 4-layers seems very expensive?5) Should I pay attention to clearance and creepage given the high voltage?The clearance is set to 0.152 but I cannot find where to set the creepage.Is the creepage usually a global parameter on EDA softwares?I still don't clearly understand what they are and how they appear on the PCB.6) Some traces are close to component leads or other traces. Can this cause errors?7) Some trace are very long on my PCB, around 160mm. Is it a bad idea?Also I use this weird pattern to connect all the nixie tube cathodes together:I never seen something like that on a PCB, so I wonder if this is bad.8) Do I miss something?9) Also, if you have any suggestion to save money, I will gladly ear it :-).Here is the link to my project:https://easyeda.com/halenthir/nixie-clockThank you for your feedbacks!
Help with picking small switch from lcsc.com - Page 1
Forum section: electronics / beginners

author: Axk
author_rank: Regular Contributor
timestamp: April 21, 2019, 11:45:11 am
content: I need a small (around 5x5mm) toggle type single pole single throw latching switch.Which category/search parameters should I use to find one on lcsc.com?

author: chagli
author_rank: Contributor
timestamp: April 21, 2019, 12:25:24 pm
content: Hi,This site seems quite awful to perform an advanced search.Nevertheless, I found this:https://lcsc.com/product-detail/Toggle-Switches_Korean-Hroparts-Elec-K3-1293S-E2_C145852.htmlIt is a right-angle SMD switch.
help with piezo buzzer - Page 1
Forum section: electronics / beginners

author: nobody
author_rank: Newbie
timestamp: March 02, 2013, 11:54:43 am
content: Is there a way to make simple door bell using piezo buzzer and 555 timer ?

author: Rerouter
author_rank: Super Contributor
timestamp: March 02, 2013, 01:29:57 pm
content: well you have 2 things a door bell must do, once triggerd play a note or tone to alert the owner of the premisis, and after releasing the button or a short time following releasing it stop the tone,in my own mind you have 2 options, either make it so when the button is pressed power the 555 and it should based on your values play its tone, and use some capacitance on the supply to keep it powered for say 1.5 seconds following a press, or 2, use a 556 and have the second 555 kill the first say 1-2 seconds after releasing the button,

author: potatogun96
author_rank: Contributor
timestamp: March 11, 2013, 03:48:44 am
content: If you made a 555 timer circuit that would play the tone you wanted, you could put a large capacitor or two in parallel with the power rails. You would wire the button to connect the power supply to the circuit, which would charge up the capacitor and power the circuit until the charge ran out. I would try a simple astable oscillator circuit set to the frequency you wanted, with a capacitor (10,000uf maybe? Experiment) in series with a 9 volt battery or wall adapter.
Help with power interference? - Page 1
Forum section: electronics / beginners

author: tribble222
author_rank: Newbie
timestamp: November 29, 2011, 09:37:23 pm
content: Sorry if this is a very beginner question, but I can't figure this one out.I've built a device that plugs into the wall outlet and uses the Recom RAC04-05SA (http://www.recom-international.com/pdf/Powerline-AC-DC/RAC04-SA.pdf) to power an atmega328p chip that drives an LCD.Everything works fine unless I have it plugged into the same outlet as my mini-fridge. As soon as the mini fridge starts up my LCD becomes all garbled and never recovers until I turn my device off and back on.I assume there's some kind of power supply problem with surges or voltage dips or something. Any idea how I can fix this? I have it set up just like the bottom of page 2 in the datasheet. I tried adding the optional capacitors they show in the datasheet but it is still having the same problem.Thanks in advance

author: amspire
author_rank: Super Contributor
timestamp: November 29, 2011, 10:30:39 pm
content: First thing I would try a much bigger electrolytic capacitor across the output. It looks like that supply can handle up to 8000uF, but something like 1000 or 2000uF should be fine. The capacitor can be any voltage rating as long as it is above 5V.Normally, the 47uF should be fine.Richard

author: Psi
author_rank: Super Contributor
timestamp: November 30, 2011, 12:17:21 am
content: yeah, fridges (or anything with a motor) are really bad on the power when they start.I agree with amspire, try a bigger output cap.Also make sure you have a dedicated 0.1uF cap for your micro and your lcd controller power channels (and any other ICs you have) mounted next to the power pins of the IC. It could be that the LCD controller is crashing from the power glitch, might not be the mcu at all.

author: IanB
author_rank: Super Contributor
timestamp: November 30, 2011, 12:27:54 am
content: What about some input filtering like a ferrite bead on the mains lead?

author: tribble222
author_rank: Newbie
timestamp: December 04, 2011, 09:43:02 pm
content: A bigger capacitor did the trick! Thanks!
Help with power supply design - Page 1
Forum section: electronics / beginners

author: Alaezae
author_rank: Contributor
timestamp: December 16, 2021, 08:25:00 am
content: HelloI've been trying to design an adjustable voltage/current power supply and I've had some issues. I've solved everything with the adjustable voltage and it works, I'm using an encoder to drive a PWM signal into the ADJ pin on an LM317 (inspired by Dave's power supply in EEVBlog #221, except without the LM3070). The constant current is achieved with a current mirror (the two IRF9540's). On one side of the current mirror, the opamp and FET act as a current sink. The voltage at the source of the FETSHOULD(at least according to LTspice simulations) be approximately equal to the voltage at the non-inverting pin of the op-amp. This means that the voltage at the source across the two resistors (a parallel value of 6.875 Ohms since I don't have resistors large enough to dissipate the power requirements) should make the voltage at the non-inverting pin proportional to the current through the resistor. Now that I've actually built up the circuit, I've found that the voltage at the non-inverting input increases and decreases as it should, but the output of the opamp stays stuck at the positive rail. When I measure the voltage at the source of the FET, I read a voltage of0.8V, which doesn't make any sense. So then I check the drain of the FET, it was at 12V. I'm not sure what's wrong, I've double checked the way I've wired the opamp, I've switched FETs, I've adjusted the 10K pot along the NULL terminals. I'm just at a loss as to what to do. I've attached the schematic and LTSpice simulation results and pictures of the problem area.If you see anything else wrong with the schematic, please let me know. It's not perfect, it only decreases down to 1.3V but this is my first power supply design and I tried to go off of what I know.Thanks!

author: Ian.M
author_rank: Super Contributor
timestamp: December 16, 2021, 08:45:55 am
content: Discrete MOSFET current mirrors don't work in real circuits due to device to device VGS(threshold)and gmvariations. You'd have to use a single die MOSFET array, probably selected on test for minimal parameter variation between MOSFETs for it to work well enough to be useful.

author: srb1954
author_rank: Super Contributor
timestamp: December 16, 2021, 08:49:42 am
content: An LM741 is never going to work off a +5V supply. It's allowable input voltage range is practically zero when operating on 5V. Its output voltage range is also severely limited on a 5V supply and won't be able to drive the MOSFET properly.You need a more modern op-amp that can handle input voltages down to 0V. You also need to increase the supply voltage from 5V to ensure enough voltage to drive the MOSFET or substitute a MOSFET with a lower turn-on voltage.An LM317 based regulator is not able to reduce its output below 1.25V unless you have a negative supply so the adjustment pin can be pulled below 0V.
Help with QSE1113 Data Sheet  - Page 1
Forum section: electronics / beginners

author: gogoman
author_rank: Regular Contributor
timestamp: May 21, 2019, 07:38:54 am
content: Hi for a given condition, the data sheet(Page2) states a minimal collector current of .300mA.but no typical or Maximum, why is this the case.Then for the given test conditions the collector is guarantee to be .300mA and it is inadvisable to use values below the .300mA, is true?Why is Vce of 5V chosen for the given condition, why not 6Vthanks
Help with raspberry powerbank schematic - Page 1
Forum section: electronics / beginners

author: micoud
author_rank: Newbie
timestamp: November 27, 2020, 09:13:17 am
content: Hello friend , i would to make a custom powerbank ... this is the schematichttps://pasteboard.co/JChc1yR.pngi have received the pcb from jlcpcb (with smt service) but not works with batteryit seems to works only with usbc cable connected (charge the battery , power on the raspberry)Can you help me?
Help with Readings - Page 1
Forum section: electronics / beginners

author: AustinTxBob
author_rank: Contributor
timestamp: January 23, 2016, 06:46:42 pm
content: I built a cheap bench power supply and was going through it checking all of the voltages. I hooked up the AC output to my DMM and my scope and am seeing something I don't understand. So my DMM (both a BK2709 and also a Fluke 23) say ~6.95 VAC but on my scope I see ~19.8 Vpp.What am I missing?Thanks.Bob

author: bobcat
author_rank: Regular Contributor
timestamp: January 23, 2016, 06:50:20 pm
content: Your scope is measuring Peak to Peak and your meter is measuring RMS or average. Set your scope to measure RMS and compare.

author: Zero999
author_rank: Super Contributor
timestamp: January 23, 2016, 06:51:09 pm
content: The multimeter is displaying the RMS voltage, not the average which will be zero for an AC waveform with no DC component.The oscilloscope is displaying the peak-to-peak voltage, which is twice the peak voltage.For a sine wave, the peak voltage is equal to the RMS voltage multiplied by sqroot(2). It isn't a perfect sine wave so the results form performing this calculation will differ slightly.

author: AustinTxBob
author_rank: Contributor
timestamp: January 23, 2016, 06:55:51 pm
content: Thanks. RMS on the scope agrees with the ~6.9 VAC.I found some doc on RMS and the math now makes sense. Thanks!
Help with Reverse Engineering simple Audio PCB  - ESD Protection and Filter  - Page 1
Forum section: electronics / beginners

author: NNeerr00
author_rank: Newbie
timestamp: September 29, 2024, 01:28:40 pm
content: Hi everyone,I’m pretty new to PCB design and reverse engineering, and this is my first attempt at trying to reverse engineer a part of a PCB. So far, I’ve managed to trace out a portion of the schematic (see attached picture and schematic), but I could use some help moving forward.What I’ve found:- The section seems to be a filter circuit with an L-C combination.- Component SX603 looks like it might be an ESD protection diode.My questions:How can I figure out the values for:- C600, L600, C601, L601, and SX603?- What’s the purpose of the 0-ohm resistor in the circuit? I’m seeing one here, but I’m not sure why it's used.- Why is the ESD diode only placed on the tip and not also on the ring of the connector? Is there a design reason behind this?Any advice or guidance would be greatly appreciated, especially since this is my first time trying something like this. Thanks in advance for your help!

author: m k
author_rank: Super Contributor
timestamp: October 04, 2024, 05:34:22 pm
content: For component values you need a substitute circuit for calculations and place unknown components there, one at the time.There's a place for SX600, but component is missing.So it has had an intention to be there sometime in the past.To where is 0R connected?There are big traces around, maybe it's shorting the other side to GND and making the thing mono.Usually 0R is a simple jumper, or two when other trace goes under it, like SX603.
Help with Rigol Power Supply Output Specifications (Accuracy) - Page 1
Forum section: electronics / beginners

author: jstarr
author_rank: Regular Contributor
timestamp: March 01, 2014, 06:19:58 pm
content: I just got a Rigol 832 three channel supply that has a resolution of 1mV and 1 mA. I am trying to figure out the absolute accuracy (assuming calibrated properly).The datasheet notes an "Annual Accuracy" (25?±5?) of ±(Output Percentage+Offset). Specifically it states Voltage 0.05% + 10mV and Current 0.2% + 10mA. Is this the absolute accuracy or is this the maximum shift in absolute accuracy over the year or is this the absolute accuracy?The only other info that sounds like a description of accuracy in the datasheet is Linear Regulation Rate ±(Output Percentage+Offset), Voltage <0.01%+2mV; Current <0.01%+250?AAny advice appreciatedjohn
Help With Schematic - Page 1
Forum section: electronics / beginners

author: AustinTxBob
author_rank: Contributor
timestamp: October 03, 2016, 05:00:37 pm
content: For my digital fundamentals class, I had to build a kit. Instead of building dice or something like that I decided to go with something I can use so I went with a small frequency counter to be used with a HF transceiver. Problem is there was no block diagram and I need to do a write up on how the thing works.From what I can tell, all of the counting and driving of the LEDs is done in a programmed chip (PIC probably but they have a label covering it up). The input into the chip is what has me confused. A 2n3904 and 2n3906 are used in what I am guessing is an amplifier configuration (class a?). Then that is fed into a 74hc02 which then goes into the programmed chip. I think the NOR gates are there so the programmed chip only counts pulses during certain times (probably driven based on the 4MHz crystal).I haven't put this on the scope yet to see what is going on and was hoping someone could tell me if I am on the right track or not. I can't find any transistors configured exactly in this way.Thanks.Bob

author: Zero999
author_rank: Super Contributor
timestamp: October 03, 2016, 10:19:39 pm
content: Yes the BJTs are configured as an amplifier. Think about what happens to the collector voltage on Q1 when the base voltage changes, note that it's connected to the base of Q2 and do the same there. Then think about what happens to the collector voltage, when the voltage at the emitter of Q2 changes. Hopefully you'll see that the emitter resistors and R25 provide negative feedback, which reduces the gain but brings about many advantages: look them up.The 74HC02 is configured as a flip-flop. notice how it's drawn as AND gates with circles on the inputs? The circles denote that there's an inverter before each input. Look up DeMorgan's theorem and you'll find they're NOR gates.Did the kit come with source code for the MCU? If not then it's not very good. The whole point of building a kit is to learn how it works!

author: Towz
author_rank: Contributor
timestamp: October 03, 2016, 11:24:49 pm
content: Looks an awful lot like some kind of dedicated frequency counter chip like the intersel 7216b. Not a uC.

author: AustinTxBob
author_rank: Contributor
timestamp: October 04, 2016, 12:50:25 am
content: Quote from: Hero999 on October 03, 2016, 10:19:39 pmNo source code. They're pretty tight on handing out info. Can't even find a manual online. :/Not sure why I didn't realize it but of course the transistors have to amplify the signal. The NOR gate needs logic voltage to work. The output from the transistors seems to be a 0-3v square-ish wave. That makes sense.I'll do some research on exactly how the transistors are doing that. I need to try and wrap my head around what exactly they're seeing and doing.Quote from: Towz on October 03, 2016, 11:24:49 pmI'm pretty sure it is a custom program they're running. It has several programmable features like blanking the display, memories for storing offsets in the case of connecting to an IF stage plus some other options. It also goes to 50MHz.
Help with Self Test Question from Basic Electricity (Valkenburgh) - Page 1
Forum section: electronics / beginners

author: troutnut68
author_rank: Newbie
timestamp: February 21, 2021, 07:23:27 am
content: Hi Guys,I'm a newbie working my way through Basic Electricity(1992) by Van Valkenburgh which is an old out of print book. I've run into a Self Test problem that I cannot completely solve. It is on page 2-87 and regards finding Voltage, Current and Resistance in a Parallel Circuit. The question is part b and asks you to find Voltage E, current I1 and I2 and resistance R2. I came up with E=300 V and I1= 1 Ampere but cannot figure out how to get R2 and I2. The attachment is a camera picture of the problem. Is there enough information to solve for R2 and I2 or is this test question broken?E=R4 x I4 = 100 ohms x 3 A = 300 VoltsI1 = E / R1 = 300 V / 300 ohms = 1 AR2 = ?I2 = ?Thanks for any help offered,Alan

author: IanB
author_rank: Super Contributor
timestamp: February 21, 2021, 08:34:18 am
content: Hi there,In the absence of further information, it does not look like there is a way to find R2 and I2.We know E as you have deduced, and we can write the equation E = R2 * I2. This is one equation with two unknowns. More information would be needed to pin down either of R2 or I2 to go any further. A common way for such problems to be set up is that the total current in the loop is given, but that doesn't seem to be the case here.

author: Ian.M
author_rank: Super Contributor
timestamp: February 21, 2021, 09:11:43 am
content: Also note there is *NO* R3 in the part (b) circuit, so it seems likely that the author accidentally submitted an incomplete circuit with the draft and the proof-reader(s) didn't notice.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: February 21, 2021, 05:04:08 pm
content: I don't see the text part of the question, so does the text mention the total current of the circuit?

author: troutnut68
author_rank: Newbie
timestamp: February 21, 2021, 06:44:21 pm
content: Thanks for the responses to my question. No, there was no further information for this question other than fill in the unknowns. This is obviously a broken question that made it into the book and I will consider it case closed. I'm moving on to the next part of the book.Thanks again,Alan

author: Terry Bites
author_rank: Super Contributor
timestamp: February 21, 2021, 06:44:47 pm
content: Convert your reistances to condcutances (1/R =S) and then its a simple matter of addition and subtraction. When you have your mystery conductance worked out, just take the inverse (1/S).I=E*SVan V as in Common Core?

author: troutnut68
author_rank: Newbie
timestamp: February 21, 2021, 06:50:10 pm
content: If total current was provided it would be simple to solve the rest of it.
Help with Self Test Question from Electricity Demystified v 1 - Page 1
Forum section: electronics / beginners

author: troutnut68
author_rank: Newbie
timestamp: March 04, 2021, 07:39:02 pm
content: Hi Guys,I am having trouble with this question from Electricity Demystified v 1. Is there anyone who can explain the answer?The power formula should be used multiplied by the Time.P = I2R ; P = IE ; P = E2/R.Thanks,AlanPS The correct answer is C but I tend to get answer B when I try to plug in the numbers.According to the book, Energy is just Power multiplied by Time.

author: bob91343
author_rank: Super Contributor
timestamp: March 04, 2021, 07:47:04 pm
content: With the added resistance, the voltage on the lamp drops in half. So does the current. So half the current times half the voltage gives one fourth of the power. The entire circuit now draws one half the power compared to before, and half of that is wasted in the timer, leaving one fourth for the lamp.This is impractical, since lamps change resistance with current change so it's not a real world situation.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 04, 2021, 09:33:49 pm
content: You don't know the lamp's I V characteristic so it can't be answered. The lamp is not a linear resistor.It's a misleading question.

author: rstofer
author_rank: Super Contributor
timestamp: March 04, 2021, 10:09:23 pm
content: Quote from: Terry Bites on March 04, 2021, 09:33:49 pmIf the author wanted the complication, answer D would be correct. As C is purported to be the correct answer, bob91343's answer is correct.But you're right, the lamp is truly non-linear and, in a perfect classroom, answer D would be correct. I just don't think the complication is warranted at this level of learning.

author: troutnut68
author_rank: Newbie
timestamp: March 05, 2021, 09:02:28 pm
content: So does the length of time 2 hrs have anything to do with the equation? Energy = Power X Time as explained in the book. I have to admit that this question seems a bit too vague or difficult at the time it was introduced.Alan

author: rstofer
author_rank: Super Contributor
timestamp: March 05, 2021, 11:43:40 pm
content: The relationship between power and energy is defined by time. If you utilize 1/4 the power for any period of time you will consume 1/4 the energy.100W light bulb for 8 hours -> 800 watt-hours energy - 100W of power over 8 hours25 W light bulb for 8 hours -> 200 watt-hours energy - 25W of power over 8 hours.https://enphase.com/en-us/support/what-difference-between-watt-and-watt-hourIt is vitally important to understand the difference between watts (rate of consumption) and watt-hours (total consumption).

author: MikeK
author_rank: Super Contributor
timestamp: March 06, 2021, 12:57:31 am
content: Quote from: troutnut68 on March 05, 2021, 09:02:28 pmNot really. The same length of time is used in both comparisons. And since it's a constant it can be removed from both calculations and you can just compare power (watts).
Help with Self Test Questions from Electricity Demystified v 1 - Page 1
Forum section: electronics / beginners

author: troutnut68
author_rank: Newbie
timestamp: March 13, 2021, 02:05:34 am
content: Hi Guys,I need some help and clarification with 3 questions on the Self Test Part 1 of Electricity Demystified v1. The first question #21 I have no clue on how to solve. The book explained how to solve for series or parallel resistance, but not both combined.The second two questions(#22 and #23) I need some clarification on. The answers are 21 - b. , 22 - d. , 23 - d. I did get #22 right. The book only gives the answers, no explanations.Thanks for any help you can provide,Alan

author: MIS42N
author_rank: Frequent Contributor
timestamp: March 13, 2021, 02:36:52 am
content: These are all questions about series and parallel elements. Numbers 22 and 23 should be pretty easy to solve if you've learned the equations. Number 21 is a little trickier, but you can get the answer by drawing the circuit in pencil on paper. Anywhere you see two parallel resistors, work out the value, rub out the two parallel resistors and replace them with a single resistor of the value you worked out. Anywhere there's two resistors in series, work out the value and replace them with a single resistor of the same value. If you do it step by step you will get a single resistor, the answer. It takes quite a few steps (I think 15 minimum, but many steps are the same as the step before but on different resistors so there's not that many calculations). You might realise after a while there's a shortcut, but you should work it out yourself or you won't learn anything.

author: MikeK
author_rank: Super Contributor
timestamp: March 13, 2021, 04:41:56 am
content: Problem 22:V x I = 81mW, right? Three cells in series is 3V, right? So 3V x I = 243.Problem 23:Same thing, but three cells in parallel is 3I, right?

author: MikeK
author_rank: Super Contributor
timestamp: March 13, 2021, 04:45:31 am
content: Problem 21:Four resistors of the same value in series is 4R, right? So 4 x 820 = 3280.Four resistors of the same value in parallel is R/4, right? So 3280 / 4 = 820.

author: MikeK
author_rank: Super Contributor
timestamp: March 13, 2021, 02:05:48 pm
content: I should have described Problem 21 like this:Each row is four resistors in parallel, which can be replaced by one equivalent resistor of R/4. You then have four resistors in series, each being R/4 in value. So 4 x R/4 = R.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 13, 2021, 06:18:00 pm
content: P=V^2/RR has doubled and the total power is halved. The total power (now half of what it was) is split equally among the lamp and the resistor. So its 1/4 of the original
Help with setup  - Page 1
Forum section: electronics / beginners

author: aleksdjankovic
author_rank: Newbie
timestamp: March 17, 2019, 04:48:20 pm
content: hello i really need help with setting up my project, I'm completely new to all of this. I have a TP4056, 2000mah lipo battery, on/off rocker switch, and string LEDs that i would like to set up so that the battery can charge when connected to a source but also power the switch for the LEDs. I detached the LEDs from their original housing so they are just the Positive and Negative wires now. Any help would be greatly appreciated. I attached a picture of what i have basically.

author: WildMOSFET
author_rank: Contributor
timestamp: March 17, 2019, 05:14:22 pm
content: Just leave the battery connected to the charge controller, and put the switch in series with the LED strip.The led + switch series must be connected to the charge regulator load output.The terminals of the regulator are very clear, I don't think there is need for an explanation.
Help with Signal Generator on Siglent Scope - Page 1
Forum section: electronics / beginners

author: veedubius
author_rank: Newbie
timestamp: February 02, 2022, 02:21:11 am
content: Hi,I have a Siglent SDS2102X and am trying to test the signal generator function on it. It came with only two probes so I have attached one probe to the waveform port and the second probe to CH1 of the scope. I have then connected these two probes together and turned on a simple sine waveform.The problem is is that the waveform measured on CH1 has an amplitude significantly less that being output by the generator. The generator is output 6Vpp and CH1 is only detecting about 130mV. I am wondering if the unit might be faulty or if it is incorrect to use one of the probes for the channels on the waveform port and I need to get a specific cable for this generator function.Thanks

author: veedubius
author_rank: Newbie
timestamp: February 02, 2022, 02:24:42 am
content: As it would happen, as soon as I posted this question I noticed the 1x-10x switches on each probe. Setting this to be 1x on both probes gave me the amplitude I was expecting so it was obviously a basic beginner mistake.Thanks

author: radiolistener
author_rank: Super Contributor
timestamp: February 03, 2022, 02:47:30 pm
content: This is incorrect to insert oscilloscope probe BNC into signal generator connector. The oscilloscope probe is designed for 1 MΩ port. But signal generator has 50 Ω port.You can test signal generator by inserting oscilloscope probe tip into signal generator BNC connector. You don't need two probes for that.
Help with signal modulation of wireless microphone system - Page 1
Forum section: electronics / beginners

author: sgaudio
author_rank: Newbie
timestamp: February 17, 2025, 10:47:03 pm
content: Hello to all members,nice to meet you,i'm glad to be here !I'm newbie on electronics,Here is the question,a friend given to me a wireless microphone to check if it is transmitting signalI have tinysa ultra spectrum analyzer,i tested it but i can't understand well what type of modulation is this if it is FSKI will post the photo of modulation which showed in tinysa ultraYour help will be appreciatedThank you

author: Benta
author_rank: Super Contributor
timestamp: February 17, 2025, 11:33:52 pm
content: Why would a wireless microphone transmit FSK?FM is much more likely, but not knowing what the microphone is listening to, it's hard to say.

author: TimFox
author_rank: Super Contributor
timestamp: February 17, 2025, 11:51:19 pm
content: I replied to your other post: double-posting is frowned upon on this site.

author: Terry Bites
author_rank: Super Contributor
timestamp: February 18, 2025, 08:01:44 am
content: http://www.mwpersons.com/tech-tips/FM/Spurs-on-FM-station.htmLook familiar?

author: Datman
author_rank: Regular Contributor
timestamp: April 20, 2025, 03:25:51 pm
content: Which microphone are you talking about? I.e., Tonor TW-550 is DQPSK...My review:https://www.amazon.it/gp/customer-reviews/R1U7NF5N9YWBTK/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B0D9JJDL7P
Help with simple mosfet switch - Page 1
Forum section: electronics / beginners

author: mayor
author_rank: Regular Contributor
timestamp: October 18, 2020, 12:00:06 am
content: Hello,I am using the following circuit to turn a MAX31855 thermocouple amplifier on and off from a microcontroller:.The microcontroller will supply 0V to keep the NMOS turned off, and thus the PMOS, or 3.3V to allow the PMOS to supply 3.3V to the MAX31855.When booting up, everything looks fine, I get 0V out of the PMOS drain, switch on the NMOS for a bit, but when I switch the NMOS off again, the PMOS output is held at roughly 1.85V:(CH1 = gate of PMOS, CH3 = drain of PMOS)Subsequent toggles look like this:I admit, I don't know why that's happening. I expected the PMOS to shut down fully because of its pullup to 3.3V.What am I doing wrong?TIA!Edit: I realize I can probably drive the PMOS directly from the microcontroller, huh?

author: ledtester
author_rank: Super Contributor
timestamp: October 18, 2020, 12:18:25 am
content: I would check the actual current draw when the PMOS is off. The MAX31855 might not draw that much current if not selected and the cap C2 might be holding a residual voltage.That said, I would check the current draw of the MAX31855 when not selected. If it is low enough you might not need to power it down.

author: SmokedComponent
author_rank: Regular Contributor
timestamp: October 18, 2020, 12:22:36 am
content: Maybe that's actually coming from MAX31855's Vcc pin, getting power through its data pins?

author: fourfathom
author_rank: Super Contributor
timestamp: October 18, 2020, 12:28:15 am
content: I haven't looked that that Maxim part, but might there be internal input protection diodes on the CS#, SCK, and SO pins? If so, these (especially CS#, which is normally pulled high) will feed current into the VCC pin, bringing it partially high. This by itself wouldn't explain why the VCC pin starts out at 0V though...[SmokedComponent beat me to it]

author: Peabody
author_rank: Super Contributor
timestamp: October 18, 2020, 12:32:58 am
content: If the voltage on the PMOS gate is 3.3V when you see 1.85V on the drain, then current may be flowing through the SO, SCK and CS pins (if any of them are high), through their protection diodes to Vcc, then back to the PMOS drain.But yes, it looks like you could power the MAX31855 directly from a GPIO pin provided you also bring those serial pins low when you want to power it down.

author: mayor
author_rank: Regular Contributor
timestamp: October 18, 2020, 01:13:36 am
content: @ledtester: it draws roughly 1.5mA (from the data sheet), which is too much for the application.@SmokedComponent, thanks for the suggestion! I was keeping CS high even when the MAX31855 was shutdown. So boom that was it!@fourfathom: the reason it starts ok is software. The first read happens at time "t", and CS was low until that first read.@Peabody: yep, as you can see above!Thanks all.
Help with single shot pulse using a waveform generator. - Page 1
Forum section: electronics / beginners

author: Andy Jones
author_rank: Newbie
timestamp: January 25, 2018, 03:30:35 pm
content: Hi All, I have to provide a single shot 5v .2A 30ms square wave to test a squib circuit. I think it can be done easily with a monostable 555 timer circuit but I have a reasonable budget and I would also like to acquire a waveform generator to increase my future capability.Does anyone have experience using generators in a single shot pulse mode? before I buy one I'd like to know if it will give me just one pulse with a long gap (around a minute to make any adjustments to test kit) I would prefer to acquire something that can be programmed simply from the front panel or without too much software involved.I emailed a couple of manufacturers and one said it can’t be done and another said go read the manual, which wasn’t helpful. Just wondered if this is a common function of modern arbitrary waveform generators?

author: danadak
author_rank: Super Contributor
timestamp: January 26, 2018, 08:32:16 pm
content: Several ways to tackle this -1) Logic pattern generators do have single shot capabilty, some logicanalyzers have pattern generation capability as well.2) Do it with a PSOC, see attached screen shot of a solution. You canuse PSOC 5LP high end part, board is $ 10, or low end PSOC 4, boardis $25, arduino footprint. Note in this instance its all HW, only takesone line of code, you have to issue a PWM1_Start(); command.Button pushes during the cycle do not retrigger until end of cycle.PWM is edge triggered so I did not bother debouncing the button,otherwise I would have used the debouncer component.Regards, Dana.

author: danadak
author_rank: Super Contributor
timestamp: January 26, 2018, 09:01:54 pm
content: This is $ 25 board used, low end part.The board with high end part, much more capability, $ 10 -Regards, Dana.

author: Damianos
author_rank: Frequent Contributor
timestamp: January 27, 2018, 12:36:24 am
content: Any function generator that supports burst mode can do this, among many other things.
Help with small video switching project. - Page 1
Forum section: electronics / beginners

author: Bradley
author_rank: Newbie
timestamp: April 07, 2015, 10:13:09 pm
content: Hi guys just here for beginner advice. I don't have much electronics experience but have built a few small circuits successfully for my RC plane hobby.I am trying to build an RSSI comparator for video switching. Please see attached circuit diagram.The first op-amp buffers and scales the RSSI. The second is the comparator.I am able to manually switch video signals just fine with the switch. My problem is that the MAX4547 requires a signal much closer to the supply voltage than what the LM358 outputs and is stuck on the low signal channel no matter the output. (peaks ~10V)Is their an opportunity to add an pull up resistor here or should I start again?Any help appreciated thanks.-Brad
Help with SMD component identification  - Page 1
Forum section: electronics / beginners

author: paul_b_78
author_rank: Contributor
timestamp: November 29, 2022, 12:03:21 pm
content: Hi EEVBlog team,I am in a bit of a pickle. This is a bit of a long’ish read and hope there is somebody out there who can help me.I like to remove components from donor PCB’s and normally store them in little individual micro boxes.However, this storage has fallen off the bench onto the floor…They are all now mixed up and although I have retrieved a vast majority, I now need to re-identify them.I have 1005, 0201 etc etc Caps, Resistors etc etc.I have a multimeter but these components are far too small.What other gadgets are out there that can speed this whole thing up please.Before anyone replies with… don’t waste your time just throw them away and start again…..I have been pulling these components for years and years and so don’t want to start again.If you have read to this far then you are keen to help me with good quality advice.Look forward to your replies

author: DC1MC
author_rank: Super Contributor
timestamp: November 29, 2022, 12:50:37 pm
content: There are the SMD RCL tweezers that were discussed here on the site as well, some of them are actually useful for in circuit measuring as well.Example:https://www.amazon.de/-/en/MS8910-Mastech-Measuring-Tweezers-Passage/dp/B07DN98GX3You can spread the parts on a piece of paper, roughly sort them into categories and pick/measure individually with the tweezers then drop them in the assigned compartment. The only question left is how much your time is worth compared with the cost of the parts.Cheers,DC1MC

author: Fred27
author_rank: Unknown
timestamp: November 29, 2022, 03:31:58 pm
content: Maybe you should take sunk costs out of the equation. Just because you spent a lot of time sorting these once, that doesn't mean it's worth spending a lot of time doing it again.

author: MathWizard
author_rank: Super Contributor
timestamp: November 29, 2022, 04:10:45 pm
content: How many of each do u need laying around ? The cost of no-name SMD resistors and caps, is not much, as side from shipping maybe.On amazon or ebay, you can probably get kits of 10pcs*30 values, for like $5I hate trying to measure SMD parts with DMM probes, especially if they have crusty old solder on them. And I didn't find tweezers much better, like on my LCR meter.

author: wasedadoc
author_rank: Super Contributor
timestamp: November 29, 2022, 05:49:16 pm
content: Multilayer ceramic capacitors (MLCC) are highly susceptible to physical damage which makes them short internally. You will frequently see advice to throw away new ones which have been dropped. That would be even more applicable in your case as they have also have been through the stress of you desoldering them.