hybridfree/eevblog-posts huggingface dataset:
compressor&power supply shopping - Page 1
Forum section: electronics / beginners

author: aurmer
author_rank: Regular Contributor
timestamp: May 31, 2019, 05:40:40 pm
content: Not sure where this question belongs, but I am working on a portable pneumatics project. Trying to figure out the best design approach when speccing out the compressor.This compressor fits our functional and sizing needs.VIAIR 350C- 12V dc- 20A- ~.5 CFM (@max pressure)- 100% duty @ 100psi- 9”L x 4”W x 6.75H”But our problem is powering it properly. I lack a complete understanding of my power supply specs. So this is where my post splits in two directions:Q1)Can I find a similar (price/size/power) compressor that accepts 120VAC? I have tried looking around... alibaba, google, etc. I don't exactly know of a place to search for "small 120VAC compressors"Q2)If I cannot go the AC route, what do I need to look out for on my power supply to make sure I don't cause early failure?EXAMPLE: We have tested with aPUB250-12power supply (output 12V ~21A). This PS can turn on the compressor, but it dips down to .5V while supplying the inrush current. I am assuming this arrangement isn't sustainable for longterm use (see attached image: Vout from power supply as compressor starts up).What risk am I running with this power supply? What would I need to change or design to mitigate that risk? Should I implement IRC limiting, or do you think it would be cheaper to get a larger supply?All thoughts welcome. Thanks in advance.

author: jmelson
author_rank: Super Contributor
timestamp: May 31, 2019, 06:56:27 pm
content: Quote from: aurmer on May 31, 2019, 05:40:40 pmThis is a quite small compressor, but you certainly should be able to find one that runs off AC. Thomas Industries is one of the makers. Also, you might look at compressors for air brush use, they have pretty low volume delivery. (But, maybe don't handle 100 PSI.)Jon

author: SkyMaster
author_rank: Frequent Contributor
timestamp: June 02, 2019, 01:25:15 am
content: Home Depot sells 120 VAC air compressors.The DEWALT model DWFP55130 has 2.5 gallons tank with a 200 psi max pressure. I suppose this unit could supply 0.5 cfm at 100 psi without having to run continuously. The cost is less than $250.It is considerably larger then the VIAIR 350C, but I doubt the VIAIR 350C ran really run continuously, as its spec reads:Max. Duty Cycle (@ 72°F & 100 PSI): 100%Minutes On/Off (@ 72°F & 100 PSI): 1 Hour Run TimeSo, it is a 1 hour run time at 72°F. And since there is no cooling of any form, I am afraid 72°F would be rapidly exceeded. Even with cooling, 72°F would be exceeded!

author: aurmer
author_rank: Regular Contributor
timestamp: June 03, 2019, 01:04:32 pm
content: Quote from: SkyMaster on June 02, 2019, 01:25:15 amWe will never run it 100%, but the next one down doesn't have enough rating to support our application.And I believe the sheet is discussing "72°F ventilated ambient temp" not internal temperature.________________________I haven't found an AC driven compressor of the same size (physical dimensions are critical). I will seek a consultation on properly speccing a power supply that can handle the inrush current.Edit: sp
Computer (switching) power supply -- assessing quality/problems "live" - Page 1
Forum section: electronics / beginners

author: 13hm13
author_rank: Frequent Contributor
timestamp: September 08, 2020, 05:49:46 pm
content: PSU issues, especially in noisy environments as standard desktop computer or server, can be tricky to diagnose.Say I've got a generic PC computer and suspect PS issues, but I don't want to:(1) dissemble the PC(2) take it down (power it off)What symptoms indicate main PS issues (and not, for example, motherboard capacitor issues)?Can I "probe" or oscilloscope various power connectors ... look for "tell-tale" ripples or noise coming from the main SMPSU?
Computer engineering for babies - interactive book - Page 1
Forum section: electronics / beginners

author: Dave3
author_rank: Regular Contributor
timestamp: January 18, 2024, 05:55:03 pm
content: This interactive book illustrates some computer logic to young children. The book is well thought out.The video is fun to watch and solve, particularly the latchhttps://www.youtube.com/shorts/oBbnINBWUoYMore info on the book for babies (and upcoming advanced book).https://computerengineeringforbabies.com/Not affiliated in any way to this book series. Just a fan.

author: liaifat85
author_rank: Regular Contributor
timestamp: January 19, 2024, 02:03:31 pm
content: I saw this on LinkedIn too. I think the book is useful for grown-ups too who are learning digital electronics. By the way, those who are trying to learn how to design logic gates in PLC simulator, can check this blog:https://www.theengineeringprojects.com/2021/11/designing-logic-gates-in-plc-simulator.html

author: zapta
author_rank: Super Contributor
timestamp: January 22, 2024, 03:30:01 pm
content: Awesome! Very well done.Does it also teach hacking? E.g. changing a page function by covering a hole with a finger?

author: Smokey
author_rank: Super Contributor
timestamp: May 13, 2024, 08:21:47 pm
content: I wasn't sure what to expect, but this is actually really cool.I can just see some 2 year old having a conversation..."Mom: So.. Billy... Do you want to go to the store OR go to your friends house?""Billy: True..""Mom: Huh?""Billy: If you want me to pick just one you should have said XOR..."
Computer Fan Tach Output Voltage Seems High - Page 1
Forum section: electronics / beginners

author: john21443
author_rank: Contributor
timestamp: February 19, 2018, 06:21:59 pm
content: I am trying to get an understand of the tach output of a fan before I hook it up to a circuit. I have worked with 5v and 12v 4 wire fans (+, -, Tach, PWM). For example, here is the data sheet on the 5v fan:https://www.mouser.com/ds/2/471/San_Ace_40GA20_E-1282436.pdfWhen I use a 10K pull-up resistor from tach output to 5V I get a clean PWM signal in the oscilloscope. I can change speed of fan and frequency of tach signal changes as I would expect. What is throwing me off is the voltage of the tach signal as reported by the oscilloscope (5 volt fan):Vmax ~ 27V Vpp ~ 54V (AC coupled)I was not expecting more than 5 volts for peak to peak voltage.I am not well versed in my Rigol 10521E so I could be hooking things up wrong or configuring things incorrectly.What am I missing?For a 12v fan:12v fan Vmax ~ 62V Vpp ~126V (AC coupled)

author: Belrmar
author_rank: Regular Contributor
timestamp: February 19, 2018, 08:03:30 pm
content: May be a stupid question, but is your oscilloscope set to 10x scope mode?

author: john21443
author_rank: Contributor
timestamp: February 19, 2018, 08:19:22 pm
content: Ugh.So apparently I only checked that on the oscilloscope and probe for the first probe. The second probe was set to 1x ! I changed the slider on the probe to 10x and that got it working as expected. I am thinking I should tape those down because that isn't the first time that has happened.Thanks for asking the obvious question!John

author: Belrmar
author_rank: Regular Contributor
timestamp: February 19, 2018, 08:30:02 pm
content: Most people have them even epoxy'd , the 1x mode is 99% of the times useless due to the lower bandwidth
Computer speaker output control in win10 ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: February 01, 2021, 10:28:13 am
content: This weekend I've noticed that youtube video's are way too quiet compared to the max speaker volume (I only have an alarm clock radio w/ a single speaker ATM)So in windows 10, an alert notification, is pretty loud, but in youtube, with the volume slider at max, in this video any way, it's not loud enough.So how do I take control of win10, and make that firefox/output volume...LOUDER ? What program can I use or what script can I write in a BASH terminal, or what autoexec.bat and config.sys file can I write like the old days....to make the output volume of firefox.utube louder ?I could press some buttons on the alarm clock radio to increase volume, but it's way too dark for that, and I don't have a convient light source on handIf real life was Skyrim, which is actually a LOT OF WORK....I'd cast a light bulb spell

author: SeanB
author_rank: Super Contributor
timestamp: February 01, 2021, 11:08:11 am
content: In the video window there is a volume control, and in the audio box in the taskbar you can select properties, and then the volume of each separate input as well, and change them to the desired level.

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: February 01, 2021, 11:29:48 am
content: You can install an equalizer app that will let you increase the volume.

author: gnuarm
author_rank: Super Contributor
timestamp: February 02, 2021, 04:23:43 am
content: Quote from: JohnnyMalaria on February 01, 2021, 11:29:48 amTo 11?

author: JohnnyMalaria
author_rank: Super Contributor
timestamp: February 02, 2021, 01:03:48 pm
content: Quote from: gnuarm on February 02, 2021, 04:23:43 amMost let you increase the gain by at least +12dB.But an "11" knob would be funny, along with Dobly instead Dolby.

author: gnuarm
author_rank: Super Contributor
timestamp: February 03, 2021, 09:28:43 am
content: Almost every control in my car goes to 11.
Concept idea. circuit possible or not? - Page 1
Forum section: electronics / beginners

author: ShadyK
author_rank: Contributor
timestamp: December 02, 2013, 06:14:34 am
content: Hey guys,In my house hold i have plenty of different gadgets and other things. All that have different charging times. i have a charging hub basically a usb hib with all the different cables on. Would it be possible for me to make a board/circuit to run with the muiltple cables with some thing on it to stop sending power to the specific device when it has charged? also with a light to say that it is finished? .. sorry if there is already something out there like this. Thank you

author: Rerouter
author_rank: Super Contributor
timestamp: December 02, 2013, 06:20:51 am
content: there is the easy way and the hard way, and neither are that easy to a beginner,the easy way would be to measure the average current consumed by the device and cut the supply after falling below some threshold, probably with some time constant so in a few hours if the device is still plugged in to switch it back on in-case it has self dischargedthe hard way is only possible if it reports its battery % to your operating system, if so them you may be able to read this when it is 100% and then force the port into a sleep state,note i am a hardware guy, so it may be flipped around the other way for software based people.

author: trackman44
author_rank: Regular Contributor
timestamp: December 02, 2013, 06:22:41 am
content: A shunt resistor with op-amp and two LEDs would do the trick. (with resistors and caps for good measure)Will

author: hagster
author_rank: Frequent Contributor
timestamp: December 02, 2013, 06:33:23 am
content: Most modern Li Ion based products do this internally anyway.

author: ShadyK
author_rank: Contributor
timestamp: December 02, 2013, 06:41:53 am
content: Excellent. thank you for your replys i was just wanting to make sure that it could be dont thats all. so i have some research to do then in how to build circuits. Would you guys use a PCB?

author: ShadyK
author_rank: Contributor
timestamp: December 02, 2013, 06:42:59 am
content: Quote from: hagster on December 02, 2013, 06:33:23 amAw yeah i kind of new that any ways. Its just a concept idea that i have thats all, this is just the protoyping of a bigger idea that i have thats all
Condensator power factor - Page 1
Forum section: electronics / beginners

author: Asterix
author_rank: Contributor
timestamp: September 07, 2020, 08:51:54 pm
content: Hello,I have this magnetron wich keeps causing trouble.To be exact. the circuit trips on it.It is a pelgrim mag555rvs/p04.I have replaced the magnetron-unit(Radiating unit)and trafo. Wich i know now are good.However the circuit keeps getting faulty.I have measured:-Diodes are okay-Trafo is okay(Primary and secondary)-Microwave-unit. Wasnt good but replaced it.-Rotating motor. is okay- Fans they spin freely and the motor's have good resistance.-High voltage Capacitor. is okay. meets the exact value as indicated.So what keeps happening is that u are able to plug in the unit. set time but the moment u put it into microwave on the buttons. it starts and than. it gives a short.It appears to be a neutral to earth sort. But not shure yet.Now i diagnosed it again and found a wire pressed between the chassis and the buttons. i have fixed this so i will try the machine once more tomorrow morning.I also found that there is a AC capacitor soldered between Line and Neutral on the power board. i measured this and it shows 0.73nanoFarad while it is supposed to be 220 microfarad.so that one has to be replaced i think. I am an electrician as my job. so i know a bit of condensators and i know it must compensate the inductive load. But is this bad capacitor enough to cause a 16 ampere fuse to shut it of? or do i need to look a bit further.Does anyone have some experience with this? and can u tell me a bit more?Or maybe where i need to look? cause i am starting to run out...Regards,

author: srb1954
author_rank: Super Contributor
timestamp: September 07, 2020, 09:17:12 pm
content: Are you sure the capacitor between line and neutral is supposed to be 220 microfarad?A capacitor this big would draw an awful lot of current from the mains, far more than what is necessary to compensate for the power factor of a typical microwave transformer.More likely it is an interference suppression capacitor and a value of 220 nanofarad would be more appropriate.

author: Asterix
author_rank: Contributor
timestamp: September 08, 2020, 02:44:55 am
content: HiI was shure i read 220uF on it.I would check tomorrow morning if it is between Line and Neutral.I forgot to mention however it is a combi so both microwave and grill.Do you happen to know what could be the fault for the circuit tripping?Regards
Conditions for Maximal Power Transfer - Page 1
Forum section: electronics / beginners

author: Dwarf158
author_rank: Newbie
timestamp: December 25, 2021, 12:33:27 am
content: Assume we want to provide maximal power transfer from a source withimpedance ZSto a load with impedance ZL. The statdard technique to archievesuch impedance match is to place a matching network between source andload consisting of certain components (eg it can be a L- or T-network or even somethingmore complicated). See attatched image below." alt="" class="bbc_img" />In several books / internet sites it is said that the required condition whichthe matching network should satisfy is Zin= Zs*, in other sources it issaid that the matching network should satisfy Zout= ZL*. I guess these twoconditions are equivalent.Problem: I nowhere found a derivation why these conditions are equivalent, ie if Zin= Zs*holds, then also Zout= ZL*and vice versa.Could anybody give a reference where an explicite derivation of the equivalence of conditionsZin= Zs*and Zout= ZL*can be found? By the way: The claim that these conditions are equivalent I found in attatched pdf file.
Conductivity Measure with CN0359 - Page 1
Forum section: electronics / beginners

author: alnstn10
author_rank: Contributor
timestamp: July 18, 2022, 02:47:42 am
content: I am using Analog Device EVAL-CN0359-EB1Z with conductivity and temperature probe from Atlas Scientific. I used a conductivity solution of 12,880 uS, but the results shown on the CN0359 are very different (range 200,000-500,000 uS) from the results I got when using Arduino UNO (close to 12,880 uS). Besides the wiring, what are the possible causes for this to happen?

author: rooppoorali
author_rank: Regular Contributor
timestamp: July 21, 2022, 09:54:17 am
content: You'd better check your code too.

author: Terry Bites
author_rank: Super Contributor
timestamp: July 21, 2022, 03:31:28 pm
content: Is your cell correctly dimensioned?
Conductivity test with BK 1688b - Page 1
Forum section: electronics / beginners

author: jamie85
author_rank: Newbie
timestamp: March 18, 2021, 04:30:22 pm
content: Hi all,New here, so any help would be appreciated.I am trying to carry out a conductivity test using the BK 1688b power supply. I need to run a current through the panel at 10 amps, then measure the voltage in millivolts with a multimeter to calculate the resistance.However, I am having some issues setting the unit up. Any advice? I set the current dial to 10 amps but is there more to it?Thanks in advance.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: March 18, 2021, 04:38:33 pm
content: What's your load?

author: jamie85
author_rank: Newbie
timestamp: March 18, 2021, 04:56:52 pm
content: The document I am working to just states increase volt to get 10 amps.

author: jamie85
author_rank: Newbie
timestamp: March 18, 2021, 06:27:47 pm
content: The load I am connecting it through is an Aluminium mesh. I have connected this to the power supply unit via leads and crocodile clips. Once connected, I want to measure millivolts across the mesh with a multimeter. Am I right in thinking that I need to short the circuit, set it to 10 amps, then just increase the voltage until the red light comes on?

author: JustMeHere
author_rank: Frequent Contributor
timestamp: March 19, 2021, 12:30:20 am
content: You need to study about the Constant Current/Constant Voltage mechanisms of a power supply.If you short the leads, the voltage will drop to satify the Ohms Law equation.V = 10A x .1 Ohms (load resistance)
conductor inductance - Page 1
Forum section: electronics / beginners

author: p.larner
author_rank: Frequent Contributor
timestamp: December 17, 2023, 06:55:36 am
content: when 2 pieces of a piece of rf gear ie hf are conneted internaly what has the least inductance copper strip or wire,i have an atu and its min inductance is too high will replacng wires with copper strip help lower the stray inductance?.

author: Terry Bites
author_rank: Super Contributor
timestamp: December 17, 2023, 11:49:56 am
content: Absolutely it will. Think of a strip of foil as an infinite number of zero thickness wires laid parallel. Sum up their inductances.(Take the integral in other words).Dont panic. You can knife and fork through the equations without having to understand them.Time for an excel formula or two.Inductors in parallel sum the same way as resistors: 1/(1/L1 + 1/L2 .....etc). Or (and I would):Approximate the inductance by working out the effective L for a single skinny wire of the length and thickness of your foil.Then parallel up the L's until you get to the width of your foil. Easy.
Confirmation and Clarification - Page 1
Forum section: electronics / beginners

author: King_bob
author_rank: Newbie
timestamp: April 02, 2019, 10:29:15 am
content: I designed a circuit with and Arduino Pro Micro (5V), and 2xADNS3050 (optical mouse sensors, 3.3V) and a bunch of other stuff. Now I am trying to optimize the circuit, to free up an extra pin as well as use one 4-channel-3.3v-to-5v-logical-level-shifter less. To do this I bundled the Motion pins of the ADNS3050 and connected these, as well as MISO, directly to the Arduino, as is visible in the image below:My first question is, Is it OK to attach the MISO from 3.3v to 5v directly without damaging the 3.3v source? My understanding is that since the ADNS3050 is the Slave and MISO stands for "Master In Slave Out", the Slave sets 3.3v to the connection, which is still fine for the Arduino. Are there any negative aspects to doing this, if it is possible?Secondly, the Motion Pins from the ADNS3050s act as an Interrupt (they go to pin 7 on the Arduino, which is the only leftover interrupt pin that I have) Would bundling them cause any issues? My guess is the same as for MISO as to why these are directly connectable to the 5v Arduino, but if this is not the case I would welcome a heads up.I do also have a coding question, but Ill dump that elsewhere.Thanks.

author: mariush
author_rank: Super Contributor
timestamp: April 02, 2019, 10:46:27 am
content: Do you actually need that level shifter, considering you can run the atmega chip with 3v on the i/o?See pages 255-256 in datasheet :https://cdn.sparkfun.com/datasheets/Dev/Arduino/Boards/ATMega32U4.pdfYou have the schematics of the Arduino Pro Micro on Sparkfun's website so you could desolder some components or cut a trace with a sharp blade if needed.

author: King_bob
author_rank: Newbie
timestamp: April 02, 2019, 11:09:33 am
content: Yes, I considered this as well, but I have an OLED display (i2c), as well as a fingerprint reader(RX/TX) that runs on 5 volts as well... And I am not certain but isn't the speed of the chip only 8Mhz at 3.3v? I do not know if or even how this would effect a mouse-ish input device... Most computer mice that I found run with 38 to 40Hhz chips, so 16Mhz is already lower than the norm. Of course I may be completely wrong in the assumption and 8Mhz may be fine, but either way Id have to use at least one 4 ch shifter, so I figure sticking with 5v should be better.
Conformal coating - Page 1
Forum section: electronics / beginners

author: HobGoblyn
author_rank: Unknown
timestamp: April 16, 2020, 01:34:09 pm
content: Been looking at getting some conformal coating, or possibly solder mask instead.I see I can get a 5ml MG conformal coating pen for £10.66https://uk.farnell.com/mg-chemicals/419d-p-bl/overcoat-pen-5ml-blue/dp/2811946?st=conformalor I can get a 55ml bottle for £7.96.https://uk.farnell.com/mg-chemicals/4223-55ml/chemical-coating-55ml/dp/2889756?st=conformalThe bottle has urethane in it and takes 60 mins to become tack dry, the pen takes only 15minsThe datasheets are slightly different, the pen goes up to 125C while the bottle goes up to 160C , and the bottle takes 60 mins to be tack free whereas the pen takes 15mins.For simply holding a few enamelled wires in place, I presume it wont make any difference which I buy, I might as well get the 55ml one and have a load spare??Or could solder mask do the same thing, I daresay I will need solder mask in the near future and maybe I could use that instead? If so, what make do you recommend please?Many thanks

author: coppice
author_rank: Super Contributor
timestamp: April 16, 2020, 01:40:05 pm
content: Are you really looking for a conformal coating? Your description sounds like you actually want an effective glue to retain things.

author: HobGoblyn
author_rank: Unknown
timestamp: April 16, 2020, 02:38:01 pm
content: I'm following a few youtube vids on repairing a PS4 (have another thread about it herehttps://www.eevblog.com/forum/beginners/beginner-desolder-complete-mess-(/)The ones I've seen, he puts conformal coating on to go from the first pic to the second pic. My repair is almost identical (except I have a few more pins)I will be scraping away some solder mask to solder the wires, hence wasn't sure which was best.Thanks

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 16, 2020, 07:02:55 pm
content: Look into soldermask style glues. UV cure, with a UV LED flashlight (one ought to be recommended by the manufacturer?), very handy.Or superglue or Loctite something or other, but I'm not sure offhand if anyone makes a quick-setting formula like PMMA that's also heat resistant? (One of the bug-and-features of PMMA glue is it breaks down easily at temperature. Good for releasing parts from holders, but not great for higher temp assemblies.)Probably just blobs of urethane glue would be fine, too. Or something like nail polish, if it's good at modest to high temps. Most bodgewires I see on assemblies are done this way, just a blob here and there to secure it, not gooped over the whole thing.Tim
Confounding transistor bias configuration - Page 1
Forum section: electronics / beginners

author: gregallenwarner
author_rank: Regular Contributor
timestamp: June 27, 2014, 04:48:16 pm
content: I've been looking around at discrete transistors with built-in biasing resistors, and I came across this part:http://www.mouser.com/ds/2/302/PIMN31-117357.pdfThese are dual NPN transistors with built-in biasing resistors. However, the configuration is one I've never seen before.I've attached a screenshot of the internals taken from that datasheet.This part has R1 (1kohm) in between the base of the transistor and the external pin, but then it has R2 (10kohm) directly connecting the base to the transistor's emitter.I've never seen the base connected to the emitter through a resistor before in any biasing configuration I've ever come across. There's usually a separate emitter resistor, and a separate voltage divider on the base. Can someone explain what the purpose of this part is please?

author: ohmineer
author_rank: Contributor
timestamp: June 27, 2014, 05:04:46 pm
content: You can find this configuration in many devices, look for pre-biased transistors (http://rohmfs.rohm.com/en/products/databook/datasheet/discrete/transistor/digital/dtc144e.pdf). The pin-to-base resistor is the base current limiting resistor and the base-emitter resistor acts as pull down.AFAIK, these kind of transistors are also called digital transistors and designed to work as switches/gates.I don't think you would use those for an amplifier. As instance, they can be utilized to turn on and off an LED directly from a microcontroller pin with only the current limiting resistor in the collector.

author: gregallenwarner
author_rank: Regular Contributor
timestamp: June 27, 2014, 05:22:18 pm
content: Ah, I see. I hear the phrase "biasing" and I automatically think amplifier circuits. It makes much more sense now that I understand this thing is just a digital switch.Thanks.

author: David Hess
author_rank: Super Contributor
timestamp: June 27, 2014, 11:05:39 pm
content: In switching and linear applications the base-emitter shunt resistor provides drive to turn the transistor off when the drive is only configured to turn it on. Monolithic Darlington transistors usually have that resistor built in on the output transistor because there is no access to its base. The base-emitter shunt resistor is also important for sinking Icb at high temperatures and in power devices.

author: SeanB
author_rank: Super Contributor
timestamp: June 27, 2014, 11:12:12 pm
content: A lot of consumer electronics use these as switches or to interface to actual switches, like in VCR players where they were used to read mechanism switches and to drive things like LED's and low power motors or solenoids. Simple and low leakage along with only having a single package to mount.
Confused about circuit ground reference. - Page 1
Forum section: electronics / beginners

author: Rene
author_rank: Regular Contributor
timestamp: March 10, 2015, 03:08:26 am
content: Hello,Looking at the attached picture, could someone please explain to me what is up with the ground references in the circuit? The circuit shows two triangles at the bottom that I am guessing represent the exact same ground reference, but it also shows another ground called VNEG. Are these all supposed to be the same ground reference or are they different?Thanks.

author: IanB
author_rank: Super Contributor
timestamp: March 10, 2015, 03:13:01 am
content: It's a bipolar supply. You have a positive supply, a negative supply, and ground mid-way between them. That's why it's called a push-pull arrangement: it can push up towards the positive supply or pull down towards the negative supply.

author: Rene
author_rank: Regular Contributor
timestamp: March 10, 2015, 05:23:41 am
content: Quote from: IanB on March 10, 2015, 03:13:01 amThanks Ian,I am still kind of confused here. I think I am able to visualize the push and pull current flow between the base and emitter connections, but for some reason I seem to be incapable of visualizing the push and pull current flow between the collector and emitter connectors.Could you be so kind as to describe to me the push and pull current flow between the collector and emitter connectors? How does the circuit completes on those two scenarios?Thanks.

author: tggzzz
author_rank: Super Contributor
timestamp: March 10, 2015, 10:30:36 am
content: Start withhttps://www.google.com/search?q=class+AB+amplifier

author: jlmoon
author_rank: Unknown
timestamp: March 10, 2015, 07:03:22 pm
content: Good way to view this is:Positive voltage imposed by a Sine Wave (goes + above ground and - below ground ) on bases of Q1 & Q2 make Q1 conduct and cause current to flow from ground side of RL1 through RL1 up through emitter to the collector of Q1 to your + Supply. Call this a Push function then, when voltage becomes negative going below ground Q2 conducts and again current flows from ground side of RL1 through RL1 and into emitter of Q2 through transistor to Q2's collector to your (-) negative supply rail. Call this the PULL function. Transistors start flowing current when the differential voltage between Base and Emitter become close to ~.6 or .7 volts. Positive for NPN and Negative for PNP.I have found a good way to remember which is which.. is this: N.P.N. = Not Pointing N or iN (arrow points away from transistor) P.N.P. (P'n the Pot) (arrow points into junction). In most cases transistors work best when the Base - Emitter junction is forward biased and the Base - Collector junction is reverse biased.A EXAMPLE; for NPN, To make a NPN turn on.. bring the Base lead (with current limiting) up higher in potential than the voltage on the Emitter. This will start current flowing from the emitter up through to the collector with a fraction of current flowing out through your base depending on the gain of the transistor and how hard you're driving it.Did the best I could to explain a really deep topic.
Confused about crytsal HC49US - Page 1
Forum section: electronics / beginners

author: desertgreg
author_rank: Contributor
timestamp: April 29, 2017, 03:37:07 pm
content: I am looking at a reference schematic which uses a 25Mhz HC49US crystal. In the schematic there are three pins on the HC49US. When I look this device up in both mouser.com and digikey.com I find that it looks like an oval metal 'can' with two leads. I've attached a picture that has a snip of the schematic and a picture of the device. I need to integrate this into a design I'm working on but what are the three leads in the schematic?Thanks for any help you can give me!

author: Vgkid
author_rank: Super Contributor
timestamp: April 29, 2017, 03:43:28 pm
content: The third pin is connected to the case, in that picture.

author: ataradov
author_rank: Super Contributor
timestamp: April 29, 2017, 05:53:02 pm
content: And there is no real evidence that connecting the case to ground makes a difference. So if case does not explicitly has a pin for that, don't do it and skip this connection, it all will work.

author: desertgreg
author_rank: Contributor
timestamp: April 29, 2017, 10:42:20 pm
content: Thanks that helped a lot!
Confused about how this induction circuit works :/ - Page 1
Forum section: electronics / beginners

author: ivyandnine
author_rank: Newbie
timestamp: February 26, 2019, 06:07:30 pm
content: Hello all :-)I've been trying to understand this induction circuit for weeks but have been having some difficulties.From what I've tried to guess so far, there is some kind of resonance network between C1, C2, L1, L2 and L3 and the diodes act as some sort ofa detector that turns off the FET they are connected to when the resonant network swings from one side to the other?Some questions that come to mind here are:(1) Why does the heating coil (L1) not have an induction value? Is it's inductance inconsequential and the symbol is just shown so that you know what it is?(2) How exactly does the resonance network between C1, C2, L1, L2, and L3 work?(3) How were the values of 330nF and 100uH chosen for the capacitors and inductors?I've also tried simulating this in OrCAD but nothing happens...Any help / insight in understanding this is appreciated <3

author: helius
author_rank: Super Contributor
timestamp: February 26, 2019, 07:14:30 pm
content: The two MOSFETs are "racing" to switch each other off. In any real circuit, one will be faster and win, which starts the circuit oscillating.To simulate this, you need to change some of the component values so the two sides aren't equal. Try increasing R1 in relation to R2 by 10%.
Confused about measuring voltage across resistor. - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: April 10, 2020, 07:06:19 am
content: Hi, i'm confused about trying to measure voltage across this resistor "R911".It seems like it only has 0.4v going across it but i'm not sure if this is a series circuit and i need to calculate the voltage across the resistor by other means?I am trying to do a repair where some part of the circuit is not getting its 12V DC, but i haven't found yet where the power dies at.

author: helius
author_rank: Super Contributor
timestamp: April 10, 2020, 07:15:56 am
content: R911 acts as a filter in combination with C909. The filter limits interference from the cable shield and the amplifier coming back into the ground plane of the circuit. The voltage across a resistor is simply the potential measured on its two leads: there is nothing else to calculate. If the potential is 0.4 V, then by V/R=I, the current is 8.5 mA.I don't think this has anything to do with your +12V supply problem.
Confused about multimeters - Page 1
Forum section: electronics / beginners

author: JacobP
author_rank: Contributor
timestamp: February 07, 2017, 03:46:11 am
content: Good evening everyone,I am fairly new to working on electronics -- I've tinkered on and off for a while, but I've been messing around with an Arduino and some very simple electronics and I'd like to start playing around with it more seriously (although still low-end hobbyist). I've been trying to make do with a multimeter I picked up at Lowes, but its really just not cutting it. The lack of a tone on the continuity tester setting alone is enough to make me want to replace it.I have spent hours over the last few days reading posts on this forum and watching Dave's videos, but I feel like I'm more confused that I was to begin with. Every time I find a model that I think would be a good choice, I feel like I run across another post explaining why it's a not a good option. I understand that in the low-end multi-meter market that there will be compromises, but I hope that I can find something that meets my needs.Here's what I think I'm looking for, although I'm novice enough that I'm certain there are things I'm overlooking.1) Reasonable accuracy2) A reasonably fast continuity tester with audible feedback4) Electronics use only -- no direct use on house power5) Auto-ranging6) Pincer clips (to attach to breadboard wires; I know these are probably a second purchase)I had it about narrowed down to the AM-510 or AM-520 (modest upgrade to get max/min). It seem to have the features I was looking for and was safe enough to use on household circuits down the road if I wanted, but then I read a review saying that the continuity testing was really slow.I would really appreciate some feedback. I don't have a strict budget; I'm willing to pay a reasonable amount of money to get an adequate tool, but I also don't want to pay for a bunch of features I don't need.Thanks!

author: rstofer
author_rank: Super Contributor
timestamp: February 07, 2017, 05:27:04 am
content: I'm sure you will get some responses in this Beginners forum but there is a Test Equipment forum more specifically oriented to this type of question.There will be dozens of recommendations.

author: JacobP
author_rank: Contributor
timestamp: February 07, 2017, 05:27:45 am
content: Thanks for the suggestion -- I will cross-post over there.
Confused about operational amplifier configuration.. - Page 1
Forum section: electronics / beginners

author: DaveHardy
author_rank: Regular Contributor
timestamp: May 19, 2013, 08:50:20 pm
content: I've got a few books about operational amplifiers that don't explain why I keep seeing this circuit below with a big electrolytic shunted between R37 and ground. I simply can't figure out the point of putting a capacitor there. Does anybody know why it is there or what it is called so that I can goole it?This circuit is for audio purposes.

author: KJDS
author_rank: Super Contributor
timestamp: May 19, 2013, 09:00:44 pm
content: RIAA equalization is the most likely

author: planet12
author_rank: Regular Contributor
timestamp: May 19, 2013, 09:06:43 pm
content: "Shunted" makes it sound like you mean "in parallel with" R37.If you're meaning a largish cap in series with R37, what this does is make the opamp work as a unity-gain voltage follower at DC, but with the programmed gain once the frequency is high enough to make the capacitors reactance small enough to no longer effect the gain; this is often used so DC offsets within the system do not accumulate and amplify (if they're not wanted - hence you'll frequently find this in audio systems).

author: DaveHardy
author_rank: Regular Contributor
timestamp: May 19, 2013, 10:23:45 pm
content: Quote from: planet12 on May 19, 2013, 09:06:43 pmYes, I meant in series.Thanks, this is the answer that I was looking for. How can I Google this circuit to learn how to compute values, learn about the pros and cons, etc? Is there any info on the web or in books that you could point me to that explains this circuit in detail?Thanks for the help everyone.

author: c4757p
author_rank: Super Contributor
timestamp: May 19, 2013, 10:33:27 pm
content: Just thoroughly readthis articleon impedance, and understand that a voltage divider works with complex impedances as well as pure resistances. Then once you understand the basic function of an op amp*, you can figure all these out with just a bit of algebra.*The most basic, useful explanation of an 'ideal' op amp that I can think of (one of them, at least) is that the inputs take no current, and it moves its output towards the sign of whichever input is higher, in an attempt to make both inputs equal. If it cannot make them equal, it's said to be saturated. Once you've ascertained that it is able to make them equal and has not saturated, just calculate the output based on the assumption that both inputs are equal.

author: c4757p
author_rank: Super Contributor
timestamp: May 19, 2013, 10:44:40 pm
content: Alternately, to simplify if you don't care about things like phase (basic filters, etc):C = capacitanceL = inductancef = frequencyX = reactance (the complex/AC part of the impedance)
Confused about PD TIA Simulation in LTSpice - Page 1
Forum section: electronics / beginners

author: marloh
author_rank: Newbie
timestamp: May 16, 2024, 12:03:38 am
content: I'm trying to simulate the feedback network on a Photodiode Transimpedance Amplifier that I am working on and I'm very confused by the results. I'm getting a gain of -40db at low frequencyThis is the procedure that I'm trying to follow:https://www.allaboutcircuits.com/technical-articles/negative-feedback-part-8-analyzing-transimpedance-amplifier-stability/Please helpI'm trying to simultaneously learn the LTSpice software and the TIA and I can't figure out where I'm going wrong

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 16, 2024, 05:32:24 am
content: You have to set up your TIA circuit correctly in LTSpice according to the schematic provided in the article you referenced. This includes the photodiode, feedback resistor, and operational amplifier (Op-Amp) configuration.Before analyzing the AC behavior, it's essential to verify that the DC operating point of your circuit is stable and within acceptable ranges. This involves checking voltages and currents at different nodes in the circuit. Perform an AC analysis to determine the frequency response of your TIA. Plot the magnitude and phase of the gain (trans-impedance) across a range of frequencies.

author: AnalogTodd
author_rank: Regular Contributor
timestamp: May 16, 2024, 01:06:16 pm
content: Important thing to look at DC bias points as @marloh pointed out. The op amp you are using is not the same as the one in the article referenced, and so there is a question as to how close the inputs can go to the negative rail. Your negative rail is at ground, and your input signal is also at ground (shows no DC offset). The LT6015 is listed as an 'over-the-top' op amp and as such can operate beyond the nominal rails. The OPA140 is listed as rail-to-rail output and does not say the inputs can handle going past nominal rails.
Confused and learning - Page 1
Forum section: electronics / beginners

author: Dark Bard Raven
author_rank: Newbie
timestamp: June 06, 2019, 10:43:00 pm
content: First of sorry I know this is long winded I am getting old. So simple question really I am trying to get into electronics as a hobby and maybe to make some money on the side fixing things. I have decent basic knowledge but was always afraid and never had any out side motivation to get into it as a kid, now that I am going into the second half of my life I am done just standing by and not getting into the things I like when I have a genuine love of electronics but I come across some really basic info but can not seem to get a solid answer sometimes. So the question is I am determined to build my own D.I.Y. Power supply and quite a few other things to give me more versatility in what I am doing. But I know to start I need some basics. One of which is a basic power supply to test my individual components before I install them all in and cross my fingers and hope I got it right. I am doing the research and understand the Voltage and Amp part but I am getting confused with the input part. Most of my life has been buy something and plug it in and it works knowing that there was more to it but not giving it much thought. But now looking at power supplies I notice more and more that they say to check the out side input and either make sure that your running 110 or 220 based on the recommendation. Can someone dumb this down for me and simply put if I buy a power supply that was build to use a standard American plug can I just plug it into my wall socket without blowing it out or do I have to take my multi meter to check the plug then regulate the power going to it to match the supply I get. In the end I will be converting a ATX power supply with out modifications for variable and static power out put so I know that will work just plugging it into the wall once done and means a normal power supply should just plug in and work but all these knock off companies say so much **** I just want to make sure can not really afford to waste money and do something stupid.

author: rstofer
author_rank: Super Contributor
timestamp: June 06, 2019, 11:20:35 pm
content: I would expect that everything you buy from a supplier inside the US to come with a US power cable. If you buy it from China, you're on your own.Many power inlets have a switch to select between 120 and 240. This is particularly true for ATX power supplies.Some items don't care which voltage you apply, they'll deal with it.IEC cables (PC cables) come with a number of male ends depending on country.I think you're overthinking this. I have been playing with this stuff for 60 years and have never had an issue plugging things in.

author: Dark Bard Raven
author_rank: Newbie
timestamp: June 06, 2019, 11:28:27 pm
content: Yeah, I am agreeing with the over thinking the wording was just throwing me for a loop.
Confused by p-channel transistor - Page 1
Forum section: electronics / beginners

author: JGAN
author_rank: Contributor
timestamp: October 28, 2015, 11:43:07 pm
content: My understanding of how a p-channel transistor works is that if the voltage at the gate is lower than the voltage at the source, then current will flow from the source to the drain. However, in the schematic I'm looking at, the input power supply PPVBUS_USB_DCIN is placed at the drain and flows to the source PPVBUS_PROT when the gate goes to 0v. The transistor is Q8123. What am I not understanding?

author: c4757p
author_rank: Super Contributor
timestamp: October 29, 2015, 12:12:07 am
content: Currenttypicallyis configured to flow from source to drain, but when the gate is at least a threshold voltage below the source, current can flow inanydirection. This is a fairly common reverse-polarity protection circuit - have a look here:http://hackaday.com/2011/12/06/reverse-voltage-protection-with-a-p-fet/

author: rs20
author_rank: Super Contributor
timestamp: October 29, 2015, 12:33:01 am
content: When the current flows in this direction, it's called third quadrant operation (as opposed to the more familiar first quadrant operation). The quadrants referring to the quadrants in a V/I graph.The interesting thing about this arrangement is that when the gate is below the source, the switch turns on and current can flow both ways -- but if the switch was turned off, the current could still flow through the body diode of the device. So in this arrangement, the MOSFET can never turn off (unless reverse polarity connection happens). This is absolutely fine in a reverse polarity protection situation as shown above, because that's the intention. What's even more fascinating is that this diode is essential to the circuit working, at least initially (if the MOSFET is initially off, and no body diode was there, Vs cannot rise above Vg, and it'd never turn on).Shameless self-promotion link to my blog post on this.Also, third quadrant operation is very commonly used in the ground-side NFETs in buck converters to replace the freewheeling diodes, among other similar applications. You'll notice a common thread -- third-quadrant MOSFETs are used as (closer-to-) ideal diodes, where the forward voltage drop of typical diodes is unacceptable.

author: JGAN
author_rank: Contributor
timestamp: October 29, 2015, 06:40:33 am
content: This all makes complete sense! Thanks again for all the help!!
Confused by powers of ten; new capacitor voltage problem - Page 1
Forum section: electronics / beginners

author: sshoptaugh1991
author_rank: Contributor
timestamp: September 10, 2017, 09:16:52 pm
content: Greetings everyone!Well, I thought I had the understanding, but something is making me think I do not. I have yet another capacitor voltage example, but this is an example problem, not just an example with the solution written out.From looking at the voltage graph in the textbook, I am able to figure out the voltage equation from 0 <= t <= 2ms, but when I proceed to the next interval, there is a problem, namely with the magnitude power.Here is what I have done so far:i(t) = [-10(10^-6) / 2(10^-3) ]t from 0 <= t <= 2msrewritten as -5(10^-3)ti(t) = -10 from 2ms <= t <= 4msi(t) = 0 from 4ms <= t <= 5msi(t) = -10 from 5ms <= t <= 10msv(t) = 1/(10^-9) [int(-5(10^-3)t] - 5 from 0 <= t <= 2ms= (10^9) [-2.5(10^-3) t^2] - 5v(2ms) = -15 V as expectedHowever, this is where I run into problems with order of magnitude with the exponents:v(t) = (10^9) [int(-10)] - 15 from 2ms <= t <= 4ms= (10^9) [-10t + 10(0.002)] - 15= -10(10^9)t + 20(10^6) - 15v(4ms) = -20000015 what??? It should come out to -35. I am confused as to my order of magnitude screw up.Anyone have any suggestions?

author: sshoptaugh1991
author_rank: Contributor
timestamp: September 11, 2017, 09:41:06 pm
content: Nevermind everyone, I figured out where I went wrong. For the second and fourth current equations, I kept writing out i(t) = -10, instead of -10(10^-6). That is where my problem came from. Those small, minute details. Watch out for those, everyone. They will certainly mess you up.
Confused by SDRAM datasheets - Page 1
Forum section: electronics / beginners

author: MasterBuilder
author_rank: Regular Contributor
timestamp: April 19, 2017, 05:24:44 pm
content: Currently I'm looking for suitable SDRAM for my project. I'm confused about what is the size in MBs of the memory devices according to the datasheet.The Micron part MT48LC16M4A2 datasheet says 4 Meg x 4 x 4 Banks, Is this 4 banks of 4MB for 16 MB total, with a 4 bit interface? The datasheet configuration section is below for this part and two other parts in this family.Configuration– 16 Meg x 4 (4 Meg x 4 x 4 banks) 16M4 3– 8 Meg x 8 (2 Meg x 8 x 4 banks) 8M8– 4 Meg x 16 (1 Meg x 16 x 4 banks) 4M16

author: bktemp
author_rank: Super Contributor
timestamp: April 19, 2017, 05:36:03 pm
content: The SDRAM has 64MBits or 8MBytes. It is available with a 4, 8 or 16bits data bus.

author: MasterBuilder
author_rank: Regular Contributor
timestamp: April 19, 2017, 08:44:32 pm
content: Thanks bktemp