hybridfree/eevblog-posts huggingface dataset:
Diodes Capacitance - Page 1
Forum section: electronics / beginners

author: takcoud
author_rank: Newbie
timestamp: April 04, 2025, 10:35:16 am
content: Hi all! Please explain me strange situation with zener diode capacitance.I have OnSemi zener diodes MM5Z3V0T1G.Datasheet says that their capacitance at 1MHz with 0V bias voltage should be typically 450 pF.However, my measurements give me about 200 pF of capacitance.My equipment is an LRC meter up to 5MHz with an adapter for SMD components.I'm measure at 1MHz 0.1VRMS 0V Bias and do all appropriate calibrations before measuring.At the same time, I have many other diodes (most of them actually) whose capacitanceis measured correctly and matches their datasheets.But there are some for which the capacitance does not match.Perhaps I'm doing something wrong in my measurements?Maybe there are some tricks to measuring diodes and zener diodes?I need some help in this situation.

author: the Chris
author_rank: Regular Contributor
timestamp: April 04, 2025, 12:48:36 pm
content: What values do you get if you perform the measurement seperated into both polarities, e.g. at +0.2V and -0.2V bias voltage?

author: golden_labels
author_rank: Super Contributor
timestamp: April 04, 2025, 05:32:45 pm
content: 450 pF is the maximum capacitance. 200 pF is below 450 pF, so within limits.

author: mawyatt
author_rank: Super Contributor
timestamp: April 04, 2025, 06:28:27 pm
content: What LCR meter & SMD adapter/fixture are you using?Did you perform a proper "Open Cal" with the SMD Fixture in place?0.1Vrms AC test voltage should be OK, maybe check with lower AC value like 50mvrms. Also check with a known good capacitor (NPO) 400~500pF as a reference check.Best

author: PGPG
author_rank: Frequent Contributor
timestamp: April 06, 2025, 12:46:46 pm
content: Quote from: takcoud on April 04, 2025, 10:35:16 amIn the table all diodes for different voltages have the same value of C. Typical capacitance for different diodes can't be exactly the same so it is not typical but maximum.

author: TimFox
author_rank: Super Contributor
timestamp: April 06, 2025, 02:37:43 pm
content: A specification without the qualifiers "typ" or "min" is almost always a "max" value.

author: golden_labels
author_rank: Super Contributor
timestamp: April 06, 2025, 03:38:01 pm
content: There is no need to guess. It is explicitly specified as the maximum, the last row of the table describing parameters used in “Electrical Characteristics” section:

author: takcoud
author_rank: Newbie
timestamp: April 15, 2025, 07:53:33 am
content: Quote from: mawyatt on April 04, 2025, 06:28:27 pmI use TH2826 High Frequency meter with SMD fixture from it's set.Yes, I perform properly open calibration.Also I trying lower RMS voltages (20 and 50 mVrms) and have similar results. Also I measured SMD capacitor 220pF and had relevant results too.

author: takcoud
author_rank: Newbie
timestamp: April 15, 2025, 07:57:02 am
content: Quote from: golden_labels on April 06, 2025, 03:38:01 pmI was blind and I should had to see it for myself! If they specified max capacitance then I have no more questions ))) Thanks a lot!
Diodes - explanation please? - Page 1
Forum section: electronics / beginners

author: igorbog
author_rank: Contributor
timestamp: February 11, 2012, 01:33:03 pm
content: Hicould you please explain when I use each type of diodes and what are important parameters for each diode type:Schottky DiodeZener DiodePN DIodeSCRs & TRIACsI'm looking for a short explanation. Thanks

author: Rerouter
author_rank: Super Contributor
timestamp: February 11, 2012, 01:44:20 pm
content: Schottkey diodes have a very low forward voltage drop, they are good in clipping circuits (if external diodes clip the signal before the internal ones, your device wont need to shunt any current through it, also are good for higher efficiency rectifiers, (lower drop means less wattage for given current)zeners give a stable voltage drop when given a stable current source, far better than a resistor divider, worse than modern reference IC's, though when around 6.3? - 6.4V? has nearly no temperature offset, and at other voltages can be used in temperature compensation, as most follow a rather static charachteristic, though with way they go, i have also forgotten,as for the rest, lack the knowledge to summerise,

author: mariush
author_rank: Super Contributor
timestamp: February 11, 2012, 01:46:12 pm
content: Watch these:(and the following videos in playlist explain shottky diodes and so on)Should explain a large part of your questions and requests.

author: Jovian
author_rank: Contributor
timestamp: February 11, 2012, 01:51:25 pm
content: You may find this link useful:http://www.sparkfun.com/tutorials/212Regards,Jovian.

author: Jovian
author_rank: Contributor
timestamp: February 11, 2012, 02:23:09 pm
content: As for SCRs and TRIACs,Basically and SCR is two transistors an NPN and PNP in the following configuration:when the SCR is "off" only a small leakage current will flow through it. however when the gate is activated (sufficient positive gate current) then TR2 starts to turn on, as it does that TR1 starts to turn on too, this feeds more current into the base of TR2 and so the cycle goes. This means that if the gate current is removed the SCR remains latched "on". To turn off an SCR the anode current must be reduced to below a value called the minimum holding current (IH).As for TRIACs they are basically SCRs for AC, essentially just two SCRs in parallel anode to cathode with the gates joined, so that it can operate in both directions.SCRs are commonly used for crowbar circuits, motor controllers, high power AC rectification.This may help:http://www.allaboutcircuits.com/vol_3/chpt_7/5.htmlRegards,Jovian
Diodes or equivalents for Tek - Page 1
Forum section: electronics / beginners

author: Greg65
author_rank: Contributor
timestamp: March 11, 2014, 12:14:06 am
content: Hiya folks,I'm looking for a little help here finding and looking to buy a couple of equivalent diodes for the SMPS section of a 2215 Tektronix scope to try and get it back up n' running again.The diodes that I need are FDH9427/IN4152 & MB2501/IN4936 or any others that would be of the same or higher specs would be the ones that I need.If any of you's have good ones lying about, would you, or could you supply me with a couple of them, I would gladly purchase them from you as I cannot seem to find any, or else point me to where I can buy them please.I am in the UK.Cheers if you can help out, here at this wonderful forum,Greg

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 11, 2014, 12:22:42 am
content: 1N914/1N4148 probably works fine in place of 1N4152. 1N4936 can be replaced by FR104, PR1004, UF4007, etc. Can probably find both in any old junker computer PSU.Tim

author: Greg65
author_rank: Contributor
timestamp: March 11, 2014, 12:37:04 am
content: Thank you T3slAll advice is much appreciated. Tim
Diodes,zener,normal....and all the other kinds - Page 1
Forum section: electronics / beginners

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: March 25, 2013, 09:15:42 am
content: Hello i now started using diodes and i am confuzed about the different types(zener , normal diodes,those who can adapt quickly )so please can you explain the most basic things and differences about the diode "species"

author: BravoV
author_rank: Super Contributor
timestamp: March 25, 2013, 09:18:07 am
content: http://openbookproject.net/electricCircuits/Semi/SEMI_3.html

author: Simon
author_rank: Unknown
timestamp: March 25, 2013, 09:20:38 am
content: wikipedia is your friend. look up silicone diode, schotky diode and zenner diode

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: March 25, 2013, 09:24:57 am
content: Thank you all for your help

author: BravoV
author_rank: Super Contributor
timestamp: March 25, 2013, 09:38:40 am
content: And .. bookmark this too ->http://www.openbookproject.net/electricCircuits/Although its valid question and you've posted in beginner section, but c'mon, that kind of so basic question shows either you're lazy or it looks like you don't know what Google is.

author: Skimask
author_rank: Super Contributor
timestamp: March 25, 2013, 09:41:09 am
content: http://tinyurl.com/cpt6l8zhttp://lmgtfy.com/?q=diode
Dip devices with pins that aren't long enough for bread boards? - Page 1
Forum section: electronics / beginners

author: cvriv
author_rank: Frequent Contributor
timestamp: March 03, 2017, 09:51:26 am
content: I just bought some dip switches and the pins are just long enough to make contact but not enough to really hold them snug with the breadboard. I bought some variable resistors a while ago and had the same problem. Whats the deal? Im about to buy some female headers to combat this problem. Am i not buying the right stuff for breadboards?

author: Ian.M
author_rank: Super Contributor
timestamp: March 03, 2017, 10:55:38 am
content: That's more common with salvaged parts - the leads get cropped after insertion in the PCB so aren't suitable for breadboarding even if they appear clean and free from solder lumps.Its usually possible to work around it by adding a turned pin socket with long pins between the offending DIL component and the breadboard.

author: jeroen79
author_rank: Frequent Contributor
timestamp: March 03, 2017, 11:52:46 am
content: A lot of (nonsalvaged) parts come with leads just long enough to poke though the PCB and short enough to not require cutting off the excess after soldering.If you want to breadboard them you could solder some extra wire to their leads.

author: cvriv
author_rank: Frequent Contributor
timestamp: March 03, 2017, 01:12:45 pm
content: The stuff im buying isnt salvaged. The leads just arent along enough for the breadboard. I thought about solder on some longer legs.

author: ZomBiE80
author_rank: Contributor
timestamp: March 03, 2017, 01:29:03 pm
content: I'm keeping around some wirewrap sockets of various sizes just for aforementioned reason.

author: David Hess
author_rank: Super Contributor
timestamp: March 03, 2017, 05:50:52 pm
content: I have had the same problem with DIP switches and other DIP parts which are not ICs. The solution is to mount the DIP switch into an IC socket which has pins which are long enough. Or if you are despirate for a solution now, solder solid extension wires onto the DIP switch leads. Cut off resistor and small singal diode leads work well because they are stiffer than soft copper.

author: GreyWoolfe
author_rank: Unknown
timestamp: March 03, 2017, 10:04:22 pm
content: Quote from: cvriv on March 03, 2017, 01:12:45 pmI have also seen it with pcb mountable switches. I have just added some hook up wire.
Diploma of Electronics Question - Page 1
Forum section: electronics / beginners

author: iwack
author_rank: Newbie
timestamp: September 21, 2019, 09:17:50 am
content: Has anyone studied the TAFE Diploma of Electronics and Communications Engineering?Does TAFE teach practical electronics properly or is it a waste of time?

author: rstofer
author_rank: Super Contributor
timestamp: September 22, 2019, 01:10:39 am
content: This question comes up from time to time but it is specific to your part of the world so many of us don't have anything to contribute.Search the entire site for TAFE and you will run into previous discussions. Among others:https://www.eevblog.com/forum/beginners/advanced-diploma-electronics-at-tafe-(kinda-want-dave-to-answer-this-question)/msg2139871/#msg2139871
Diptrace adjusting breakaway tabs and mouse bites - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: March 24, 2025, 04:15:18 pm
content: Please refer to attached image, red circled castellated holes are overlapping mouse bites how can i relocate breakaway tabs and mouse bites

author: HwAoRrDk
author_rank: Super Contributor
timestamp: March 24, 2025, 04:31:35 pm
content: If this has been done using the panelisation feature, then you simply click on the tab and drag it to another position.
Diptrace and Pin Swapping - Page 1
Forum section: electronics / beginners

author: admiralk
author_rank: Regular Contributor
timestamp: May 11, 2018, 08:56:52 pm
content: I am building a little keypad and wanted to clean up the layout a bit by rearranging the pins on the header. Instead of 1, 2, 3, 4, 5, I assigned the pads as 1, 4, 3, 5, 2. When I update the layout, I get 1, 5, 3, 2, 4, however.Would I be OK to just ignore what Diptrace is telling me? I am already pretty much ignoring the ratlines as Diptrace does not seem to recognize the internally connected pins on the buttons. Or, is there something else I should be doing?Mark this as stupid question #1, for me, on this forum.
diptrace how can i make edge smd pads - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: March 03, 2025, 06:58:49 pm
content: I'm not sure what exactly its called, please refer to attached picture I want to make this kind of smd pads on the edge of pcb how can i do it using diptrace.

author: Neilm
author_rank: Super Contributor
timestamp: March 03, 2025, 07:25:15 pm
content: Those are known as castellated pads. I have made similar by putting plated through holes on the edge of the PCB, such that when it is routed out the hole is cut leaving half of it on the edge of the PCB. Best thing would be talk to your PCB supplier
Diptrace to Eagle PCB conversion - Page 1
Forum section: electronics / beginners

author: belzrebuth
author_rank: Frequent Contributor
timestamp: February 12, 2021, 06:39:49 pm
content: Hi all,I've got a Diptrace schematic and board file that I want to convert to Eagle format.I downloaded Diptrace for this reason alone so I know nothing about it.Exporting to Eagle seems easy but when I opened the exported .sch and .brd file (I had to rename a net in order to do that)the .brd and .sch are inconsistent (ERC) fails.I also get a ton of dimension/spacing errors when I run Eagle DRC.The files are published as working and I suspect other people have manufactured PCBs from them so they are correct.I guess that something is wrong with the conversion.Can anyone with some knowledge of both programs take a look at the attached Diptrace files?I attached a picture of the ERC errors I get in Eagle.Perhaps it's a trivial task to correct those in Diptrace?Thanks:)

author: jpanhalt
author_rank: Super Contributor
timestamp: February 12, 2021, 07:53:28 pm
content: The "close but not connected" error is from using a line draw tool instead of the draw connection tool. I am not surprised the import has those errors.In schematic editor, confirm that is the case by moving a device's symbol. The connections should drag with it. If not, then you have confirmed the cause.A messy fix may be to just dot the connections or use the make connection tool to connect. I am not sure either will work.A clean fix is to go one-by-one, delete the lines and draw a new connection. I am assuming you are familiar with Eagle. I have the legacy icons, and the connection tool icon looks like the bus tool icon, except the line thicknesses are different, and of course, the description window is different.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: February 12, 2021, 09:05:11 pm
content: I was talking more about the the first "real" errors,the red ones, the warnings are not critical..But yeah I should definitely clean the schematic up once it's synced with the .brd file.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 12, 2021, 09:30:28 pm
content: I would disagree about the significance of close but not connected. It can cause havoc when you get to the PCB phase.As for the net classes, those need to get fixed. Does your version display net properties automatically? Otherwise, you can see them with the "show/edit properties" icon ("I" in version 7.2).
DIR9001 No output - Page 1
Forum section: electronics / beginners

author: Michaelaudio
author_rank: Regular Contributor
timestamp: August 29, 2022, 07:58:07 pm
content: I have soldered together this DIR9001 circuit, but i have no output Data. I can only measure ~200mv DC on pin 10/11. The Error pin is low. Have i done something wrong in the circuit, or have i damaged the ic?

author: jwet
author_rank: Frequent Contributor
timestamp: September 29, 2022, 03:11:32 pm
content: This post is a bit old- perhaps you've worked it out but I am putting together a Toslink reciever and was looking at posts that are related. Did you get it running? What was the issue?If you haven't gotten it working- here are a few things that I noted to watch for in reading the data sheet and other notes on the web.1. The chip requires an active low reset after power is up and stable. You show this as a module port on your schematic- I assume this goes to a GPIO on something.2. The 30 pF cap on the RXin- is the recommended by the Toslink receiver? The 9001 DS says input for RX is direct.3. I'm sure you've tried different input streams. The error being low means the internal PLL is locked on I believe. Can you put in bad material and get this to go high as a sign of life4. Have you probed things with scope or logic analyzer. Those output signals being at 200 mV, could be low duty cycle digital data.Good luck and let me know your experiences if you cracked the code on this issue.

author: Michaelaudio
author_rank: Regular Contributor
timestamp: October 25, 2022, 08:01:57 am
content: I have worked on it, and it was the chip, somehow i damaged it.Now it works, but Not how i expected, sadly. The Output of the PM1753 is clipped, like almost a perfect rectangle and i dont know why. I dont know If its an issue from the DA converter but i guess so. Im not that familiar with the inner workings of a DA converter so i dont know how i get a clipped Output signal.@jwet yea, the 30pf is recommended for my jack.
Direct baseband input purpose - Page 1
Forum section: electronics / beginners

author: fonograph
author_rank: Frequent Contributor
timestamp: May 21, 2017, 11:27:40 pm
content: Keysight N9020B,N9030B and Rohde & Schwarz FSW,all three of these spectrum analyser have option called analog baseband input.I am not totally sure what it is,or what is the advantage in using it but I think its lets relatively low freqency 10hz to 40MHz go inside without going through any local oscilator intermediate freqency mixing stages directly to 16bit ADC.I compared some specs and I found it offers no advantage in terms of phase noise,or distortion.Or did I read the specs incorrectly? What is this baseband input for? In what way is it better than looking at signals with the LO mixing technique?Its R&S®FSW-B71 and R&S®FSW-B71E an BBA Analog I/Q Baseband Inputs for Keysight

author: KE5FX
author_rank: Super Contributor
timestamp: May 21, 2017, 11:34:52 pm
content: For a vector signal analyzer, you'd typically use the complex baseband input jacks to study the output of an I/Q demodulator (or the input to an I/Q modulator) in another piece of equipment.For a conventional spectrum analyzer, you might use the baseband input to look at noise on a power supply rail, or to examine an audio signal that's too low to go through the RF path. Also useful for more specialized purposes like control system work and phase noise testing.There usually will be a noise advantage to the baseband inputs, whether it's documented or not, simply because the ADC clock is quieter than the microwave LO in the front end.

author: David Hess
author_rank: Super Contributor
timestamp: May 22, 2017, 12:26:18 am
content: The specifications show a 20dB phase noise improvement when using the optional baseband inputs.

author: fonograph
author_rank: Frequent Contributor
timestamp: May 22, 2017, 01:05:22 am
content: Quote from: David Hess on May 22, 2017, 12:26:18 amwhere did you read that?

author: David Hess
author_rank: Super Contributor
timestamp: May 22, 2017, 01:38:52 am
content: Quote from: fonograph on May 22, 2017, 01:05:22 amI had to read both PDFs which include specifications.

author: fonograph
author_rank: Frequent Contributor
timestamp: May 22, 2017, 02:02:27 am
content: what PDF? give me link please

author: David Hess
author_rank: Super Contributor
timestamp: May 22, 2017, 10:13:56 am
content: I mean both specifications PDFs for the Keysight N9020B which are located here:http://www.keysight.com/en/pdx-2642774-pn-N9020B/mxa-signal-analyzer-multi-touch-10-hz-to-265-ghz?pm=rsc&nid=-32508.1163247&cc=US&lc=eng
Direct Box (DI) 2n3904 phantom powered and ground lift - Page 1
Forum section: electronics / beginners

author: Ale
author_rank: Contributor
timestamp: December 13, 2017, 01:45:22 pm
content: Hello,I'm working on a DI stage, for now I tested the central part (figure 1), without phantom and ground lift. It seems to works pretty well, I tested it with the soundcard oscilloscope I made a week ago and the results are in the figure 2. In the figure 3 I added the phantom power I found in a Jensen's DI schematic, I don't really know if the ground lift part will work though.What do you think?
Directly powering this cam - Page 1
Forum section: electronics / beginners

author: geebee
author_rank: Newbie
timestamp: June 01, 2025, 10:06:17 am
content: Hi everyone.I have an old reolink CCTV camera that will not charge so I would like to bypass the battery charging circuit and power out directly from a micro usb cable.I believe the two PCB's in the pictures are for the battery charging process?How can I get power to the camera ?

author: geebee
author_rank: Newbie
timestamp: June 02, 2025, 08:53:18 am
content: Many views but no replies, did I ask this question incorrectly or not provide enough information ?

author: lakis70
author_rank: Contributor
timestamp: June 02, 2025, 09:26:11 pm
content: not specific for your problem but you need to replace the battery with a power supply with the same voltage, forget the charger.If it is lithium battery use a trial voltage about the middle in the range between full and empty battery, care the polarity, and try. If it doesnt work because it doesnt recognise the battery then power the bms witth your supply.Maybe the small pcb is the bms, foto your battery.

author: Bud
author_rank: Super Contributor
timestamp: June 02, 2025, 10:34:42 pm
content: Quote from: geebee on June 02, 2025, 08:53:18 amYes you asked question incorrectly. If you asked "Does anyone know how I can get power to the camera?", then you'd understand why there were no replies.

author: abeyer
author_rank: Frequent Contributor
timestamp: June 03, 2025, 02:35:02 am
content: That looks like an i2c charge controller, so the host may expect to communicate with it. Bypassing it completely could prevent the device from working at all. I'd probably first try to look at that i2c bus and see if/what fault the controller is reporting when it fails to charge.
Disable LDO from microcontroller - Page 1
Forum section: electronics / beginners

author: metRo_
author_rank: Regular Contributor
timestamp: August 24, 2017, 11:04:12 am
content: Hello,I'm going to use aTPS706LDO on my circuit:Could I use the EN input to enable it from a pushbutton and then disable it from the uC as I designed? +BATT will vary from 6.5V to 4V.EDIT:I just figured out that as soon as I shutdown the LDO the microcrontroller IO will be floating and the LDO will turn on againEDIT2:Do you think that way it will work?

author: Ian.M
author_rank: Super Contributor
timestamp: August 24, 2017, 11:44:06 am
content: Yes, that can work, but when the button is pressed, you could get up to 260uA flowing through your MCU's input protection diode into the 3.3V rail. That could cause problems for the MCU. A Schottky clamp from the pin to the 3.3V rail would be advisable, which would also help satisfy the 0.4V max EN pin low threshold when the regulator output is disabled.It gets more complex if you also want to be able to detect if the button is pressed while the MCU is running, and even more complex if you want to do that without using an extra I/O pin.

author: metRo_
author_rank: Regular Contributor
timestamp: August 24, 2017, 12:05:00 pm
content: Thank you!Quote from: Ian.M on August 24, 2017, 11:44:06 amI don't need to detect if the button is pressed.Quote from: Ian.M on August 24, 2017, 11:44:06 amWhen the regulator is disabled the microcontroller is also disabled, how could it not satisfy the 0.4V?

author: Ian.M
author_rank: Super Contributor
timestamp: August 24, 2017, 01:05:09 pm
content: It only takes a few uA to develop 0.4V across a silicon PN junction of the area of a typical MCU protection diode. For comparison, a 1N4148 rated at 200mA, will need about 20uA If to develop that Vf. If due to contamination the leakage resistance across the switch drops below 3.5Meg it will no longer meet the EN low threshold.You are also going to have problems holding the pin low enough as the 3.3V rail drops and the MCU resets - you'll probably need to add a capacitor from the 3.3V rail to the pin end of the 10K resistor with a 100R resistor between that point and the pin.

author: StillTrying
author_rank: Super Contributor
timestamp: August 24, 2017, 03:04:11 pm
content: The TPS706's EN switching levels seem to be 0.9V for a guaranteed On, and 0.4V for a guaranteed Off, and the current only 300nA, so I can't see the problem with the 10k and 2 Si diodes, maybe a 10 to 22nF across the 10k so the EN state doesn't change while the uP does its power up and down.
Disc capacitor polarity - Page 1
Forum section: electronics / beginners

author: iamnothim
author_rank: Regular Contributor
timestamp: March 08, 2013, 06:32:19 am
content: Hello,In my tube tester project I'm trying to make the schematic jibe with the photos I took during tear down. In the process I did not note the polarity of the disc capacitors.Can anyone help with the two photos?Many thanks.

author: amyk
author_rank: Super Contributor
timestamp: March 08, 2013, 06:45:47 am
content: Ceramic capacitors are unpolarised.

author: SeanB
author_rank: Super Contributor
timestamp: March 08, 2013, 03:07:47 pm
content: Ceramic and film capacitors are not polarised, though you will find on a lot of film units a black band at one end. This is to indicate ther end that is connected to the outer side foil, and you normally connect this end to ground if you are using it for decoupling, as this reduces the RFI that the capacitor can emit from the outer surface ( only really important if you have it right next to a valve grid with a very high impedance, otherwise it makes no difference) in certain circumstances.Electrolytics on the other hand generally are polarised, unless you get unpolarised ones.
disconnect battery when external voltage supply is connected - Page 1
Forum section: electronics / beginners

author: kolonelkadat
author_rank: Regular Contributor
timestamp: October 07, 2015, 02:21:21 am
content: Im planning on making a small device. It will be powered by a cr2012 coincell battery. I would like for it to have optional usb connectivity as well, but I feel like in order to do that, the battery needs to be protected to prevent bad things from happening.with a dc jack this is obviously trivial. If it were a more powerful battery, id be happy enough with just a diode. Im thinking a transistor would do the business, but im not sure.any advice?

author: Throy
author_rank: Regular Contributor
timestamp: October 07, 2015, 12:11:38 pm
content: You could use a p channel mosfet in a reverse polarity protection configuration.Drain: +BatterySource: +VccGate: GND

author: Paul Price
author_rank: Super Contributor
timestamp: October 07, 2015, 12:16:18 pm
content: A single schottkey diode in series with the battery plus terminal is all that is required.

author: Jeroen3
author_rank: Super Contributor
timestamp: October 07, 2015, 12:24:07 pm
content: You can get pretty low forward voltage diodes nowadays. But with low forward voltages comes high reverse leakage.Batteries can handle a small amount of charging, but if you have batteries under this reverse bias for a long time they might leak.

author: Paul Price
author_rank: Super Contributor
timestamp: October 07, 2015, 12:32:52 pm
content: The reverse leakage current of a schottky diode will not surpass any battery self-discharge effect over time.To have any chance of effect at all, the USB connection would need to be maintained on and for many years at higher than normal use temperatures.It is almost impossible to get a button cell lithium battery to be damaged or "explode" with only a few micro-amps of charge current.
disconnected solar panel: heats up? - Page 1
Forum section: electronics / beginners

author: Erwin Ried
author_rank: Regular Contributor
timestamp: August 20, 2024, 08:24:14 am
content: Hi, I have a basic electric question, does a solar panel that is not connected to anything (like a power bank) heats up more than one that is being used?because what happens with the potential energy otherwise?

author: Zero999
author_rank: Super Contributor
timestamp: August 20, 2024, 08:48:43 am
content: Yes, because the radiation hiting it is all converted to heat.
Discord server for audio amp dac nerds? - Page 1
Forum section: electronics / beginners

author: uul
author_rank: Newbie
timestamp: February 17, 2021, 10:00:26 pm
content: Hi thereMy intention of starting a discord server was to learn more about audio electronics. Anybody here who wanna join and spread some knowledge or maybe learn something from other joiners?It is very new channel :-)I am starting a cmoy headphone amp build and will be posting my first projekt.........if this thread is not permitted I apologize on beforehand.I am very open to suggestion about groups where I can learn about audio amps discord or another place :-)

author: uul
author_rank: Newbie
timestamp: February 21, 2021, 05:23:51 pm
content: Anybody who wanna join my newly started discord are welcome. Its called SoundWorkshop with audio electronics in mind. It can be anything music related. Instruments, DAC, AMPS etcInvitation link:https://discord.gg/P3yje4K6Az
Discount code for HakkoUSA - Page 1
Forum section: electronics / beginners

author: docsalr
author_rank: Contributor
timestamp: May 24, 2024, 03:13:03 am
content: Hello,New member here. Does EEVblog have a special discount code for hakkousa?Thanks in advance!

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 24, 2024, 02:02:53 pm
content: I do not think they have.

author: donlisms
author_rank: Frequent Contributor
timestamp: May 25, 2024, 02:39:11 am
content: In my view, they're already quite affordable for the quality.

author: Shock
author_rank: Super Contributor
timestamp: May 25, 2024, 03:12:01 am
content: There is a Tequipment discount code (they are Hakko distributors).https://www.eevblog.com/forum/testgear/eevblog-members-discount-at-tequipment/

author: docsalr
author_rank: Contributor
timestamp: May 25, 2024, 10:28:47 pm
content: Thank you all for your responses. I guess I will wait till August 7th for their annual customer appreciation sale.
Discovering and Experimenting with Electronics - Page 1
Forum section: electronics / beginners

author: Mprentice1
author_rank: Newbie
timestamp: October 11, 2012, 03:58:27 pm
content: Having just started what I hope will be 6 years at University in the UK, finishing with a masters, I have started my own blog to document projects that I undertake and general playing around.Starting off with arduino but I hope to expand into more platforms as my competence expands.Please do have a look, I'll be trying to add a new post at least once a week. =]http://mpeleceng.wordpress.com/
Discovery Board with No VCP how to interact with PC - Page 1
Forum section: electronics / beginners

author: rakeshm55
author_rank: Regular Contributor
timestamp: November 03, 2017, 10:18:51 am
content: Hi,Recently i procured STM32 Disco board STM32F411(http://www.st.com/en/microcontrollers/stm32f411.html?querycriteria=productId=LN1877) .....I am able to load simple codes and do debugging.....Board has a ST-LINK/V2 as the debug link ..... with no VCP(Virtual COM Port).... In this case how can interact with PC .... My aim is to use python script to interact with the board...Is there any means of using SWD ??....Please suggest...

author: rstofer
author_rank: Super Contributor
timestamp: November 03, 2017, 01:54:41 pm
content: Direct your serial IO through one of the UARTs that is connected to pins. Then get a USB->Serial cable likehttps://www.amazon.com/KEDSUM®-CP2102-Module-Download-Converter/dp/B009T2ZR6W/ref=sr_1_6

author: mbless
author_rank: Regular Contributor
timestamp: November 03, 2017, 08:51:36 pm
content: Quote from: rakeshm55 on November 03, 2017, 10:18:51 amYou have several options:1. You can send data through the SWD Debug channel with semihosting to your IDE. Keep in mind you have to be debugging, though, otherwise semihosting will lock up the MCU.2. Get a usb serial cable like rstofer said and use one of the STM's UART.3. If you have thisDiscoverythen there is another USB port that is connected to the STM's USB OTG peripheral. You then add STM's USB VCP middlewares so the MCU shows up as com port with which you can communicate.
Discrepancy between a circuit diagram and a photo of the hardware., do - Page 1
Forum section: electronics / beginners

author: makerman
author_rank: Regular Contributor
timestamp: February 16, 2019, 02:59:52 pm
content: Hi, there's a small circuit i want to make, i have the diagram but i also have a photo of it and in the photo there seems to be an extra resistor, what might it be for?The circuit is for a mega2560 to drive a pulse motor, a hall sensor is used to get frequency and the circuit pulses the coil that drives the motor.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 16, 2019, 03:35:34 pm
content: It's very near to pin 1 of the opto coupler, and therefore probably to limit the current through the Opto's LED.

author: makerman
author_rank: Regular Contributor
timestamp: February 16, 2019, 03:58:08 pm
content: Thanks Doctor, are you referring to the lower resistor in the photo ?

author: makerman
author_rank: Regular Contributor
timestamp: February 16, 2019, 04:07:01 pm
content: Oh no i see now, the lower one is across opto and diode.

author: rstofer
author_rank: Super Contributor
timestamp: February 18, 2019, 04:02:02 pm
content: Hopefully, it is series with the LED portion of the optocoupler. The schematic seems to indicate that no such resistor exists, probably with the thought it is located elsewhere. Nevertheless, the resistor is necessary. Probably a low value, less than 1K I would guess.The lower resistor in the photo is clearly 20k which is the value of R1 in the schematic.
Discrete Amplifiers and Linearity - Page 1
Forum section: electronics / beginners

author: krivx
author_rank: Frequent Contributor
timestamp: March 18, 2014, 02:23:13 pm
content: I'm trying fill some of my knowledge gaps. I've done bipolar and FET circuits but generally when linearity was important (audio, instrumentation etc) I used opamps. I've never had a great grasp on designing for low-distortion with discrete parts (apart from "add some feedback somewhere"). Are there any good references for this? Books are fine, ones with old editions I can get cheap are even better.

author: krivx
author_rank: Frequent Contributor
timestamp: March 19, 2014, 10:42:41 am
content: No one?

author: nanofrog
author_rank: Super Contributor
timestamp: March 19, 2014, 03:19:22 pm
content: Here's a few books that might be of interest:Designing Audio Power AmplifiersHigh-Power Audio Amplifier Construction ManualThe Audiophile's Project Sourcebook: 80 High-Performance Audio Electronics ProjectsAnother good source (free), would be papers/articles by Nelson Pass (here, andhere).

author: Marco
author_rank: Super Contributor
timestamp: March 19, 2014, 03:38:58 pm
content: Audiophiles and linearity ... that seems a contradiction in terms.

author: krivx
author_rank: Frequent Contributor
timestamp: March 19, 2014, 04:24:24 pm
content: Quote from: nanofrog on March 19, 2014, 03:19:22 pmThanks, I'll take a look through these.I've also had Paul Gray's "Analysis and Design of Analog Integrated Circuits" recommended, I may look into this first as there are lots of used copies available cheap.

author: planet12
author_rank: Regular Contributor
timestamp: March 19, 2014, 08:55:58 pm
content: To add to the book list, Douglas Self's Audio Power Amplifier Design:http://www.amazon.com/Audio-Power-Amplifier-Design-Douglas/dp/0240526139

author: nanofrog
author_rank: Super Contributor
timestamp: March 19, 2014, 09:07:41 pm
content: Quote from: planet12 on March 19, 2014, 08:55:58 pmGah. Knew I missed one.
Discrete auto zero op amp where to put sampled offset voltage? - Page 1
Forum section: electronics / beginners

author: Victorman222
author_rank: Regular Contributor
timestamp: September 21, 2022, 07:20:02 pm
content: I am trying to build discrete auto zero op amp using op amps and cmos switch ic. I plan to implement this schematic.What pin(s) of OP07 like op amp(OP37) would I have to connect the offset voltage to? Are the inputs high Z?I have set up some things on the breadboard but I'm afraid of breaking the op amps.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 21, 2022, 07:48:17 pm
content: With some op-amps one can use the offset adjustment pins as auxiliary input. The details (e.g. maximum range and polarity) depend on the OP-amp used.P.S. LT's An21 has an example on how to combine am LT1028 with an AZ op, that could give an example on how to shift the offset.

author: magic
author_rank: Super Contributor
timestamp: September 22, 2022, 02:14:50 pm
content: Quote from: Victorman222 on September 21, 2022, 07:20:02 pmNope, input impedance of offset trim pins is hundreds or thousands ohms, so the approach of holding them constant with C2 wouldn't work well. You could insert a JFET/CMOS buffer between C2 and the OP37 and use a fairly large resistor (like in AN21) to minimize the influence of buffer's noise.Or simply use the AN21 technique, but then it isn't a discrete auto-zero anymore, everything is hidden in the 1052 chip.
Discrete element synchronous charge pump doubler - Page 1
Forum section: electronics / beginners

author: obuone
author_rank: Contributor
timestamp: August 04, 2021, 03:57:09 am
content: Hello everyone,Currently working on a small project making a charge pump doubler (2xVin). Instead of the standard doubler using clock source 2 diodes and two capacitors, I am trying to replace the two diodes with two P-channel MOSFETS and bootstrapping circuit achieving synchronous rectification.Using LTSpice I made both standard and synchronous version of the charge pump. Vcc is 10V, the clock frequency 10 kHz and 1k resistor is used to load the circuit with 20 mA. For now i am using voltage source as the clock source but in reality will switch it with 555 timer circuit.The transistor circuit has 0.5 V lower output voltage, than the diode circuit. Even if the diodes used are Schottky, shouldn't the transistor circuit have higher efficiency and therefore higher voltage? Do you have any ideas of improving the transistor circuit? i would appreciate any help.

author: Whales
author_rank: Super Contributor
timestamp: August 04, 2021, 09:15:40 am
content: Are your top P-channel mosfets turning on fully? Might be worth graphing Vgs of each.If they're not turning on then they will act similarly to silicon diodes (due to the "intrinsic body diodes" in each mosfet, drawn in red).EDIT: the gate of M4 can only be pulled low once, then C3 is charged and there is no way of it discharging ever again.EDIT2: The gates of M3 and M4 can never be pulled low, D1 and D4 keep them high permanently. This means M3 and M4 never turn on.

author: Terry Bites
author_rank: Super Contributor
timestamp: August 04, 2021, 11:42:42 am
content: The kind of inegrated circuit doubler that you are trying to implement uses very small geometry very low threshold low gate charge devcies. They also use body biasing schemes Its going to be hard to replcate in discrete fets.Have you considered a Dickson?Happy readinghttps://www.google.co.uk/url?sa=i&url=https%3A%2F%2Fwww.mdpi.com%2F2079-9292%2F8%2F5%2F480%2Fpdf&psig=AOvVaw1qcz4CNdYgQdxm8bfQs6lC&ust=1628163138352000&source=images&cd=vfe&ved=0CAgQjhxqFwoTCKiEwL6il_ICFQAAAAAdAAAAABAX
discrete JFET logic - Page 1
Forum section: electronics / beginners

author: Dan Moos
author_rank: Frequent Contributor
timestamp: December 09, 2016, 05:01:09 pm
content: Just for fun, I've been trying to make a discrete JFET inverter (NOT gate).I know I can just take a simple common source amplifier and do it that way.I just want to make sure I understand one particular thing. I think I do, but just looking for confirmation.If I have a 5 volt single sided supply, I won't be able to make a textbook complimentary inverter out of JFETs, right? And specifically it won't work because all JFETs are depletion mode devices, thus I will never be able to turn the n-channel JFET off. Is this correct?

author: Audioguru
author_rank: Super Contributor
timestamp: December 09, 2016, 05:48:59 pm
content: Both Jfets will not be able to be turned off.
Discrete linear audio power amplifier schematic KENWOOD KA-7300 - Page 1
Forum section: electronics / beginners

author: strawberry
author_rank: Super Contributor
timestamp: May 20, 2017, 07:22:42 pm
content: Is this good amplifier schematic?

author: tatus1969
author_rank: Super Contributor
timestamp: May 20, 2017, 09:26:00 pm
content: its a classic design from 1990s or earlier, served well until it died and was replaced by an UcD amp.

author: BrianHG
author_rank: Super Contributor
timestamp: May 20, 2017, 10:49:48 pm
content: What are your objectives?The amp schematic you provided should work fine.Do you want something just to copy?How much power do you need?What are your skills in making such a circuit? A +/- 60v, or 120v total supply can do some damage and possible harm if you are not careful.Do you have just a volt meter, or, do you have access to a scope?What kind of sound quality are you expecting?This amp still has an op-amp IC in it, so, it's not really considered all discrete.

author: strawberry
author_rank: Super Contributor
timestamp: July 24, 2017, 01:47:56 pm
content: To replace/repair KENWOOD KA-7200 power amplifiersupply rails +/-50VIs it necessary to equalize currents between both differential amplifiers?
discrete op amp input voltage range - Page 1
Forum section: electronics / beginners

author: sahko123
author_rank: Frequent Contributor
timestamp: July 05, 2020, 06:52:43 pm
content: Here is the circuit for a discrete opamp for error compensation in a class a power stage. The goal is to have the power amplifier to operate down at dc and up to beyond 20khz.Can anyone tell me how can i get it take to negative voltage swings

author: Kleinstein
author_rank: Super Contributor
timestamp: July 05, 2020, 07:15:05 pm
content: The circuit show is just a first input stage. The input voltage can already go to some VEE+1 V as the lower limit. So just make VEE negative enough.The output voltage range is however quite limited. Usually there is more following so that the output has a higher voltage swing and lower output impedance.

author: Benta
author_rank: Super Contributor
timestamp: July 05, 2020, 07:18:50 pm
content: Quote from: Kleinstein on July 05, 2020, 07:15:05 pmI don't see ANY output voltage. Presumably between Q2 and Q5, but who knows?

author: sahko123
author_rank: Frequent Contributor
timestamp: July 05, 2020, 07:21:50 pm
content: sorry for that but yes thats where im taking output from

author: David Hess
author_rank: Super Contributor
timestamp: July 06, 2020, 11:16:52 am
content: Quote from: sahko123 on July 05, 2020, 06:52:43 pmDo you mean more negative than Vee? Do you mean negative down to Vee or slightly lower?If you operate the operational amplifier in inverting mode, then the input voltage can be higher or lower than the supply voltages.
Discrete voltage regulator with two transistors. - Page 1
Forum section: electronics / beginners

author: Mint.
author_rank: Frequent Contributor
timestamp: March 03, 2012, 06:03:43 am
content: I have trouble understanding this circuit (Damn transistors). If I am correct in understanding this, we start from the unregulated voltage, then it goes to r1 to activate the transistor q1 and we get a flow of current, then it goes to the 1k and comes into q2 which from the collector takes away a certain amount of current from the base of q1 to lower the voltage passing. What I don't understand is why there has to be r2 and three diodes.

author: Rerouter
author_rank: Super Contributor
timestamp: March 03, 2012, 06:18:25 am
content: just went and simulated that particular one and it seems the diodes and resistor are used to hold the adjustable voltage above 3 diode voltage drops, nothing more, infact removing the diodes allows adjustment down to 1 transistor drop of about 700mV,here is the simulation if you want to play around with it.http://tinyurl.com/7ppe4l2

author: Mint.
author_rank: Frequent Contributor
timestamp: March 04, 2012, 02:04:18 am
content: Thanks Rerouter!

author: johnmx
author_rank: Frequent Contributor
timestamp: March 04, 2012, 12:38:57 pm
content: Usually the error amplifier in a series voltage regulator is an opamp. But in its simplest way it can be a single transistor. In the present circuit Q2 is the error amplifier.The voltage applied to Q2 emitter terminal is more or less constant (Vref) with a value of 3x diode voltage drop. And the voltage at its base is a sample of the output voltage. So, if the output voltage raises the base-emitter voltage of Q2 also raises which increases the Q2’s collector current. This decreases the current from the base of Q1 which forces the output voltage to drop. In a similar way, if Vout drops then Q2’s Vbe also drops and the collector current decreases. Then Q1’s base current increases and the output voltage raises. This negative feedback behavior keeps the output voltage constant.If P1is represented by two resistors R3(top portion) and R4(bottom portion), then the output voltage is given by:Vout= (R3+R4)/R4* (Vref+ VbeQ2)

author: tecman
author_rank: Frequent Contributor
timestamp: March 04, 2012, 04:17:29 pm
content: The three diodes provide a reference voltage for the regulator. Unfortunately the diodes have a temperature coefficient of 2.2mv/deg C. One diode is offset by Q2 BE voltage, but you still end up with 4.4 mv/deg C drift in the voltage. You can substitute the three diodes for a zener for better stability. A 3.3 v zener has a tempco close to the Vbe of Q2 and will have even better temp stability.paul