hybridfree/eevblog-posts huggingface dataset:
Zener voltage of automotive alternator diodes - Page 1
Forum section: electronics / projects

author: Circlotron
author_rank: Super Contributor
timestamp: July 26, 2022, 02:10:09 am
content: I understand that the rectifier diodes in car alternators are made to avalanche at something like several tens of volts so they can protects themselves against transients in an automotive electrical environment. Does anyone have any figures on what this avalanche voltage might be? I want to see how much voltage I can get out of an alternator (no particular application, just messing around) but don’t want to cook the diodes if they begin to reverse conduct unexpectedly.

author: bob91343
author_rank: Super Contributor
timestamp: July 26, 2022, 03:45:28 am
content: Measure a few.

author: Psi
author_rank: Super Contributor
timestamp: July 26, 2022, 08:56:10 am
content: Usually automotive stuff is rated to handle double the voltage for 1 hour without releasing the magic smoke.So you should get at least 24V out of it before the diodes kick in.but YMMV

author: Mazo
author_rank: Regular Contributor
timestamp: July 26, 2022, 09:58:42 am
content: I remember voltages in the 30-40V range.YMMV.

author: SeanB
author_rank: Super Contributor
timestamp: July 26, 2022, 11:26:04 am
content: Yes, somewhere between 30 and 60V, depending on just how the process was controlled. Some will do 100V with little issue, though when they do go at that voltage they tend to pop. If you want more reliability simply replace with external 3 phase rectifier block.

author: Psi
author_rank: Super Contributor
timestamp: July 26, 2022, 09:42:33 pm
content: Can also use a 24V truck alternator if you want more output voltage headroom
Zeners Power Dissipation - Page 1
Forum section: electronics / projects

author: edmundopt
author_rank: Regular Contributor
timestamp: February 03, 2014, 08:11:55 pm
content: Hello again,Maybe if I study more I will find the answer, but here is the question:Why does the 15v zener diode dissipates more power then the 12v ?Because Pzener = (Vin - Vzener) * Izener, so I think in practice the 12v zener will dissipate more power and clear the spike faster.What I am missing ?If you are not familiar with this circuit, check BIAS POWER Application Note AN-126The zip files contains the simulation file from LTSpice 4.19u

author: dannyf
author_rank: Super Contributor
timestamp: February 03, 2014, 08:44:21 pm
content: QuoteReally?

author: c4757p
author_rank: Super Contributor
timestamp: February 03, 2014, 09:14:02 pm
content: Quote from: edmundopt on February 03, 2014, 08:11:55 pmPower equations aside, this should be intuitive. An electron has more energy at a higher voltage, so electrons losing more voltage are going to drop off more energy as heat into whatever device they happen to go through at the time.Now, the current flowing is going to be the same in both cases. An inductor's current cannot change instantaneously. So, at the moment the inductor is switched off, the exact current that was flowing from the power supply through the coil is now diverted through the diode, and tapers off as all the energy that was stored in the magnetic field is dissipated into the diode.So, which one involves the same number of electrons losing more energy?One thing to note is that because the amount of energy stored in the coil is fixed (determined by the current and the inductance) the amount of energy (heat) dissipated in the diode will be equal. One will just dissipate it faster.

author: edmundopt
author_rank: Regular Contributor
timestamp: February 03, 2014, 10:14:39 pm
content: UUUUpppssss....Wrong formulas, sorry guys, really lame question... I was looking in the wrong direction..Anyway, ignoring the schottky diode , the math is :The current flowing through the circuit is :I = (Vspike-Vzener)/Rand that current is dissipated in the zener diode(like all diodes) as a factor of the voltage drop:P = Vzener * ISo, the performance will increase using the highest possible zener diode.The highest possible value is near the transistor collector-emitter breakdown voltage.Ok, I'm in the right direction now. Thanks

author: dannyf
author_rank: Super Contributor
timestamp: February 03, 2014, 10:16:55 pm
content: QuoteDepending on what you meant by "performance".

author: edmundopt
author_rank: Regular Contributor
timestamp: February 03, 2014, 10:27:54 pm
content: I mean dissipating the coil energy faster so that the relay can be reliable switched again.
Zenith Z-Note 425 Lnc Battery Charging Issue - Page 1
Forum section: electronics / projects

author: FRParker
author_rank: Newbie
timestamp: June 26, 2021, 02:26:29 am
content: My friends gave me the laptop model mentioned above and said it needed a look over. It didn't have a charger, so I had to order one (output requirements are 15.5v @ 1.3A). I found that the CMOS battery had long since corroded, affecting five traces on the underside of the motherboard (which I have since bridged with wire, checking to make sure there were no shorts created while I was working on it).This is not the main issue though. I removed the old CMOS battery, and have ordered a new one, which is in the mail. The charger came today, so I decided to do a little open case test run to see what would happen. I pressed the power button, and nothing happened. The HDD didn't spin up, I didn't even see a flicker on the screen. I left the charger plugged in, only to come back later and see that the battery charging light turned from amber to red.I am 99.9% sure this means there is a problem, but with what, I don't know. Could it be that the main battery pack is dead, or is this related to the absence of a CMOS battery?Thanks,Forrest
Zeo Personal Sleep Coach - Page 1
Forum section: electronics / projects

author: karthik4096
author_rank: Newbie
timestamp: April 27, 2010, 08:04:04 pm
content: http://www.myzeo.com/anyone tell me how it detects deep sleep.

author: DJPhil
author_rank: Frequent Contributor
timestamp: April 27, 2010, 08:51:10 pm
content: I don't know for sure, but I'll guess.The EEG probe picks up low voltage, low frequency oscillations which are amplified, converted to digital, and fed into a microcontroller.Standards have been agreed upon that define sleep stagesby characteristic changes in these oscillations, and the microcontroller will compare what it's sensing against a reference to determine sleep stage.From there it's standard microcontroller stuff (actually, the whole thing is pretty standard). The uC will handle datalogging, display, alarms, and other input as desired.

author: MTron
author_rank: Regular Contributor
timestamp: May 04, 2010, 12:34:50 pm
content: Pretty much hit it right on the mark! Thats exactly how it worksThere are a few characteristic waveform shapes that one must look for that define deep sleep. These were defined experimentally by examining a number of people while in different sleep states to define a general baseline average.Wikipedia has a great page if you want to know morehttp://en.wikipedia.org/wiki/Electroencephalography
ZephPaste: Six month shelf life without refrigeration?? - Page 1
Forum section: electronics / projects

author: rs20
author_rank: Super Contributor
timestamp: November 01, 2013, 01:08:16 am
content: Does anyone have experience with this stuff:http://www.zeph.com/zephpaste.htm"In-Stock! Always Fresh! Six Month Shelf-Life Without Refrigeration. Formulated Specifically for the Bench."Sounds like a fantastic product if everything they say is true?

author: vtkkorhanjoh
author_rank: Contributor
timestamp: November 01, 2013, 09:42:27 pm
content: Not sure what to say, but for 15 bucks you can't go wrong! The only real way to find out wether it is bullshit or not is to try it! Personally, i think 6 months no refridgeration solder paste sounds a bit suspicious, but you never know...

author: Corporate666
author_rank: Unknown
timestamp: November 01, 2013, 11:13:25 pm
content: If you buy some, can you let us know how it works?I use Kester R276 with fantastic results, and truthfully, I don't refrigerate it. We use it for R&D/proto/rework. I have tubes a year old or more that work perfectly when we open and use them.I've been burned with bad pastes before... bought some filled syringes on eBay that someone was obviously just filling from a larger container, and they were full of air bubbles, and didn't dispense worth shit. And have had pastes that you need to reflow within an hour or they just won't flow correctly.So I'm real hesitant to try anything new unless someone can vouch for it.
ZERO Cross MOC i.e. 3061 with BT139 With AC Inductive Loads - Page 1
Forum section: electronics / projects

author: Abubakar
author_rank: Newbie
timestamp: March 30, 2018, 11:30:53 pm
content: Dear All,I want to know, Is the subjected configuration good to trigger AC Inductive loads ?I have heard that Zero Cross MOC are not supposed to work properly with inductive loads.Thanks and Regards

author: rstofer
author_rank: Super Contributor
timestamp: March 31, 2018, 05:34:01 pm
content: Interesting topic!https://www.fairchildsemi.com/application-notes/AN/AN-3004.pdfYes, inductive loads require some consideration. It is discussed in the paper linked above.

author: Abubakar
author_rank: Newbie
timestamp: March 31, 2018, 09:27:38 pm
content: Thanks for the link,So after reading it, I can assume that I can use subjected configuration easily on low inductive loads i.e. <2KVA?Regards

author: djacobow
author_rank: Super Contributor
timestamp: April 01, 2018, 05:15:01 pm
content: The app note clearly indicates that if you want to switch very inductive loads you may need a snubber, and that determining the correct RC values for the snubber depends on the load and requires some experimentation. You can also buy special "snubberless" triacs that (may) solve your problem (if you have a problem) without a snubber.Basically ... it depends.You will know if you need a snubber if your triac won't turn off.One interesting result of having a snubber network is that the load will always receive some power through the RC network. For small loads, it can even be enough to operate. Because of this, you really can't design just one snubber network that will manage any load.

author: Abubakar
author_rank: Newbie
timestamp: April 02, 2018, 05:14:07 am
content: Dear,I have heard that Zero Cross Moc with BT139 causes only negative cycle to pass not the positive. Is this true? (for inductive loads)if Not, Then I ha e no other question.
Zero Crossing implementation ideas - Page 1
Forum section: electronics / projects

author: generic_username
author_rank: Regular Contributor
timestamp: October 22, 2019, 11:05:01 am
content: Hello everyone,I have a sensor which is disturbed by my mains earth frequency lucky me I have a sync Pin to sync the sensor with 50/60 Hz So I tried that to sync the sensor IC with a zero crossing circuit on a rather crude setup and it worked way better than anticipated. But on my actual circuit I only have1 AC line to switch a Triac availablehttps://www.onsemi.com/pub/Collateral/FODM3083-D.pdfat page 8.So the ZC circuit I used can't be implemented, and I doubt I can get L and N of mains earth on my PCB due to various resons.One Solution would be if I could have a zero crossing triac driver which would have an output for when the ZC is- I couldn't find any so far that would have this ability (and I doubt I will find one)I have found a workaround for this probelm, but I'm not really happy with it.I probed my analog signal going to my sensor IC and noticed that the AC line noise is really huge (around 1V PP ) when the sensor IC is disconected/ turned off. So I used this signal and amplified and filterd it and to my surprise I coud actually do a zero crossing with that signal. I only can use this signal to get the sync started with a µC and then disconnect my circuit and connect the measurement IC but that would be feasable...I think.So I have this solution which worked in a quick and dirty test but I doubt this will really work all the time.So I'm a bit of a loss right now how to make that work other than this method?Any Ideas would be welcome.cheers.

author: Ian.M
author_rank: Super Contributor
timestamp: October 22, 2019, 11:52:32 am
content: If your board 0V is grounded via its PSU, tap the AC line via a class Y capacitor (so it doesn't fail any DC Hi-Pot insulation tests) and a chain of high value series resistors to keep the current under 75uA RMS (10% max permitted leakage current for most applications), Zener clamp it and feed a comparator input to get a line frequency reference you can PLL your sampling to. You need a resistor chain rather than one resistor so it can withstand >1KV fast transients on the mains supply. The capacitor impedance at your line frequency should be several orders of magnitude below that of the resistor chain for negligible phase shift.If your board 0V is floating, consider a conventional optoisolated zero crossing circuit across the TRIAC + an isolated current sensor in series with it. One or the other should always give a result if the load remains connected. You may need to compensate for any phase shift of the current.

author: generic_username
author_rank: Regular Contributor
timestamp: October 22, 2019, 12:36:55 pm
content: Thanks a lotthe class Y cap sadly won't be possible as I have a really tight height restriction, but the current Sensor may be worth a shot
Zero ohm resistor wattage - Page 1
Forum section: electronics / projects

author: AlfBaz
author_rank: Super Contributor
timestamp: December 27, 2012, 03:47:43 pm
content: I want to use a zero ohm SMD resistor, its rated at 0.1W. I'd like to work out the max current but I^2*R isn't going to do it and +-1% tolerance of 0ohms to get the deviation is somewaht mute also.Unfortunately thedata sheetis a generic one for the model line, so not much help there iether.Any ideas?

author: c4757p
author_rank: Super Contributor
timestamp: December 27, 2012, 03:51:09 pm
content: Well, what is the real resistance? It ain't zero...

author: AlfBaz
author_rank: Super Contributor
timestamp: December 27, 2012, 03:54:08 pm
content: Quote from: c4757p on December 27, 2012, 03:51:09 pmGood question. Haven't ordered it yet and how do you work out the tolerance of 0 ohms

author: SeanB
author_rank: Super Contributor
timestamp: December 27, 2012, 04:15:56 pm
content: Normally it will be between 50 to 200 milliohms per unit, all it is is a metallised film with a set of ends. Not really a high power unit, use the ratings for the lowest value resistor in the range.

author: AlfBaz
author_rank: Super Contributor
timestamp: December 27, 2012, 04:22:42 pm
content: Quote from: SeanB on December 27, 2012, 04:15:56 pmof course...Thank you

author: SeanB
author_rank: Super Contributor
timestamp: December 27, 2012, 05:06:50 pm
content: You are not alone, i have seen many nominal zero ohm links that have been cooked by the current flowing through them.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: December 27, 2012, 07:40:02 pm
content: The real datasheet should mention a maximum current.This Royalohm datsheet specifies a max working current of 2amps for a 0805 (1/10W) package.As you can see its handles as a special case; working current instead of voltage and no tolerance specified.
Zero power voltage limiter for logic suggestions... - Page 1
Forum section: electronics / projects

author: Boscoe
author_rank: Frequent Contributor
timestamp: May 06, 2021, 12:22:05 pm
content: Hi all,I'm a little stuck on creating a simple, low cost, very low power voltage limited for the input to a logic gate.The gate is on a 3.3V rail and doesn't like anything above 3.6V. I have a signal from a battery management system that is VBAT + 6V where VBAT is two lithium ion cells (8.4V maximum) when logic 1 and 0V for logic 0. I need to interface this with the gate however struggling to do it in jus ta couple of parts with current consumption less than uA. Naturally I went for the zener + resistor option but keeping the voltage above the gate threshold throughout the whole VBAT range is tricky while maintain low power. Are there any gates or buffers that can tolerate high input voltages?ThanksBoscoe

author: ledtester
author_rank: Super Contributor
timestamp: May 06, 2021, 10:21:13 pm
content: How about something like this:Choose the MOSFET to be able to withstand a V_GS of the 8.4+6 V signal. R will have to be in the megaohms to make the quiescent current in the microamps, but it might work for you.

author: langwadt
author_rank: Super Contributor
timestamp: May 07, 2021, 12:07:36 am
content: Quote from: Boscoe on May 06, 2021, 12:22:05 pmif the current is limited to 1uA I doubt the logic gate has any problems input voltages above 3.6V

author: BrianHG
author_rank: Super Contributor
timestamp: May 07, 2021, 12:23:17 am
content: Most CMOS logic gates have input protection diodes. If your IC does, you can just use a series resistor, like a 10 or more megaohm, from battery to input. Though, the logic input needs to have no load, IE, it cannot have an internal pull-up resistor.The battery will need to drop below 1.5v for the input to be considered a logic low unless you add a pull-down resistor at the logic input.This will work for sensing low frequency / DC levels. It may fail if your PCB has a ton of dirty crud/really dirty flux residue all over the place.Zeners wont work as their internal minimum current will be too high.If you want an added voltage drop, like a zener, try using a simple old fashioned red or green led (in series with the 10 megaohm resistor (it should never light up...)). They will provide a ~1.5v(red)-2.0v(green) voltage drop with a few nano-amps whereas a typical zener will provide a 0v drop at 500na, almost like a short when drawing a few nano-amps. IE, a 10 megaohm pulldown will only be ~600na.(Please excuse the ultra low current drop of the LEDs if I got them wrong, it's been 10 years since I used LEDs as ultra low Iq voltage drop/regulators. You can measure this by placing the LED on a battery+ and your volt meter all on it's own from the LED cathode and battery GND.)

author: David Hess
author_rank: Super Contributor
timestamp: May 07, 2021, 10:30:02 pm
content: Discrete solutions are possible but the simplest "zero power" implementation involves using a comparator with a push-pull output so not pull-up resistor is required.
Zero RCA / Phono Connectors on LCSC? - Page 1
Forum section: electronics / projects

author: ssashton
author_rank: Frequent Contributor
timestamp: April 26, 2022, 11:49:11 am
content: Am I being dumb? I can't find a single RCA connector on LCSC!Anybody help me out?Lots of headphone jacks in 'Audio Connectors' and lots of XLR in 'Circular Connectors'. No phono?I just want something like this

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: April 28, 2022, 07:20:44 pm
content: Try a larger distributer or china as most audio parts are located there.Arrow, Digi-Key, Mouser are some.Jeff
Zero Voltage Switching with separated gates - Page 1
Forum section: electronics / projects

author: Neukyhm
author_rank: Contributor
timestamp: September 05, 2017, 10:28:18 am
content: Hi forum, I bought a ZVS on eBay, the input voltage is 12-36V but I will run it at 48V.I'm going to separate the MOSFET gates from this 48V PSU so these gates will run at 12V with another PSU.The thing is that I read somewhere that it isveryrecommended to first apply 12V to the gates, and then the voltage you will run the ZVS at.Is this true? I mean, for me It doesn't matter or the opposite, apply first 48V and then 12V to gates.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 05, 2017, 10:05:34 pm
content: If you remove gate drive while load current is flowing, the load voltage surges.It's a constant current commutated circuit, meaning the transistors must be default on.It's not a circuit with any protection features whatsoever, AFAIK, so expect frequent transistor poppings.Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 06, 2017, 11:16:58 am
content: In principle, 12V should be first on and last off, but as you note, initial current is zero, so it is okay to turn it on second.Tim

author: Ian.M
author_rank: Super Contributor
timestamp: September 06, 2017, 11:33:38 am
content: The first couple of cycles on startup of a Mazilli (ZVS) resonant transformer driver circuit may be anomalous, due to lack of initial flux in the core and limited gate drive. Since you intend to overdrive the module, a soft start circuit that inserts a series resistor in the 48V supply then bypasses it with a relay once oscillation is established may be advisable.
Zhenxing DT-890 voltage reference upgrade - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: May 11, 2015, 07:41:39 pm
content: I tried to calibrate my Zhenxing DT-890 (low battery) against a MC1403 reference chip. It was way out of calibration.I was trying extra hard to find the reference device of my Zhenxing DT-890 and I cannot find one. Some Chinese documents I read told me that DT-890 used a resistive divider across the battery voltage as its reference. Fail.Upgrade plan: get rid of the upper and lower fixed resistors R12 and R13, replace R12 with a short and leave R13 open, and dead bug the reference and ground pins of MC1403 directly across the trimpot.

author: Vgkid
author_rank: Super Contributor
timestamp: May 11, 2015, 07:45:48 pm
content: Since it has a icl7136, that has its own internal reference.

author: technix
author_rank: Super Contributor
timestamp: May 11, 2015, 08:30:15 pm
content: Quote from: Vgkid on May 11, 2015, 07:45:48 pmThe schematics told me that it is not using its internal reference. I have to add an external one or rely on battery voltage.

author: technix
author_rank: Super Contributor
timestamp: May 11, 2015, 08:47:46 pm
content: Putting it back for now. Calibrating it requires significant effort and tongue angle control.Also the trimmer is a normal trim pot, not a 10-turn pot, which makes calibrating extra difficult. Probably should send it to a cal lab for this.

author: retiredcaps
author_rank: Super Contributor
timestamp: May 11, 2015, 08:58:54 pm
content: Quote from: technix on May 11, 2015, 07:41:39 pmI'm not sure what you are trying to do. Please clarify for us.If your multimeter battery is low, getting incorrect readings is expected. If you put in a fresh battery, do you still get 2.61 for a 2.5 reference?

author: Vgkid
author_rank: Super Contributor
timestamp: May 12, 2015, 03:20:17 am
content: It looks like using a 2.5v ref would be easiest.

author: technix
author_rank: Super Contributor
timestamp: May 12, 2015, 06:15:53 am
content: Quote from: blueskull on May 11, 2015, 10:30:59 pmGovernment-owned cal labs here in Shanghai provides calibration services to general public at a very affordable price.
Zigbee device no - Page 1
Forum section: electronics / projects

author: rakeshm55
author_rank: Regular Contributor
timestamp: June 04, 2013, 04:00:27 am
content: Hi,I have some Zigbee devices which require different device nos. Each device transmits its own device no as a part of its data packet. This no is used to identify the device at the central station so that corresponding data could be mapped.As of now the device no is assigned while burning the code. Here Our GUI tool adds the relevant device no to the output file(modifies o/p file) burned into the controller. The device no is burned to flash data memory of controller.Here the issue is next time when we have to load a new version of the code the device no changes or forcefully user have to assign previous device no. This is because we use the device BSL the data memory is also erasedCan I make the Device no totally independent of code(output file)??How I can do this??If I can assign a device no independent of the code to be burned ......I have seen 1 wire Maxim with unique serial nos....How to program the device no to them....What are the other techniques??

author: cthree
author_rank: Frequent Contributor
timestamp: June 06, 2013, 04:52:58 am
content: The 'device no' is the MAC address. You should read the ZigBee specs. You need an IEEE MAC address programmed onto the dice in EEPROM or UID area of FLASH or what not. Your ZigBee software stack will have support for fetching this from somewhere and using in the network init code.You need to read the docs on this man, sorry.

author: Codemonkey
author_rank: Regular Contributor
timestamp: June 06, 2013, 07:28:01 am
content: Another option is to modify or (if not already your own) create your own flash programmer software for the device to do the following...Create your binary images with no MAC address in them (just an array of 0xff's).When you come to program the device, get your flash programmer software to:1) read out the previous MAC address (you must know where its located in FLASH)2) read in from disk your new binary image3) overwrite the 0xff's in the binary image with the device's MAC address you just read4) erase the FLASH in your micro5) write the new image in complete with the device's original MAC address.Done!
Zingyou BM-800 mic phase reversed? - Page 1
Forum section: electronics / projects

author: Tim88
author_rank: Regular Contributor
timestamp: July 13, 2022, 03:36:26 pm
content: I bought a Zingyou BM-800 mic on the interweb a few weeks ago new from Amazon for $25. I knew it was a cheap microphone but lots of mods out there for them so thought it would be a fun project. Anyway, I traced the PCB and laid out a schematic for it:In one of the modification threads out there, the guy mentioned that almost every BM-800 he saw had the XLR phase outputs reversed. I managed to find a schematic for that particular mic and if it is correct, my outputs are indeed phase reversed:Am sure someone above my paygrade in electronics could look at my schematic and tell if the phases are reversed. Not sure if phase reversed matters, I could see in a stereo mic setup they would cancel each other out.On a sidebar about the mic, it doesn't sound bad for $25. It had some hiss that was able to eliminate with a filter:For giggles, ordered a 34mm capsule for it from Aliexpress for under $20...

author: CaptDon
author_rank: Super Contributor
timestamp: July 14, 2022, 01:21:37 pm
content: I would guess the only way to be sure is to hook it to a triggered scope and see if a positive pressure wave (use the plosive of the 'p' sound into the microphone and look at the scope trace) produces a positive going output on pin 2 of the XLR with respect to pin 3. In the U.S. we have pretty much standardized (finally) on pin 2 being '+'. All of my Carver PM-2.0T amplifiers were built with pin 3 hot back in the day. We built entire studios wired with pin 3 hot, it seemed logical the hot pin would be in the center surrounded by ground and 'cold' for noise protection. The U.S. standard for hot originally did not agree with the European standard for hot. I bought a 7 piece kit of Pyle dynamic drum mics and even they were mis-wired from each other. I had to test and verify each one!!
Zobel network/filter  - Page 1
Forum section: electronics / projects

author: rex1232
author_rank: Contributor
timestamp: November 27, 2019, 11:48:29 am
content: Hey guysI am a little bit confused on why you would use Coil in the zobel network circuit.I understand that the zobel filter is there to "compensate" for the output impedance.But why would you put a coil in when you already have the cap?I have linked the zobel with the coil and one without the coil.Thank you in advance

author: Gyro
author_rank: Super Contributor
timestamp: November 27, 2019, 08:13:53 pm
content: It looks like somebody's got a bit confused there.It's normal to have a zobel network (series R and C) directly across an amplifier output so that it always sees a resistive load at high frequencies. This is oftenfollowedby parallel R and L, in series with the output to isolate it from capacitive loads. Both can aid stability.I'm not sure how the network shown would work in practice, it would be hard to optimize the conflicting component values at least. It doesn't look worth it to save one resistor.

author: magic
author_rank: Super Contributor
timestamp: November 27, 2019, 08:24:46 pm
content: According to SelfCapacitive loads may put the global feedback loop in oscillation so a coil isolates the amplifier from all the cables, crossovers etc.Inductive loads may cause local oscillation in the output emitter followers, so a Zobel network provides a low impedance at RF path to ground. Since the output coil is an inductive load too, it has to come after the Zobel.

author: Gyro
author_rank: Super Contributor
timestamp: November 27, 2019, 08:35:30 pm
content: Quote from: magic on November 27, 2019, 08:24:46 pmBob Cordell too.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 27, 2019, 08:49:02 pm
content: If the output is coming directly from a low impedance amplifier, the RL is necessary to provide some matched resistance for the parallel capacitor to act against. Otherwise it's just shorting out the amplifier, and the amplifier will win*.*For small signals. For large signals, it will go into current limiting, which manifests as slew rate limiting. And, assuming it doesn't oscillate, which is a stability issue in poorly made designs.Tim

author: magic
author_rank: Super Contributor
timestamp: November 27, 2019, 09:08:22 pm
content: Quote from: Gyro on November 27, 2019, 08:35:30 pmSo it's settledFor all we know, this schematic could be somebody simulating stability with 150nF load in SPICEeditOr a clever trick to save one resistor, yeah, Gyro already mentioned it.

author: gbaddeley
author_rank: Regular Contributor
timestamp: November 28, 2019, 08:42:04 am
content: The “with the coil” zobel is a load for an amplifier, as already explained.The “without the coil” zobel across a loudspeaker is to compensate for its rising impedance at higher frequencies. This would be preceded by a passive crossover network, which works more effectively into a reasonable constant load impedance, hence the zobel. Very common on woofers.
zombie hands like the walking dead - Page 1
Forum section: electronics / projects

author: stoppi
author_rank: Newbie
timestamp: November 20, 2016, 09:00:53 am
content: Hello!In one of my projects I tried to realise a Zombie-hand-scanner using IR-LED's. The principle is simple: Under the hand there are positioned high power IR-Led's. They radiate through the hand an the radiation is detected by a Webcam or camera, which have to be modified by removing the IR-block-filter.For bright Pictures the exposures must be about one second. Therefore the Video is a bit dark. I hope you like itMy YouTube-channel:https://www.youtube.com/user/stopperl16/videos

author: jonovid
author_rank: Super Contributor
timestamp: November 20, 2016, 09:34:44 am
content: this is about using electronics in theatrical FX
ZVS Flyback Driver Failing at lower voltages - Page 1
Forum section: electronics / projects

author: skyler
author_rank: Regular Contributor
timestamp: July 09, 2013, 01:05:48 pm
content: I built a really cool ZVS driver from herehttp://www.instructables.com/id/ZVS-Driver/. I used IRFP250 MOSFET's. I had nice large arcs with a 24 volt input, but when I increased the input to 36, the inductor got very hot, and when I loop turned off/turned on, the oscillation stopped and there was a dead short with the inductor being the only load. I replaced the MOSFETS and rewound the inductor and went back to 24 volts (which didn't burn out before). The same thing happened. (inductor got hot, then it failed). I checked the diodes and resistors and they seemed to work. (possibly the fast-switching diode has got "slower".) Does anybody have any idea what is going on, and how I can prevent MOSFET failure in the future?

author: Paul Price
author_rank: Super Contributor
timestamp: July 09, 2013, 05:40:40 pm
content: can you post a schematic?

author: Psi
author_rank: Super Contributor
timestamp: July 09, 2013, 10:48:57 pm
content: Are you using the secondary from a TV flyback, because those can burn out inside very easy if you push them too far.

author: Niklas
author_rank: Frequent Contributor
timestamp: July 10, 2013, 05:26:04 am
content: Change the MOSFETs to another type with higher voltage rating for max Vds. Are there any specifications on the core material in the inductor? We tried different materials for filter/storage chokes in a frequency inverter (350V, 3A, 400kHz) to find alternatives to Magnetics Cool Mu. Some chokes became very hot (>100'C) within seconds. As the temperature rises, at some point you end up with effectively only an air wound coil.

author: skyler
author_rank: Regular Contributor
timestamp: July 10, 2013, 03:00:07 pm
content: Do you have any suggestions for MOSFETS? Preferably digikey?

author: Andy Watson
author_rank: Super Contributor
timestamp: July 10, 2013, 09:07:32 pm
content: Quote from: skyler on July 10, 2013, 03:00:07 pmGet the cheapest. That circuit looks like it was designed to eat mosfets. It is noted in the comments that the oscillator sometimes fails to start!
ZVS Flyback driver for X-ray project - Page 1
Forum section: electronics / projects

author: SpectrHz
author_rank: Contributor
timestamp: September 03, 2013, 02:08:10 am
content: So today I built up this ZVS flyback driver to drive a high voltage triode that I picked up off eBay. The tube I picked up has an x-ray warning printed on it and the datasheet mentions 2.5 mr/h of x-radiation. Not a great deal but certainly enough to experiment with and also enough to require appropriate shielding and detection. This is a step in a larger project that I have been planning. I received an x-ray intensifier from my dentist upon request and wanted to put it to use in some way. After tearing down my Fluorescence spectrometer I figured a good experiment would be to cut a piece of intensifier out and put it in the Photomultiplier chamber. I will use that to detect the extremely low light levels of high energy waves illuminating the screen such as cosmic rays and x-rays. X-rays will most likely saturate the photomultiplier due to the fact that the intensifier is designed to illuminate when struck by them. I will also use the rest of the intensifier to take x-ray scans of objects of course. Not living things, but perhaps everyday objects such as a cell phone, or remote control. Aside; X-rays can be dangerous if one does not take into account x-ray safety. More importantly, The incredibly high voltages can be lethal, so care must be taken when working with them.

author: firehopper
author_rank: Frequent Contributor
timestamp: September 03, 2013, 10:52:36 am
content: your going to mess with xrays? make sure you invest in lots of lead shielding please. its nothing to take lightly. personally I'd not even bother with it, its just too dangerous.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 03, 2013, 11:50:02 am
content: You'll find some discussion of homebrew X-Rays herehttp://4hv.org/e107_plugins/forum/forum_viewforum.php?10Bear in mind that with a glass tube, you're going to need a pretty high drive voltage (as non x-ray tubes go) to get anything past the glass - not sure a TV flyback would be a viable source.And just because it has an x-ray warning doesn't mean the electrode geometry will produce a spot small enough to usefully image anything. You can pick up used dental X-ray heads pretty cheap these days.

author: SpectrHz
author_rank: Contributor
timestamp: September 03, 2013, 12:18:10 pm
content: I'm not sure on how well it will work either, but I should be able to produce high enough voltages from the zvs as the datasheet tells that shielding is needed as low as 30 kv. I'm not going to be exposing film with this probably, but I would imagine that the photomultiplier would pick up the light emitted from an X-ray cassette, even if extremely low level. I'm aware that it won't be a point source, and I definitely will pick up a dental x-ray head when I get some spare change. I just wanted something to play around with, the imaging was just wishful thinking
!!I need help with an old UDSSR Tsch3-54 Frequency Meter!! - Page 1
Forum section: electronics / repair

author: backbofen
author_rank: Newbie
timestamp: March 16, 2020, 09:33:32 pm
content: Hey There!Recently, I found an old Tsch3-54 Frequency Meter, but sadly its broken. And thats where I need your help. Maybe you have a working one laying around? Or a similar one? Or maybe you have a circuit diagram? I dont know if it was built in Germany or Russia but its atleast 20 years old. Here are some pictures:!!!!https://drive.google.com/drive/folders/1DmV8kPePvcbaCTHuTaqsae9N7fEbAhtX!!!![ Attachment Invalid Or Does Not Exist ]Its front.[ Attachment Invalid Or Does Not Exist ]The Thing in all its old beauty... Nixie Tubes!!!And now we come to the part where you can see whats broken. Someone desoldered or snipped off the old power connector and didnt reconnect it. I tried to reconnect some wires but didnt turn it on because I didnt want to destroy something. So if you have one please send me a picture of how the power wires are connected because i cant really assume where you should connect them. Some more pictures:[ Attachment Invalid Or Does Not Exist ]Here is the Area where the mains power comes in. But someone messed it up and I have no reference how to reconnect it.[ Attachment Invalid Or Does Not Exist ]Closeup.. (If you are wondering, this picture is older than the others)I would really appreaciate every bit of help I can get. Thank you!!!!!!!!!!Sorry for my bad english but im from Berlin

author: backbofen
author_rank: Newbie
timestamp: March 16, 2020, 09:35:01 pm
content: Im sorry about the pictures.. but you can find all the pictures in the given link.

author: chekhov
author_rank: Regular Contributor
timestamp: March 16, 2020, 10:20:20 pm
content: Hi,Try this schematics for example -https://www.qrz.ru/schemes/download/16350Use "Ч3-54" to find more about this meter on the internet.
[[AUDIO AMPLIFIER]] KONZERT AV302 -- ONE CHANNEL BROKEN - Page 1
Forum section: electronics / repair

author: ActiveRegion
author_rank: Contributor
timestamp: December 23, 2021, 12:14:52 am
content: One channel is playing at max volume compared to the other. The volume control works on the other one. So the speaker output is imbalanced one being always at full volume the other depends on my volume knob.I just want to understand why is there a pair of power transistors for the left and right channel. So there are total of 4 power transistors in this device. One pair of PNP and NPN per channel. Can you point me where i can read about the design concept of audio amplifiers. Is my understanding correct that it caters bothpositiveandnegativeside of the audio waveform so it needs two transistors?Thanks

author: ambrosia heart
author_rank: Regular Contributor
timestamp: December 23, 2021, 02:33:22 am
content: Can you point me where i can read about the design concept of audio amplifier. Books are written by 鈴木雅臣 in japanese translated to chinese. For foreigners, only a crappy book called audio amplifier design by self Dxxxxx.鈴木雅臣accuphase designer and of course my teacher. China Mainlanders salute to him, LOL.Is my understanding correct that it caters both positive and negative side of the audio waveform so it needs two transistors? Yes, you are correct. They‘re emitter follower to amplify current. The preceding stage is pre-amp to amplify voltage by 1 or 2 differential amp connected to a constant current source, CCS, formed by a npn transistor and a zener(high end with mirror image) connected to voltage amp(driver stage) then to idlng current adjust. P = V x I. They are also called power amp. No matter how much they are, design has these 2 stages. voltage amp will have DC Servo circuit to monitor DC offset OR have a VR to adjust. In some high end amp, an isolation stage will be found in pre-amp to keep white noise as low as possible and emitter follower will have several power transistors connected in parallel to increase current output stage such as Accuphase and Mclntosh. If pre-amp include an op-amp for voltage amplification, OH DEAR, it is a nightmare for a C FU(師傅)[a technician] to repair.

author: Kim Christensen
author_rank: Super Contributor
timestamp: December 23, 2021, 03:10:50 am
content: QuoteThis sounds like a faulty volume control. These pots are dual gang. (Two pots controlled by the same shaft)Probably the lower leg of one of the pots is open or it has a bad solder joint between the lower leg and ground.
[audio amps] The input differential pair: Preferred replacement parts? - Page 1
Forum section: electronics / repair

author: cvanc
author_rank: Frequent Contributor
timestamp: May 16, 2025, 10:12:21 pm
content: The last I knew the favored devices for input pair use were (npn) ZTX694 and (pnp) ZTX795. Do we still like those, or has something better come along? Thank you.

author: Haenk
author_rank: Super Contributor
timestamp: May 17, 2025, 07:17:57 am
content: I suggest asking this question on diyaudio. Lots of people in the knowing of exactly this topic.

author: Smokey
author_rank: Super Contributor
timestamp: May 17, 2025, 07:53:00 am
content: https://www.eevblog.com/forum/beginners/making-my-own-guitar-amp/msg5862935/#msg5862935

author: Kleinstein
author_rank: Super Contributor
timestamp: May 17, 2025, 08:46:09 am
content: The given ZTX transistors are quite high current and have a relatively high capacitance. Chances are they can have low noise due to a low R_base. However the capacitance could be a problem when used with a relatively low current. So it depends on the circuit, if the these transistors are a good choice. They can be a good choice for use with rather high current (e.g. > 1 mA) for low voltage noise at the cost of high current noise - e.g. for a really low impedance source.

author: David Hess
author_rank: Super Contributor
timestamp: May 17, 2025, 11:21:59 am
content: I do not know of anything better for low impedance applications except monolithic parts like the MAT series. ZTX transistors are based on the old Zetex "E-line" series of transistors which use perforated or ring emitter structures resulting in low base spreading resistance for low noise. A bunch of companies make low saturation high gain transistors like this now, but it is not always easy to identify them.
[fixed] repair Agilent E8267C, power down, 10Mhz error - Page 1
Forum section: electronics / repair

author: tagchen
author_rank: Contributor
timestamp: January 08, 2020, 03:02:36 pm
content: after looking on measurement place the generator Agilent E8267C is power down and no action.Device runs for long time (45800h).Note!! is device in standby, everytime warming the clock and can be damage by power lost or/and to fast transport!first check service manual 1. See no fuse external on power supply.-> check inside , two fuse (blue) to check and the typical ceramic thermal fuse (red) are ok.-> but design mistake, Fan blow outside (in picture below) and the warm air flow about caps, caps looks little defect (166µF on LCF)-> chance in one was inhouse.ok power up! but error in selftest 10MHZ-> check voltage, but all good. ok PS-fault red led on -> hm-> change big powersupply caps to mouser 871-B43547A9187M000, TDK long life, old was 3000h new are 8000h871-B43547A9187M000-> so look clock board, 10MHZ clock (red marked) and on side warming resistor. Clock and Resistors are bad soldering and i fixed.but after rebuild and test, the powersupply fan doesnt work, think doesnt work bevor and wasmain problem to fault device.changed in Conrad.biz ordernr. 1926405-VQ, EBM Papst 3412NHH with little more power.https://www.conrad.de/de/p/ebm-papst-3412nhh-axialluefter-12-v-100-m-h-l-x-b-x-h-92-x-92-x-25-4-mm-1926405.htmlafter that looks nice.
[fixed] repair Anritsu MG3692A LOCK ERROR - Page 1
Forum section: electronics / repair

author: tagchen
author_rank: Contributor
timestamp: January 08, 2020, 02:00:54 pm
content: an Anritsu generator was in our maintshop for a long time, unrepaired by Anritsu error not solvable.I found the block diagram and so lock some points in device.Note!! is device in standby, everytime warming the clock and can be damage by power lost or/and to fast transport!Error with Lock error / course loop Errorgenerator is runing but varies 20.xxxxxxGHZ.... , fine loop mistakeI have a device in vintage design, with 26,84mhz gen.lock insidehelps find in internet, use a other 100MHZ Clock.http://jr2wjm.blogspot.com/2017/02/mg3692b.htmlfind easy 0mhz on any cable to A3 Board, 10Mhz to external is perfect. --> 100Mhz Fine Loop defect!Measure witch an adapter outside VCC, voltage control, signalMeasure signal first with Frequency Counter Microwave 3401 and than Lecroy Wavepro 735Zi 3.5GHz 40Ga/s100MHz her is PTI XO5081-013 an some of unprofessional pcb redesign to fix or adapt somthing.10Mhz from MTI 200-0274Order new 12V VCOXO , OD100LP-81212SV-100.0M Digikey CW1006-ND (188euro)problem is to find any clock with 12V VCC, mostly 3.3 or 5V orderable.Pinlayout is same as original and is plug and play.But, 12V VCC, Voltage regulator goes from 0.5V-12.5V (with load tested) and the chip max is 9V. I use without adapter.works great

author: bav
author_rank: Newbie
timestamp: October 28, 2024, 08:55:27 pm
content: Have you finally got rid of the error Lock err?
[fixed] repair HP 4155A / 41501A power down - Page 1
Forum section: electronics / repair

author: tagchen
author_rank: Contributor
timestamp: January 08, 2020, 04:00:52 pm
content: After Power lost inhouse, HP 4155A power down and no action.since some year SMU-5 41501A was defect and unrepaired from HP.looks inside and tested the power supply.Fuse are ok.after long search, i began measure in power supply point for point to check how ends the power and i found that under the ceramic resistors (red marked), glued an thermalfuse. after changedAnd for me lucky day, the power supply for 41501A are mostly the same and found the same fault.power supply 41501Afinish

author: dxl
author_rank: Regular Contributor
timestamp: September 09, 2022, 03:51:57 pm
content: I had the same problem on my 4156A. Of course i discovered this thread *after* i figured out that the thermal fuse is blownWhat glue did you use to glue the new thermal fuse to the resistors?

author: chilternview
author_rank: Frequent Contributor
timestamp: May 24, 2023, 09:19:14 am
content: I've got a 41501A which may have the same problem. On power up, the fans don't start. I have checked the voltage after the bridge rectifier and it's 350v so ok. But it appears the switching mosfets have no signal to their gates and no activity on the driver (IR2110) either. The MB3759 is oscillating but no output.Is this a similar case to yours? What did you replace the thermal fuse with?

author: Swake
author_rank: Frequent Contributor
timestamp: September 15, 2023, 07:36:41 pm
content: Got the same supply in a 4155A too and guess what..... the thermal fuse is blown too!There is a marking on the PCB of 133°C. Thank you Voltex Electronics Corp. Japan for this information.The model of the power supply is: FPS1 D2160The HP P/N: 04155-60003And apparently there is a replacement unit with P/N 04155-69013, but I have no information if this is indeed an improved version or just a component update.