hybridfree/eevblog-posts huggingface dataset:
Low leakage 100nF caps? - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: September 07, 2013, 06:01:03 am
content: A circuit has the following warning about the need to use low leakage caps. How do I check the ones I have ARE low leakage please?"TO LIMIT INFLUENCE OF 74HC86 INPUTMAX LEAK CURRENT OF 0.2?A @ 6V @ 55°C(EQUIVALENT TO 30 Megohms)ALL TIMING RV'S: 2.2 Megohms MAXIUSE LOW LEAKAGE CAPACITORS !!"Thanks!

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 07, 2013, 08:07:59 am
content: You'll struggle to find 100nF that isn't low leakage. I don't know if they still make 100nf electrolytics, but pretty much any other type (ceramic, polycarb, polyprop etc.) is fine.

author: Chris Wilson
author_rank: Super Contributor
timestamp: September 07, 2013, 09:38:58 am
content: Thanks Mike, I used new branded ceramics from Farnell, so should be OK. I appreciate the advice (and your videos...)Cheers.

author: SeanB
author_rank: Super Contributor
timestamp: September 07, 2013, 01:26:32 pm
content: If you want really low leakage use caps rated at over 250V, 400V or 630v film units are guaranteed to have a very low leakage at rated voltage, and at CMOS levels it is pretty close to being equal to the PCB surface leakage. 16V ceramic units can have a quite high leakage, and with the lovely voltage dependence of capacitance timing will be pretty poor with supply voltage variations. If you are going to use ceramic use 100V units, though they will be a lot bigger than 16V units

author: Harvs
author_rank: Super Contributor
timestamp: September 07, 2013, 01:58:08 pm
content: If you're using brand named caps, then this should be fairly easy to calculate.They typically spec the insulation resistance in Mohm - uF's, so you can just divide the insulation resistance by the capacitor value in uF (so 0.1 for 100nF.)For example this X5R dielectric:http://www.ece.ucdavis.edu/vcl/asap/asap_v1/docs/X5R_D.pdfI get 5Gohm. So at 5V you should get about 1.2nA leakage.Also note, depending on the dielectric you get, this is highly temperature dependent.
Low leakage capacitor - Page 1
Forum section: electronics / beginners

author: fixit7
author_rank: Regular Contributor
timestamp: May 18, 2019, 04:44:53 pm
content: I am trying to find info about what a low leakage capacitor is.I read that aluminum electrolytic caps have a higher leakage rate than most other types.How do you determine if a capacitor is low leakage?I was looking at this one.0.1µF 250 Volt 10% Metallized Film Capacitor AxialSpecificationsCapacitance: 100000 pF / 100 nF / 0.1µFVoltage rating: 250 VDCTolerance: ±10%Size: 14mm x 8.5mm x 4.5mm (W x H x D)Axial leads

author: Gyro
author_rank: Super Contributor
timestamp: May 18, 2019, 05:34:54 pm
content: All Film capacitors are low leakage for normal purposes.Where leakage is particularly important, for instance high performance, high impedance measuring equipment, then Polypropylene, Polystyrene and Teflon (PTFE) are lower leakage than Polyester/Mylar and Polycarbonate.P.S. Insulation resistance is normally specified in the datasheet.

author: bob91343
author_rank: Super Contributor
timestamp: May 18, 2019, 05:58:09 pm
content: All practical capacitors leak. Whether leakage is considered low or not is a value judgment based on the intended use and the specifications for a particular unit.Sometimes leakage is specified in milliamperes and sometimes as insulation resistance. Electrolytic units are poor in this regard due to their chemical composition and structure. Mica, paper, plastic, air, ceramic, etc. all have peculiatirites that make them desirable or not for a specific use.Electrolytic capacitors have the additional property of polarity which limits their use.

author: BravoV
author_rank: Super Contributor
timestamp: May 18, 2019, 07:16:50 pm
content: Quote from: fixit7 on May 18, 2019, 04:44:53 pmFor sure you need to test it at the rated voltage.Did some cap leakage measurements while ago, but my DC PSU only maxed out at 37 Volts, that was the only maximum I could test with the ad-hoc test jig I made using DMM.For high voltage cap like yours, even using lower voltage, still you will have some clues how it compares to other more leaking cap like electrolytic, check this out ->HERE.Hope this helps.
Low-Mid-Range Function Generator - Page 1
Forum section: electronics / beginners

author: seancsnm
author_rank: Regular Contributor
timestamp: January 15, 2016, 06:46:42 pm
content: I'm looking for a general purpose function generator in the price range of up to $150 US; ideally lower because I'm a poor college kid. I'd like the typical 3 waveforms plus PWM and a frequency range of up to 10 MHz. 2 MHz as an upper end would suffice if it means a huge price difference.I'm not opposed to building one or repairing one - the important thing is that it doesn't require a whole lot of effort to get up and running, and that it's reliable and consistent. I'm not sure how commercial/lab function generators are designed, but it sounds like for quick n' dirty op amp-based ones it's a bit difficult to get good sine waves. Also, output protection and low noise are important. A good output voltage range as well is important. I plan to be using this function generator as my primary unit for at least a few years for anything from clock timing (not terribly tight, but it should be pretty good) to audio design. You might tell me that nothing under $1000 could get me that but keep in mind I'm still a student and anything I do is going to be more educational than to be sold to consumers. Still, for my budget getting the best I can would be ideal.I've looked at a few units, mostly older ones, and it looks like I can fit my budget if I just look for long enough:http://www.ebay.com/itm/Agilent-33120A-15-Mhz-Function-Arbitrary-Waveform-Generator-/131701375647?hash=item1eaa03829f:g:G6EAAOSw5dNWmEUghttp://www.ebay.com/itm/HP-Hewlett-Packard-3310A-audio-function-generator-/291657326776?hash=item43e821a0b8:g:MhMAAOSwKtlWkw9bhttp://www.ebay.com/itm/Siglent-SDS-2000-FG-25MHz-Function-Arbitrary-Generator-Option-/331746992519?hash=item4d3da96187:g:vQAAAOSwX~dWiuj~Lastly, how does WaveTek fare with their function generators? They are generally much cheaper than HPs/other brand names even when similarly spec'd. What about Siglent? Simpson? Topward Electronics?

author: ice595
author_rank: Regular Contributor
timestamp: January 15, 2016, 07:28:39 pm
content: if you use if for clock generation, you probably gonna need some additional hardware (e.g schmitt trigger).some of the cheaper DDS function generator can only generate 5-10MHz max for square wave.but you can always generate a sine wave then "square" it with a simple schmitt trigger sircuit.
low noise regulator - Page 1
Forum section: electronics / beginners

author: user99
author_rank: Contributor
timestamp: March 15, 2017, 02:27:49 am
content: As part of a learning project I'm designing a bench power supply. My goal is for it to build it using parts in the bin and digitally controlled, low noise, reasonably safe and reliable.I tried out a few pre-regulator designs in spice and the simplest one ended up being a mosfet switched with a comparator.One of my concerns is transients generated when the mosfet turns off under a heavy load. There doesn't seem to be much visible on the scope when it switches but I'm limiting the breadboard circuit to 20v and about 500mv load.A diagram is attached.
Low pass filter - LC or RC phase response better for specific attenuation level? - Page 1
Forum section: electronics / beginners

author: julian1
author_rank: Frequent Contributor
timestamp: September 20, 2016, 09:53:09 pm
content: I know that LC can have much sharper attenuation response.But what about phase differences at a specific attenuation level?Does an LC circuit have less phase change than an RC circuit - or are they the same for a given attenuation level?I'm thinking about the case of frequency compensation, where the goal is to roll-off the gain, between amplifier sections, before negative feedback turns into positive feedback due to phase lag in the different sections.Most of the filters seem to be RC rather than LC - ie in the internal compensation of an op-amp between diff-amp and output section.

author: danadak
author_rank: Super Contributor
timestamp: September 20, 2016, 10:44:54 pm
content: RC basically a one pole solution, LC two, therefore phase contribution is greater inLC. LC also exhibits resonance behavior, so in this case of LPF examples show greaterG and phase change. Attached, you will see great phase change with LC.RC single pole are inherently loss, but its possible to get G out of a purely passiveRC. See attached.Regards, Dana.

author: danadak
author_rank: Super Contributor
timestamp: September 20, 2016, 11:14:35 pm
content: "Normally" active filters employ just RC and OpAmps. This allows thegeneration of L type characteristics for use in the filter. There area number of issues using L, T dependence, size, microphonics, sens-itivities to component changes....Regards, Dana.
Low power consumption ram to save just 4 bytes - Page 1
Forum section: electronics / beginners

author: sairfan1
author_rank: Frequent Contributor
timestamp: June 04, 2025, 05:12:17 pm
content: I'm working on a project where I have to turn of MCU to save power, but I want to keep a 4 bytes wide ID. I was thinking if there is some SPI serial ram that consumes around a couple of nano amps (nA) and I store last ID before power cut off to MCU. I can't use EEPROM as it needs some time on write/read each byte (I'm using 8 bit PIC)any other ideas are welcome to solve the problem.

author: Nominal Animal
author_rank: Super Contributor
timestamp: June 04, 2025, 05:56:32 pm
content: How about SPI F-RAM like 3.3VInfineon FM25L16B? Mouser sells them in singles for1.27€ apiece, LCSC for$1.92, and JLCPCB for assembly$1.88apiece in singles. You can completely turn off the power, as it is nonvolatile. There are no erase operations or wait states, you just read or write to it at SPI bus speeds (up to 20 MHz). Just remember to pull /CS up after a write before disconnecting power to it.I don't think you even need to do wear leveling on it, just use specific addresses (in the 2048-byte address space). If you wrote 8 bytes once per second to the exact same addresses, no wear leveling at all, the manufacturer claims it would still last for at least 39 years.

author: David Hess
author_rank: Super Contributor
timestamp: June 04, 2025, 06:43:48 pm
content: There are various serial access SRAMs. Some have a standby current below 1 microamp.What is wrong with the SRAM in your PIC microcontroller? It keeps its content in standby mode.There are inexpensive EEPROM backed up SRAM parts like the Microchip 47L04 which operate like SRAM, but when power is removed automatically save their contents to internal EEPROM while powered by an external 4.7 to 10 microfarad capacitor. These would draw no current when shutdown.

author: djacobow
author_rank: Super Contributor
timestamp: June 04, 2025, 06:53:38 pm
content: OP mentions "a few nA", which honestly, makes me suspect that the application has not been thought through.I just got though development of a product designed to work for years on a single coin primarily cell and we got our average power down below 3uA, with an accelerometer still running and able to wake the processor. We were happy to get accurate current measurements on the order of 100nA and getting there is not trivial: things like fingerprints on the board, slight differences in how the board was washed, etc, can make bigger differences.In any case, this number was actually below the self-discharge rate of the cell we were using. If we had gone lower it would have little benefit.

author: sairfan1
author_rank: Frequent Contributor
timestamp: June 04, 2025, 08:40:06 pm
content: as i described in my question power will be totally off for MCU and I wan minimum current drain in power mode

author: PGPG
author_rank: Frequent Contributor
timestamp: June 04, 2025, 09:30:17 pm
content: I think all RTC ICs have also some bytes of RAM. I remember using in 90s RTC consuming 200nA (with clock running). Interesting what is its supply current when clock not running.
Low power DC DC converter (step up) - Page 1
Forum section: electronics / beginners

author: daljaz
author_rank: Newbie
timestamp: April 27, 2015, 03:29:29 pm
content: Hey everyone, first post. Love the EEVblog on youtube!I was wondering what's the best (meaning least hassle) way to make a battery powered DC DC step-up converter. It has to supply low current, around 25mA, but has to step up the voltage from a 6-cell NiMH battery to 85V (or so). I was looking for ICs, but they seem to only step up voltages to a max of 20V-30V or the input voltage has to be higher in order to output 85V, so this way I would require two stages, I guess?Another idea I had was to use a crude topology with an inductor, switching FET, diode and output capacitor, since the output does not need to be that smooth. I'll be running a string of LED's and before you say "why not run them in parallel..." I just wanted to explore this option and learn about step-up converters along the way. I tried doing some LTspice simulations of this topology, but since I lack an oscilloscope and proper inductors, I can't really try out too much without risk of killing my LEDs. Thanks for the info!

author: mariush
author_rank: Super Contributor
timestamp: April 27, 2015, 05:49:30 pm
content: There are plenty of switching regulators that are capable of what you want, but usually they need special inductors or tiny transformers.If money is not a problem, see for example LT3757 ... the datasheet even has an example circuit to boost 5-12v to 350v 10mA - you can easily adjust the circuit to 85-90v and ~25mA.Product page herehttp://www.linear.com/product/LT3757and datasheet herehttp://cds.linear.com/docs/en/datasheet/3757Afd.pdf
Low Power Design - Page 1
Forum section: electronics / beginners

author: lilmantis
author_rank: Contributor
timestamp: January 09, 2015, 09:37:14 am
content: Hello, can someone suggest a book on Low Power Design?(not chip level)

author: lilmantis
author_rank: Contributor
timestamp: January 12, 2015, 09:28:02 am
content: Anyone?

author: leppie
author_rank: Frequent Contributor
timestamp: January 12, 2015, 09:35:59 am
content: Here is a good article:http://www.ganssle.com/reports/ultra-low-power-design.html

author: lilmantis
author_rank: Contributor
timestamp: January 12, 2015, 01:06:50 pm
content: Thank you.

author: owiecc
author_rank: Frequent Contributor
timestamp: January 12, 2015, 04:33:46 pm
content: There is a little bit in the Art of Electronics (chapter 14: Low-power design).

author: lilmantis
author_rank: Contributor
timestamp: January 14, 2015, 10:46:36 am
content: Thank you for the suggestions, the Jack Ganssle article was quite good, I hope the new version of TAoE will be out soon and with a good chapter on the subject. Once again thank you all for the suggestions.
Low power GSM module+Uart interface MCU - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: November 10, 2014, 04:50:57 pm
content: 1. I am looking for a complete GSM module for battery powered application, which can be then interface with MCU over uart with AT commands.Module should be complete i.e. insert sim & make connections with uart over MCU & ready to go.2. Earlier I have tried both SIM900A & SIM300, they are not suitable for battery power application.One I had tried is:http://www.amazon.in/SIM900A-MODEM-MODULE-ANTENNA-Communication/dp/B00LE7VHMS?tag=googinhydr18418-21

author: Wilksey
author_rank: Super Contributor
timestamp: November 10, 2014, 05:49:34 pm
content: Not 100% sure how long it will run from a battery, but you could look at the specification for this:http://www.sainsmart.com/siemens-tc35-sms-gsm-module-voice-adapter.html
Low power small voltage source to charge high voltage storage - Page 1
Forum section: electronics / beginners

author: raff5184
author_rank: Regular Contributor
timestamp: September 06, 2018, 08:52:58 pm
content: Hi,what is normally used (if it is even possible) to completely charge a storage such as a capacitor or supercapacitor that has say 5-6V or even 15V of maximum rating voltage if the charging source is a low DC power (4-5mW) and can't reach the 5V, but is a 1V or 2V source?

author: David Hess
author_rank: Super Contributor
timestamp: September 07, 2018, 06:35:04 pm
content: A boost switching regulator would commonly be used but several other switching regulator topologies are suitable also. There are dedicated "energy harvesting" ASICs intended for this application now.
low profile female header? - Page 1
Forum section: electronics / beginners

author: exe
author_rank: Unknown
timestamp: September 24, 2018, 07:48:00 pm
content: I was watching one of Dave's videos and noticed connector I didn't see before: female, low-profile, smd with pins going through it (so the board has to have holes).It looks like using it I can make distance between the boards substantially small than using conventional headers. I'm curious if I can buy one as well? Does anyone have any relevant part number or something? So far I failed to find anything on aliexpress or tme.eu (with 2.54 pitch).

author: dmills
author_rank: Super Contributor
timestamp: September 24, 2018, 08:06:11 pm
content: Samtec have a part like that, used them on a few projects, see the SSM series.I suspect that is a knock off however, the Samtec part not being the cheapest thing in the world.Regards, Dan.

author: exe
author_rank: Unknown
timestamp: September 25, 2018, 11:53:46 am
content: Thanks for helping! I checked SSM series, looks like it has 7.32mm height, which feels like a standard width for headers. It does have holes at the bottom.Using digikey I foundhttps://www.digikey.nl/product-detail/en/harwin-inc/M20-7811045R/952-3227-2-ND/6564963. Looks like what I was looking for.
Low quiescent 12VDC->5VDC step down module, plus weatherproof - product or DIY? - Page 1
Forum section: electronics / beginners

author: mortrek
author_rank: Contributor
timestamp: October 15, 2019, 04:57:35 pm
content: I'm trying to make an outdoor rig which runs off of a lead acid battery but it takes a USB/5V input. The device has low, intermittent current usage, so the adapter does not need a high current capacity.I wanted to find a 12VDC->5VDC step down module that was potted/weatherproof, but all I've found so far are cheapo ones with 10mA quiescent current. I want the rig to run for a year or more. Normally it runs off of AA lithiums, which have 2000mAh or so capacity, and they only work for about 3 months. Even a smallish marine battery would last much longer, unless of course the adapter has a high quiescent current, thus my problem.Is there such a product available, or do I need to make my own from scratch or even get a good efficient one (from say Pololu) and pot it myself in potting compound/put it into a weatherproof housing? What would you recommend?If my entire premise is flawed, please let me know. I'd be fine with a small recharageable lithium battery + solar charger, but all of the solutions I've found have been very lacking in reliability and/or weatherproofing.Edit:Example of non-weatherproof module I could consider:https://www.pololu.com/product/2850- put it in a small ip65+ case with small drilled holes, put wires through, seal with silicone, or pot it and hope it doesn't overheat...

author: pigrew
author_rank: Frequent Contributor
timestamp: October 15, 2019, 05:11:33 pm
content: Some CUI modules are a bit better, for example the VX7805-500 (which is already potted), and has about 0.3 mA quiescent current. However, maybe an ultra-low IQ LDO would be better, even with the inefficiency of the linear regulation.Also do think about the self-discharge rate of lead acid batteries. Lithium primary cells have much lower self-discharge and would have a voltage closer to your target.There are suitable converters from Linear Technologies and TI, but they're less likely to be available in easy-to-solder pre-built modules. For example, theLMZ21700 has ~30 uA Iq, but you'd have to weatherproof everything yourself.

author: jhpadjustable
author_rank: Frequent Contributor
timestamp: October 15, 2019, 06:08:34 pm
content: The weatherproofing is the better-known aspect so I'll treat it as solved. Almost all switching converter ICs offer an enable/shutdown input, though few modules expose it to the user. On most modules, you can lift the pin and connect your own controls to it.What event or condition starts the high-current period?Do you have a signal that you can see ahead of the high-current period, or can you delay the high-current activities for a brief moment? A few milliseconds would be enough.Is it feasible to turn the entire load on and off in response to that signal? Alternatively, is it feasible to run an LDO all the time and enable the switching converter only during the high-current periods, using a Schottky diode on each one's output to avoid back-powering the other and any possibility of grief due to that?
Low resistance Ohmmeter  - Page 1
Forum section: electronics / beginners

author: 0x007
author_rank: Contributor
timestamp: February 18, 2016, 09:21:21 pm
content: Hello every one , I am in need of assistance.I need to create a circuit to measure low resistance (0-10 ohm), the thing is I'll be measuring sensitive components so it must be low current probing (5mA max).I tried doing some thing with simple voltage divider or Wheatstone bridge and then use an LM358 to get a dissent voltage that will be measured by an A>D converter,but I cant get an accurate measurements because of the low current limitation.I tried looking up ohmmeters on google but I couldn't find anything use full, all I get are circuits of analog ohmmeters that doesn't help me in any way.I don't want to reinvent the wheel , I just need a simple circuit that will be able to measure resistance in the range between 0 to 10 ohm with 0.1% error max, and it has to be single supply.I will appreciate any help , thanks in advance.

author: TimFox
author_rank: Super Contributor
timestamp: February 18, 2016, 09:38:07 pm
content: For low resistance, you need a four-wire measurement, where one pair of wires passes a current through the resistor and a second pair goes to a voltage sensor. For a single supply, this would need a good differential amp for the second pair. The current could come from a current regulator, or be measured with a second voltage sensor across a series resistor, requiring some computation.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: February 18, 2016, 09:41:57 pm
content: Check Linear Technology's AN98http://www.linear.com/docs/6159, pages 10 and 11

author: Gyro
author_rank: Super Contributor
timestamp: February 19, 2016, 09:58:54 am
content: Also try Maxim AN106:http://www.wentztech.com/radio/resources/Projects/AN106.pdfSimple and elegant.(Sub your own ref and opamp and trim for required accuracy)EDIT: Just re-read your original post - you'll want to add another current setting resistor to get a 1mA range.

author: kripton2035
author_rank: Super Contributor
timestamp: February 19, 2016, 10:18:14 am
content: you can find lots of ideas on my repositoryhere :http://kripton2035.free.fr/continuity-repos.html
Low Shunt Value and sub mA resolution - Page 1
Forum section: electronics / beginners

author: lukaev3
author_rank: Newbie
timestamp: November 21, 2024, 12:58:26 am
content: Hello together,I was wondering how it is possible that a lot of manufacturers use a shunt of few milliohms, and still get sub mA resolution.If you look at the teardown of the BK Precision 8601 Load, you will see a very low ohmic shunt used(my guess below 50mOhm).Please look at the attached pic to get a example.But how do they get that impressive resolution(0.1%FS + 0.05%)I'm really wondering how, because quick math shows: 1mA*50mOhm = 50uVThat means they can amplify a voltage of 50uV with a accuracy of 0.05% neglecting the offset.That is a burning question for me.Thanks in advance

author: EEEnthusiast
author_rank: Frequent Contributor
timestamp: November 21, 2024, 10:20:40 am
content: Fine resolution -> EasyFine Accuracy -> Difficult.A resolution of 1mA in a 60A range corresponds to an effective resolution of 16bits. It is not hard to achieve this resolution with a 20+ bit Sigma Delta ADC or equivalent.But the major issue is to get the accuracy improved. Note that this is not the same as resolution.In the 60A range, if you measure 2A, then you have an error of 0.061A, which is about 3% which is not that great.Also while using small shunts, it really helps to use 4-terminal shunts, when compared to 2-terminal ones. The 4-T ones have separate sense lines which do not carry any current. These improve the overall accuracy as you are not impacted by the contact resistance or PCB routing resitances.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 21, 2024, 10:34:40 am
content: The 0.1% FS part would be quite a lot if one measures at the low end the range.Measuring voltage to the 10 µV level is relatively easy, 1 µV is still OK with care. The point is not the offset, but the offset drift. The initial offset is easy to measure and correct.The 0.05% for the gain is a question of the calibration and stability of the shunt. Manganin shunts can be quite accurate, if they don't get excessively hot. The bend bare wire may look simple, but it can be a really good solution, though the version shown with 4 shunts in parallel is aready not ideal.

author: David Hess
author_rank: Super Contributor
timestamp: November 21, 2024, 05:33:29 pm
content: Quote from: lukaev3 on November 21, 2024, 12:58:26 amResolution down to 50 microvolts is not difficult. 1 microvolt and lower is feasible. The chief limits are noise and offset drift with noise below 0.25 microvolts and offset drifts down to 0.1 or even 0.05 microvolts per degree C possible. The limit then becomes thermocouple errors from self heating of the shunt itself.
[SOLVED: Broken mosfet] Low-side switching of resistive load not working - Page 1
Forum section: electronics / beginners

author: ppff
author_rank: Newbie
timestamp: June 19, 2018, 01:06:32 pm
content: Hi everybody,Doing some research on the web about my problem, I found out about this forum and decided to give it a try.As you can see on my schematic, I have a battery connected to a heating resistor, their low sides are separated by a NMOS (https://www.infineon.com/dgdl/IPB039N10N3+G_Rev2.1.pdf?folderId=db3a304313b8b5a60113cee8763b02d7&fileId=db3a30431ce5fb52011d1ed1fd3915e0)BATT- is then connected to the GND of my circuit through a sensing resistor (10 mOhms) for other purposes.I tried this circuit with a power supply in place of the battery and noticed it would immediately drain current. To be sure it wasn't a command problem, I removed the gate resistor (R12), but it's still happening. When my power supply is at 20V, Vds = 2V and Vgs = 300mV, and the mosfet acts as a very small resistor. But it should act as an open circuit!I tried with R13=10k, R13=0 and without R13, and it's always conducting.What is going on? Everything I've found elsewhere displayed the exact same schematic, even a board I've already used worked the same way. What am I missing here?Thank you for your help, strangers!

author: wraper
author_rank: Unknown
timestamp: June 19, 2018, 01:17:36 pm
content: Probably your MOSFET already failed. Also from your circuit is not obvious if BATT- is connected to GND as it should be to work properly.

author: ppff
author_rank: Newbie
timestamp: June 19, 2018, 04:00:06 pm
content: God damn that was it. It had no reason to be broken, but it wasThanks for the idea!

author: Ian.M
author_rank: Super Contributor
timestamp: June 19, 2018, 04:54:29 pm
content: Leave a MOSFET gate floating and it can get biased into its linear region by static charge. If you powered it up without a gate pulldown resistor or good gate drive it probably fried itself due to excessive dissipation in a fraction of a second.
Low Temp Hot Melt Glue Gun how to increase Heat - Page 1
Forum section: electronics / beginners

author: mrbear
author_rank: Newbie
timestamp: August 04, 2015, 10:28:45 am
content: HelloI am trying to recycle plastic polystyrene from model kitsProof of concept pushed plastic tree pices from the kit into the Low temp hot melt gun.With a bit of presure startet to melt or elastic in nature.Low temp Hot melt gun needs more heat.I have purchased a few of these hot melt gunsI have a Cheap hot melt glue gun have pulled it apart it consists of 240 Volt ac across resistive element to generate heatAc power lines run to flat conectors one on one side and the other going to the other side of the resistive element All wrapped up in some kind of like orange Cellophane.Big Question Can i put two across resistive elements wrapped together in the orange Cellophane will this generate more heatany ideas

author: Psi
author_rank: Super Contributor
timestamp: August 04, 2015, 10:53:35 am
content: The element is ceramic, its resistance increases as it gets hotter which reduces the current.So it naturally regulates temperate to the correct level for hot glue.If you look on the side you may notice the gluegun is 110-240V. It gets up to temp faster on 240 but 110 gets up to peak temp just the same due to this natural temp regulation.

author: rs20
author_rank: Super Contributor
timestamp: August 04, 2015, 10:55:22 am
content: Fwiw, the "orange cellophane" is probably Kapton tape.

author: Muttley Snickers
author_rank: Unknown
timestamp: August 04, 2015, 11:50:25 am
content: You should be careful when working on projects such as these as melting plastics may generate toxic or carcinogenic fumes and in addition some plastics will combust at given temperatures.I still have scars from melting toy soldiers as a kid, just another battle I lost.Muttley
Low temp LF paste Mechanic V8BN45, Sn42Bi58 - Page 1
Forum section: electronics / beginners

author: newtekuser
author_rank: Frequent Contributor
timestamp: February 06, 2024, 05:42:24 am
content: Does anyone have any experience with this solder paste? Planning to use it in a t962a oven.Is this compatible with the Amtech NC-31 profile?https://a.co/d/dM6lelg

author: tooki
author_rank: Super Contributor
timestamp: February 08, 2024, 08:54:55 pm
content: Don’t buy that crap. It doesn’t even know what it is: “SAC305 Sn42Bi58” is a contradiction, since those describe two very different alloys:SAC305: 96.5% tin, 3% silver, 0.5% copperSn42Bi58: 42% tin, 58% bismuthThat contradiction tells you that the seller doesn’t know (or doesn’t care) what they’re selling, so who knows what you’ll get. Probably counterfeit god-only-knows-what.Given that you can order a tub of bismuth-based low-temp solder paste from ChipQuik (a reputable vendor) for the same price (e.g.https://www.amazon.com/Smooth-Solder-Paste-Bi57-6-Ag0-4/dp/B08KWLLFT4) I don’t know why you’d dick around with Chinese crap.As for the profile: that’s fundamentally determined by the alloy, not the manufacturer. So the profile Amtech recommends for their Sn42Bi58 (and similar alloys) solder will work with anyone else’s Sn42Bi58 (or similar) solder.
Low THD sinewave generator - Page 1
Forum section: electronics / beginners

author: david77
author_rank: Frequent Contributor
timestamp: May 11, 2012, 01:37:36 pm
content: Hi guys.I'm in the first stages of a new project and the need for a low distortion sinewave generator has arisen.So I'm looking at circuits and I'm not quite sure what to use.What I want:-------------------- THD <1%- Frequency: Switchable 333Hz, 1kHz, 3.15kHz, 6.3kHz, 10kHz, 15kHz, 20kHz- Output voltage 1,55VrmsSo what would you suggest? A Wien-bridge? Using an XR2206?David

author: jimmc
author_rank: Frequent Contributor
timestamp: May 11, 2012, 02:08:05 pm
content: XR2206 will struggle to meet 1% distortion, Wien bridge based oscillators can easily achieve it.http://cds.linear.com/docs/Application%20Note/an43f.pdfp 29or if you want to go to extremeshttp://cds.linear.com/docs/Application%20Note/AN132f.pdfHowever if you want frequency stability better than around 1% look at DDShttp://www.analog.com/library/analogDialogue/archives/38-08/dds.pdfJim

author: T4P
author_rank: Super Contributor
timestamp: May 11, 2012, 02:12:12 pm
content: Go for wien bridges for low THD and not too high frequencies...(I'm thinking high = >20MHz)

author: david77
author_rank: Frequent Contributor
timestamp: May 11, 2012, 02:28:01 pm
content: I thought I might go the Vienna way.Thanks for the literature, Jim Williams has been busy. Something to read in bed tonight.I'm purely in the audio spectrum, nowhere near 20MHz, if I can achieve <1% THD and maybe 5% frequency and amplitude accuracy I'll be happy.

author: T4P
author_rank: Super Contributor
timestamp: May 11, 2012, 02:36:55 pm
content: Quote from: david77 on May 11, 2012, 02:28:01 pmThen that will make you a nice audio gen. Good luck!

author: tekfan
author_rank: Frequent Contributor
timestamp: May 11, 2012, 03:20:34 pm
content: I know I've posted this lonk in another thread but I am so impressed with this oscillator that I have to post it again:http://sound.westhost.com/project22.htmIt's THD was below 0.02% when I measured it on a Hameg distortion analyzer. It wasn't even meant to measure such low distortion, so it is probably even lower than that.This is a great little oscillator for audio work and measurments.

author: david77
author_rank: Frequent Contributor
timestamp: May 11, 2012, 03:32:37 pm
content: Stupid me. Why didn't I look at Mr. Elliot's truly magnificent site? That's basically exactly what I had in mind, push-pull output and all.Thanks tekfan.
low voltage 300A dummy load - Page 1
Forum section: electronics / beginners

author: mazurov
author_rank: Frequent Contributor
timestamp: April 11, 2014, 06:24:28 pm
content: Hello,I'm designing multi-phase buck to provide 0.5-1V at 300A. What is a good way to test this kind of circuit (I'm mostly interested in a step load)? Linear AN133 describes 100A load which (prolly) can be scaled up but it doesn't work very well with low voltages.Thank you,Oleg.
Low voltage AC inside power and ground plane - Page 1
Forum section: electronics / beginners

author: braincat
author_rank: Contributor
timestamp: January 09, 2021, 05:27:37 pm
content: Newbie here... I am working on a thermostat pcb; the board receives 24V AC from the furnace, and uses LM2596 to convert it to 3.3V DC. Logic runs on ESP32 which switches three through hole relays (fan, power, heat/cool). The board has a ground plane and a 3.3V plane covering the whole board. I have a (hopefully) very simple question: is it ok to run 24V AC traces inside these planes, or would I be better off not doing that? I didn't give it a second thought at the beginning, but recently discovered a bridge of solder between one of relay contacts that switches 24VAC, and a 3.3V plane. I would lean towards routing AC traces away from the planes if I were doing the board from scratch, but unfortunately it is almost complete.Thanks.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: January 09, 2021, 08:01:56 pm
content: The use of copper polygons does not have any clear rules and it is often a creative process based on calculations and experience. You have gained experience with the jumper and now probably want to make the interval longer to protect against jumpers. But this is a question of making a board and it has little to do with the polygon itself - in good conditions, jumpers do not arise. Copper polygons require attention in high-frequency and power circuits, in other cases it is most often saving solution for etching boards. Perhaps your device could do with just one layer.However, the separation of circuits of different voltages in space is a good practice. It is better to group 3.3V circuits in one area and 24V circuits in another so that they have as little overlap as possible.
Low Voltage Alarm for Dewalt 20v Max - Page 1
Forum section: electronics / beginners

author: DeepwoodMotte
author_rank: Newbie
timestamp: December 12, 2021, 05:44:27 pm
content: Hi all! Thanks for taking a look and trying to answer my question.Is it possible to modify the board linked below to alarm at about 15-16v? Perhaps with a bigger potentiometer? If so, may I ask for potential part numbers that will work for this purpose?https://aliexpress.com/item/32826286598.htmlI have an adapter that converts the Dewalt 20v Max batteries to use with the Craftsman C3 19.2v tools. The problem is that neither the battery nor the tools have a low voltage cutoff. I thought perhaps a circuit that sounds a buzzer when voltage is getting low would suffice. The circuit must be relatively small because I want to fit it into the existing adapter.Thanks again!

author: Kim Christensen
author_rank: Super Contributor
timestamp: December 12, 2021, 06:12:27 pm
content: Browsing the comments on AliEx came up with this:QuoteIt looks like it draws quite a bit of standby current (5.6ma) so it would drain the battery if left in circuit. ie: You'd lose 134mAh a day.
Low voltage constant current battery drain - Page 1
Forum section: electronics / beginners

author: vincevl
author_rank: Newbie
timestamp: July 15, 2012, 02:30:06 am
content: Hi Folks,I've been experimenting with building a Nickel Iron battery and I have my first cell working. I've been able to charge the cell using my bench power supply. However I want to drain the battery using a constant current load so I can test the cell performance.Presently I've been draining the battery using a Joule thief LED circuit that draws about 25mA but the problem is that as the battery drains the load drops. The charged cell is 1.4V and I want to drain it down to 0.8V at about 50mA.I searched the web and found LM317 circuits but they are unstable with Vin < 1.25V.Any suggestions for a circuit would be appreciated. Please keep it simple I'm a newbie to electronics.Many thanks,Vince

author: IanB
author_rank: Super Contributor
timestamp: July 15, 2012, 03:03:47 am
content: There is a classic two transistor circuit for constant current sinks. You can see it illustrated in this recent video of Dave's:
Low voltage differential oscilloscope probes/preamps - Page 1
Forum section: electronics / beginners

author: kelemvor
author_rank: Regular Contributor
timestamp: December 18, 2023, 09:16:08 pm
content: I'm looking for a low voltage differential probe to use with my riglol mso5354.I'm sure someone must have asked this before, but when I search on the site, I get almost exclusively results related to high voltage differential probes such as those made by micsig.Hopefully, everyone doesn't find this post to be super annoying in that regard.I'm looking to probe audio signals and maybe the odd low-frequency device with it.My home office/lab has a lot of common mode noise. I've taken various approaches to eliminating it, but it's still there unless I turn off all the lights and most of my extra gear.My budget is only about $400, so true pro gear will be out of the question.So far, I've come across very few:e-equipment ee-701https://www.ee-quipment.com/products/differential-preamplifier?variant=35410631368Oscilloscope Preamplifier LNA10https://www.alphalabinc.com/products/lna10/generic scamazonhttps://www.amazon.com/Virtual-Oscilloscope-Differential-Bandwidth-Amplifying/dp/B0CJQLZ5VBAre there others or a build-it-yourself kit-type project that I should be looking at?Honestly, I'm not even sure I'm describing the thing right. In some places, it's a differential probe; in others, it's an LNA. As far as I can tell, the devices in question are a lna and diff, and the manufacturer picked just one for the product description. Am I wrong about that?

author: TimFox
author_rank: Super Contributor
timestamp: December 18, 2023, 10:36:24 pm
content: Look at eBay for PAR (Princeton Applied Research) differential preamplifiers, which are suitable for DC through high audio, and include switchable lpf and hpf filters.

author: CaptDon
author_rank: Super Contributor
timestamp: December 18, 2023, 11:29:04 pm
content: You could build your own easily. Go with a pair of 9 volt batteries through a D.P.S.T. power switch to give a dual polarity supply. Pick almost any suitable 8 pin DIP quality opamp 5532 etc. Bring out the + and - inputs through perhaps 10K resistors and set the loop for a gain of 10 to preserve bandwidth. You could even add another D.P.S.T. switch arranged so you have capacitor coupling into the 10K resistors and use the switch to short across the capacitors for D.C. response. With a S.P.D.T. Center Off switch to bridge the loop resistor you could even have selectable gain set up as 1, 100, 10. If you have a good junkbox collection you probably already own everything you need. You won't be able to use this rig for plate voltage signals in tube amps but it should work well for almost any low voltage signal in grid and cathode circuits or nearly any solid state preamp / driver circuits you may encounter. I have used exactly the described device to look at differential noise between signal nodes. Granted, the 10K resistors may load your device under test. There are tradeoffs like perhaps FET input opamps and higher value input and loop resistors. Battery power helps reduce noise that would be generated if using a local line operated power supply.
Low voltage high current power supply - Page 1
Forum section: electronics / beginners

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: August 04, 2017, 05:27:45 pm
content: I already have a linear bench top power supply - 0 - 30 VDC and 0-5A with current and voltage control but I occasionally also need to high current power supply for certain hobby projects like electroplating etc. The requirement is for a DC output may be around 0.5 to 1V and current upto 25A.I don't need anything elaborate something quick and dirty would do.Is there any switching topology (non-isolated ok) that can convert the bench top 0 to 30 to say something like 0.5V, 25A, If I look at it the other way I would say a 0-25A adjustable constant current power supply.What kind of simple switching topologies can provide this kind of constant current.In case this can be done with a PC ATX power supply with minor modifications etc. is also OK.TIA

author: mariush
author_rank: Super Contributor
timestamp: August 04, 2017, 06:06:49 pm
content: Don't waste your time, much cheaper to just buy ready made20A:12$ 0.6 ~ 5.5 V20A3V - 14.4V Input :https://www.digikey.com/product-detail/en/cosel-usa-inc/BRNS20/1776-1112-ND/704423516.4$ 0.51 ~ 3.63 V 20A 4.5V - 14.4V Input :https://www.digikey.com/product-detail/en/ge-critical-power/UJT035A0X3-SRZ/555-1399-1-ND/681892417.5$0.45~ 5.5 V 20A 3V - 14.4V Input :https://www.digikey.com/product-detail/en/fdk-america-inc-a-member-of-fujitsu-group/FGMD12SR6020NA/SY-618CT-ND/414626935A :31.5$ 0.51 ~ 3.63 V 35A 4.5V - 14.4V Input :https://www.digikey.com/product-detail/en/ge-critical-power/UJT035A0X3-SRZ/555-1399-1-ND/681892440A:0.45 ~ 2 V40A 4.5V - 14.4V Input :https://www.digikey.com/product-detail/en/ge-critical-power/MDT040A0X3-SRPHZ/555-1303-1-ND/3131780You can configure the output with a resistor (potentiometer).More options here (some filters pre-applied, you can remove them) :https://www.digikey.com/short/3v1ddd

author: ZeroResistance
author_rank: Frequent Contributor
timestamp: August 04, 2017, 08:00:53 pm
content: @mariushThese are amazing devices... Many thanks.I see that the voltage is programmable via an external resistor, what if I want to set it to constant current mode I mean are there any parts available where I can set a current of say 20A although the datasheet does say that it has over current protection.It would be interesting to know what kind of topology do this devices use?
Low voltage LM317 power supply power up - Page 1
Forum section: electronics / beginners

author: Tim T
author_rank: Contributor
timestamp: August 18, 2015, 02:04:48 am
content: Several years ago before becoming interested in electronics I built a low voltage power supply to be used as a diagnostic tool for quartz analog watch movements, the idea being to see how low a voltage under which the movement will still run. A movement in good condition should still work at about 0.8v, possibly lower.Anyhow, the circuit I followed uses variable output from a LM317 going to the positive terminal on the watch movement while the 5v output from a LM7805 is fed into the negative, allowing for overall voltage to be as low as 0.2 or so and topping out about 3v.The interesting part are these scope readings taken at power up with no load, just the probe attached to the power supply output terminals, or output from the individual regulators. where voltage first goes slightly negative, then ramps up to a mid point (overshooting a bit), then ramps up a second time to get to the 3v target in this case.Would this be a correct description of what is happening? As a newbie, it appears to me that it takes about 100us for the 317 to match the 5v from the 7805, it then ramps up and settles down for about 400-600us to an overall output of +1.25v (the 317's reference voltage) where regulation kicks in. At this point the 317 then brings the final output up to the +3v (+8v from the 317 , – 5v from the 7805).This might be old hat to many people but it is pretty cool to me.thanks,
distortion at low volume stereo amp - Page 1
Forum section: electronics / beginners

author: kasumyku
author_rank: Regular Contributor
timestamp: January 30, 2014, 03:57:25 am
content: hello everyone!found a pair of pc speakers in recycling room( wrong place to discard electronics...) and hoped that wont work so I can learn more about electronics and my wish came true:))) but now I cant figure out what the problem is...-symptoms:sounds OK up to about 10% of the volume, anything after that sounds distorted.-what I have checked so far:1)looked for shorted wires, but doesn't sound like shorted wires because it sounds clear up to 10% of its volume2) found a leaky capacitor, checked it with ESR meter, much higher resistance than what it should be... replaced bad capacitor and same symptoms...Brain of this little amp is a TEA2025B chip... everything else on the board is only caps, 1 pot for the volume(also is for on or of )and 1 transistor which i pulled it out of the board and it checked good.Any guidance would be much appreciated and thanks in advance!!!

author: Greg Robinson
author_rank: Regular Contributor
timestamp: January 30, 2014, 04:02:34 am
content: 1st rule of electronics repair: measure voltages!

author: kasumyku
author_rank: Regular Contributor
timestamp: January 30, 2014, 04:06:02 am
content: Quote from: Greg Robinson on January 30, 2014, 04:02:34 amAny wake up call its more than welcome, but guidance would more appreciated...

author: Greg Robinson
author_rank: Regular Contributor
timestamp: January 30, 2014, 07:49:48 am
content: Well, have you actually measured voltages? If you did you didn't mention it, just testing caps and a transistor, something beginners will often do while forgetting about voltages.

author: Unknown
author_rank: Unknown
timestamp: January 30, 2014, 02:49:29 pm
content: a) As everyone's mentioned, measure voltages. Without that basic level of troubleshooting you're not fault-finding, your guessing.b) Dunno about that chip particularly but most similar ones of that time & ilk are notorious for either being really prone to supersonic oscillation unless the layout and surrounding circuitry is spot-on, or half-dying and distorting at higher volumes.Voltages. Datasheet. Compare...

author: SeanB
author_rank: Super Contributor
timestamp: January 30, 2014, 08:31:14 pm
content: Distorted sound means change the 100uF capacitors attached to pins 3 and 14. Use ones rated for 25V or more. That should improve things a lot, but it is still a pretty low fi unit.Datasheet here.http://www.futurlec.com/Datasheet/Linear/TEA2025.pdf