hybridfree/eevblog-posts huggingface dataset:
Red SMD glue, what is it and where can I get some - Page 1
Forum section: electronics / projects

author: jeremy
author_rank: Super Contributor
timestamp: June 12, 2014, 01:10:01 am
content: Hi all,I've seen a lot of devices that have SMD components glued down with some red glue. I've been told that this is to allow a double sided board to only pass through one reflow cycle.Does anyone know what this stuff is? Or where I can get it?

author: ovnr
author_rank: Frequent Contributor
timestamp: June 12, 2014, 01:16:17 am
content: Unless you bump the board while it's reflowing, it's generally fine to not glue small parts. Anything bigger than a 1206 would need to be glued down, though, unless it's got large pads (think QFN).The glue is mainly used for wave soldering processes. It also requires an oven cure process, which is somewhat inconvenient.As for where to get it: A quick search yieldedthis oneon Digikey, and there are a variety of hits on eBay.

author: Stonent
author_rank: Super Contributor
timestamp: June 12, 2014, 01:17:13 am
content: Loctite maybe?Ah. I see the digikey stuff is made by loctite also.

author: SeanB
author_rank: Super Contributor
timestamp: June 12, 2014, 04:38:36 am
content: Speak to Digikey as above or ask your local Loctite agency if they have it in stock or can order it for you. Part number 235130. Nothing else works, and it is likely to be quite expensive, but you only use a small amount at a time. You need to place it, place the components then cure at elevated temperature for a specific time then reflow it.

author: jeremy
author_rank: Super Contributor
timestamp: June 12, 2014, 05:16:09 am
content: Well I just called Henkel, and apparently no one sells it in all of Australia. The only supplier I found that knew anything about it said they hadn't stocked it for 15 years. Apparently no one was buying it and they were constantly throwing it out due to shelf life. Shame.Digikey it is I suppose. Thanks for the tips guys.

author: jeremy
author_rank: Super Contributor
timestamp: June 12, 2014, 05:51:35 am
content: Ok scratch that, even digikey won't sell it to me:"Due to restrictions, we are unable to add this item to your order." And if you search for it on digikey.com.au, it doesn't show up.Any ideas?Edit: Talked to a digikey rep, apparently contains hazardous substances so only ships to continental US.

author: amc184
author_rank: Regular Contributor
timestamp: June 12, 2014, 06:17:08 am
content: RS Australia has some listedhere, might be worth a try.I thought the main application of these types of glues was for wave soldering. You'd wave solder both the SMT and THT components at once, with the SMT stuff glued to the bottom side and the THT stuff loaded on the top side. That may be a bit dated now though.

author: jeremy
author_rank: Super Contributor
timestamp: June 12, 2014, 06:26:15 am
content: Well looks like the RS equivalentherehas no datasheet, just an MSDS. So I have no idea what the curing process isEdit: found the datasheet here:http://www.esmanelektronik.com/files/Electrolube/tds/ER2117.pdf
reduce Ripple in Negative Voltage - Page 1
Forum section: electronics / projects

author: dpjb2923
author_rank: Newbie
timestamp: November 20, 2020, 05:46:01 am
content: Hello, I am a newbe here at eevblog.Presently I am building a power supply with both adjustable positive and negative voltage. (220VAC to 24VDC)Due to David's reducing ripple video, I understand how to do it with adjustable positive voltage but not negative voltage.I will use an LM337 to adjust negative voltage. I am not sure how to set it up to reduce Ripple on the negative voltage side.here is a schematic of about what I am doing.does anyone have a link or can confidently advise how to do it?Thanks for your time

author: dpjb2923
author_rank: Newbie
timestamp: November 21, 2020, 04:56:37 am
content: I am assuming by the lack of response there is no way to do this?I was hoping to use a BJT, or Darlington pair or Mosfet to accomplish low ripple for lower ripple in negative voltageShould I just be satisfied with RC filter?Thanks

author: gcewing
author_rank: Regular Contributor
timestamp: November 21, 2020, 06:13:17 am
content: Whatever you're planning to do on the positive side, do the same thing upside down on the negative side with complementary parts (PNP instead of NPN, P-channel instead of N-channel, etc.)

author: ejeffrey
author_rank: Super Contributor
timestamp: November 21, 2020, 04:53:21 pm
content: Link to the video you are taking about?You can make most any transistor circuit work on a negative rail by flipping NPN and PNP transistors. But generally you don't need to add additional ripple rejection after a linear regulator. If you are taking about a capacitance multiplier circuit that is normally used to reduce ripple on an unregulated supply.

author: dpjb2923
author_rank: Newbie
timestamp: November 22, 2020, 11:15:03 am
content: Here is the link:Is it possible to have on a diagram?

author: gcewing
author_rank: Regular Contributor
timestamp: November 24, 2020, 11:03:16 am
content: Something like this.

author: dpjb2923
author_rank: Newbie
timestamp: November 24, 2020, 04:31:36 pm
content: My most sincere thanks for you efforts and time to do this for meSeems I still have a lot to learn in electronics

author: sam[PS]
author_rank: Contributor
timestamp: December 20, 2020, 09:22:06 pm
content: I think you are misunderstanding the video. What Dave is presenting here is what's called capacitor multiplier. It generally goes in place of a regulator in applications that demand high curent and/or very low bom cost. If you want both ripple filtering and regulation the ripple filtering IE cap multiplier (what Dave is presenting on this video) should go before the regulator in place of C1/C8 on your 1st post schematics.As for how to apply it to negative side use what's been showed by gcewing. I would just had another cap in parallel with the input to get at least some filtering on higher frequency where your transistor hfe is dropping, beware that high current darlingtons generally have much lower maxF than small signal ones.Just my 2cts...
Reduce Tantalum Capacitor Leakage - Page 1
Forum section: electronics / projects

author: edba
author_rank: Contributor
timestamp: September 20, 2023, 10:08:21 am
content: Is it possible to reduce the tantalum capacitor leakage by connecting two capacitors in series? I don't think it is as you still need the same capacitance.e.g. if I have a 50 uF capacitor running at 5 V and the CV (uA) leakage characteristic is 0.1 CV such that 50 uF x 5 V x 0.1 = 25 uA. If you connect two 100 uF capacitors in series you get half the voltage across them so 100 uF x 2.5 V x 0.1 = 25 uA.

author: wraper
author_rank: Unknown
timestamp: September 20, 2023, 10:14:56 am
content: You probably be better just using a capacitor with higher voltage rating. However if current leakage is an issue, why use tantalum to begin with?

author: moffy
author_rank: Super Contributor
timestamp: September 20, 2023, 10:26:47 am
content: If it is a dc voltage you can use 2 capacitors in series with a high value resistor connected to where the two caps connect, so that the voltage applied to the other end of the resistor is roughly the same as the input voltage, so that the input cap has nearly 0V across it and almost no leakage current. It only works for certain configurations and means you are effectively bootstrapping one of the capacitors. Don't know if it would work in your case, it is effective for the low pass filter of voltage references.

author: liaifat85
author_rank: Regular Contributor
timestamp: September 20, 2023, 10:28:09 am
content: You may find this article helpful in this regard:https://www.linkedin.com/pulse/tantalum-capacitor-leakage-current-control-prediction-vladimir-azbel?trk=article-ssr-frontend-pulse_more-articles_related-content-card

author: cathykai
author_rank: Newbie
timestamp: July 10, 2025, 07:30:22 am
content: Connecting two capacitors in series increases the total leakage resistance, which lowers the overall leakage current you measure. Since the voltage divides between them, each capacitor experiences less voltage, further reducing leakage per capacitor.That said, the intrinsic leakage of each capacitor remains unchanged—this only reduces the combined leakage seen at the terminals. Also, remember that total capacitance decreases and voltage imbalance can occur if the capacitors aren’t well matched.For a deeper explanation, there’s a good discussion on tantalum capacitor leakage on Stack Exchange that you might find useful.
Reducing Current Consumption in the PCB - Page 1
Forum section: electronics / projects

author: A.Ersoz
author_rank: Regular Contributor
timestamp: March 21, 2019, 04:58:33 pm
content: Hi,I tested my custom design PCB with four SPST analog switches and four opamps and total current consumption seems on power supply around 80mA. Now, I added 28 analog switches and 28 opamps on PCB. Now, the current level is 700mA. The linear voltage regulator is heating too much. So, why the problem can be occur? Output of linear regulator is 150mA.Thanks

author: TimNJ
author_rank: Super Contributor
timestamp: March 21, 2019, 05:33:56 pm
content: Are you asking why your linear regulator is getting too hot? It seems you've already kind of answered that!

author: Kleinstein
author_rank: Super Contributor
timestamp: March 21, 2019, 05:46:01 pm
content: Usually the CMOS SPDT switches use essentially no current (e.g. < 100 µA). For OPs using 80 mA is quite a lot - there must be quite some load to them.With 7 times the circuit one can expect 7 times the power supply: 7 times 80 mA would be 560 mA so already quite a bit. 700 mA is little more, but not that much.Chance are the circuit is bad from the beginning - either a poor plan, a wrong inserted part or a broken one.So back to the simpler 4 OP circuit and bring the current down to some 10-20 mA or less.

author: iMo
author_rank: Super Contributor
timestamp: March 21, 2019, 06:18:17 pm
content: 4kg of apples cost $80.How much (4+28)kg of apples cost?32/4*80=$640.You can hardly get 640mA out of a 150mA voltage regulator.The temperature of a LINEAR voltage regulator package could be calculated as follows:T = Tamb + (Vinput-Voutput)*Ioutput*thermal_resistance_of_the_packageExample:Tamb = 25degCVinput=15VVoutput=12VIoutput=150mAthermal_resistance_of_the_package=60degC/WattT=25C+(15V-12V)*0.15A*60C/W=25C+27C=52CThe thermal resistance of the package you will find in the datasheet, it depends on the copper area beneath the smd package, or the type of a heatsink attached.
Reducing inductor whine? - Page 1
Forum section: electronics / projects

author: Pack34
author_rank: Frequent Contributor
timestamp: March 27, 2017, 04:29:40 pm
content: I'm noting some coil noise (inductor whine) in one of my designs.The current design uses an Abracon 10uH 4A inductor (datasheet can be found at the end). I've used this inductor in the past with similar designs (modulating a TEC) and have not noticed an issue until now. The change was moving towards a much higher current TEC. The audbile noise seems to creep up when I get into the 1.0A to 1.5A range. I had assumed that these would be fine since both the current rating and current saturation far exceed the maximum expected current (3A for 10 seconds).My main question is what parameter could be used as an indicator to mitigate this? The switching frequency of the TEC driver is 550 kHz with the datasheet for the inductor states that the part should be good for applications up to 3MHz.Everything seems to be within spec and the circuit operates fine, but it still has that audible whine. Any ideas on what I could be overlooking?https://www.digikey.com/product-detail/en/abracon-llc/ASPI-0630LR-100M-T15/ASPI-0630LR-100M-T15CT-ND/3060143

author: Benta
author_rank: Super Contributor
timestamp: March 27, 2017, 04:35:24 pm
content: If you can hear it, it's subharmonic oscillation. This can be a problem of the chosen topology, or also an issue with the loop compensation.

author: MagicSmoker
author_rank: Super Contributor
timestamp: March 27, 2017, 04:37:49 pm
content: An audible whine from an inductor with a switching frequency of550kHz???That means your feedback loop is unstable and oscillating. This eventually results in the destruction of the switch...NB - it's not subharmonic oscillation as that is almost always at 1/2 the switching frequency so still not audible.

author: Benta
author_rank: Super Contributor
timestamp: March 27, 2017, 06:19:03 pm
content: QuoteI beg to differ. That's topology dependent and can be any fraction of the switching frequency.The old MC34063 had a tendency to do this under partial load.

author: MagicSmoker
author_rank: Super Contributor
timestamp: March 27, 2017, 07:33:30 pm
content: Quote from: Benta on March 27, 2017, 06:19:03 pmSubharmonic oscillation is a phenomenon peculiar to current mode converters and is caused either by too much inductance (ie - too little ripple current) or premature pulse termination on one cycle - usually due to stray capacitance in the inductor causing a leading edge spike - followed by an extra wide pulse on the next cycle to make up for the energy deficit (this is the classic definition of subharmonic oscillation).The '34063 is a hysteretic mode controller so it is incapable of either kind of instability. Any audible noise from its operation at partial load is likely from it skipping pulses (I've never seen it do this, though I don't doubt it is possible, especially if the inductor isn't varnished or potted).
Reducing noise in microphone pre-amp. - Page 1
Forum section: electronics / projects

author: DanKalc
author_rank: Newbie
timestamp: December 25, 2013, 03:04:15 pm
content: Hi,I'm trying to build a simple microphone circuit, but my results aren't so great. I have very high noise level on the output, is it possible to reduce it?I'm using OP07 with has a low noise level about 10nV/rHz. Supply voltage for this amp is +-3V. I made it on a breadboard and tried to lock it in a faraday cage from tin foild, but noise is still very high.datasheets:OP07 (http://www.analog.com/static/imported-files/data_sheets/OP07.pdf)

author: Zero999
author_rank: Super Contributor
timestamp: December 25, 2013, 03:29:17 pm
content: What power supply are you using?Is the microphone cable screened?

author: Sander
author_rank: Contributor
timestamp: December 25, 2013, 04:22:45 pm
content: The higher the values of the resistors get, the higher their noise will be. I will suggest you lower the value on the input filter (and as a result, increase the value of the cap). Also your gain is a bit high as far as I can see. Lower the feedback resistor, 1Meg is really high! You might want to increase the voltage on the microphone “pickup element” (only if it is a capacitor microphone configuration!) to about 50 volts to get more signal on the input of the amplifier.Oh, and ditch the breadboard. Solder it point to point on a piece of blank PCB.

author: w2aew
author_rank: Super Contributor
timestamp: December 25, 2013, 04:42:57 pm
content: ...and, don't forget the power supply bypass capacitors!

author: fcb
author_rank: Super Contributor
timestamp: December 25, 2013, 09:00:54 pm
content: You need to put a BIG filter on the 4k7 biasing resistor. Every uV of noise on the Vcc is going to be 'audio'.Measure the noise with (1) the input shorted to gnd (2) with a 4k7 to gnd (3) with no microphone [noise from the 4k7 bias resistor].OP07 is good, but not worth the extra c.f. NE5534/32

author: KJDS
author_rank: Super Contributor
timestamp: December 25, 2013, 09:07:32 pm
content: First, work out how much gain you need then reduce the 1M0 down to something sensible. If you drop the gain by 10 then the noise will also drop by that amount.Then add some supply decoupling. That 4k7 may be better off going to a well decoupled linear regulator powered of Vcc. That would remove a lot of power supply noise. Is the mic cable properly screened?

author: mhzghz
author_rank: Contributor
timestamp: December 26, 2013, 05:37:02 am
content: Quote from: DanKalc on December 25, 2013, 03:04:15 pmR4 should be 10x your source impedance.Adjust C1 according, but you really want C1 as large as possible to reduce your source impedance noise.Reduce R3 to something more reasonable, say 10k, with a 1000 pF cap in parallel.Replace R2 with a series 2.2 uF / 100 ohm resistor for your filtering.Add series 10 ohm resistors in the +/- Vcc power lines and large caps as close to +Vcc and -Vcc as possible.
Reducing output noise from PWM LED driver (Chinese jammer-in-a-lamp!) - Page 1
Forum section: electronics / projects

author: ironcurtain
author_rank: Regular Contributor
timestamp: June 17, 2015, 05:45:40 pm
content: Hi!I've been doing some tests with an infamous LED driver that multiple people have reported as extremely noisy. 30dB output wideband noise.... I can post spectrum analyzer photos later.These come marked as 'CE' but that is absolute horsesh*t (100% counterfeit markings, I've seen private correspondence between one buyer and the manufacturer where they clearly state it never passed any certification and their CE certificate is completely fake):http://www.aliexpress.com/item/Free-Shipping-led-downlight-ceiling-panel-lights-15w-super-bright-lighting-smd-2835-flat-lamp-for/1798227452.htmlThings I tried:Use material 43 ferrite toroids at outputs and a proper AC input filter.The above plus shielded case.Neither of which worked. I'm going to test soon with a 1000uF 100V electrolytic at the output, plus probably a decoupling capacitor to the ground plane.I'm curious if anyone has suggestions, before I proceed to tell people to report these and throw them away. It seems we cannot trust the government(s) in Europe anymore to properly inspect the crap that importers rebrand and repackage from China (these are sold for 2-3x after rebranding in local stores across Europe, including big 'ole house improvement chains).If you know someone doing ham radio or RF work... these are his greatest enemy only after plasma TVsThe harmonics go up to UHF still at 40-50dBm levels. They will also interfere big time around 230MHz, beyond the HF/shortwave spectrum.

author: technix
author_rank: Super Contributor
timestamp: June 17, 2015, 08:04:30 pm
content: Rip the thing apart and replace all inductors and caps in it?

author: ironcurtain
author_rank: Regular Contributor
timestamp: June 18, 2015, 01:17:20 am
content: Quote from: technix on June 17, 2015, 08:04:30 pmI will upload pictures soon.This thing is quite barebones. When you say replace caps, you mean adding a Pi network or some filter?The PWM IC is marked CL 1226, 4wDA22C. I have found a datasheet in Chinese only. Multiple M7 diodes, a low ESR 10uF electrolytic and B102K cap rated for 1kv. It has a small transformer, but no markings.

author: ivan747
author_rank: Super Contributor
timestamp: June 18, 2015, 12:55:47 pm
content: Chinese jammer in a lamp ha-ha, good oneI am guessing this is an experiment to see how much would it take for this design and layout to pass any sort of EMI testingSent from my XT1063 using Tapatalk
Reducing switching power supply noise seen on o-scope? - Page 1
Forum section: electronics / projects

author: Plasmateur
author_rank: Regular Contributor
timestamp: March 27, 2018, 05:33:22 pm
content: Can an isolation transformer or some other component help eliminate noise from a switching power supply?

author: rhb
author_rank: Super Contributor
timestamp: March 27, 2018, 10:54:09 pm
content: It's rather case specific. Depends on whether the noise is conducted or radiated. Ferrite cores over the power lead will reduce conducted noise, but not radiated noise. The latter requires shielding.I'm looking at a bunch of noise produced by the LED fluorescent tube replacements and wondering what to do about that.Good luck.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: March 28, 2018, 12:45:12 am
content: Simple, turn them off or use incandescent or halogen, they don't generate noise.

author: rhb
author_rank: Super Contributor
timestamp: March 28, 2018, 12:51:59 am
content: I jealously guard my stash of 100 watt incandescent lamps.I really do need to suppress the noise pickup. I've also got lots of other noise sources. It's a bit hard to do embedded work without a computer.

author: Edwin G. Pettis
author_rank: Frequent Contributor
timestamp: March 28, 2018, 12:57:54 am
content: Plasmateur, most of what you are seeing on your scope is likely radiated noise which is being picked up by not only your scope probe but the circuit you are probing, shielding is the first line of attack in the case of a 'finished' commercial switcher but the best line of attack is to minimize the noise at the source. When dealing with a commercial power supply that is not so easy to do, most of that noise is radiated right in the power supply, primarily in the magnetics and then to a lessor degree in the components/wiring. The case of the supply is usually grounded but that often has less than great results in damping the noise. You can try putting ferrite cores on the wiring comping out of the power supply but this will not dampen the lower frequencies, mostly above 10MHz. Another tact is to keep the power supply as far away from the circuitry as possible, radiation drops with the square of the distance. Appropriate shielding around your circuits can help keep noise out of them, aluminum is not good for that, steel is better. In sensitive circuitry you can go to mu-metal but that is a more expensive solution.
Redundant Power Input Protection  - Page 1
Forum section: electronics / projects

author: Sivand12
author_rank: Contributor
timestamp: November 18, 2014, 11:28:32 am
content: A bit of a generic / fundamental question regarding protection redundancy within circuits. Am grateful for your thoughts!For good product design, is it still valid to rely on the built-in protection and filtering of an external DC wall-pack? For a low-power device (5 V input), hooked up to a quality DC wall adapter with proprietary polarized connectors, is it necessary to ALSO build in redundant power input circuitry onto circuit itself, for dealing with gross transient and reverse polarity conditions?My circuit is battery powered and only plugged in for short periods of time to charge an internal lithium-ion battery. There's power management that will switch to wall power and charge the battery at the same time. There's some sensitive analogs in there and I’ve incorporated ESD protection, overcurrent protection, and minor overvoltage protection (i.e., Tolerating few volts above nominal by means of Zener). But is it sufficient to assume large overvoltage conditions (transients, etc.) will be filtered by the quality wall pack? In this case, it might open a large can of worms having to deal with thermal considerations during handling of large transients due to the battery aspect.Thanks very much in advance,

author: Paul Price
author_rank: Super Contributor
timestamp: November 18, 2014, 04:37:38 pm
content: IMHO,No, not necessary, with proprietary connector if good quality of charger p/s components chosen.

author: splin
author_rank: Frequent Contributor
timestamp: November 18, 2014, 06:37:52 pm
content: It looks like this has been comprehensively answered in the previous reply but just a few thoughts:I'm guessing it partly depends on exactly how 'unique' the power connector is - don't underestimate how determined an uninformed/distracted/forgetful/drunk user may be in attempting to force-mate the connector from the wrong PSU.Because of the safety risks associated with LI-ion batteries, which in the worst case could lead to a fire causing loss of life, I think you need to be very careful - especially if your product is to be sold in the USA, where product liability lawsuits can bankrupt individuals and companies. I'm no expert in this area and definately not a lawyer though.What about high voltage transients due to overhead lines shorting together in storm conditions, or lightning strikes which in some areas is very common? Are you going to specify exactly what protection is to be provided by the PSU - 'quality' doesn't mean much in this context. Typical wall-warts that I've opened up (to repair) don't provide much beyond a fuse and sometimes the filtering of an electroytic capacitor (for non-switch mode supplies at least).Your equipment becoming non-functional due to a mains transient is one thing; damage which could subsequently, perhaps long after the event, cause your circuit to malfuncton and cause a lithium battery to catch fire is another.Tony H
Redundant Power Input Protection - Page 1
Forum section: electronics / projects

author: stoic
author_rank: Newbie
timestamp: June 26, 2014, 06:38:16 pm
content: A bit of a generic / fundamental question regarding protection redundancy within circuits. Am grateful for your thoughts!For good product design, is it still valid to rely on the built-in protection and filtering of an external DC wall-pack? For a low-power device (5 V input), hooked up to a quality DC wall adapter with proprietary polarized connectors, is it necessary to ALSO build in redundant power input circuitry onto circuit itself, for dealing with gross transient and reverse polarity conditions?My circuit is battery powered and only plugged in for short periods of time to charge an internal lithium-ion battery. There's power management that will switch to wall power and charge the battery at the same time. There's some sensitive analogs in there and I’ve incorporated ESD protection, overcurrent protection, andminorovervoltage protection (i.e., Tolerating few volts above nominal by means of Zener). But is it sufficient to assume large overvoltage conditions (transients, etc.) will be filtered by the quality wall pack? In this case, it might open a large can of worms having to deal with thermal considerations during handling of large transients due to the battery aspect.Thanks very much in advance,-S
Reed Relay for Janis 9T 1.5K measurement system - Page 1
Forum section: electronics / projects

author: mechknoll
author_rank: Contributor
timestamp: January 05, 2015, 05:32:35 pm
content: Good day!I have a measurement system a colleague and I have pieced together for material characterization. Its a 9 Tesla superconducting magnet with a CCR that is capable of reaching 1.5 Kelvin. Pretty sweet piece of equipment. For one of our measurements we use an AC resistance bridge. The instrument can only measure one sample at a time (4 probe), but we can mount two samples in the chamber with electrical leads going to a homemade router box. This requires us to manually switch BNC cables to measure the separate samples. What I have been looking into and what my question is about is reed relays. I have the whole system programmed through LabView and want a box with reed relays to switch between the two samples at each measurement interval (Temp, and Field). I am looking at the Meder BE series of relays and using a NI-DAQ to control the switching.These are very sensitive measurements, nano-Ohm range. Are there some obviose pitfalls with reed relays? Leakage? or any advise from someone more experienced.Thank you in advance. Don't want garbage in then publish garbage

author: mechknoll
author_rank: Contributor
timestamp: January 05, 2015, 05:39:09 pm
content: Here is a pic of the system. Also the relay will be located on the instrument rack. The stray field there is minimal so it shouldn't effect the operation of the relay.

author: MK
author_rank: Regular Contributor
timestamp: January 05, 2015, 06:50:46 pm
content: You might do better with latching relays, as they do not have to be continuously powered, so have less thermal emf's

author: Vgkid
author_rank: Super Contributor
timestamp: January 06, 2015, 11:19:21 pm
content: no thermal emf's to worryabout in the system, though you could always use these.Nice mix of Linear Research, and Lakeshore gear. I was contomplating bidding on a really beat up LR400 ac bridge, on ebay.

author: MK
author_rank: Regular Contributor
timestamp: January 07, 2015, 06:50:07 am
content: Quote from: Vgkid on January 06, 2015, 11:19:21 pmI was meaning the thermal emf's of the relays, reed switches use Kovar leads through the glass, ~40 uV C-1, and the relay pumps in power to run the coil, so the lead ends heat up and give small emf's at the lead/pad termination.

author: mechknoll
author_rank: Contributor
timestamp: January 07, 2015, 06:50:41 pm
content: Thanks for the reply, any thermal drift may pose a problem with these sensitive measurements. Im looking into some latching relay like you advised @MK. Also our LR700 is a very nice piece of equipment. astounding how it stays in spec after so many years.
REED Relays ELECTROL - Page 1
Forum section: electronics / projects

author: frantisek
author_rank: Regular Contributor
timestamp: November 05, 2024, 08:38:13 am
content: Does anyone know or even have a catalog for about ELECTROL reed relays? Somewhere it says ELEC-TROL. It is specifically type RA 3023-1051-96. They look like IO DIL, they have 8 pins. Thank you
Reed switch coil design - Page 1
Forum section: electronics / projects

author: edba
author_rank: Contributor
timestamp: April 28, 2020, 06:39:31 pm
content: HiI have a reed switch (STANDEXMEDER MK23-85-C-2) and I want to wind a coil onto the glass body to be able to operate as a reed relay. The reed switch glass body winding area is 15mm appx x 2.75mm dia winding area. The contacts are specified to close between 15-20AT. I know I had a book years ago explaining how you could wind a coil on the body to operate it. Ideally I would want to operate the reed relay with a 20mA current at 5V. Does anyone know about the calculations involved in working out the number of turns required?Edba

author: langwadt
author_rank: Super Contributor
timestamp: April 28, 2020, 08:25:08 pm
content: something along these lines 20AT/20mA = 1000 turns, adjust wire size until you get 5V/20mA = 250 Ohm

author: edba
author_rank: Contributor
timestamp: May 01, 2020, 07:59:29 pm
content: HiThamks for your reply. I would like to do a bit more reading about this, do you know of a good tutorial on the web? Also do you know of the formula for calculating the length of wire vs no. of turns for thickness of wire. I have done some coil design but not for about 25 years!Edba
Reed switch vs Hall Switch for 3/4" or more sense distance - Page 1
Forum section: electronics / projects

author: 1sciguy
author_rank: Contributor
timestamp: July 21, 2022, 09:44:36 pm
content: Anyone here have experience with Hall switches in comparison to Reeds? Can I generally get a longer sensing distance for any given magnet strength with Hall than with a typical reed? I am contemplating building a coded switch with a specific north-south configuration of multiple magnets and it just seems easier with Hall, although I know it can be done with pre-biased reeds.Thanks.
Reed Switch - Page 1
Forum section: electronics / projects

author: josue
author_rank: Newbie
timestamp: December 07, 2016, 09:37:44 pm
content: Hello,Some body could help me with suggestions how I am getting higher Final Resistance in a Fuel Float Switch ?I discard processes during the assembly, but we believe the problem is the Reed Switch, but Contact Resistance, Pull in and Drop Out all these test are ok in the switch

author: kxenos
author_rank: Frequent Contributor
timestamp: December 07, 2016, 09:49:27 pm
content: Weak magnetic field? (distance or orientation problem)Bad solder joint?

author: stj
author_rank: Super Contributor
timestamp: December 07, 2016, 11:31:01 pm
content: a reed should be open or closed, unless they are damaged by previous over-current i would suspect the soldering or wires.

author: Niklas
author_rank: Frequent Contributor
timestamp: December 08, 2016, 12:01:53 am
content: What resistor values do you have in series with the reed switches? Is it a low ohm (100-200) or high ohm (several kohm) type of sensor?

author: calexanian
author_rank: Super Contributor
timestamp: December 08, 2016, 06:18:47 am
content: If its an exposed glass reed switch they are notorious for breaking and acting strange.

author: BurningTantalum
author_rank: Frequent Contributor
timestamp: December 08, 2016, 07:55:26 am
content: I'll second Calexanian's comment: Many years ago I developed a commercial project using hordes of reed switches. The leads had to be snipped (if at all) using full flush cutters as standard cutters imparted a huge G-shock acceleration along the lead and damaged the glass/lead bond. This shortened the life of the reeds randomly and dramatically.BT
Reel to reel tape recorders free to a good home - Page 1
Forum section: electronics / projects

author: Sengcid
author_rank: Regular Contributor
timestamp: February 19, 2024, 03:21:11 pm
content: Racal Store 4D (4 track) and Store 7D (8 track) including carrying cases plus technical manual and lots of unused tapes free to anyone willing to collect from near Huddersfield (not far off the M62).They are configured as data recorders (down to DC) but could be converted to direct audio recording.The tape speed/tension servos are excellent (standard fixed speed settings or continuously variable up to 60 inches/s). The 8 track has a problem in the power supply and one channel is faulty. It was my intention to replace the PSU with more modern chips but I no longer have access to the requisite facilities/equipment.Converting to audio recording is a fairly ambitious project. The alternative is the skip.If interested PM me but be quick – I will not be around for much longer.

author: cncjerry
author_rank: Unknown
timestamp: February 19, 2024, 10:10:32 pm
content: Too bad we aren't in the same geography. I have a TASCAM R2R that was considered a mastering deck to 2-track, has Dolby SR noise reduction. Sounds fantastic, great for vinyl duplication. I live in the thick of some of the greatest ex-recording studios. Almost had a 1" deck but my wife said, "NO". Oh well. Problem is that most of the tapes I've purchased are flaking now. There is a person, great guy, that last I checked was still refurbishing capstan pressure rollers.Good luck.Jerry
REF 102 Noise Reduction Capacitor Question - Page 1
Forum section: electronics / projects

author: ELzekio
author_rank: Contributor
timestamp: November 05, 2021, 07:39:11 pm
content: Hello everyone, I had a quick question about adding a noise reduction capacitor on pin 8 of the ref 102 and a bypass capacitor on the Input.While I understand these capacitors may not really be required, If I was going to use a ref 102 in the following current source application where pin 4 (common) of the REF 102 gets lifted off of ground, would it be better to connect the ground side of the bypass and noise reduction capacitors to the common/ground coming from the power supply, or would I still just connect them to pin 4 of the chip even though it is lifted from circuit ground.This is a similar question to what this individual had, but didn’t get a response:https://electronics.stackexchange.com/questions/475859/how-do-i-connect-noise-reduction-capacitors-for-stacked-ti-ref102-chips

author: Kleinstein
author_rank: Super Contributor
timestamp: November 05, 2021, 08:00:29 pm
content: Why should the capacitors go to ground ? The reference has no real reference to ground, just the load is connected to ground. So ground is no a good reference in the circuit, one could as well call it negative supply.The two capacitors should go towards Pin4. This however creates a new problem: the OP does no like the capacitive load.The noise reduction cap is no a problem, as pin 8 is a relatively high impedance input. However the supply decoupling is tricky: if one has enough supply voltage, one can add some resistand to the supply input and things are find. With a constant current to the supply the extra resistor just lowers the voltage and it makes the reference happy with isolating it from noise of the positive supply.
REF5040 maximum supply voltage - Page 1
Forum section: electronics / projects

author: nemail2
author_rank: Regular Contributor
timestamp: April 23, 2021, 09:33:59 pm
content: Hi,the datasheet for the REF5040 voltage reference (clicky:https://www.ti.com/lit/ds/symlink/ref5040.pdf?ts=1619211127644&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FREF5040) says 18V for absolute maximum input voltage and for recommended operating conditions as well.I'm asking myself now, can I run this voltage reference on a L7818CV continuously without having to fear lifetime or reliability shortage or not?It will only be powering two DAC8311 DACs which draw 160µA each MAX so that would only be around 4mW of power dissipation on the REF5040 if I'm correct.Thanks

author: bob91343
author_rank: Super Contributor
timestamp: April 23, 2021, 09:40:00 pm
content: That leaves no safety factor. I would run it at a lower voltage.

author: Vovk_Z
author_rank: Super Contributor
timestamp: April 23, 2021, 09:42:32 pm
content: It is a bad idea to run it at Absolute Maximum Rating voltage. Something like 15VDC will be safer.

author: nemail2
author_rank: Regular Contributor
timestamp: April 23, 2021, 09:50:48 pm
content: why are they putting the 18V rating into abs. max and into the recommended range as well anyway? Do they want to say something like "do it if you absolutely have to but don't expect it to last very long"?haven't really seen something like that before...

author: The Soulman
author_rank: Super Contributor
timestamp: April 23, 2021, 09:58:08 pm
content: Recommended is anywhere between V_out +0,2V and 18V.For REF 5040 anywhere between 4,3V and 18V should be ok, so conveniently a 5V supply is sufficient, anything above isunnecessary and 18V borderline dangerous.

author: KT88
author_rank: Frequent Contributor
timestamp: April 23, 2021, 10:29:36 pm
content: As the L7818CV has a tolerance of +/-2% plus a little bit of temp drift you would violate the abs. max. ratings by about 400mV.Also if any ESD event happens onto the PCB, your REF5040 will leave the building...CheersAndreas
Refactoring a "cost effective" linear power supply - Page 1
Forum section: electronics / projects

author: ovi_mv
author_rank: Unknown
timestamp: April 27, 2013, 05:14:14 pm
content: HelloI started this topic because i believe it is possible and feasible to mod the "one huang lo" linear power supply ( the ones with 2x fine+coarse adjustment pots & 2 panel meters, analog or 3½ digit ), which were sold in 10k pcs.To have a starting point i will add here the early version of the schematic (without the 7107 measurement board) used until 2006-2007. In few days time i will add up the "new" version of the schematic that i believe it to be used even on the relay&analog control of the Atten power supply described in episodes #439 and #440.
References for large signal analysis in digital CMOS - Page 1
Forum section: electronics / projects

author: ddr_controller
author_rank: Contributor
timestamp: April 08, 2023, 11:49:39 pm
content: I have been taking analog and VLSI courses and I find that while in Analog every minute detail is considered, in VLSI after the large signal analysis of the static inverter everything after looks "qualitative", for example, when introducing Latches and FFs they only talk about the stable and metastable state but never did anything quantitative, for example, where does setup and hold times come from? (I mean it is not even obvious that they should even exist)Or when they explain SRAMs the sizing of the transistors are qualitatively explained, nMOS should be big, pMOS should be small and access transistors should be in between, but how big? how small?If anyone has references of large signal analysis of digital CMOS circuits please I would be very glad if you could cite them.
References for product design methodology - Page 1
Forum section: electronics / projects

author: Ribster
author_rank: Frequent Contributor
timestamp: January 20, 2019, 04:25:40 am
content: I am looking for a guideline / methodology of designing products.It's more of a guideline/flow i am searching for, a checklist of sorts.Where you define the project, see if it's viable financially with ROI.I can think of a list, but i was wondering if there was an industry flow that could be followed or added upon.I'm looking to make a product specification that includes :- General description of the product- Financial ROI breakdown- UI / UX aspect- Software specification (how to break the software up in chuncks)- Hardware electronics- Mechanical hardwareAre there books / references / examples that can help me make my own standard project development flow, i'd love to hear it!

author: Doctorandus_P
author_rank: Super Contributor
timestamp: January 20, 2019, 04:48:02 am
content: Big Clive has made a nice video on youtube of how he etches home built circuits.All his other video's are worth watching too, so just start with the oldest untill you've seen them all.

author: Ribster
author_rank: Frequent Contributor
timestamp: January 20, 2019, 05:09:08 am
content: I know altium myself, i build my own pcb's and know how to put a project together.It's the development phase of a new project, how to manage it, that i am asking about.
References on how to control magnetic slider position - Page 1
Forum section: electronics / projects

author: mklivoslov
author_rank: Newbie
timestamp: July 24, 2025, 05:43:21 am
content: Sorry for any misrepresentation, I didn't know how to call it or whether this was the right panel...I've just came across this mechanism (photo attached) with a coil controlling the slider relative position to the fields of two static permanent magnets. I've realised it's similarity to the hard disk head mechanism; this system, however (circa 2002), uses two EOL L2724 opamps to drive the coil.Are there any materials on this type of mechanism, and how would you call it?73,MK

author: ledtester
author_rank: Super Contributor
timestamp: July 24, 2025, 06:27:47 am
content: The generic term is servomechanism or servo for short:https://en.wikipedia.org/wiki/Servomechanism

author: mikerj
author_rank: Super Contributor
timestamp: July 24, 2025, 09:23:37 am
content: A servomechanism is simply a closed loop position (or speed etc) controller, it could use any kind of actuator. The generic name for this device would be something like "moving coil linear actuator".

author: Ian.M
author_rank: Super Contributor
timestamp: July 24, 2025, 09:45:33 am
content: "voice coil actuator"https://www.machinedesign.com/mechanical-motion-systems/article/21836669/what-is-a-voice-coil-actuator

author: mklivoslov
author_rank: Newbie
timestamp: July 24, 2025, 03:19:52 pm
content: To all,Thanks for the term "servomechanism"! I've found multiple results upon the term (also for the name "moving coil linear actuator"), even came across the voice coil actuator. Even so, they're quite robust and bulky for the likes of mine. I think it fairly resembled the voice coil actuator, except the magnets are on the sides and not in the centre of the coil.Simple tracing of the control board revealed that the coil current feedback is used to position the actuator (the optical bridge on the side is just for parking detection). The device manual said that the position signal is a DAC output, but the traces on PCB told me that the signals come straight from the FPGA to 2-3 opamps before driving the actuator (haven't traced that part yet; multi-layer PCB).Anyone had any documents, schematics and theories for this servomechanism?73,MK

author: ledtester
author_rank: Super Contributor
timestamp: July 24, 2025, 10:16:48 pm
content: Quote from: mklivoslov on July 24, 2025, 03:19:52 pmOne way a digital device like a FPGA can generate an analog signal is by outputting a PWM signal which is then filtered by a low-pass filter - usually a RC filter.
Reflections in an autotransformer - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: March 14, 2025, 02:45:01 pm
content: Suppose we have a circuit driving the ends of an autotransformer. Let there be some load across the lower winding, and assume some winding resistance.How does the reflected impedance from the secondary circuit look at the primary (especially how do we deal with the secondary's winding resistance)?
Reflow advice - Page 1
Forum section: electronics / projects

author: dobsonr741
author_rank: Frequent Contributor
timestamp: December 03, 2023, 03:03:52 pm
content: I making a single PCB, experimenting with hot plate reflow on an ET-10, and placed and reflowed about half of the components. I used SAC305 mixed with flux, as I do not use a stencil. All components on a single side.Now it’s time to place the 2nd half of components, I can choose to do it again with SAC305 or I can use low temp solder. Anyone aware any risk going to 240C degree again witch SAC?No irreplaceable components are on the board, just some analog parts with passives.
Reflow hot plate controller - do I need a fuse? - Page 1
Forum section: electronics / projects

author: Peabody
author_rank: Super Contributor
timestamp: February 09, 2019, 02:44:48 am
content: I'm doing a reflow controller for the cheap Walmart hotplate, although it could also be used for a toaster oven. The mains switching is shown in the attached schematic. I've looked inside the hot plate, and see nothing that looks like a fuse, although it does have a temperature control that will open if things heat up. And I don't see anything in the SSR datasheet to suggest that it has a fuse. And even if it did, the SSR is 25A, and the hot plate is only 1000W, which at 110VAC is gonna be on the order of 10A. So if there was a short, I doubt the SSR would go open before the mains circuit breaker tripped.I'd kinda like to not bother with a fuse. But not being formally trained, I don't know what the rules are. Apparently the hot plate didn't need one, so I'm hoping I don't either, particularly since that circuit breaker (20A I assume) is there in the distribution box.
reflow station for diy? - Page 1
Forum section: electronics / projects

author: fuzzysig
author_rank: Newbie
timestamp: April 03, 2018, 03:50:38 am
content: it seems like the later electronics all commonly suffer from cold solders or solders breaking due to flexis there a small reflow station that is reasonable price that is available to use that can heat up a small portion or a single component solder?i recently realized that its a very common problem now after having to reflow a motherboard in the oven and a keyfob for mercedes and few other things...now i wish i had a specialized reflow station to make the job easier

author: fuzzysig
author_rank: Newbie
timestamp: April 04, 2018, 01:23:00 am
content: unless theres another name for that kind of tool

author: nanofrog
author_rank: Super Contributor
timestamp: April 04, 2018, 02:00:32 am
content: There's such a thing as areflow oven.Are you looking for a soldering station or hot air station? Or both?I ask, as the latter types can single joints and small areas respectively (hot air isn't all that precise, but shields can be used to prevent heating nearby components).
Reflowing my first BGA: Tips needed - Page 1
Forum section: electronics / projects

author: lawrence11
author_rank: Frequent Contributor
timestamp: September 17, 2019, 02:42:38 pm
content: So I have my controleo3 all ready, its been "learned" and received high grade, the profile program has been tested.I am reflowing on 1 chip ATM due to them being the only leadfree BGA of the gang, a 216 bga .8mm with no balls in the middle.Should I risk aligning manually? Or should I contatc somebody with an xray to help? Is manually best I can good enough?Should I put some flux on the pcb copper pads of the bga?This my fluxhttps://www.amazon.com/Solder-Welding-Electronic-Soldering-Lead-free/dp/B076M49M63/ref=sr_1_47?keywords=solder+flux&qid=1568731253&s=gateway&sr=8-47
Regarding CSR8645 BLE Module - Page 1
Forum section: electronics / projects

author: unicornBoi
author_rank: Newbie
timestamp: November 13, 2018, 08:30:54 am
content: I'm working on a bluetooth music player project for my motorbike helmet to play music on the go, and I'm using the CSR8645 BLE module. For low power applications such as small speakers/earphones, would I need an external amplifier to amplify the signal from the SPK_L and SPK_R lines? Or is the signal from the chip strong enough to power the speakers?Theres not much documentation on this chipset, apart from this website i found below.https://www.electrodragon.com/w/CSR8635