hybridfree/eevblog-posts huggingface dataset:
9V AC from a common Power Bank?.. Portable DC-AC low voltage inverter? - Page 1
Forum section: electronics / projects

author: dabrowski
author_rank: Newbie
timestamp: February 01, 2024, 03:09:58 pm
content: Greetings!I have a device called Art Tube MP, it is a small tube microphone preamp that runs from a 9V Alternating Current 1000mA power supply.I would like to use it outdoors, so I need to power him somehow from a portable source. My power bank can output 5V 3A / 9V 2A /12V 1.5A, all DC of course. Is it even possible to get 9Vac 1000mA from a standard Power Bank like that, using some kind of inverter?This is the closest thing I could find(sorry, no Amazon or eBay, only AliExpress available in my country):https://www.aliexpress.com/item/1005004693081624.html?But, it outputs 12v AC, AND it provides "square" wave. Even being a total newbie, square feels wrong. I don't think the OEM power supply for my preamp provides square, though I wouldn't know, don't have an oscilloscope, probably just reduces regular 220v sine from a socket to 9V.So, can someone please share any thoughts on this? Thanks!

author: Andy Chee
author_rank: Super Contributor
timestamp: February 01, 2024, 03:21:40 pm
content: If you supply your AliExpress inverter module with 9VDC input, the output of the inverter should be a 9VAC square wave.Whilst your preamp probably won't be damaged with a square wave, I suspect that the square wave harmonics may get into the low level audio chain.

author: dabrowski
author_rank: Newbie
timestamp: February 01, 2024, 04:17:36 pm
content: Quote from: Andy Chee on February 01, 2024, 03:21:40 pmHi!Interesting, good to know. Does it always works like this with these kind of inverters, or it's because the seeking 9V being rather close to 12V, which is stated for this particular AliExpress inverter?Quote from: Andy Chee on February 01, 2024, 03:21:40 pmOh well... unnecessary harmonics is exactly what I'm trying to avoid by building a chain that 100% relies on battery power, since my house electrical network is extremely "noisy"...

author: Andy Chee
author_rank: Super Contributor
timestamp: February 01, 2024, 05:14:29 pm
content: Quote from: dabrowski on February 01, 2024, 04:17:36 pmIt's an educated guess based on the connections visible in the picture. A schematic diagram would be required to 100% confirm, but I'm 99% sure.Quote from: dabrowski on February 01, 2024, 04:17:36 pmAny tube amplifier is going to be tricky to make portable. This is because tubes operate from high voltage, and portable high voltage sources of power are not as common as low voltage batteries (thus inevitably requiring voltage conversion of some sort).

author: Andy Chee
author_rank: Super Contributor
timestamp: February 01, 2024, 06:14:55 pm
content: Quote from: dabrowski on February 01, 2024, 04:17:36 pmIncidentally, if you want to clean up your household power, consider using a ferroresonant power line conditioner.https://www.emerson.com/documents/automation/product-guide-solahd-power-conditioners-en-us-99748.pdf
9v x2 powered JFET audio splitters - Page 1
Forum section: electronics / projects

author: systemic_fault
author_rank: Newbie
timestamp: May 23, 2020, 11:45:39 pm
content: I've been thinking of feeding two volumes from single guitar pickups using JFET's, but I'm not sure if I need to worry about whether the power source, which will be two 9v batteries, would be a clean enough signal, and whether I need to worry about noise in the power supply. This will be used on a bass guitar, so I wouldn't want any added noise added to the audio signal from the power supply through the JFET's.One concern that was raised when talking to someone about it is that there could be some weird audio effects when both volumes are nearly the same, like problems with similar harmonics and cancellation. Each volume per pickup would also be sent to one of two EQ's.

author: Zero999
author_rank: Super Contributor
timestamp: May 24, 2020, 03:46:17 pm
content: Some sort of schematic/drawing would help.Batteries are generally considered to be the cleanest power supplies available, but it depends on what else is connected to the battery.
"7805 replacement" modular buck converter - Page 1
Forum section: electronics / projects

author: LukeW
author_rank: Frequent Contributor
timestamp: November 12, 2016, 03:19:41 pm
content: I'm looking for a buck module in a TO-220 like package (a little bit bigger is fine) with a 78xx equivalent pinout.2A 5V out, 12-24V Vin. I might be able to live with a lower input voltage like 12-17V.Any particular recommended brands or suppliers for this sort of thing?The CUI V7805-2000R looks OK, but it seems really expensive.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: November 12, 2016, 03:28:12 pm
content: Unfortunately, I think they're expensive because it's a niche thing. There seems to have been more choice about 5 years ago. I think TI bought Power Trends or something.Is this for production or a hobby thing?

author: KerryW
author_rank: Regular Contributor
timestamp: November 12, 2016, 03:41:27 pm
content: I use the OKI-78SR-5/1.5-W36-C, ~$4.30 from Mouser. That's a lot compared to a 7805, but cheap compared to the CUI V7805-2000R.

author: kxenos
author_rank: Frequent Contributor
timestamp: November 12, 2016, 04:33:41 pm
content: You can check here:http://www.digikey.com/product-search/en/power-supplies-board-mount/dc-dc-converters/4325599?FV=401c68%2C402fde%2C1140050%2C15c0002%2C17d4003e%2Cfff40042%2Cfff800df&mnonly=0&newproducts=0&ColumnSort=1000011&page=1&stock=0&pbfree=0&rohs=0&quantity=1&ptm=0&fid=0&pageSize=25The cheapest is 2.84$

author: kripton2035
author_rank: Super Contributor
timestamp: November 12, 2016, 04:41:14 pm
content: surely made of clone parts, but if it's for hobby things, this could go (and it is on sale this week)https://fr.aliexpress.com/store/product/8pcs-10W-Breadboard-Power-Module-DC-6-5V-23V-12V-to-5V-DC-DC-Converter/1525466_32326359914.html
"advanced" lifepo4 managment board - Page 1
Forum section: electronics / projects

author: dutchy
author_rank: Newbie
timestamp: June 14, 2015, 07:19:08 pm
content: howdy folks,i would like some input from you fine gentlemens as i am having some difficulty in connecting the dots.here is the deal:my car battery is starting to die and i want to replace it before it craps out. in my experience it's better to replace batteries before they die.that it was a really expensive AGM battery (did last me 10+ years) and i want some more 21 century to crank my dinosaur liquid burner.my plan is to use 4 40Ah lifepo4 cells (the blocks, not the round ones).so what i need to make this pack run fully unattended is a fairly standard BMS but the crap from china is missing some key features for me (quality is number one).so i need to make my own and make it reliable with possible external checking (external ports for manually measuring cells and stuff)it needs to balance the cells at whatever the alternators's voltage is giving (usually 14v, 13.8v with cooling fans running) so standard balancer overvolt resistor burn off won't work as the battery is never full so regular balancers will never activate unless there is a massive inbalance.so i thought of solving the balancing issue with a arduino as that can read half a dozen analog voltage inputs. it can read the cell voltage directly and if it sees a inbalance it can activate a FET or whatever to bleed off cells to keep the balance. the trick is that it only starts balancing when the engine is running as keeping a arduino running 24/7 is a bit overkill, it has to be done simpler and fully passive if at all possible.i have also thought about just having a regular balancer trying to keep the cells at their natural float voltage of 3.475v (13.9v) but that would mean that it would be constantly burning off when the car is running. that would not be ideal to say the least .i can find plenty of balancing schematics on the intertubes but most have really small balancing resistors (150ish? at best) and they only start at a specific voltage and are usually built to be very small with smd components. that is not going to work for me, i dont have any smd experience or tools.do you guy's have any bright idea's on how i can build a balancing board that can deal with this variation?ps: lovely community here, i have been lurking in the shadows for quite some time.
"best" capacitive touch solution - Page 1
Forum section: electronics / projects

author: luky315
author_rank: Regular Contributor
timestamp: March 06, 2014, 07:53:48 am
content: (Nearly) every manufacturer claims to have the "best" capacitive sensing solution for their microcontrollers. But which technology is the most accurate? Atmel? Cypress? Silabs? Or someone else?I need to missuse it to cheaply measure small capacitive changes in humidity sensors (300pF base capacitance and changes in the range of 0.1pF)

author: Rerouter
author_rank: Super Contributor
timestamp: March 06, 2014, 11:00:18 am
content: if all your after is to measure the capacitance and not a touch, have a look at the $20 transistor tester thread, that device will happily measure that capacitance with that accuracy, (the code and schematic is published)

author: luky315
author_rank: Regular Contributor
timestamp: March 06, 2014, 12:30:25 pm
content: The build-in capacitance measurement should use less power than an external circuit + frequency measurement in the MC. And as allways: Fewer components = fewer problems.

author: dannyf
author_rank: Super Contributor
timestamp: March 06, 2014, 01:44:19 pm
content: Try CTMU from Microchip. Essentially a programmable current source charging up the capacitor.The challenge, in your case, is actually drift. With calibration, you may be able to counter it.

author: nctnico
author_rank: Super Contributor
timestamp: March 06, 2014, 02:02:22 pm
content: A couple of years ago I spoke with people who make capacitive buttons. They used Cypress exclusively. Afaik some Cypress chips have a debug mode where you can read the sensor data.

author: uwezi
author_rank: Unknown
timestamp: March 06, 2014, 07:43:50 pm
content: Quote from: luky315 on March 06, 2014, 12:30:25 pmThe 20$ tester doesn't use other external parts than 2 resistors of different size connected to GPIO pins and the analog comparator of an ATmega microcontroller. The detailed documentation describes the capacitance measurement cycle, see page 48:http://www.avrtester.tode.cz/upload/ttester_en.pdf
"Best" online circuit design/simulation test software? - Page 1
Forum section: electronics / projects

author: Wisnaeme
author_rank: Unknown
timestamp: August 18, 2015, 10:51:45 am
content: Hi All,I'm looking for an online circuit simulator to help me relearn and design some analog projects.Been out of this for about 10 years or so and need to get my head back into it.Only wanting simple things like op-amps but interfacing to Arduino would be useful.Being a Scotsman, I'd prefer a free service.Ta peeps!Robert

author: MyElectronsFellOut
author_rank: Regular Contributor
timestamp: August 18, 2015, 11:36:16 am
content: LTSpice is ideal for simulating just about anything. Plus it's freeI'm sure somewhere, someone has figured out how to add an arduino model to it....?The only other good program i've used which would let you load Hex files into a MCU model is ISIS Proteus from LabCenter, but it's not free. MPLAB is also handy as you can write code from within the environment and link it directly with the proteus software as a simulator, but not sure if you add atmel chips to it??

author: fcb
author_rank: Super Contributor
timestamp: August 18, 2015, 11:47:38 am
content: +1 for LTSpice.theamphour had an episode sometime back with the chap behind LTSpice. Quite interesting.

author: ElektroQuark
author_rank: Unknown
timestamp: August 18, 2015, 11:54:05 am
content: He is looking for anonlinesolution.

author: MyElectronsFellOut
author_rank: Regular Contributor
timestamp: August 18, 2015, 12:02:43 pm
content: In my experience there is not such thing as a goodonlinesimulator. At least all the ones I have used have been pants.

author: Wisnaeme
author_rank: Unknown
timestamp: August 18, 2015, 12:44:31 pm
content: Online would be ideal as I spend a lot of time at "work" waiting for stuff to happen and quite some time travelling with my Android tablet.I'll look into the suggestions offered too.

author: ElektroQuark
author_rank: Unknown
timestamp: August 18, 2015, 12:52:36 pm
content: You have a little app for Android called EveryCircuit.Just to play, nothing serious thought.

author: TheAmmoniacal
author_rank: Unknown
timestamp: August 18, 2015, 01:03:29 pm
content: Embarrassed to say this, but I quite like this one:http://www.falstad.com/circuit/

author: Kalvin
author_rank: Super Contributor
timestamp: August 18, 2015, 01:24:09 pm
content: ssh -X to your linux computer or use the remote desktop to connect to your windows machine and start the LTSpice
"compatible" accessories  - Page 1
Forum section: electronics / projects

author: lacek
author_rank: Regular Contributor
timestamp: October 11, 2017, 07:59:56 am
content: I have a general question: why there seem to be no "compatible" accessories for quality soldering stations. The JBC tip magazine goes for 150 EUR and I could easily imagine someone manufacturing one that has better tip arrangement/three, not two-level/with cool wooden finish for less or even more if the accessory is superior to the JBC one.Are there some legal restrictions or simply the market isn't large enough?

author: ebclr
author_rank: Super Contributor
timestamp: October 15, 2017, 08:27:14 pm
content: Isn't so hard to found thenhttps://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20171015122638&SearchText=jbc+tip
"Feeltech" FY2300-12M waveform generator vs Siglent SDG1025 - Page 1
Forum section: electronics / projects

author: robertbaruch
author_rank: Regular Contributor
timestamp: November 06, 2016, 06:14:21 am
content: I put "Feeltech" in quotes because you see these things on ebay from different companies and they look the same. I ordered one, and while I was waiting for the boat to arrive I got impatient and just got a Siglent SDG1025. I hooked up the Siglent to my Rigol scope and took it up to a 12V square wave at 12 MHz, 11 MHz, 10, 9, 8, 7, and so on, and the waveform looked nice and stable.Then I hooked up the Feeltech also at a 12V square wave at 12 MHz. It also looked nice. But 11, 9, 7, and 6 MHz were jittery! I figured I knew what that meant: this thing was probably powered by a micro that was being interrupted. Figured I would open it up, check out the chips and what kind of MPU it used, maybe dump the program.Instead, I found an Altera Cyclone FPGAWhat a disappointment. It's that jittery with custom logic. No reverse engineering for you!

author: TheAmmoniacal
author_rank: Unknown
timestamp: November 06, 2016, 07:15:52 am
content: Does replacing the power supply (with a linear/stable) improve the output waveform? Someone on the forum (SDG electronics?) went through some trouble building a custom linear supply for it, but I can't remember if it was for safety reasons only (~90 VAC @ 0-1 mA on the BNC iirc).

author: Kleinstein
author_rank: Super Contributor
timestamp: November 06, 2016, 02:24:39 pm
content: I also saw the video on changing the supply. It was done to get better insulation and less leakage current (from EMF cap in switched mode supply). This does not change the quality of the waveform.The relatively poor signal quality has several reasons:1) The square wave is produced through ADC, so no steep slope an jitter it the frequency is not made by dividing the internal clock (e.g. only a few special frequencies are good, like the 12 MHz). However if 12 MHz are good - so should be 6 MHz and 4 MHz, unless they use correction for the exact crystal frequency. So the good frequency could be slightly off 6 MHz.2) The output amplifier has limited bandwidth and slew rate: so distortion at high frequencies and amplitudes. Not that bad - even good instruments might have limits here, not to allow the full amplitude at maximum frequency, but at least they give you a warning.3) No real reconstruction filter for the DDS - so quite some RF crap possible, especially with high output frequency.4) Poor quality R2R DAC (e.g. 6 Bit precision) - heavy artefacts visible in triangle waveform. It might be possible to improve on this a little with adjustment of 2 or 3 resistors.The version shown here looks different from the one in the other thread - they might have saved on the VGA and used an cheap attenuator.
'force field' type alarm? - Page 1
Forum section: electronics / projects

author: ja421
author_rank: Contributor
timestamp: August 07, 2016, 06:31:38 pm
content: years ago; I had a circuit that would sense when anything (human, animal, or metal/car) got near it... Of course, I can't find it now.I believe it worked off a low power radio receiver to sense changes as things approached it. Sort of like a proximity sensor in 360 degrees.I've searched in vane to find a similar circuit (pre made or not).The idea is to give a beep if a car gets too close to a motorcycle while parked (to avoid it from being hit/knocked over, which has happened from people 'not seeing it' or thinking their bumper could clear it)Since I'm after detecting cars, not people, I don't think a bunch of PIR sensors are a solution...Any ideas?Thanks.

author: NottheDan
author_rank: Frequent Contributor
timestamp: August 07, 2016, 07:24:49 pm
content: AnRF proximity sensor? Google gives quite a few results to those keywords. Or do you mean something else?

author: Dataforensics
author_rank: Unknown
timestamp: August 07, 2016, 07:26:24 pm
content: Perhaps get an ultrasonic parking sensor kit as intended for cars. One of the simple ones with just an led bargraph, then pick off the signal for the warning distance required.

author: ja421
author_rank: Contributor
timestamp: August 08, 2016, 02:15:56 am
content: Quote from: NottheDan on August 07, 2016, 07:24:49 pmIt is amazing how you can search for something and not find it because you don't know the proper term to search for... Like asking a small child to look up "Knee" -- if they don't know it starts with K, it would take them forever to go thru the dictionary page by page. (of course, that dates me)Thanks -- This looks like what I am after.Quote from: Dataforensics on August 07, 2016, 07:26:24 pmI thought of that; but they are fairly directional.I think "RF proximity sensor" is what I'm after....
"Generator Buffer" function? - Page 1
Forum section: electronics / projects

author: JP16A60
author_rank: Unknown
timestamp: September 09, 2016, 04:02:37 pm
content: Greetings, all.I'm considering the purchase of some electronics training boards for use with the Lab-Volt FACET system (seehttp://www1.labvolt.com/publications/product_guides/94004_00.pdffor more info), but I'm stumped about one of the hardware requirements.Several of the boards have a placeholder for a "generator buffer"; the Lab-Volt literature describes this module as being "...required for generators used in lab experiments not having an output impedance of 50 ohms."Some of the trainer boards with this requirement include:91010-20 FET Fundamentals (ex.http://www.ebay.com/itm/Lab-Volt-91010-20-FET-Fundamentals-Trainer-Board-AS-IS-UNTESTED-/391552908055)91007-20 Transistor power Amplifiers (ex.http://www.ebay.com/itm/Lab-Volt-91007-Transistor-power-Amplifiers-Course-Circuit-Board-Labvolt-FACET-/122100547711)91005-20 Semiconductor Devices (ex.www.ebay.com/itm/Lab-Volt-91005-20-Semiconductor-Devices-Trainer-Board-w-Base-Unit-/351831293176)91003-20 AC 1 Fundamentals (ex.www.ebay.com/itm/Lab-Volt-91003-20-AC-1-Fundamentals-Course-Interface-Training-Board-682-/321858764993)My assumption it that this "generator buffer" is a required component to fully leverage these training boards, but I have had no luck in finding such a component on eBay (nor much else in the way of even basic documentation).The Big QuestionTM: Does anyone here have a decent notion of what this thing does, or what/how I might create or locate some reasonable substitute?Last-minute thoughts: Maybe I'm a bit dense, but: 1.) Is the "generator" mentioned simply referring to a standard "function generator", and if so, 2.) Do typical mid- to high-end Tektronix and/or HP function generators feature 50 ohms output impedance?JP

author: Dave
author_rank: Super Contributor
timestamp: September 09, 2016, 04:17:06 pm
content: The generator buffer is just a buffer amplifier with a 50R input impedance and a low output impedance.Yes and yes to your last two questions.50 ohm impedance is required to properly terminate signals to prevent reflections and all of the other nasties. Those only come into play with higher frequencies, so I imagine that whoever designed your training course, decided on the buffer amplifier to simplify things, so your function generator becomes an approximation of an ideal one, instead of having to keep thinking of the output impedance.

author: JP16A60
author_rank: Unknown
timestamp: September 09, 2016, 04:20:54 pm
content: Awesome--that makes perfect sense now. Thanks, Dave!JP

author: edavid
author_rank: Super Contributor
timestamp: September 09, 2016, 04:57:58 pm
content: Quote from: Dave on September 09, 2016, 04:17:06 pmI think it probably has a high impedance input and 50ohm output impedance.Yes, most lab function generators have 50ohm output.
'Hacking' RFID Alarm keypad - Page 1
Forum section: electronics / projects

author: SadE54
author_rank: Newbie
timestamp: April 28, 2016, 07:01:59 pm
content: Hi,I'm developping an homemade home alarm system using rfm69 modules .I bought an Etiger RFID keypad to modify it (it's better looking than all I could makeAfter some hours of reverse engineering I have almost what I need to connect my homemade mcu ( the one soldered is an specific chinese one, no avr here !).The last thing is to be able to decode the RFID data. The tag is a 125khz one. I used a teensy 3.1 to timestamp all the data stream and converte dit to a sigrok file.The Sigrok file can be dowloaded here :http://s000.tinyupload.com/?file_id=98525172856803099296I thought it was EM4100 but it seems it's not the case even if we can observe repetitive data.In the last part of the file (not on the picture) there's a sequence there's not seem to be modulated even if we can observe pulses with other widthI don't know the modulation scheme I have to use to decode the data :-/If there's RFID specialists here , you're welcome !...
"High voltage" linear piezo driver - Page 1
Forum section: electronics / projects

author: jeremy
author_rank: Super Contributor
timestamp: April 11, 2016, 08:10:10 am
content: Hi all,I'm on the lookout for a linear piezo amplifier/driver circuit, does anyone know of a good reference for this? I'm specifically not interested in the PWM style ones, I really need it to be a linear amplifier. My requirements are:0-10v inputBW > 500k, ac coupled is fine as the lowest input signal of interest is 10kDrive voltage 0 - 60V minimum, but I would be perfectly happy with 60V or however close one can get with a 60V power railDrive current less than 20mA, likely less than 10mAOf course I could live with +/- rails and output as well. Right now I'm looking at a mosfet push-pull stage on the front of an op-amp. Commercial units are for sale all over the place, so I was hoping someone could enlighten me on any tricks here, or perhaps point me to an old service manual which is onlineThanks!

author: uncle_bob
author_rank: Unknown
timestamp: April 11, 2016, 12:33:09 pm
content: Quote from: jeremy on April 11, 2016, 08:10:10 amHiIf the system really *is* AC coupled and 10K to 500K is the bandwidth ... just use a transformer on a very normal amp.Bob

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: April 12, 2016, 02:00:56 am
content: sure about the current?you should give the piezo C, need it to calc the I @ 500 kHzalso the C load can destabilize amps, may want neutralizing/isolating series L||R for many feedback amps

author: moffy
author_rank: Super Contributor
timestamp: April 12, 2016, 02:09:22 am
content: Quote from: uncle_bob on April 11, 2016, 12:33:09 pmYou would likely run into serious resonance issues as the leakage inductance of the transformer reacted with the capacitance of the piezo.

author: jeremy
author_rank: Super Contributor
timestamp: April 12, 2016, 03:46:13 am
content: Thanks all for your replies. I do realise that the major problem will be the capacitive loading, hence I was hoping there would be a book somewhere on this topic. I don't know the exact current, but you gotta start somewhere and this is a ballpark number I've come up with.

author: moffy
author_rank: Super Contributor
timestamp: April 12, 2016, 11:58:38 pm
content: All you need to know is the piezo you are driving and its capacitance. From that you can easily calculate your loading/current. Classic way to stabilise an opamp driving a capacitor is to place a 50 to 100 ohm resistor between them.

author: uncle_bob
author_rank: Unknown
timestamp: April 13, 2016, 01:18:59 am
content: Quote from: moffy on April 12, 2016, 11:58:38 pmHiOr ... since it's just a capacitor, calculate a matching network to handle the reactive portion of he load.Since that's never going to be perfect, the normal approach is to match in the top octave and let it look like an open circuit below that. How well that works depends a *lot* on what your device looks like.Bob
"high" voltage Op Amp needed - suggestions ? - Page 1
Forum section: electronics / projects

author: rob77
author_rank: Super Contributor
timestamp: June 30, 2014, 07:42:09 pm
content: Hi Guys,i'm trying to find a suitable op amp for my project and apparently it's a bit of a problem (at least for me)my basic requirements are:80V supply voltage (sym. +/-40V)GBP of 1-2 MHz (1MHz is enough , 2MHz would be perfect)acceptable price <= $10-$20linear makes a perfect fit - LTC6090 (140V supply , 12MHz GBP, and approx $10 @ digikey ) , but not a single supplier got those on stock. many of them don't even have the LTC6090 listed. and of course i need something like 2-4 pieces for prototyping - therefore i can only buy from those selling also in single piece quantities.i found a couple of other op amps with max 80V supply, but GBP was too low.are you Guys aware of any op amp with specs fitting my requirements ?thanks in advance for suggestions.Rob.

author: rob77
author_rank: Super Contributor
timestamp: June 30, 2014, 08:10:35 pm
content: Quote from: AcHmed99 on June 30, 2014, 07:59:58 pmactually i googled for high voltage opamp - and i found that LTC6090 and apparently overly focused on finding a supplier for that oneyour suggestion of ADA4700-1 seems to be a perfect fit . thank you very muchand DK has them on stock

author: rob77
author_rank: Super Contributor
timestamp: June 30, 2014, 08:54:25 pm
content: yes i'm aware of the heat dissipation, but that shouldn't be a problem. it will source/sing approx 1 mA only - therefore it should be something like 40-50mW from the output stage + the 170mW for the chip itself. considering the 45celsius/watt of that ada4700 in a soic8 package , it should be just ok even for a 2 layer board (with the exposed bottom pad soldered to few square centimeters of copper).but anyways, thanks a lot for the advicebtw.. going to check the Apex ones as well, but i think i made the choice already

author: Bored@Work
author_rank: Super Contributor
timestamp: June 30, 2014, 09:26:26 pm
content: Quote from: rob77 on June 30, 2014, 07:42:09 pmLinear sells them directlyhttp://www.linear.com/purchase/LTC6090_LTC6090-5Seems like minimum quantity is two.

author: Zad
author_rank: Super Contributor
timestamp: July 01, 2014, 01:36:03 am
content: You could always use a "Mosfet with a pilot light" as an output stage. Very high voltage and power capability with those things, but a bit of a pain in the arse for power supply and cooling.(That's a thermionic valve or tube btw)

author: rob77
author_rank: Super Contributor
timestamp: July 01, 2014, 07:13:42 am
content: thanks to all for the suggestions/comments !@ Bored@Work - thanks for that link i never though that a manufacturer will jump into direct selling in single-piece quantities@ gazelle - will check those OPAs , and regarding the external output stage - yes that's the way how i built it with an NE5534 (44V max supply) as a proof of concept.@ Zad - it took me a while till i realized what is a "Mosfet with a pilot light"but anyways... i think that wouldn't be manageable
"Homemade" Oscilloscope Probe - Page 1
Forum section: electronics / projects

author: Christopher
author_rank: Frequent Contributor
timestamp: April 09, 2015, 05:42:42 pm
content: All,I am looking to create my own crude-ish 10:1 probe to embed inside some test gear.The story is: I have a 0-60V square wave which is coming out of a product into a scope. Originally I thought No problem, just connect some coax straight into a scope. It works! But the scope can only handle 0-20V on the display. So we have to divide it down by 10:1. The impedance of the output is fairly low.Just putting a resistive 10:1 attenuator got rid of all of the HF content, obviously.The scope input impedance is 1M || 15pF. Can I put a series resistor and compensation cap across the series resistor? My maximum frequency is about 1Mhz.I have drawn an example of my circuit. What do you think about my idea?

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 09, 2015, 06:44:26 pm
content: thats how they do it in many 10:1 probes, the most work is in compensating it to the right BW and attenuation. alas the higher quality probes dont use the normal joe coax cable like that.

author: tggzzz
author_rank: Super Contributor
timestamp: April 09, 2015, 09:13:58 pm
content: It all depends on the frequency content and the length of the coax.With the design as you have shown it, the 50ohm coax is improperly terminated, and thiswillmanifest itself as a ripple in the amplitude vs frequency response of your probe+scope. Professional scope probes avoid that by replacing the "good" transmission line with a very lossy transmission line of very special coax (>100ohms/metre DC resistance, centre conductor not being straight, etc). To see those effects, you can quickly model the system using a lossless transmission element. Fundamentally, it is difficult to make a good homebrew high impedance passive probe.An alternative, since you have a low impedance source, youcaneasily homebrew a "low impedance Z0" passive probe - and these have remarkably good frequency response; 40 year old professional probes had 1.5GHz bandwidth, and modern ones have 6GHz bandwidth.FFI, have a look at the references athttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/

author: DanielS
author_rank: Frequent Contributor
timestamp: April 09, 2015, 09:26:54 pm
content: Since you have a low-impedance driver, you could simply use a 200-450 ohms attenuator in your product and a proper 50 ohms cable termination at the scope. That way, you get either 5:1 or 10:1 attenuation, solve your improper cable termination issue and won't need to worry about compensation - at least not until you start looking at 100+MHz.
"Inductor Blaster" for measuring saturation current and inductance - Page 1
Forum section: electronics / projects

author: cjk2
author_rank: Contributor
timestamp: January 28, 2016, 12:57:00 am
content: Here is a small project I did for measuring the properties of unknown inductors. This one goes from 1 to 100 Amps max current. I also built one that goes to 10A max(change R11 to 0.1 Ohms).This tester includes open and short circuit protection. The energy for "blasting" is stored in a 20V 1F capacitor from the car audio world. Rockford Fosgate brand are the ones to buy. A current limited power supply is needed to charge the cap.The tester is current limited and latches off once the current threshold is reached or when a built in time limit is exceeded(for open circuit protection).The scope shot shows an example of a ferrite core inductor showing saturation around 10A.

author: TerminalJack505
author_rank: Super Contributor
timestamp: January 28, 2016, 05:06:10 am
content: Thanks for sharing.

author: station240
author_rank: Unknown
timestamp: January 28, 2016, 07:33:55 am
content: Now this would be handy for my box 'o random inductors. I'm secretly hoping there is one suitable for a project.Only problem I see is no one needs more than one, so is someone planning on selling the PCBs ?ps: What are the contacts you use for the high current PCB connections ?

author: bktemp
author_rank: Super Contributor
timestamp: January 28, 2016, 10:24:57 am
content: Such testers are really useful for characterising unknown inductors. You made a nice looking board for it.I see some problems with your design:Your cables are much too thin. Any resistance counteracts the rising current slope. So you want to minimize any resistance as much as possible, especially if you also want to calculate the inductance. I have put an array of low ESR caps right onto the board. The pulse has a width of only 10 or 500us for most inductors, therefore you don't need huge capacitors. If you do the math you will see the voltage drop due to the resistance (and inductance) of the cables will have a larger effect than the voltage drop due to the discharge of the capacitor during the pulse.Also the current shunt should have the lowest possible resistance.
"Industrial" wire stripping and tinning - Page 1
Forum section: electronics / projects

author: mrkva
author_rank: Unknown
timestamp: August 25, 2015, 10:24:56 pm
content: Hello everyone,for one of my products I am doing a lot of wire stripping and tinning of audio cables. I wonder what are the most efficient "industrial" ways of doing this. My goal is to save time and increase precision (lengths of the stripped leads, etc.). I found out there are thermal wire strippers, which seem very cool. What are your suggestions?Also - is there a solution for quick tinning of the wires?Thank you

author: Fsck
author_rank: Super Contributor
timestamp: August 25, 2015, 10:27:14 pm
content: usually a solder pot for tinning

author: lincoln
author_rank: Regular Contributor
timestamp: August 25, 2015, 11:10:14 pm
content: Hello,Up to "medium" production, we used a little old Asian lady and this:http://www.kleintools.com/catalog/standard-wire-stripperscutters/wire-strippercutter-16-26-awg-strandedwhich is a rip off of the older Ideal brand (or were they bought ?)For production termination it is crimp connectors all the way.You mentioned audio connectors, I have not seen xlr / ts / trs in anything else other than solder. At that point you best bet is a plastic soda cap full of flux and a solder pot. Multi-pin stuff is often available in crimped pins.

author: ConKbot
author_rank: Super Contributor
timestamp: August 26, 2015, 02:14:26 am
content: If you need to strip a lot of wires, it's hard to beat good automatic strippers, though thermals are better for Teflon insulated wire, unless you got the right dies for the automatics. (The strippers opening is bigger than the wire to prevent nicking, Teflon is usually a thin jacket, so you need a tight tolerance die, to the point of different openings for stranded and solid)http://www.amazon.com/Knipex-1221180-Automatic-Insulation-Strippers/dp/B003RWS8UWis probably a decent pair since its knipex, but haven't used them personally.Do avoid the "self adjusting" kindhttp://www.amazon.com/Automatic-Wire-Stripper-with-Cutter/dp/B0002KR95Wthey scrape the wire at best, and sometimes mangle it.For lots of tinning, +1 to flux and a solder pot with a thermostat. The non thermostat ones get too hot, and you'll have a lot of dross/oxides on the surface.

author: calexanian
author_rank: Super Contributor
timestamp: August 26, 2015, 05:35:37 am
content: As far as hand held self adjusting types we use Stripax types. In the US they go under the Paladin name. They are actually renamed tools from Germany. For larger wires we use an older version of the current PA1113 model and for smaller wires such as the center conductor on small coax or for guitar instrument cables we use the model 1115P which is specified for small diameter teflon. Otherwise we order pre cut and stripped from our vendor who happens to be Wieco wire and Cable in Edgewood N.Y.As for tinning wire, even the nighest volume houses still dip in small solder pots. Leaded solder with RA flux line Kester 44 goes super fast. It is critical to use a temp controlled model though. Otherwise you will melt the insulation.
"Jelly bean" VFD driver - Page 1
Forum section: electronics / projects

author: Harvs
author_rank: Super Contributor
timestamp: September 20, 2013, 09:46:31 am
content: I was digging through a shelf to find something and came across this old project from 12 months ago.I never ended up using it for anything, and as such never got around to laying out and building an SMT version of it. However, it all works quite nicely. These little displays for $3 from Jaycar look quite nice to, pity they're not about double the height.Anyway, thought it might give someone an idea for something. I might end up including it in an instrument one day, who knows.Licence: Do whatever you want with it...

author: BravoV
author_rank: Super Contributor
timestamp: September 20, 2013, 09:52:43 am
content: Really nice, thanks !Btw, isn't that vfd looks a lot like commonly used at those high digit counts bench type calculator ?

author: Harvs
author_rank: Super Contributor
timestamp: September 20, 2013, 09:57:36 am
content: Yeah it probably is, this is display:http://www.jaycar.com.au/productView.asp?ID=ZD1880&form=CAT2&SUBCATID=975#1However, you could use the circuit with most small VFDs I'd imagine, might just need to adjust the voltages to whatever they require.

author: dannyf
author_rank: Super Contributor
timestamp: September 20, 2013, 01:08:32 pm
content: They reminded me of those old Casio calculators.

author: ResR
author_rank: Regular Contributor
timestamp: September 21, 2013, 07:56:34 am
content: I was looking for the alternative for specialized VFD driver chips for ages. Thanks for sharing, mate. Is it possible to make a clock-calender using this schematic?

author: Harvs
author_rank: Super Contributor
timestamp: September 21, 2013, 09:44:00 am
content: Umm, maybe I'm uncultured, but what's a clock calendar? A clock the has the date?Essentially you can put whatever you want on the display. If you need real letters, then you're going to need to find a display with at least the star segments, not just the 7 segments. The circuit should work fine for the majority of vfds.The avr is very lightly used, so there's plenty of processing time and io for it to be doing other stuff.
"Jim Williams" style simple digital clock - Page 1
Forum section: electronics / projects

author: CodyShaw
author_rank: Contributor
timestamp: April 28, 2014, 01:25:35 pm
content: Hey all,I just finished up a little project I've been working on yesterday. I thought you guys might like to see it!http://codyshaw.ca/2014/04/27/jim-williams-style-digital-clock/It's a simple digital clock in the style of something you would see on Jim Williams desk. I really like the look of such designs, so I decided to make something like that.The next step will be to encase the clock in epoxy resin as to electrically isolate the clock and make it look completely badass!Questions and critiques are welcome.

author: SeanB
author_rank: Super Contributor
timestamp: April 28, 2014, 01:36:40 pm
content: Simpler to just get some clear acrylic sheet cut and make up a cube to hold it using acrylic glue. Will look transparent, and if you want you can fill it with silicone oil and plastic flakes to make a snowball effect.

author: sacherjj
author_rank: Frequent Contributor
timestamp: April 28, 2014, 01:50:03 pm
content: I was going to post the same exact thing with the Acrylic sheet. One thing on the design. If you use AC in from a wall wart transformer and rectify inside, it would require embedding a electrolytic. However, it would allow you to use the power grid frequency, which has to be very accurate over time. Probably much more so than an RTC.

author: CodyShaw
author_rank: Contributor
timestamp: April 28, 2014, 02:08:25 pm
content: Quote from: SeanB on April 28, 2014, 01:36:40 pmThis is a possibility, I was going to do something along the lines of this:http://runawaybrainz.blogspot.co.uk/2012/04/audio-crystal-cmoy-freeform-headphone.htmlQuote from: sacherjj on April 28, 2014, 01:50:03 pmIt's already made with an RTC, using the mains frequency as the clock would probably have been more "Jim Williams"y as well.

author: CaptnYellowShirt
author_rank: Frequent Contributor
timestamp: April 28, 2014, 05:26:05 pm
content: That polish job is teh hot.
"memory" cable - cable that flexes and keeps position - Page 1
Forum section: electronics / projects

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: December 22, 2015, 04:10:58 pm
content: So, I need to have better desklighting, and found something like this (picture at the bottom for readablility)The cable is kinda stiff, and keeps the last position but it doesn't feel solid core, as it's too willing to bend in any shape or form, I was thinking of doing this myself with some cable (somehow) and just attach some medium-high strength leds to it and have them come from behind my desk monitors to have nice adjustable lighting. Any suggestions as for cable? Going to try some stuff myself, but I really haven't found anything like it. Nice silicone insulation material. Light is not mine so I can't sacrificially break it to find out. Tried:Cat6e patch cable: flexible enought but doesn't keep shape well. Not really strong enought to support itself past a twenty-or-so cm.Cat7 solid core cable: Too stiff, will just slap you in the face as it springs back2.5mm^2 power cord - solid core: best results yet but it sufferd the same weakness as the cat6e - can't support its own weight for anything past an arms length.Anyone ever came into contact with this kind of stuff? I can't find anything on farnell or RS since I don't know what I am supposed to call it. I don't mind having to buy this in (largish) quantities, I think this can also be very usefull in photography for small flexible lights and so on.

author: jeffeb3
author_rank: Newbie
timestamp: December 22, 2015, 04:30:31 pm
content: What about ROMEX? The stuff used for home A/C wiring? I have some 12ga here, and it holds it's shape pretty well (it definitely has some rebound though).

author: Marco
author_rank: Super Contributor
timestamp: December 22, 2015, 04:30:36 pm
content: Semi rigid coax?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: December 22, 2015, 04:39:03 pm
content: That semi-rigid coax seems great... Gonna order some of of amazon tonight I think, see how it goes. Thanks!

author: SeanB
author_rank: Super Contributor
timestamp: December 22, 2015, 05:18:52 pm
content: Seen it done with standard stranded house wire, as it is somewhat flexible, but stiff enough to bend. 10mm will hold itself well. Otherwise a microphone gooseneck will hold up quite heavy loads, though if you go to the Fong Kong shop and look for laptop USB lights you will get a thinner one around 6 inches long, with a 3 led head on it already and a USB plug on the end. If you go to the machinery suppliers you can buy flexible coolant tubing by the meter, which simply clips together and which is quite strong for the length, and which is hollow to take the cable, along with having ends which can fit standard electrical outlets and screw into boxes.

author: cncjerry
author_rank: Unknown
timestamp: December 22, 2015, 08:39:28 pm
content: Coax cable inserted into standard 1/4" copper tubing. The round coax keeps the tubing from kinking, somewhat. Can't remember the size coax that fits.
"Multi"-Meter - Page 1
Forum section: electronics / projects

author: meerweten
author_rank: Contributor
timestamp: August 24, 2015, 08:00:00 pm
content: Hi all,i'm Desiging a simple "Multi"-Meter that can measure multiple things.Currently i'm working on a C/ESR Measurements for Capasitors.Anyone can think of other great items i can add to this "Multi"-Meter?If you are interessed in making your own, i'll post my updates here, and make the project as open source as possible :pIf you yourself made a great instrument that you think could be in here just post itUsed hardware/software:µC: PIC24FJ seriessoftware in: MikroCMore information will follow!!! (and i'll add a page for it on my poor and nooby website too:http://www.greendigit.be/en/,jhe sorry peeps, english version not operational yet :p )Greetings,Meerweten
'Old' Serial to USB - Page 1
Forum section: electronics / projects

author: NH-GrizzlyBear
author_rank: Contributor
timestamp: November 14, 2015, 02:04:41 pm
content: Hi,I have an 'old' Kraft serial trackball that uses +/- 12VDC and I was hoping to try and convert it to USB so that it would be compatible with my KVM that uses USB. I've seen serial to USB converters before, but I think they relied on +/- 5VDC.I think I'll need a level shifter and probably I'll have to modify the original driver to get this to work.Does anyone know what I'm talking about and have any advice on how to proceed?Thanks,Jon

author: SeanB
author_rank: Super Contributor
timestamp: November 14, 2015, 02:09:10 pm
content: Should work on 5V, as there were a lot of computers that only produced +-5V serial data. Some of the serial converters do have a built in charge pump that provides 10v rails and proper RS232 data.Otherwise try to find an old USB mouse with a ball, and use the board from that to interface with the trackpad encoders, which use the same principle. Should be enbough room in the case to fit the mouse board, and all you need to do is use a few wire links to connect to the switches, encoder light and phototransistors. 10 wires will do it and will all fit inside the case.

author: retrolefty
author_rank: Super Contributor
timestamp: November 14, 2015, 02:10:50 pm
content: You just need to find and adapt a 'true' RS-232 to USB converter or cable. That will handle converting dual polarity signal voltages to standard 0-5vdc (or 3.3vdc) serial (UART) levels and also invert the logic states.

author: NH-GrizzlyBear
author_rank: Contributor
timestamp: November 14, 2015, 02:12:21 pm
content: Quote from: SeanB on November 14, 2015, 02:09:10 pmGreat idea! Thanks!
"on request" - signal generation - Page 1
Forum section: electronics / projects

author: jazzalex
author_rank: Regular Contributor
timestamp: January 24, 2012, 10:50:41 am
content: Hi everybody,I have a HANTEK DDS 3x25 signal generator, which -- apart from some known basic issues -- works fine. However, rather than periodically generating an arbitrary signal I want to do it "on request":In this specific case I am sending binary data of a RS232 interface and whenever I am sending a 1 I want the DDS 3x25 to output the signal only once and nothing in case of sending a 0 respectively.Is this possible at all (by modifying the device or applying patches etc.) or would I need to apply a totally different setup with different gear ?Thanks in advance,any help appreciatedBest regardsAlex

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 24, 2012, 01:35:14 pm
content: inreview Hantek DDS 3X25. Anyone own onethere's discussion by a member marmad about using the external trigger (trigin port at the back), you may search or ask him how, i never try.