hybridfree/eevblog-posts huggingface dataset:
Zenth ZF-171-42 - a new hope err.. problem  - Page 1
Forum section: electronics / repair

author: Gen-8bit
author_rank: Newbie
timestamp: December 01, 2024, 07:23:17 pm
content: Well, I'm still trying to resurrect my Zenith schlepptop, and have encountered a new problem that can only be traced to tinker error:I completely neglected to document the position and orientation of all cables and wires that connect to the power board, and while most were self explanatory, one two wire cable has stumped me and senty anxiety sky rocketing fue to the high voltage involved.You see, the cable in question emerges from the display area and is supposed to supply the lcd backlight. It consists of two wires (black/yellow), terminating in a two pin plug. The only connector it can reach and I remember pulling it from is a three pin, non keyed connector, situated behind a yellow transformer on the right end of the power board.My dilemma here is Idk which orientation and position I need to plug this wire in, and I don't want to fry the poor thing again!So anyone with experience in working with and fixing this kind of computer, please help me, thanks!

author: MathWizard
author_rank: Super Contributor
timestamp: December 06, 2024, 01:45:14 am
content: I'm looking at some service manual and I've never heard of any LCD screen that uses anything like 308Vpp. So is that what's on connector P3 ?In the LCD waveform picture, it's at 500Hz, and it's about 109VAC, but on a typical DMM, it would read less, IDK what the voltage roll-off with frequency is, of a typical DMM, but 500Hz isn't that high though. Now if that's really that AC signal on P3, it should be centered around the common/GND, and the polarity shouldn't matter. It would measure about 0 VDC, and maybe 40VAC on some DMM.But I'd want to see the circuit myself, or at least the schematic, and trace it out, to know for sure.Have a look at page81,82 of the pdf.https://www.minuszerodegrees.net/manuals/Zenith%20Data%20Systems/Zenith%20Z-171%20PC%20Series%20-%20Service%20Guide.pdf
Zero Ohm Readings on AMD FCH Chip’s On-Chip Capacitors–Normal Behaviour or not? - Page 1
Forum section: electronics / repair

author: Z. Khalid
author_rank: Contributor
timestamp: October 03, 2025, 11:48:43 am
content: Hello everyone,I’m currently troubleshooting a motherboard and would appreciate some technical insight. Here’s the situation: I discovered that four SMD capacitors on the bottom layer of the board appeared shorted in-circuit. After removing them, the short remained on the board, confirming that the capacitors themselves were not the issue. I then measured a capacitor that is actually on the AMD FCH chip itself and found it reading literally zero ohms (marked in red).While I understand that a low resistance can sometimes be normal, I’m concerned that a perfect zero-ohm reading on a capacitor directly on the chip might indicate an actual short rather than normal behaviour.I’d really appreciate any insights or similar experiences.Please refer to the attached photograph.Thanks in advance!

author: kripton2035
author_rank: Super Contributor
timestamp: October 03, 2025, 11:56:15 am
content: if you're in the fixing stuff jobs, it would be a good idea to build yourself a shorty-with-display...you can pinpoint a short within 1mm or so.link in my signature.
Zhaoxin CVCC 60V 50A bench supply KXN-6050D - Page 1
Forum section: electronics / repair

author: najrao
author_rank: Regular Contributor
timestamp: January 29, 2024, 09:52:41 am
content: Looking for a easy-to-use high power unit for testing motors, I scored this rather elderly PRC? made bench switcher ps for a few dollars. Opening the cover revealed that I was the first one in. Of course it does not work.Went through variac and dim bulb start up, it draws only a small current direct on mains (230V). The inrush stopper relay ticks as it should. The auxiliary supply comes up, and turns on the fan (Only to shut it down, said to be thermo controlled); the display lights up all digits, voltage climbs slowly to an indeterminate 10 or 12V, only to collapse equally slowly to zero. CC and OVP settings have no effect. After the first flareup, the CV knob too does nothing further.I found that the CC pot was completely OPEN between each two pins, and have substituted it. Nothing changed for this, except that the CC LED no longer lit up as used to.It has only a two-layer board and all through-hole soldered components. But the IC faces are sanded off, and disassembly of even the connectors is a royal PITA.I am hoping someone with such switcher has seen this model before and would kindly advise me on how to proceed.Edit: I have now fully restored this animal. Reported for providing closure to topic.
Zif Connector - Page 1
Forum section: electronics / repair

author: bostonman
author_rank: Super Contributor
timestamp: July 26, 2021, 02:45:57 am
content: My oscilloscope has a broken Zif connector; it was broken when I got it.Replacing it isn't too important because it goes to a probe board that I think is useless. If I can find a replacement, then it would be cool.I looked for a part number on the connector and saw some letters (the second letter was scratched). Between the visible letters, and looking at manufactures lists on DigKey, it appears it's a Kyocera.The only other letters/numbers I saw was AD on the top left corner and 526 on the bottom. Looking on DigiKey, I'm not finding anything that resembles mine or has any relation to these letters/numbers.From what I can tell, all I need is the plastic snap piece and I don't need to resolder a whole new one - obviously I'll need to buy a whole connector though.Does anyone have any idea whether the AD and/or the 526 has any meaning on the model number?

author: perieanuo
author_rank: Frequent Contributor
timestamp: July 26, 2021, 05:40:10 am
content: connectors like that one are not so complicate to find. soldering your ribbon cable at that end either is piece of cake, remove the connector and solder and you're done in 20 minutesyou don't need to find that old one, just find one for the same number of tracks, the same pin count an for the same ribbon type (i mean the ribbon thickness). the pitch between the pins is the key issue here, maybe it's a 2.54 onei bet the connector pins will align correctly, some extra plastic for connector alignment can be cut, if the new one has themgo with soldering if the other ribbon end has some connector, you will separate the boards with the other one if you have to

author: tszaboo
author_rank: Super Contributor
timestamp: July 26, 2021, 09:56:46 am
content: Measure the pitch and count the number of pins. Most ZIF connectors are more-less compatible, so you don't need a 1-1 replacement, something which is close enough works.
zip250 does not power up. - Page 1
Forum section: electronics / repair

author: Doris
author_rank: Newbie
timestamp: March 08, 2021, 05:36:36 pm
content: I followed your blog on how to get the covers off. Very helpful, however the gray cover gets brittle over time so pieces came off without much force. Also there are pin holes around cover that can aid in taking off cover.But my problem is it's dead. I tried many cables to make sure it's not that. I made sure gears are not bound. It sounded like for a brief moment that the motor tried to work. Soldering looks secure, no burnt parts. of course my eject button does not work, have to use paper clip to get disc out. I'm thinking the motor is dead? It's been sitting around for 10 years. I just want to get it going to read some discs I have.Thanks so much.

author: CaptDon
author_rank: Super Contributor
timestamp: March 08, 2021, 07:34:01 pm
content: Which one do you have? The parallel port unit or the USB unit? How is it powered, I am guessing an external wall wart 5vdc at 1 amp or so? Most of those ZIP drives just went click,click,click,......... when they died. Sadly I sold my external ZIP250 drive and the only one I still own is a ZIP100 internal drive that I have mounted into a removable hard drive caddy. Maybe your wall wart power pack is dead or has a bad power lead. Can you check voltage on the ZIP250 control board?

author: Doris
author_rank: Newbie
timestamp: March 10, 2021, 06:30:45 pm
content: USB.
Zoom F6 SD card slot sourcing, Mitsumi CIM-J35N - Page 1
Forum section: electronics / repair

author: DrGear
author_rank: Newbie
timestamp: February 16, 2022, 01:56:13 am
content: Ah the joys of being an authorized service tech and not being able to get parts or schematics from the manufacturer! I've got a Zoom F6 with a busted SD card slot and despite all my searching round, I can't find an equivalent from any other company but the original manufacturer. Can't even get a replacement board from them either.Because of how it's on the board above other components, it's got standoffs AND an unusual 13 connection. After much google fu, I was able to find the datasheet for it and it's a CIM-J35N (linked below). That hasn't helped me though as I cannot for the life of me find these outside of some shady marketplace site that's a third party for Taobao.If anyone has a lead on where I could source these, or even an equivalent that would be greatly appreciated.

author: Renate
author_rank: Super Contributor
timestamp: February 16, 2022, 07:14:08 pm
content: Too bad that you're doing it for somebody else as a service.Me? I'd just solder in an SD card.
Zoom HD16 Hard Disk Randomly Parking - Page 1
Forum section: electronics / repair

author: paul_g_787
author_rank: Frequent Contributor
timestamp: April 23, 2021, 05:03:02 pm
content: I have a Zoom HD16 here which has an issue where the hard disk randomly stops, causing the software to lock up. If there is anything playing back either from the hard disk or CD it starts looping like a scratched record.When it happens there is a click from the hard disk then the HDD access LED goes out at the same time. The only way to recover from this state is to power down the unit and reboot.It can take anywhere from 5 seconds to a few hours for the issue to happen. Once it happens it usually happens more frequently for some time but not always.Things I have tried:I have tried recovering the software on the hard disk - basically a complete format with the CD ROM. This fixes the issue for a while then it plays up again.I have replaced the hard disk with a brand new old stock 80GB PATA (IDE) disk which I tested on the PC before hand. The issue still happens.I have also completely replaced the CD ROM drive for another identical model, this has not resolved it either.The HDD is set to master on it's jumpers and the CD ROM set to slave (same as factory drives).The unit has clearly never been opened from factory when I took it apart to fit the hard disk.I cannot see any damage to any of the cables in the unit.I can see no bulging capacitors anywhere including power supply.Using a different mains lead did not help eitherI am completely at a loss for what to try next. I was very sure the hard disk was just worn out, but of course that doesn't seem to be the case.I have tested the original hard disk on my PC and I am pretty sure it is OK as no errors came up during the test.Can anyone suggest what to try next? I am stumped.Thank you.
ZOTAC GTX 1070 MINI - Page 1
Forum section: electronics / repair

author: vuxe
author_rank: Newbie
timestamp: March 12, 2022, 06:24:14 am
content: I plugged in my gtx 1070 mini from zotac n when I turned my pc on a load pop sound came from my card. I checked out the card n I saw this. check the picture below. c247, c626, n c389 all look popped does anyone happen to know the size of these?

author: kripton2035
author_rank: Super Contributor
timestamp: March 12, 2022, 08:02:38 am
content: one of the mosfet Qxx probably shorted...

author: testpoint1
author_rank: Frequent Contributor
timestamp: March 13, 2022, 06:42:06 am
content: just replace all of them, you are lucky seems no other problem, the capacitor is 10uf/16V, but here the voltage is 12V, so 16V design is incorrect, please use 50V 10uF install it.

author: PKTKS
author_rank: Super Contributor
timestamp: March 13, 2022, 08:40:17 am
content: Replace them all but check for shorts before power onPaul
ZT-MD1 stripes on the display - Page 1
Forum section: electronics / repair

author: Aldo22
author_rank: Super Contributor
timestamp: July 27, 2025, 10:15:25 am
content: Yesterday I dropped my ZT-MD1 quite hard on the floor.At first I thought it was completely ruined, but it actually still works and measures correctly.Unfortunately, there are now stripes on the display.You can still read it, but it just doesn't look good.I opened it up and looked at the ribbon cable connection with a magnifying glass.I didn't notice any damage directly, but it's so tiny that you hardly dare touch it.Is there a trick for fixing this?Thanks!
ZT–702S Multimeter/Oscilloscope Reading Pulsed 6.3 V heater supplies! - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: October 28, 2024, 02:53:51 pm
content: . . .I'm providing technical assistance down at a local Retro Arcade near where I live, and I'm currently having difficulty with one of those Zotek ZT–702S not reading the pulsed 6.3 V CRT heater supply on C.R.T. arcade game display chassis – it detects the frequency as "15.84 kHz" but the voltage shown is negligible!. . .Have I got a faulty instrument or has it got such a poor frequency response that the so–called "true–r.m.s." converter can't read it?. . .Will the ZT–703S read this type of supply in Multimeter Mode?Chris Williams

author: abeyer
author_rank: Frequent Contributor
timestamp: October 28, 2024, 06:04:22 pm
content: The specs say: Frequency response of ACV: 40Hz-1kHzhttps://zotektools.com/products/zoyi-zt-703s/

author: Chris56000
author_rank: Frequent Contributor
timestamp: October 28, 2024, 06:51:41 pm
content: . . .It can't be a very good so–called "true–rms" converter in it, my UT61E is only quoted up to 1 kHz in the leaflet I got with it, but the UT61E can read that type of supply – I took it down there today and tried it on one of their C.R.T. displays and read back 6.1 V!. . .The Arcade Staff would buy me a suitable meter if they're not horrendously expensive – can anybody suggest anything quoted up to 15 kHz or better – or would I be better with an analogue True RMS Meter for these supplies?Chris Williams

author: Xena E
author_rank: Frequent Contributor
timestamp: October 28, 2024, 06:54:56 pm
content: I assume the heater being a winding on the sweep transformer: the 15*** kHz would indicate that.To accurately measure the heater power it can be compared with a suitable hot wire or thermionic measuring instrument.If niether are available, compare the emission of a suitable indirectly heated valve between being powered from 6.3 volts DC and the HF source, this will be best measured by comparing the current in short circuit between the cathode and first grid.Most meters won't make any sense of the hf frequency or waveform from the sweep transformer.X

author: timop
author_rank: Newbie
timestamp: October 28, 2024, 08:58:02 pm
content: I would recommend the Brymen BM869s DMM. The AC+DC true rms bandwidth is 100kHz, and the inputs are rated CAT IV/1000V. IMHO it's a reliable and robust meter that provides a lot of features and good accuracy for the price.

author: beenai2018
author_rank: Contributor
timestamp: October 29, 2024, 06:33:23 pm
content: Quote from: Chris56000 on October 28, 2024, 06:51:41 pmAre you sure about your ut61e bandwidth ?Its accuracy is specified to 10Khz in the manual.
Battery and laser welding - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: July 12, 2024, 08:30:11 pm
content: Anyone has any experience with laser welding when connecting batteries?(Spot welding is not powerful enough for our need)

author: Benta
author_rank: Super Contributor
timestamp: July 12, 2024, 09:22:21 pm
content: AAA? AA? Car batteries? Truck batteries?

author: Stray Electron
author_rank: Super Contributor
timestamp: July 12, 2024, 10:55:34 pm
content: They spotweld steel car frames together so I have to wonder what size battery cells the OP is talking about. All of the LARGE cells that I've seen have all been connected by bolted on straps or cables of some sort. The largest battery cells that need to be spotweldedthat I'm aware ofare D sized cells and a spotwelder can certainly handle those. X-cells are larger but have terminal lugs on them.The OP needs to tell us more about what she's trying to do.

author: thm_w
author_rank: Super Contributor
timestamp: July 12, 2024, 11:20:56 pm
content: You can get spot welders in excess of 200KVA for a few thousand dollars. You can't get a laser that is that powerful for anywhere near the cost.AFAIK laser battery welders are chosen for speed not for power.
Is my soldering iron (Pinecil) dead?  (re: used incorrect tip) - Page 1
Forum section: electronics / beginners

author: sofakng
author_rank: Regular Contributor
timestamp: May 14, 2024, 06:59:13 pm
content: I have aPinecilportable soldering iron and a KSGER 2.1S and I accidentally confused the tips by using a T12 tip inside the Pinecil which uses T100 tips.Now the Pinecil doesn't detect the T100 tip when it's inserted AND it gets incredibly hot (including the body of the iron).Is the iron dead or is there maybe something I can check?I only have one T100 tip so I can't try a different tip to see if it does the same thing...

author: ledtester
author_rank: Super Contributor
timestamp: May 20, 2024, 11:37:11 pm
content: What does the pinecil say for the temp when it is heating up? If it is low then probably the temp sensor is busted.You might also consult this forum:https://forum.pine64.org/forumdisplay.php?fid=162

author: aliarifat794
author_rank: Regular Contributor
timestamp: May 27, 2024, 01:12:45 pm
content: The most probable causes are damage to the temperature regulation circuits or the thermocouple.
Functions generator which I should buy to build Syncrometer - Page 1
Forum section: electronics / beginners

author: kbm
author_rank: Newbie
timestamp: April 09, 2024, 06:44:18 pm
content: To build Syncrometer from H. Clark I need to buy functions generator. The equipment are expensive, which I should buy?This model is ok JDS6600 15-60MHz DDS Function Signal Generator CNC Arbitrary Waveform Pulse Wave ? It is not professional but its price is low. It costs around $90-$100.This is link to Syncrometer: huldaclark.com/syncrometer/

author: shapirus
author_rank: Super Contributor
timestamp: April 09, 2024, 07:01:05 pm
content: Quote from: kbm on April 09, 2024, 06:44:18 pmThat device does not look like it requires any equipment of particularly high accuracy and/or precision to build, so yeah, JDS6600 should be fine, and a cheaper alternative, JDS2800, should be equally fine.In fact, even a very basic one like thishttps://www.aliexpress.com/item/32973535746.htmlor thishttps://www.aliexpress.com/item/1005006314511446.htmlshould be okay for the purpose.If you don't have an oscilloscope, spend the difference on a very basic (unless you're willing to spend more) scope likehttps://www.aliexpress.com/item/1005004972406356.htmlorhttps://www.aliexpress.com/item/1005005644784105.html-- you'll find them very handy for debugging your circuit (and verifying the output of your sig gen), and they're perfectly fine for the audio frequency range that you'll apparently have to deal with, and well above that.

author: kbm
author_rank: Newbie
timestamp: April 09, 2024, 08:22:07 pm
content: Ok, I will buy at the begin your generators, they are a lot of cheaper.Yes, I don't have oscilloscope. I will buy. Thanks
Help identify part off fluke meter - Page 1
Forum section: electronics / beginners

author: algorithm
author_rank: Regular Contributor
timestamp: January 04, 2024, 04:37:15 pm
content: This was a part I assumed was a metalized polyester film capacitor, you know a narrow plastic box, white. But lacking any marking. Well it has a encircled "T" and "4" on the top edge. But googling t4 to an exhausting degree didnt find any match.So I decided to remove it to see if I could figure anything out upon closer scrutiny.The plastic casing turned out being a sheath around an internal part.After unclipping the cases base clips and removing the part its thisThe interior parts grey plastic case has "taiyo" printed in the plastic but that also didnt help me find a datasheet or identify it.Tried google lensing it and that failed to find a match too.Strangely I feel like ive seen this part before but cant recall what it is.Thanks in advance if anybody knows.

author: tooki
author_rank: Super Contributor
timestamp: January 04, 2024, 04:50:38 pm
content: I’m pretty sure it’s a spark gap. (Looks like they stopped making those a while back, but if you google for “taiyo yuden spark gap” you’ll find old datasheets for them, e.g.https://www.digikey.ch/htmldatasheets/production/177655/0/0/1/AG15-20-Spark-Gaps.pdfOne of the styles looks just like the one you “undressed”.)

author: bdunham7
author_rank: Super Contributor
timestamp: January 04, 2024, 04:56:44 pm
content: It would help to know the model of the meter, where in the circuit board this part is and approximate dimensions of the device--perhaps put a coin in the picture for perspective. The space between those two electrodes looks big for a spark gap, but without actually knowing the dimensions I can't tell.

author: algorithm
author_rank: Regular Contributor
timestamp: January 04, 2024, 05:55:48 pm
content: Thanks tooki and bdunham7! Really appreciate your reply.Funny because I googled yesterday "taiyo t4 spark gap" and couldnt find anything.But I just searched omitting the t4 and bingo I thinkhttps://www.ebay.com/itm/325463005657Definitely looks the part.And I suppose that makes sense considering its between the probe inputs.Bdunham7, sorry for not being more specific.Its a fluke model 30 clamp meter that ive been trying to fix for the past week and really just not having success. Ive removed lots of parts to test off circuit and everything I think is bad is good out of circuit. Lacking a schematic im really being put to test. The parts about the exact size of a metalized polyester film cap. And between the probe inputs on the meter. Ive gone so far to remove the lcd to see the brains under it. But still have no culprit as to why the amp clamp wont work.Im guessing its either the opamp or a surface mount cap, which lacking the schematic complicates things. At least I can look up the main ic datasheet and see example circuit values for those little caps. But yeah.
How smartphone charging power management works? - Page 1
Forum section: electronics / beginners

author: noobfrombd
author_rank: Newbie
timestamp: April 20, 2021, 11:37:07 pm
content: Hi, for a long time I wanted to implement smartphone like power feature in my projects. But after tons of searching on YouTube and Google I can only find Power management IC's. But no one to explain how they manage charger connection. Like if I connect my charger to phone it automatically charges, but if I use the phone at very high load, like gaming on it, the phone provides maximum power to it's cpu and other circuitries, then if some power is left from usb, it provides that to battery. It's like if the circuitry load is its 1st priority and charging battery is 2nd priority. There are also some other features are present on smartphones, such as if I disconnect the usb, there is no sudden power blackout on the smartphone, like there is no switching happening from usb to battery, unlike my pc UPS, which takes some time to switch the relay and for that some time i see my pc restarting automatically during power outage. Laptops also behave like smart phone. But how? I know some people uses 2 diodes to feed usb 5v and 3.7v on the same line, but that's creates more problems than it solves. Like how can I change the battery like smart phone does?I just want to power some esp32, STM32 and few other controller projects with batteries. Like my ESP 32 rgb led project has lots of LEDs, so I only power it through usb, no battery system. That's also the case for other projects. I don't want to recharge the battery manually. But I also can't use complex PM IC's. Any help?Sorry for the trouble, If anything doesn't make sense, please ask me. Thanks in advance.

author: amyk
author_rank: Super Contributor
timestamp: April 21, 2021, 12:10:36 am
content: I recommend studying laptop schematics.

author: cortex_m0
author_rank: Regular Contributor
timestamp: April 21, 2021, 12:27:16 am
content: Take a look at this issue of LT Journal. It describes the functionality of Linear Tech's "PowerPath" family parts. Other ICs have a similar topology. It's the first article, pp 1-5.https://www.analog.com/media/en/technical-documentation/lt-journal-article/ltmag_v18n2_jun08.pdf

author: noobfrombd
author_rank: Newbie
timestamp: April 21, 2021, 04:38:10 am
content: Thanks cortex_m0. It's a big help. Appreciate it👍
Simple Auto standby circuit (for an amp) - Page 1
Forum section: electronics / beginners

author: Michaelaudio
author_rank: Regular Contributor
timestamp: August 17, 2020, 06:30:04 pm
content: Hello folks,so I need a standby circuit for an amplifire board, that switches a Mosfet if ~10minutes is no audio signal applied. What would be the best and easiest solution, is there an ic who can do this?
Synology DS216+ H255L passive or pass through crystal? PLEASE HELP - Page 1
Forum section: electronics / beginners

author: GOD
author_rank: Contributor
timestamp: November 07, 2019, 11:50:21 am
content: hey guys what is the h255L component is a active or passive type. how do i tell if its it active or not. Also is the component a crystal or a oscillator? This is in a synology ds216+ nas

author: Ysjoelfir
author_rank: Frequent Contributor
timestamp: November 07, 2019, 03:02:31 pm
content: Looks like a 25MHz Crystal to me with the two caps beside it...Regarding the difference active/passive: an active component is capable of amplifying or routing a signal in some way. A passive can't do that, it can only dampen a signal.
which parts for wiring a 4pin connector - Page 1
Forum section: electronics / beginners

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: May 13, 2019, 10:54:32 am
content: Does this need ferrules or something else?https://www.digikey.com/product-detail/en/1-480703-0/A1453-ND/29345/?itemSeq=291952439Perhaps Digikey carries the appropriate parts for this specific connector I haven't done much connectors not sure which is correct method to get this working.

author: MarkF
author_rank: Super Contributor
timestamp: May 13, 2019, 01:12:05 pm
content: The mating connector and associated contact pins/sockets are shown at the bottom of the Digikey page you linked to.You will also need a crimping tool.

author: oliver602
author_rank: Regular Contributor
timestamp: May 13, 2019, 06:31:02 pm
content: Hereis a selection chart for the different TE Mate-N-Lok contacts and housings.

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: May 13, 2019, 09:58:13 pm
content: Going to obtain thesehttps://www.digikey.com/product-detail/en/350547-1/A14300-ND/213765/?itemSeq=292610804how do they plate the inside with 2 separate metals without plating the outside with the same metals?

author: oPossum
author_rank: Super Contributor
timestamp: May 13, 2019, 11:50:41 pm
content: Probably plated before stamping.

author: akowalczyk
author_rank: Contributor
timestamp: May 14, 2019, 05:49:26 am
content: Helpful hint: Proprietary crimping tools can be very, very expensive. I recommend a good set of needle nose pliers to close up the crimp much like the real tool would. Do NOT solder them, as they will be unreliable and the resistance can vary/cause fires and other badnessHappy Crimping!
Reverse sawtooth Vco won't oscilate below 96 hz  - Page 1
Forum section: electronics / beginners

author: Ryan OMalley
author_rank: Newbie
timestamp: February 08, 2020, 08:50:22 pm
content: Hello everyone, I'm currently working on a reverse-sawtooth volts/hz vco for an analog polyphonic synthesizer that I'm planning to build. I had initially hoped for a frequency range of 32hz to 2500hz, but the circuit will not oscillate below 96 hz. It is a comparator based design that charges 3 capacitors, turns off the input voltage once the capacitors reach 5 volts, then discharges the stored voltage in the capacitors through an npn transistor that is in series with 2 frequency range resistors to ground. the npn transistor is controlled by an op amp with a 0-5 v control voltage on its non-inverting input. I have the circuit built on a breadboard at the moment, and suspecting loose connections, I checked all of the positive, negative, and ground power supply connections and they were fine. My next step was to change the comparator reference to a higher voltage using a 9v battery and a 500k trimpot as a voltage divider. This resulted in stable oscillation at 32 hz, but this caused the circuit to stop oscillating at frequencies above 300hz, and also raised the amplitude to about 8.5 volts, which Is much higher than the 5 volt amplitude i want. I also tried adding more 2700pf capacitors in series with the 3 original ones shown in my schematic, and with 10 capacitors total and a capacitance of 27000pf, the circuit still won't oscillate correctly. I'm not sure what to do next at this point other than possibly adding either a single capacitor or multiple ones with a higher value. I've attached my schematic for the circuit below, and I greatly appreciate any suggestions or ideas that will help me get this circuit to work correctly. thanks, Ryan
LTSpice ram/logic/eeprom ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: March 27, 2020, 03:22:53 am
content: I have some logic chip models in ltspice. Can it do stuff like remember states and put it into a ram chip model ? What about an eeprom, or is that actual code put on a chip and not what spice can run anyways.What about some freeware programs meant for digital design, or just basic digital IC circuit sim ? Maybe ltspice is fine at this.

author: krayvonk
author_rank: Regular Contributor
timestamp: March 27, 2020, 04:13:37 pm
content: (take this with pinch of salt, im only beginning.)I'm not sure if the circuit sims on the net are realistic, but if the one your using is, it should work fine for simulating registers and computer like circuits - they are no different from any other. But ive never used LT-SPICE yet.Nothing beats actually making a prototype for real and testing it in real life tho, otherwise your trusting the developers of these simulators, and i'm not sure how good they actually are.Im sure they work well with a certain set of tested circuits, but if you circuit falls out of this alley you will get stuff ups.This one is good(ish)https://www.falstad.com/circuit/it seems to work a little, but ive got my issues with it and id rather get real results than using it.If it were true and all you needed was to virtual simulate, designing would be HEAPS easier! Having to wire things up sucks, if u had a realistic circuit sim it would speed up the design workflow by 1000%.Only sims I really trust are gate model sims like logisim, then it should be ok cause its just logic gates. But the actual plumbing based sims? (especially for passive circuits...) - Doesnt look good from my perspective. But my circuit theory isnt the best either - so I could be wrong saying its wrong. But I stand by my logic, and until its ok with me, its not ok.
SPI/MMC signal via <6.5 Ohm path - Page 1
Forum section: electronics / beginners

author: permal
author_rank: Regular Contributor
timestamp: September 14, 2018, 07:44:11 pm
content: Hi,For various reason I need to connect my MCU and SD Card via both SPI and the MMC interface, though only one at a time. To achieve this I've opted for a MX4948 to switch between the two, but I'm concerned that the extra resistance of <6.5 Ohms of theMX4948will interfere with the signals.Am I right to be concerned, or can this work without issues?

author: rstofer
author_rank: Super Contributor
timestamp: September 14, 2018, 08:43:13 pm
content: When signals leave FPGA boards, it is fairly common to have 330 Ohm series resistors to protect the device. This sometimes shows up in uC boards as well.So, I wouldn't spend the least bit of time worrying about a 6.5 Ohm resistance. If you want to do the math, find out what the input current is on the SPI/MMC devices and compute the voltage drop across the resistance. Then compare the result with the switching threshold voltage. You can do all this and still come up with the fact that 6.5 Ohms is insignificant.What I don't understand is how the turn-on and turn-off times can be so slow (on the order of 800 ns each) and the device still has a -3dB frequency of 300 MHz. I'd need to think about that. Even so, it might not matter.

author: permal
author_rank: Regular Contributor
timestamp: September 14, 2018, 09:13:15 pm
content: Thanks!Quote from: rstofer on September 14, 2018, 08:43:13 pmLets see if I undertand that. You're saying that the 300MHz is unexpectedly high for a -3db signal reduction? (I need to watch Dave's video about signals again)

author: rstofer
author_rank: Super Contributor
timestamp: September 14, 2018, 10:27:08 pm
content: I think what I am saying is that the total of turn-on plus turn-off is about 1.6 us. Given 0 ns actual on-time or off-time, the maximum frequency would be 625 kHz. That was my original thought as I just glanced at the datasheet.The thing is, I also think I am wrong! I suspect the turn-on/turn-off times apply to switching sources and this makes sense. It generally wouldn't matter much how long it took to select devices. Then the 300 MHz frequency also makes sense because, once a source is selected, the actual signal can be quite fast.I like the second explanation. That and I should really read the datasheet in detail to understand what they're getting at. I think you should disregard my original comments re: speed and move on. It's going to work fine!
Battery charging protection in mobile phone - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: June 04, 2018, 06:44:02 am
content: When I charge a mobile phone , there is a charging management system on the main board of a mobile phone, that prevents the battery from overcharging . In case the charging management system is damaged, there should be overcharging protection in a battery. But what happens if that overcharging protection in the battery is not working either or there is not such overcharging protection at all?Will the battery blow up /burn ? Or what happens?

author: james_s
author_rank: Super Contributor
timestamp: June 04, 2018, 07:05:09 am
content: If a lithium ion batter is overcharged, it will usually catch fire. Fortunately it is quite rare for both the charger and the protection circuit in the battery to fail but it does happen occasionally, mobile phones have caught fire.
Nixie clock - Page 1
Forum section: electronics / beginners

author: manubali
author_rank: Contributor
timestamp: June 05, 2017, 10:03:52 am
content: Hi, i am a beginner learning to design circuits, recently i got inspired by dave's nixie tubes project and decided to build one, i have choosen this circuithttps://www.instructables.com/id/SMD-Nixie-Clock/Author have used IN-14 nixies for this project, but they are bit expensive, i found IN-12a and NL-841, (nzd $26 and $90) for Lot of 6, and i am going for NL-841, but i have confusion with pin configuration.The 14th pin in datasheet is called "int. conn." What does that means?? I know its a stupid question.

author: danadak
author_rank: Super Contributor
timestamp: June 05, 2017, 11:00:06 am
content: Have you got a datasheet you can post ?Just speculating that this is a pin used internally as a header and has "int"-ernalconnections to it. Not to be used by user ? Just a thought.Regards, Dana.

author: manubali
author_rank: Contributor
timestamp: June 05, 2017, 11:44:04 am
content: https://www.google.co.nz/url?sa=t&source=web&rct=j&url=http://www.tube-tester.com/sites/nixie/dat_arch/NE-data_03.pdf&ved=0ahUKEwjNhJ3iz6bUAhULO7wKHTdLBqQQFggbMAA&usg=AFQjCNFqPUXkSfA2rLThPrNkmGIvl5mLUA&sig2=vW7ZJCK3818PwYo-dntanACheck page 5 for NL-841 pin configuration

author: james_s
author_rank: Super Contributor
timestamp: June 06, 2017, 08:29:43 pm
content: Pins with names like that are frequently used as mechanical supports for the internal structure of the tube. Often they're effectively in parallel with other connections, occasionally they're used to power a coil wrapped around a getter pill. Whatever the case you should avoid connecting anything to them unless you know for sure what you're doing.
A good ADC for a diy osciloscope. - Page 1
Forum section: electronics / beginners

author: shobo
author_rank: Regular Contributor
timestamp: April 03, 2017, 06:43:10 pm
content: Hey all,Could anyone suggest a ADC for a diy osciloscope?10-15$ one off would be nice.

author: gnif
author_rank: Unknown
timestamp: April 03, 2017, 07:39:55 pm
content: Not sure if this would help you, but your sound card can be used for low frequency stuff if you want a mostly complete DIY solution.

author: danadak
author_rank: Super Contributor
timestamp: April 03, 2017, 09:23:24 pm
content: For a very effective low cost logic analyzer (use Saleae free software download) -https://www.saleae.com/downloadshttp://www.ebay.com/itm/New-Set-USB-Logic-Analyzer-Device-USB-Cable-24MHz-8CH-24MHz-for-ARM-FPGA-/291457642276?hash=item43dc3aaf24:g:3D4AAOSwBahVTC~qSound card and function generator and spectrum analyzer scope (freeware) -https://www.zeitnitz.eu/scope_enhttp://www.zelscope.com/Google "protect sound card inputs" for circuits to keep yoursound card from overload.Regards, Dana.

author: danadak
author_rank: Super Contributor
timestamp: April 03, 2017, 09:26:31 pm
content: If you want to do a DIY scope A/D requirements set by sampling rate youwant to achieve and resolution.What are your requirements for scope BW and resolution ?DIY scope with a PSOC which has A/D, ARM Core, DSP engine (for filtering),and so much more.http://www.embedded.com/design/prototyping-and-development/4421857/2/Configuring-a-PSoC-for-a-DIY-oscilliscope-logic-analyzer---Part-1http://www.embedded.com/design/prototyping-and-development/4421858/Configuring-a-PSoC-for-a-DIY-oscilliscope-logic-analyzer---Part-2Regards, Dana.

author: capt bullshot
author_rank: Super Contributor
timestamp: April 04, 2017, 07:26:34 am
content: http://www.ti.com/product/adc32rf45SCNR :-), it is slightly out of your price limits

author: PointyOintment
author_rank: Frequent Contributor
timestamp: April 14, 2017, 08:06:49 am
content: What specs are you looking for? Bandwidth? Sample rate? Resolution? Channels? Output format?
Over current and over voltage protection for power cable without using fuses - Page 1
Forum section: electronics / beginners

author: e100
author_rank: Frequent Contributor
timestamp: February 18, 2017, 05:26:36 pm
content: I'm running several micros at various locations along a 45 meter long cable which is rated at 1A per conductor.Currently I put 10v in at one end which drops to about 9v at the far end and the normal current draw is about 220mA in total.The micros have linear regulators on board which further drops the voltage to 5v.Currently I'm using a lab power supply with an adjustable current limit set to 300mA.Eventually I would like to replace this with a plug pack to free up the power supply for other projects.To save the cable, and prevent the micros from being accidentally fried would something like a LM317T configured as a 300mA constant current source followed by another LM317T configured for a 10 v constant voltage output followed by a some kind of crow bar circuit make sense? I know the LM317T has built in thermal shutdown circuitry so in theory if bad things happened, the arrangement would eventually end up in some kind of thermal shutdown state that would be able to recover if the power was temporarily shut off and things were allowed to cool down.

author: Ian.M
author_rank: Super Contributor
timestamp: February 18, 2017, 06:03:34 pm
content: Sounds over-complex. A suitably rated unregulated DC supply with an output less tha the max input voltage of the 5V regulators (allowing for load current and dissipation) + a 500mA Polyfuse is probably the way to go. If you use a cheap SMPSU, then you may want to add a crowbar circuit in case it looses regulation.
Switch to power microcontroller with time delay - Page 1
Forum section: electronics / beginners

author: cowana
author_rank: Frequent Contributor
timestamp: June 30, 2015, 07:23:28 pm
content: I'm working on a project which has multiple switches. When any switch is activated, the always-on-supply (VBATT in the attached diagram) needs to be power the microcontroller (powered by +3V3). When the switch is released, the microcontroller needs to continue operating for a brief period (in the order of 10 seconds).The current draw of the microcontroller will be around 5mA, so to provide this storage purely via capacitance would require a large amount of capacitance (which there isn't physically room for).Each switch is read by a microcontroller input, so paralleling the switches together is not an option.I'm looking for a very simple, low component count solution - timing accuracy is not a concern at all. I'm fairly happy the attached circuit will work - but it would be good to hear some agreement before I order the board!Theory of operation:- Normally gate of Q2 = 0v, base of Q7 = VBATT, +3v3 output is disabled.- If any switch closes...- C6 charges up through the specific switch's diode, gate of Q2 goes high- Q2 switches on, base of Q7 pulled low- Q7 switches on, +3v3 output is active- Switch closes- Time delay as C6 discharges through R20- After a while, Q2 switches off, Q7 switches off- +3v3 output is disabled

author: HalfSpace
author_rank: Regular Contributor
timestamp: July 03, 2015, 11:07:38 pm
content: Hi cowana,If you have a free output pin on your microcontroller, connect it via a resistor to Q2 (see below). This pin can hold Q2 on for a period of time set in your code and then turn the pin off turning itself off.HalfSpace
USB Programmer solution to write bios chip Winbond 25Q128FVIQ - Page 1
Forum section: electronics / beginners

author: Prog
author_rank: Newbie
timestamp: July 28, 2016, 07:41:06 am
content: Hey there,First of all nice to meet you, I'm glad that I've found this community.I have a situation and wanted to know your point of view in choosing a decent USB programmer to (re)write bios chip Winbond 25Q128FVIQ.I've found this productCH341Abut reading the technical specs I can't find the above chip series.Supported WINBOND chips are:WINBOND·W25P10, W25X10, W25Q10, W25P20, W25X20, W25Q20, W25P40, W25X40, W25Q40, W25P80, W25X80, W25Q80, W25P16, W25X16, W25Q16, W25P32, W25X32, W25Q3, W25P64, W25X64, W25Q64Have anyone used this device for the specified type of bios chip please?Any other recommendation will be much appreciated.RequirementsUSB, Windows 8/10 64-bit.

author: ebclr
author_rank: Super Contributor
timestamp: July 28, 2016, 07:44:59 am
content: I have this onehttp://pt.aliexpress.com/item/Tl866cs-tl866a-reprogrammed-ic-testing-seat-adapter-sn-004-sop44-psop44-socket-programmer-ic-test-seat/32645870454.html?spm=2114.02020208.3.319.XlujA8&ws_ab_test=searchweb201556_10,searchweb201602_3_10057_10056_10055_10037_10049_10033_10059_10058_10032_10017_405_404_10040_10060_10061_412,searchweb201603_7&btsid=20071a97-2872-44a3-b2a2-5e9a0b62d65bAnd work well

author: Prog
author_rank: Newbie
timestamp: July 28, 2016, 07:55:42 am
content: Thank you for your feed-back;@blueskull Kind of strange they said :Perfect support and router16 feet25L6405 25L6445 25Q64 MX25L12805 MX25L25635W25Q128; but the chip have; am I unerstood something wrong !?@ebclr, TL866 looks good similar to theseSofiseries SP-8, SP-16.let's say that in the future we will have another type of chip; the unit will be able to self-update through the newest version of firmware supporting the newest types of chips or we have to upgrade the unit itself buying another one?Generally speaking, a software programmer unit will have the possibility to auto-detect the chip type?

author: jkf1000
author_rank: Regular Contributor
timestamp: July 28, 2016, 11:06:21 am
content: Another vote for the TL866cs here. A great little multi-use programmer for the money.. Karl

author: ebclr
author_rank: Super Contributor
timestamp: July 28, 2016, 12:07:59 pm
content: No you dont need to buy another one for update , the list of supported devices is really big, and get updates regularly.This device can even test logic IC's , it's worth the money
Bnc Ground ?? - Page 1
Forum section: electronics / beginners

author: Ranger14
author_rank: Regular Contributor
timestamp: June 08, 2016, 06:16:35 pm
content: I got a couple more parts for my scope and Function generator.. But in the parts lot I got a couple 50 ohm terminations that have a ground wire soldered to the outside of the termination..I have never seen these before and does anyone know what these are used for

author: edpalmer42
author_rank: Super Contributor
timestamp: June 08, 2016, 07:30:10 pm
content: It's not actually a ground wire. It's so you can attach the terminator to the panel so it can't run away and hide. Some equipment specifies that the connector should always be terminated except when a cable is attached. Often, instead of a wire, a chain is used.Ed
Fixing A Broken Lead - Page 1
Forum section: electronics / beginners

author: Kdog44
author_rank: Contributor
timestamp: May 12, 2015, 02:07:27 am
content: I have a beginners question regarding soldering, Is it possible to fix the photo-diode in the attached pictures. If so, then how would I approach this. Note that the lead is broken off right at the base. The photo diode in the picture is an expensive part and I would like to be-able to fix it rather then use my spare. I was not the one who originally soldered the yellow/red wires onto it. Thanks for any help.

author: xrunner
author_rank: Super Contributor
timestamp: May 12, 2015, 02:10:20 am
content: Your attachment isn't showing ...

author: Kdog44
author_rank: Contributor
timestamp: May 12, 2015, 02:18:13 am
content: hmm my mistake, I was pretty sure I attached the image. Here it is.

author: xrunner
author_rank: Super Contributor
timestamp: May 12, 2015, 02:27:41 am
content: I think so, but it's gonna be very weak mechanically. But if you must ...Put a small amount of flux on the spot so solder will take fast. Drop some solder on it and see if it takes. Then, get a pre-tinned wire and attempt to solder it to the drop of solder on the cut wire. Might work.

author: Paul Moir
author_rank: Frequent Contributor
timestamp: May 12, 2015, 02:34:51 am
content: If you have no luck attaching, file or grind away a bit of the plastic to expose more of the lead.

author: Kdog44
author_rank: Contributor
timestamp: May 12, 2015, 03:02:06 am
content: Quote from: xrunner on May 12, 2015, 02:27:41 amI tried this, I could never get enough solder on the small exposed part of the photo diode. Thanks anyways.

author: xrunner
author_rank: Super Contributor
timestamp: May 12, 2015, 03:03:44 am
content: Quote from: Kdog44 on May 12, 2015, 03:02:06 amThen do what Paul said - what have you got to lose?

author: ElektroQuark
author_rank: Unknown
timestamp: May 12, 2015, 07:59:12 am
content: Sand the side slighty until you reach the inner pin laterally. Then solder the wire.