hybridfree/eevblog-posts huggingface dataset:
Please Help: Tektronix 2205 Distorted Traces - What's Wrong? - Page 1
Forum section: electronics / beginners

author: mianchen
author_rank: Regular Contributor
timestamp: September 06, 2012, 10:33:36 pm
content: I was given this tek 2205 CRO by a friend who has no clue about electronics after hearing my older CRO is dead. This scope seems to work ok except that the traces are distorted (see pictures). The first pic is showing both channels with a signal from the same source. The second pic is showing the same thing but with the 'scope physically turned 90 degree - they seem to have 'shrunk' in width.Is this caused by magnetisation of the CRT shield (Google search for 'similar' symptoms seem to point to this cause)?I've made a degaussing wand, but just want to ask here in case it will do more harm than good.Any suggestion is appreciated! Thank you.

author: w2aew
author_rank: Super Contributor
timestamp: September 08, 2012, 09:33:44 pm
content: It looks like it may have gotten magnetized - either that or there might be a power supply problem in the vert/horizontal driver circuits. I'd start by degaussing the chassis and shield of the the scope.

author: djsb
author_rank: Super Contributor
timestamp: September 09, 2012, 12:45:51 pm
content: For a quick answer post a link to this topic on the Yahoo TekScope grouphttp://tech.groups.yahoo.com/group/TekScopes/?yguid=330951138You'll have to join it first though.There are many experienced Tek folk on there.David

author: mianchen
author_rank: Regular Contributor
timestamp: September 18, 2012, 06:33:58 pm
content: I've posted this on other forum but I think it doesn't hurt to post it here as well.This is how the traces behave:This is the CRT pulled out of its metal shield:Too bad!This scope is really clean and tidy inside, almost looks new! oh well
CRO TYPE HTC-OS-16A ,200V POWER SUPPLY FAILUARE. - Page 1
Forum section: electronics / beginners

author: RAJENDRA
author_rank: Newbie
timestamp: September 04, 2020, 03:13:42 pm
content: HELLO,IN SAID CRO 200V POWER SUPPLY SOME COMPONENTS ARE BURNT.R152 &R153 RESISTOS ARE BURNT.CAN SOMEONE LET ME KNOW THE VALUES OF THESE RESISTORS SO AS TO PROCEED WITH THE REPAIRS. OR PROVIDE THE CIRCUIT DIAGRAM.THANKS.

author: Halcyon
author_rank: Unknown
timestamp: September 23, 2020, 06:30:58 am
content: Please don't post the same thing in multiple forums. I have retained this one and deleted the rest.Also, all caps is considered shouting. I can appreciate that English might not be strong, but you may also wish to consider how you word your posts if you want to be taken seriously.
cross-over cancellation method - Page 1
Forum section: electronics / beginners

author: fady232
author_rank: Contributor
timestamp: April 24, 2025, 07:09:00 am
content: Hello all, i was simulating this push-pull stage, where the cross-over gets cancelled.But i didnt understand how it works, like who's forward biasing here the diodes? the power supply of 9V and -9V? ( like the circuit i show near to it )or the signal vin is responsible for the forward biasing? and if its the power supply then why the vin doesnt matter? like ur not applying 2 signals?

author: Zero999
author_rank: Super Contributor
timestamp: April 24, 2025, 08:19:54 am
content: The power supply is biasing the diodes.The voltage on D1 is always about 0.7V above the signal and the voltage on D2 is always 0.6V below the signal. This results in a DC bias of +0.7V on the NPN and -0.7V on the NPN which keeps them on slightly.Post the .asc file.

author: fady232
author_rank: Contributor
timestamp: April 24, 2025, 08:42:02 am
content: why the d.c voltage is forward biasing the diodes and not the vin signal?btw i added Spice file if u wanna check

author: mikerj
author_rank: Super Contributor
timestamp: April 24, 2025, 09:21:52 am
content: Quote from: fady232 on April 24, 2025, 08:42:02 amBecause your supply rails are symmetrical so the voltage in the middle of the two diodes is 0v, and your input signal is also centred around 0v. If you added an offset to the input signal, or made the supply rails non-symmetric then your input source would affect the bias.

author: fady232
author_rank: Contributor
timestamp: April 24, 2025, 11:00:46 am
content: if i give an offset i will have a signal that is gonna reach more than 9V, in this way the diodes are polarized in reverse mode no?secondly the vin is gonna be higher than power supply so circuit goes in saturationthats why right? these can be the 2 bad scenarios, or i didnt understand what u meant?

author: Zero999
author_rank: Super Contributor
timestamp: April 24, 2025, 11:12:12 am
content: If Vin exceeds the power supply voltage, then yes the diode will become reverse biased and the transistor turn on as much as it can, with its base connected to the supply rail via 10k. Note that although the amplifier's output stage would be considered to be saturated i.e. not go any further, paradoxically neither transistor can saturate, as they're emitter followers.Try plotting the base voltages vs Vin.

author: fady232
author_rank: Contributor
timestamp: April 24, 2025, 11:25:40 am
content: Ye i tried plotting a ramp and i saw this issue
Cross Reference for Technics/Matsushita Partnumbers? - Page 1
Forum section: electronics / beginners

author: schwarz-brot
author_rank: Regular Contributor
timestamp: April 22, 2014, 05:41:32 pm
content: Hi there,working on a turntable at the moment. Nothing expensive but I hunted the problem down to a single IC. It is a Hall IC, whatever Technics ment with that term. Actually it is a complete motor regulating IC based on the measurements made via hall effect.The Technics Partnumber is sviba808. This IC is no longer available. I think this part was just relabeled for Technics/Matsushita. On the actual IC it says 808 and 049A, both terms don't lead nowhere with a basic search.I was wondering if there is a cross reference for Technics/Matsushita parts like there is for agilent?

author: HalfSpace
author_rank: Regular Contributor
timestamp: April 26, 2014, 02:31:14 am
content: Hi Schwarz-brot,The part is listed under Panasonic. Try the links below I hope it helps.http://www.ued.net/ued/viewItemAction.do?itemCode=MSCSVIBA808http://www.acme-sales.net/portal.php?country=OTHER&p_id=SVIBA808HalfSpace
Crosstalk on disconnected inputs - Page 1
Forum section: electronics / beginners

author: Rapsey
author_rank: Contributor
timestamp: October 06, 2018, 12:36:24 pm
content: I'm trying to control aDotStar 0.5m LED strip(72 RGB LEDs) from a Raspberry Pi 3 model B (via SPI). Since DotStars are 5V devices and the Pi's logic is 3.3V I am using a74AHCT125as a logic level shifter, as recommended by the manufacturer:A = 3.3V logic input, Y = 5V logic output, OE = output enable (low = enabled, high = disabled).So I have a tiny circuit board built around this IC with 3 things connected to it:5V DC power supply (VCC, GND)5V output cable to the LED strip (VCC, DAT, CLK, GND)3.3V input cable from the Pi (DAT, CLK, GND)The input and output cables are very short (40cm max). All the GNDs are interconnected.This all works very well as long as the Pi is supplying input signals. The problem arises when there is no input, i.e. when:The 3.3V input cable isn't connected to the Pi at allThe 3.3V input cable is connected but the Pi is powered offThe 3.3V input cable is connected and the Pi is powered on but not providing input signalsNote that this is all with the input cable connected to the circuit board. When the input cable is not connected to the circuit board there is no problem.It seems clear that this is caused by crosstalk. Moving or fiddling with the input cable causes random LED flickering (doing the same thing on the output cable does nothing). The IC seems to be picking up input signals where there are none and although there's no voltage on these cables from the other end, the IC itself seems to apply some voltage to them.Since I was using fairly thin 24 AWG stranded wire I first made a new input cable with much thicker, better insulated and probably overkill wire (17 AWG stranded power wire) and also sleeved the wires individually instead of having the 3 wires in 1 sleeve. The interference seems to be a bit less but it's still there.Now I'm thinking, rather than trying to completely get rid of the crosstalk, maybe I should put those OE's to good use? The example provided by the manufacturer has them all tied to GND (= enabled). I should be able to have them tied to VCC (= disabled) and use an additional input pin on the Pi to make them low only when the LED strip is in use.Do you think this an acceptable way of working around the problem or am I just being stupid here?EDIT: Added one way of making OE high by default and low when the Pi commands it (so basically an inverter) using an NPN transistor. I'm not sure if these are sane resistor values but in simulation it works.Input disconnected (or low):

author: hsn93
author_rank: Regular Contributor
timestamp: October 07, 2018, 08:30:21 am
content: i think u need to pull down your transistor inputs.100k from v2 to gnd
Crosstalk  - Page 1
Forum section: electronics / beginners

author: Andrew-s
author_rank: Newbie
timestamp: June 02, 2024, 04:36:48 pm
content: Hello new to the form so forgive me if answered elsewhere.Im making a xilinx fpga Dev board i am interfacing with a single 16 bit 4gb ddr3 ic and using a 8 layer board. My question is will i have a cross talk problem if i have data and control lines routed underneath and parallel with each other if i put a gnd layer between each other i did try to eliminate it as much as possible though.

author: CaptDon
author_rank: Super Contributor
timestamp: June 02, 2024, 05:32:00 pm
content: Perhaps the question is better asked in the FPGA or Microcomputer section? Move the question, don't cross post. I think equal impedance / length lines seem to be most important and I sometimes see resistors of around 22 ohms in series. I was told they help stop reflections. If laid out with care (I always said "It just looks right") with a ground layer in between you should be fine. After years of trouble shooting boards that have no bad components but still give random faults you can sort of visually see the difference between a well laid out board and a board done by someone who was clueless about fast high speed signal routing. 'Then the stories start!!' Cheers mate, best wishes.

author: Andrew-s
author_rank: Newbie
timestamp: June 08, 2024, 11:18:51 pm
content: thank you very much for the advise and i will move it over
crowbar or TVS  ? - Page 1
Forum section: electronics / beginners

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: June 21, 2016, 09:54:17 pm
content: I want to protect the output of a bench power supply that is providing fixed 5V output.I had the surprise once to see this output jumped to 15 V.Now I understand that this can happen if the transistor that is driving the main power transistor fails.I made on a prototype board the crowbar that is given in the Art of Electronics (3rd) in Fig. 9.102Cwith an added fuse.But will a simple TVS (Transcient Voltage Suppressor) as the ICTE5 with an additional fuse do the same thing ?http://www.vishay.com/docs/88356/icte.pdf

author: uncle_bob
author_rank: Unknown
timestamp: June 21, 2016, 11:31:12 pm
content: Quote from: JacquesBBB on June 21, 2016, 09:54:17 pmHiIf it is a real fuse and a real TVS, the TVS will go up in smoke before the fuse opens.Yes, you *can* have a TVS the size of your fist and a $10 50 ma fuse and it will work fine.Bob

author: uncle_bob
author_rank: Unknown
timestamp: June 21, 2016, 11:50:46 pm
content: Quote from: blueskull on June 21, 2016, 11:40:58 pmHiSome TVS's go short and then go open after the over current.. Like a fuse, they have an energy level they will deal with. Past that energy level, all bets are off.Replacing both an expensive fuse and a TVS each time there is a spike seems silly. If you have a supply that spikes once, it's likely to do it on a regular basis.Bob

author: Gyro
author_rank: Super Contributor
timestamp: June 22, 2016, 09:11:07 am
content: The 'problem' with TVSs is that they are not perfect clamping devices.Firstly they have a tolerance that you can do nothing to change (other than selecting another sample). They also have three important parameters:1. The holdoff voltage. That's the voltage where none of the devices, over the full manufacturing tolerance spread will conduct any significant current. This is the maximum voltage of the rail you would use them on.2. The conduction voltage. That's the voltage where the TVS will conduct a specified current ( just like Vz @ Iz for a zener diode).3. The clamping voltage. This is the point will conduct hard, again at a specified (large) current. This is the point where your fusewould startto blow.In practice, for a 5V (holdoff) device, the spread of these three voltages will be quite high, you probably won't hit the clampiing voltage until about 8.5V... probably higher.In contrast, your crowbar circuit with its nice accurate TL431 and trimmable resistive divide can be made to trip at, say, 5.5V. Even if you replaced the Thyristor with a big beefy transistor to act as a voltage clamp rather than a crowbar, it would still perform better than a TVS in your situation.
Crowd funded item, will it work? Wayv - Page 1
Forum section: electronics / beginners

author: Another Dave
author_rank: Contributor
timestamp: May 26, 2016, 11:56:44 pm
content: I stumbled across this item on a camping forum and thought Dave may be able to give us an ideaon how it works and if it will actually work.Its a portable Microwave. The Wayv website says 200W and it will run for upto 30 minutes or cook upto 6 meals.http://home.bt.com/tech-gadgets/tech-news/theres-a-portable-microwave-going-on-sale-next-year-11364063857758www.wayvtech.com/Will it work or a debunking video on its way?My first thoughts, 6 meals or drinks and upto 30 minutes, how do you charge it in the field? Maybeits got a batteriser?Thanks.

author: rstofer
author_rank: Super Contributor
timestamp: May 27, 2016, 12:26:41 am
content: Quote from: Another Dave on May 26, 2016, 11:56:44 pmThe article mentions in-car recharging so, just run your gasoline engine long enough to recharge the Li-Ion batteries. I guess most people take their car camping... Then there is the solar recharging. We don't have any clue how much charge it will take but the solar panel could be large if we plan to eat 3 meals a day.
Crt monitor problem - Page 1
Forum section: electronics / beginners

author: Serge125
author_rank: Regular Contributor
timestamp: October 30, 2018, 07:12:44 pm
content: Hi all! Ok got my little 1084 monitor foxed and powers up nicely BUT now the display is kinda distorted. Half of the screen is kinda pinched at the middle to the bottom of the screen while it get's bigger from middle to top. Before I saw this I had a screen that the top menue bar was way up in the screen that I couldn't see it so I checked if I could adjust the V-Size and the V-Position that kinda corrected the problem but now I have this screen distortion problem and need advice on how to correct this (if I can).THANKS!!

author: Photon939
author_rank: Regular Contributor
timestamp: November 01, 2018, 02:42:14 pm
content: I do not have much experience with CRT repair but I believe this is likely due to a leaky capacitor in the vertical oscillator circuit. Do you have a schematic for the monitor?

author: Serge125
author_rank: Regular Contributor
timestamp: November 01, 2018, 04:11:33 pm
content: Quote from: Photon939 on November 01, 2018, 02:42:14 pmYep have it here!

author: floobydust
author_rank: Super Contributor
timestamp: November 01, 2018, 04:53:47 pm
content: Serge125 you already posted about this here:https://www.eevblog.com/forum/repair/crt-monitor-display-distortion-problem/It really helps to put the make/model number in your posting title.

author: Benta
author_rank: Super Contributor
timestamp: November 01, 2018, 05:24:18 pm
content: Reading your schematic, the problem is somewhere around I 301.
crt televisions - Page 1
Forum section: electronics / beginners

author: p.larner
author_rank: Frequent Contributor
timestamp: December 20, 2023, 03:50:40 pm
content: is anyone still making them?.

author: sparkydog
author_rank: Regular Contributor
timestamp: December 20, 2023, 04:15:39 pm
content: LMGTFY...

author: u666sa
author_rank: Frequent Contributor
timestamp: December 20, 2023, 04:36:52 pm
content: Quote from: p.larner on December 20, 2023, 03:50:40 pmCan't answer that. My guess no.But can you buy them? Yes you can. Go on free ads site for your country. You will find a whole bunch of them for $1 to $5, local pickup only. I sold one last year. People buy them, then get a DVB-T2, and watch them at work, etc.

author: Andy Chee
author_rank: Super Contributor
timestamp: December 20, 2023, 07:24:14 pm
content: If you search for "crt" on aliexpress, you will definitely get lots of hits, which seems to imply that at least in China, CRT manufacturing is still alive.CRT manufacturing isn't exactly high tech intellectual property theft, so is probably one reason why China feels free to make what most of us would regard as obsolete.

author: soldar
author_rank: Super Contributor
timestamp: December 20, 2023, 10:11:57 pm
content: https://rsscloud.org/when-was-the-last-crt-tv-made/
CRT TV Funamentals - Page 1
Forum section: electronics / beginners

author: Votality
author_rank: Contributor
timestamp: September 05, 2015, 11:55:21 pm
content: Sorry if this has already been posted, and also for posting in this subform. I wasn't quite sure how to categorise this. But anyone wishing to learn how crt tv,s work need to watch this fantastic explanation from bjork.http://youtu.be/75WFTHpOw8Y

author: IanB
author_rank: Super Contributor
timestamp: September 06, 2015, 12:46:01 am
content: What's a CRT TV?

author: Macbeth
author_rank: Super Contributor
timestamp: September 06, 2015, 12:51:35 am
content: Beautifully bonkers. She is quite right of course, Icelandic poets are not as good as the Dutch when explaining the CRT. Now if she got to read my English City & Guilds books she could have expanded her repertoire with "Aquadag", "phosphor", "shadow mask", "trinitron", "EHT", etc. So many good songs to be made...

author: Deathwish
author_rank: Unknown
timestamp: September 06, 2015, 01:49:54 am
content: She can come and sing in my shower anytime. TV included

author: Shock
author_rank: Super Contributor
timestamp: September 06, 2015, 04:30:26 am
content: ...and here is the big fat 30KV wire that goes up into the clouds to make the sun shine, bzzzzzt!

author: isaiahA
author_rank: Contributor
timestamp: September 08, 2015, 10:09:07 pm
content: it is kind of like a city.
Crt viewfinder image horizontally squished to one side. - Page 1
Forum section: electronics / beginners

author: Maliaris
author_rank: Newbie
timestamp: February 02, 2020, 04:20:54 pm
content: Hey GuysRecently i managed to repurpose an old crt viewfinder into a tiny monitor with some help from reddit. Everything works fine except when i power it on, a small vertical segment on the right side of the display doesn't light up. The issue persist when i hook it up to a signal source. See image bellow:I'm not able to see any faulty components on the controller board. There are adjustment screws for contrast , brightness and vertical image size, but i couldn't find anything that adjusts the horizontal size/position. Here is the schematic for the viewfinder module:My guess is that something is wrong with the deflection coils or a component leading to them?Do you guys have any idea what is causing the issue or any recommendations on how i could diagnose it?Here are some images of the board:Thank you.

author: Benta
author_rank: Super Contributor
timestamp: February 02, 2020, 04:50:58 pm
content: First thing to do is to completely resolder the PCB. Preferably using solder wick to remove the old solder, and solder again with fresh eutectic solder.It was probably originally wave soldered, and during a production run the solder bath mixture moves away from eutectic, producing mediocre joints.

author: Maliaris
author_rank: Newbie
timestamp: February 02, 2020, 04:53:52 pm
content: Thanks for the advice!

author: SeanB
author_rank: Super Contributor
timestamp: February 02, 2020, 07:42:25 pm
content: I would change C809 as well, 10uF 25V, as that is likely slightly low in value, leading to the reduced scan width. Unfortunately horizontal scan is set by the inductor L802 in series with the capacitor, and that is probably a part set at the factory and locked solid, so will not be adjustable. Capacitor is a likley suspect, they do tend to fail in this application from the high scan current passed through it. I would suggest using a 10uF 63V film capacitor as replacement, as it will last longer in this application, as it is subject to reverse bias, but will be physically larger, and often the space to fit it is limited.About the smallest is the following from Digikey, though RS and Farnell probably also stock it. Should fit there in the same volume as a 10uF capacitor.https://www.digikey.com/product-detail/en/wima/MKS2B051001N00JSSD/1928-1631-ND/9370551

author: Maliaris
author_rank: Newbie
timestamp: February 02, 2020, 09:40:01 pm
content: Thank you for the info and for the capacitor recommendation!

author: Maliaris
author_rank: Newbie
timestamp: March 14, 2020, 11:44:56 am
content: You were spot on! I finally got my soldering iron and swapped out the capacitor you pointed out and now the CRT works flawlessly!!! Thanks again for the help!
Crydom D1225 Solid State Relay DC/AC Can the output be DC, instead of AC? Solved - Page 1
Forum section: electronics / beginners

author: t1d
author_rank: Super Contributor
timestamp: December 10, 2024, 03:04:30 am
content: Intended Use = To drive/control/hack/vary the speed of an existing 12V air handler (brushed DC) fan, in an enclosed camper trailer. Max start up amps, for the motor is 8A and less when running, of course.So, I really need a DC/DC SSR. However, I have several Crydom D1225 in stock. Its capabilities (volts, amps, etc.) will work, for what is needed. However, it uses DC, for the control side andAC, for the output side.I am wondering if its output can also be used as DC? Looking at the Equivalent Circuit Diagram, in the Data Sheet, it appears that using it for a DC output might be possible. However, I know that an Equivalent Circuit Diagram does not tell the whole story.I want to control the D1225 with a PWM module, in order to control the speed of the Brushed DC Motor.1) Is it possible to use the D1225, in this configuration? a) If not, why? b) If yes, then how should I configure it?2) What should I be careful about?Data Sheet Attached.I am aware of other solutions, but I only want to consider this one, because I need to install it quickly. Or not...Thank you, so much, for your help!

author: inse
author_rank: Super Contributor
timestamp: December 10, 2024, 03:19:29 am
content: No, you unfortunately cant use it for DC.It uses Thyristors which cannot be switched off by the gate control signal, they need an AC zero crossing or load interruption to switch off again.Search for an automotive smart switch or smart FET or PROFET

author: t1d
author_rank: Super Contributor
timestamp: December 10, 2024, 04:10:54 am
content: Quote from: inse on December 10, 2024, 03:19:29 amThanks, inse! This a beautifully concise, highly informative reply = Very well done! Truly!Much appreciated. You saved me soooo much time, chasing a dead rabbit...
Cryptic notes on schematic - Page 1
Forum section: electronics / beginners

author: jeffjmr
author_rank: Regular Contributor
timestamp: March 26, 2022, 04:02:15 pm
content: Attached is a section of the schematic for my LPS-152.Can someone explain the meaning of the codes 4MF-TD and the (MF) near the capacitors circled in blue, and the (M) near those circled in red and (F) near the resistors circled in yellow?The parts list specs the blues as “Plastic 400v 10%”, the reds as “Plastic 50V 10%” and the resistors as “Metal 1% 1/4w”.No notes exist elsewhere in the manual about those codes.Thanks,Jeff

author: MasterT
author_rank: Frequent Contributor
timestamp: March 26, 2022, 05:05:03 pm
content: My guess is "F" - film. Metal thin film for resistor, means lower noise compare to carbon or carbon composition resistors. Mylar Film (MF) for capacitors, low leakage, perfect thermal stability of parameters - they don't have COG in 20-th century

author: TimFox
author_rank: Super Contributor
timestamp: March 26, 2022, 05:13:58 pm
content: "MF" could also mean "metallized film", where the film is probably MylarTM(polyester, PET).NP0 and C0G both existed in the 20th century, and both are spelled properly with 0, not O.The terms are also essentially synonymous: C0G is a military designation and NP0 is an EIA designation.

author: jeffjmr
author_rank: Regular Contributor
timestamp: March 26, 2022, 08:11:35 pm
content: Seems odd to put F on the schematic and Metal on the parts list if MF is what they meant and they use MF elsewhere.And TD?Thanks,Jeff

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: March 27, 2022, 07:25:11 pm
content: On resistors could be flameproof or fuseable, CF would be carbon film, MF for metal film (resistors).Capacitors MF I have seen used in place or before uF was used but as values are already listed it must refer to type.Jeff

author: Monkeh
author_rank: Super Contributor
timestamp: March 27, 2022, 07:43:31 pm
content: Quote from: TimFox on March 26, 2022, 05:13:58 pmC0G is the EIA code and NP0 is a description of the theoretical temperature coefficient - in this case zero. N100 would be negative, P100 positive.The old military standard includes CG, which is 0±30 ppm/°C, equivalent to C0G.

author: TimFox
author_rank: Super Contributor
timestamp: March 27, 2022, 08:42:27 pm
content: My error: I exchanged the two codes. There are many lowish-loss ceramic capacitors with "N" codes for negative tempco, up to more than N5000.Mica capacitors have positive temperature co-efficients.

author: bdunham7
author_rank: Super Contributor
timestamp: March 27, 2022, 08:50:37 pm
content: It might help in decoding these cryptic notes if you posted photos of the actual components. I don't know why any of those components would have a critical type requirement just looking at the circuit.

author: jeffjmr
author_rank: Regular Contributor
timestamp: March 27, 2022, 09:13:49 pm
content: Good point about the pictures. I’ll get to it when I return home.Thanks, all.Jeff
Cryptic pin in datasheet (Interfacing with I2C) - Page 1
Forum section: electronics / beginners

author: Sudo_apt-get_install_yum
author_rank: Regular Contributor
timestamp: October 02, 2018, 09:42:12 am
content: Hi all!This is a quick question about a pin on a FFC.I got a handful of cheap Chinese OLED's from a buddy of mine and I want to hook it up using I2C. When looking in the datasheet it gives me the info I expected (SCL, SDA and address select) but it has a forth pin "RESB" that the datasheet considers an interface pin. In the pinout table it says that RESB is "This is a reset signal input pad. When RESB is set to “L”, the settings are initialized. The reset operation is performed by the RESB signal level."Assuming L=Low=GND but when I hook it up to GND it doesn’t do anything. I know the code is working since it is working on the OLED modules/breakouts with the same interface and driver. I’ve hooked it up to 3V3 and nothing happened.Not sure what’s going on here, did I fry them?Thanks for any help

author: tsman
author_rank: Frequent Contributor
timestamp: October 02, 2018, 01:23:53 pm
content: RESB just sounds like an active low reset signal. Keep it at 3.3V normally then pull it to 0V temporarily to reset the module.

author: bson
author_rank: Unknown
timestamp: October 03, 2018, 09:27:37 pm
content: What controller? Here's the external bus pinout for the SSD1306:I'd recommend working from the controller datasheet rather than the panel; it looks like the panel just runs the controller bus to a connector.Oh, and if it's SSD1303 or 1306 I'd say forget I2C and use SPI instead. These are hella flaky using I2C and will randomly lock up on you, for no apparent reason - clean signals, clock independent, etc - the interface just dies, wedging your bus and they will need to be reset. Can't clock out of it, so it's not a lost clock.
Crystal clock oscillators - Page 1
Forum section: electronics / beginners

author: Richardcavell
author_rank: Contributor
timestamp: February 22, 2023, 01:36:32 pm
content: I want to understand devices such as this one:https://www.mouser.co.uk/ProductDetail/ABRACON/ACH-4.000MHZ-EK?qs=2xLVn2jvFusUYAlFEbtCfg%3D%3D1. Am I to understand that you just put a voltage in, ground it, and it produces a 4 Mhz square wave between pins 5 and 4?2. The “DIP” in the title of the datasheet - I take it that it’s referring to dual inline packaging, even though this thing only has 3 or 4 pins?3. The output frequency should be plus or minus 100 parts per million. So for a 1 MHz device, it wil be 999,900 to 1,000,100 Hertz?4. It says “Output load” of 10 or 5 TTL. Does this refer to fanout? (Ie it can drive 10 or 5 logic gates).5. The version known as “Tri-state” can take up to 4 milliseconds to switch on. Am I right in thinking this is a huge amount of time in the context of a circuit that goes at, say, 1 megahertz?Richard

author: BillyO
author_rank: Super Contributor
timestamp: February 22, 2023, 01:55:38 pm
content: 1) Yes.2) Yes. The 4 pins are in positions 1, 4, 5 and 8 of an 8-pin layout.3) Yes. But that also includes thermal drift over it's operating range. More than likely it will be more accurate than that at 20C.4) Yes. It can drive up to 10 standard TTL loads. Which is quite a bit.5) That depends entirely on what you need it to do.

author: TimFox
author_rank: Super Contributor
timestamp: February 22, 2023, 04:47:15 pm
content: Reading between the lines on the datasheet linked by Mouser, with the tri-state option "A" selected, I believe that the output disable actually stops the oscillation internally, which is why the delay time on enable is so long.The statement "10 TTL" is not well specified: is that 74, 74LS, 74S, etc.? My guess is 74LSxx, but that is not clear.

author: james_s
author_rank: Super Contributor
timestamp: February 22, 2023, 06:18:34 pm
content: I would not expect the switch-on delay to be an issue in most cases. If you have a microcontroller it will normally be held in reset longer than that.

author: TimFox
author_rank: Super Contributor
timestamp: February 22, 2023, 06:42:41 pm
content: In some applications, it would be nice to stop the oscillator with power on to avoid interference with another process.Oscillators do take a bit of time to start up.If one needs to tri-state the oscillator output without stopping the oscillator, an external gate can be used.
Crystal diagnosing, only have DMM- shotgun replace or not? - Page 1
Forum section: electronics / beginners

author: taste_tester
author_rank: Regular Contributor
timestamp: May 20, 2022, 03:49:54 am
content: Three crystals i am suspicious of, two the values are known (22.75mhz; 32.00mhz ) and one is rubbed off, service manual makes no note of the crystal values.I either have to put off attempting to repair this old PCB for about ~2 weeks until I can get my scope out of storage or do the best i can with my DMM until thenI have a Fluke 101 which does have frequency mode 10 Hz – 100 kHz. I don't care about an accurate measurement of the crystal, rather just want to see if it's totally dead or not.I will try the "flip around" trick on the crystals.
Crystal Frequency ? - Page 1
Forum section: electronics / beginners

author: alin_im
author_rank: Regular Contributor
timestamp: May 23, 2015, 03:32:50 pm
content: Hey guys,How can I find the frequency of a crystal if it does not have any marking on it

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 23, 2015, 03:41:45 pm
content: Build an oscillator and measure itBut really, no markings at all seems a bit odd. Did you take it from a pcb? Any pictures?

author: continuo
author_rank: Frequent Contributor
timestamp: May 23, 2015, 04:30:46 pm
content: W2AEW made a very nice vid on building such an oscillator, check it out

author: alin_im
author_rank: Regular Contributor
timestamp: May 23, 2015, 04:53:04 pm
content: Quote from: continuo on May 23, 2015, 04:30:46 pmwow nice ! thank you very much that is exactly what i wanted.

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 23, 2015, 06:20:20 pm
content: I planned to post that after you came back with maybe more info, but I see somebody already did! Good luck, you will learn something new.

author: w2aew
author_rank: Super Contributor
timestamp: May 23, 2015, 08:01:17 pm
content: It's always great to see when one of my videos helps someone.

author: PA0PBZ
author_rank: Super Contributor
timestamp: May 23, 2015, 08:16:32 pm
content: Quote from: w2aew on May 23, 2015, 08:01:17 pmYour videos get quoted a lot here Alan, because you are very good at explaining the basics and you cover a lot of different subjects.Well done

author: Isad
author_rank: Frequent Contributor
timestamp: May 23, 2015, 09:44:27 pm
content: I watched that video 5 times before bulding one for my self dont knowwhy i watched them but they just seemed helpfull.Btw justasking i have build that circuit and i am measuring the out with arigol ds1074z oscilloscope and i wanted to know whats theprecision on the frequency counter on the rigol?Sorry if this might be of topic.
Crystal HC49 1813NR 2MHz (IQD) - Page 1
Forum section: electronics / beginners

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 21, 2019, 01:31:01 pm
content: I bought a crystal just to experiment with and see how it will work.However, the datasheet had no example circuits and, even though I tried a few from the Tinterweb, I can get it to oscillate.Does anyone have a simple circuit that will work please?Cheers.

author: Zero999
author_rank: Super Contributor
timestamp: June 21, 2019, 03:01:39 pm
content: Have you just tried Googling 2MHz crystal oscillator schematic?The image search comes up with lots of hits.https://www.google.com/search?q=2MHz+crystal+oscillator+schematic&safe=active&client=firefox-b&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiVlb-f6_riAhVjoVwKHa_WBZAQ_AUIECgB&biw=1280&bih=900

author: PerranOak
author_rank: Frequent Contributor
timestamp: June 21, 2019, 04:48:22 pm
content: Cheers. I did try three but none worked. I wondered if there was a "tried and tested" one. I'll try that one.

author: bob91343
author_rank: Super Contributor
timestamp: June 21, 2019, 04:51:18 pm
content: A crystal behaves like a tuned circuit. If your oscillator has enough gain but doesn't oscillate, you may have a bad crystal. Try a different one. If the Q is too low it won't have enough loop gain to oscillate.
Crystal load - Page 1
Forum section: electronics / beginners

author: IvoS
author_rank: Frequent Contributor
timestamp: July 17, 2023, 08:16:11 pm
content: I need a 16MHz crystal for ATMEGA328P. Those 2 caps will by 22pF. Does it mean I am looking for crystal with 22pF load? Only one cap on one side means the load is 22pF? Thanks.

author: iMo
author_rank: Super Contributor
timestamp: July 17, 2023, 08:24:10 pm
content: The load is 11pF.

author: Gyro
author_rank: Super Contributor
timestamp: July 17, 2023, 08:28:34 pm
content: The 22pF capacitors are effectively in series (as the crystal sees them). Allowing for a little stray capacitance, for 2 x 22pF you should be looking for a crystal with around 12pF load spec. This is the most common value from distributors.P.S. The coverage of crystal loading in section 8.3 / 8.3 of the ATmega328P datasheet is particularly useless!

author: GromBeestje
author_rank: Frequent Contributor
timestamp: July 17, 2023, 08:42:32 pm
content: Have a look at this Adafruit articlehttps://blog.adafruit.com/2012/01/24/choosing-the-right-crystal-and-caps-for-your-design/

author: IvoS
author_rank: Frequent Contributor
timestamp: July 17, 2023, 08:53:11 pm
content: OK, so I'll be using this crystalhttps://www.digikey.com/en/products/detail/iqd-frequency-products/LFXTAL027945BULK/10106622. It has load capacitance of 22pF. So if I put 33pFx2 for example, it would be 16.5pF + some trace capacitence (length based).... close enough?

author: Gyro
author_rank: Super Contributor
timestamp: July 17, 2023, 09:00:54 pm
content: Probably, yes. Stray capacitance is obviously layout dependent, proximity of ground plane etc. I can't see an input capacitance spec for the Xin pin of the ATmega but that would count as stray too. On the other hand, the (useless) datasheet recommends a maximum value of 22pF for the caps.EDIT: 18pF is also a very common 16MHz load spec, as is 16pF (22pF isn't), which would allow you more stray budget with lower value caps.

author: TimFox
author_rank: Super Contributor
timestamp: July 17, 2023, 09:43:22 pm
content: If the frequency is critical, you can use a small adjustable (trimmer capacitor) with the fixed capacitors to tweak the result.I like piston trimmers for this application, but they are a bit large, physically.
Crystal load capacitance - Page 1
Forum section: electronics / beginners

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: August 30, 2019, 12:20:40 pm
content: Hi!I'm working on a project which has a MCU(STM32F373) and I'm looking at crystals when I suddenly came across a crystal that didn't specify load capacitance it just said series. So I started doing some research but I still can't wrap my head around it.This articlehttps://ecsxtal.com/news-resources/video-learning/126-everything-you-need-to-know-about-quartz-crystal-resonators/133-understanding-load-capacitancesays I can just ignore load capacitance when dealing with series resonance crystals.So what can I just drop it in there and be done with it, no caps no nothing, it's just gonna work?? Sounds to good to be true.Can someone fill me in?!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 30, 2019, 12:23:32 pm
content: ST's appnote on crystal oscillators will be more beneficial:https://www.st.com/content/ccc/resource/technical/document/application_note/c6/eb/5e/11/e3/69/43/eb/CD00221665.pdf/files/CD00221665.pdf/jcr:content/translations/en.CD00221665.pdfIt's a parallel oscillator; the specs of a series crystal will be slightly different (may not be the desired C and ESR leading to poor startup or an error of some kHz).More importantly, ST's oscillators tend to be weak (low transconductance), so need a relatively high ESR / low C crystal. Shop for this.Tim

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: August 30, 2019, 12:29:08 pm
content: Tanks for the link and reply, I'll absolutely follow your advice.

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: August 30, 2019, 12:50:24 pm
content: Quote from: T3sl4co1l on August 30, 2019, 12:23:32 pmOn a side note, would would be considered low load capacitance?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 30, 2019, 03:29:38 pm
content: Your average crystal is something like, say, 8MHz, 100 ohms ESR, and 20pF specified loading. Or something around there. ST oscillators are more stable with like 200 ohms / 10pF.Tim

author: TheHolyHorse
author_rank: Regular Contributor
timestamp: August 30, 2019, 06:07:12 pm
content: Quote from: T3sl4co1l on August 30, 2019, 03:29:38 pmAlright thanks, I'll stay in that ballpark.
Crystal Load Capacitance calculation incorrect - Page 1
Forum section: electronics / beginners

author: Freshman
author_rank: Regular Contributor
timestamp: September 20, 2024, 04:18:25 am
content: I am using this device (https://ww1.microchip.com/downloads/aemDocuments/documents/UNG/ProductDocuments/DataSheets/USB251xB-xBi-Data-Sheet-DS00001692.pdf)On page 44 of the datasheet, they have given the formula to calculate the crystal load capacitance.I have a crystal. It's datasheet mentions that it's load capacitance is 6pF and Shunt capacitance is 3pF.And considering 3pF for CB1 and Cxtal of 6pF (mentioned in the pin capacitance table), CS1 = 3pf + 6pf = 9pf.​If I substitute CS1 in the formula,C1 = 2*(CL - Co) - CS1CL = 6pfCo = 5pfC1 = 2*(6pf - 5pf) - 9pfC1 = 2pf - 9pfC1 = -7pfI am getting negative capacitor values for the load capacitances.Am I missing something or doing incorrectly.So, does this crystal not support this device?

author: PGPG
author_rank: Frequent Contributor
timestamp: September 20, 2024, 09:04:00 am
content: I would expect PCB track capacitance being smaller than 3pF.You write that your crystal has Shunt C = 3pF and then use 5pF in equations. Which value is correct?

author: Benta
author_rank: Super Contributor
timestamp: September 20, 2024, 10:14:20 am
content: I think you forgot to read Note 7-1 and 7-2.
crystal load  - Page 1
Forum section: electronics / beginners

author: hsn93
author_rank: Regular Contributor
timestamp: March 16, 2020, 01:15:52 pm
content: hi,im trying to choose crystal oscillator for phy chip DP83848phy datasheet:http://www.ti.com/lit/ds/symlink/dp83848k.pdfphy application note:http://www.ti.com/lit/an/snla079d/snla079d.pdffrom datasheetsection 7.2.1.2.2:https://snipboard.io/LUIswG.jpgtable 7-3:https://snipboard.io/ngbv47.jpgsection 7.2.1.2.2 Crystal suggests:20-pF load crystal resonatortable 7-3load capacitance of Crystal: minimum 25-pF and maximum 40pF======================================================================from Application Notesection 6.2:https://snipboard.io/BE5AMW.jpgtable 2:https://snipboard.io/zixe3b.jpgsection 6.2 recommends CL (load caps) = 2*Crystal Load C - 7pFfrom my understanding. this tell me the capacitance of the phy pin is ~7pFor less because sometimes they use pcb trace stray capacitance Cstrayfor me this is odd. because if (Cl = 2*crystal load - 7)then crystal with capacitance of 10pF is more than enough right? (Cl = 2*10-7 = 13pF)why 25pF is the minimum in their application noteagain application note table 2:minimum crystal load capacitance is (15pF) including C1 and C2i feel lost and cant choose right oscillator for this chipthis one is in my mind because it has good drive level: FC5BQCCMM25.0-T1https://media.digikey.com/pdf/Data%20Sheets/Fox%20Electronics%20PDFs/FQ5032BR-25.000.pdfbut its not within capacitance range
Crystal mhz - Page 1
Forum section: electronics / beginners

author: NeoRecasata
author_rank: Newbie
timestamp: April 03, 2013, 05:22:37 am
content: what does a crystal do

author: Bored@Work
author_rank: Super Contributor
timestamp: April 03, 2013, 05:35:13 am
content: Your Google broken?

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: April 03, 2013, 10:26:10 am
content: Tricks a woman into marrying you.

author: G7PSK
author_rank: Super Contributor
timestamp: April 03, 2013, 11:23:26 am
content: Magic's away all harmful radiation. Better get yours quick as the Japanese Atomic authorities are buying them all up.http://www.emfblues.com/index.htmlOr resonates at a fixed frequency to pull an oscillator to that frequency.

author: NeoRecasata
author_rank: Newbie
timestamp: April 04, 2013, 01:58:55 pm
content: To G7PSK thanks for the positive feedback
crystal oscillator question - Page 1
Forum section: electronics / beginners

author: ccesaretto
author_rank: Newbie
timestamp: August 16, 2016, 12:34:57 pm
content: Hello.This question is very basic, sorry for that.For a project I am considering this crystal oscillator:http://uk.farnell.com/abracon/abm8g-12-000mhz-4y-t3/crystal-12mhz-10pf-3-2-x-2-5mm/dp/2467837It's different from the oscillators I have previously used because it has four pads instead of just two.Two of the pads are marked with GND in the datasheet so it looks like they have to be connected to ground.or not?Thank you for they help.Cristiano

author: dannyf
author_rank: Super Contributor
timestamp: August 16, 2016, 12:39:45 pm
content: You likely had a crystal: tough for an oscillator to have just two pads. A crystal needs a driver to output a clock.A crystal oscillator is just a crystal plus it's driver.

author: ccesaretto
author_rank: Newbie
timestamp: August 16, 2016, 01:02:52 pm
content: Thank you for the reply but now the confusion in my head is even biggerAt the moment I am using this:http://uk.farnell.com/multicomp/hc49sm-12-30-50-60-16-atf/crystal-hc-49-4hsmx-12-0mhz/dp/1667016connected to the two OSC pins of a PIC microcontroller and to the load caps.I was thinking of replacing it with this:http://uk.farnell.com/abracon/abm8g-12-000mhz-4y-t3/crystal-12mhz-10pf-3-2-x-2-5mm/dp/2467837just because it is smaller. but it has the two GND pins that the first one does not have.

author: bobaruni
author_rank: Regular Contributor
timestamp: August 16, 2016, 01:04:37 pm
content: Yes it is the same, just has extra pads for mounting onto PCB.Also remember to change your capacitors to match the crystal, in this case 10pF.

author: dannyf
author_rank: Super Contributor
timestamp: August 16, 2016, 01:20:21 pm
content: Both are crystals, not crystal oscillator.

author: ccesaretto
author_rank: Newbie
timestamp: August 16, 2016, 01:25:57 pm
content: Quote from: dannyf on August 16, 2016, 01:20:21 pmOk, thanks. Now it is clear
Crystal oscillator startup time - Page 1
Forum section: electronics / beginners

author: HwAoRrDk
author_rank: Super Contributor
timestamp: January 14, 2024, 09:57:00 pm
content: If a crystal oscillator - for example a common 4-pin 3225-package 32.768 kHz oscillator - has specified a startup time of a few milliseconds, what exactly defines "startup"?What I mean is, is that the time it takes from power-up (i.e. power applied to VDD pin) for the output to be stable? Or is that the time it takes the output to be stable after the 'enable' pin is activated? None of the datasheets I've seen specify exactly.I suspect it's the former, but I'm not sure.Also, another question: what would be the point of having an AC-coupling cap, for instance 100 nF, in series with an oscillator's output? I have seen a reference design with this. It would seem to serve no purpose to me.

author: MarkT
author_rank: Frequent Contributor
timestamp: January 14, 2024, 10:29:07 pm
content: Can you provide the part number?

author: langwadt
author_rank: Super Contributor
timestamp: January 14, 2024, 10:35:50 pm
content: I'd expect it to be time from enable, it takes time to get the xtal oscillatingThe series cap might be for when driving an input meant for an xtal and not an oscillator?

author: HwAoRrDk
author_rank: Super Contributor
timestamp: January 14, 2024, 11:07:58 pm
content: Quote from: langwadt on January 14, 2024, 10:35:50 pmI was thinking that the enable pin would simply be gating the buffer on the output, and that would have no effect on the internal crystal circuit. You think the opposite?Quote from: langwadt on January 14, 2024, 10:35:50 pmI believe it's going to an input that is just meant to take a ~50% duty cycle square wave 3.3V clock signal.
Crystal oscillator worked 1 day, not the next ? - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: September 29, 2018, 10:58:20 am
content: The circuit was working, I put it on the shelf, now it's not working. It's a slightly different room temperature ?This is very annoying

author: Benta
author_rank: Super Contributor
timestamp: September 29, 2018, 11:27:27 am
content: Could you be more specific? I've mislaid my crystal ball.