hybridfree/eevblog-posts huggingface dataset:
HP parts 1990-0531, 5082-7616 and 1990-0619 pinouts - Page 1
Forum section: electronics / projects

author: polymood
author_rank: Newbie
timestamp: March 23, 2025, 01:01:17 am
content: Hello,I want to document here information about the following HP parts : 1990-0531, 5082-7616 and 1990-0619.As I have acquired some and didnt find any information on them, I want to share it here as I was able to determine the pinouts.3V with 120 ohm resistors work great.HP part 1990-0531 : 8 segment LED Display COMMON ANODEHP part 1990-0619 : 8 segment LED Display COMMON CATHODEHP part 5082-0619 : 6 segment LED Display
HP power supply clone problem - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: January 24, 2015, 03:02:44 pm
content: HI guys,I tried to do power supply using the exact schematic using HP E3620A . I used LM358 for the control opamp and it works fine. Now I tried to do the same using LF353 every thing works fine expect a problem. under no load the output is good (attached the screen shot of scope) but when loaded above 500mA the ouput is oscillatory about 200mV peak (attached the screen shot of scope) I tried to used caps from 10pf to 470nf across the feedback loop of the opamp but the same oscillation persist. any suggestions. I used IRFP150N . the power supply designed for 42V ,5A.

author: kjs
author_rank: Regular Contributor
timestamp: January 24, 2015, 07:19:37 pm
content: Try a series resistor in series with the feedback capacitor you implemented. That normally cures that problem. It looks like your modified circuit doesn't have sufficient phase margin.Juergen

author: jman
author_rank: Contributor
timestamp: January 28, 2015, 11:59:17 am
content: can you post the Schem?

author: prasimix
author_rank: Unknown
timestamp: January 28, 2015, 12:35:03 pm
content: Quote from: jman on January 28, 2015, 11:59:17 am+1Question: are you entering CC mode of operation with such load?

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 28, 2015, 08:49:38 pm
content: Quote from: electros6 on January 24, 2015, 03:02:44 pmGreat someone cloned it. +1 do post a schematic.LF353 is a General Purpose Amplifier,The original design uses an LF422 for both CC and CV loops. To begin with, the LF422 op-amp offset is 5.0mV(Max) where the LF353 is 10mV(Max) see attachments and compare the differences.see attachmentsAnother thing, why a FET?, the pass through power transistor uses a BJT 2n6056 (Darlington Power Transistor). you have deviated tremendously. honour the design by supplying the original components first, then proceed to mod.Also note, the power Mosfet gate channel being driven from the *non-ideal* op-amp thanks to that low output impedance forms a nice RC loop, this creates phase shift and positive feedback makes a nice oscillator.The difference between this design, and other power supply design attempts floating is this..., we know this power supply works! an its a pretty simple design (all the hard work has been done thanks to Keysight) all you have to do is use the original parts.

author: bdivi
author_rank: Regular Contributor
timestamp: January 29, 2015, 07:05:41 am
content: Some experimental results with replication of exactly E3620A from my side:Opamp - first tested TL072 with no issies and then leplaced with OPA2134 in the final schematics - higher speed and lower offsetPower transistor - two 2SC5200 in paralel, I wanted fast transistors in order to keep phase control within the opamp capacitive feedbackOverall very stable with different loads.
hp printer teardown - Page 1
Forum section: electronics / projects

author: blackjames
author_rank: Regular Contributor
timestamp: January 24, 2013, 03:03:54 am
content: a few months back i bought a second hand HP printer/photo copier/scanner for 10 or 15 dollars. the ink cartriges needed replacing and it would of cost 40 or 50 dollars to do so. so i followed my original plan.... to take it apart. i found a agilent processor chip on the main board with 2883-0005 on it, there are also two ti chips with part numbers; SN105117 and SN10496. one on the ink cartridge interface board and the other in the motor controller area, but i cant find the datasheets to them, can anyone help?

author: amyk
author_rank: Super Contributor
timestamp: January 24, 2013, 11:38:51 am
content: It'd help if you posted images and more information likewhich of the many hundreds of printers it is.
HP PS output connector - Page 1
Forum section: electronics / projects

author: rodrigopires
author_rank: Regular Contributor
timestamp: January 30, 2016, 08:15:52 pm
content: Hi, i have a HP PS-3701-1 and I want to use it to power a HHO cell. How can i make a good connector on the output strip? Thanks!

author: rdl
author_rank: Super Contributor
timestamp: January 30, 2016, 11:18:16 pm
content: Best way looks like soldering some kind of standard connectors to the circuit board, or possibly just soldering some wires directly on to the board. There are videos on youtube if you just google HP PS-3701-1
HP10811 Oven Oscillator Crystal Temp Marking - Page 1
Forum section: electronics / projects

author: rfdes
author_rank: Regular Contributor
timestamp: August 25, 2021, 10:34:43 am
content: Hi -It is my understanding that HP marked the proper compensation temperature directly on the oscillator's crystal package. This was done in the lab to determine what the correct 'select at test' resistor needed to be at installation time. Is this true? On two separate crystal packages that I inspected, I saw a numerical digitwritten on the ceramic part of the package but no actual temperature. One showed '2' and the other '10'. Do these numbers represent a 'temperature'? If so, how does one determine this temperature? I would appreciate any advice.ThanksJim
HP34401A with Agilent look - Page 1
Forum section: electronics / projects

author: Miti
author_rank: Super Contributor
timestamp: April 02, 2023, 02:46:47 am
content: Does this belong in the 3D Printing section?Anyway, if you have an older HP34401A with red sockets but you like the newer Agilent look with black LO sockets, all you need to do is to print the attached in black and stick them (press fit) to the LO jacks. Easy!PLA, 0.12mm layer height.Enjoy!
HP3478a Lost calibration - Page 1
Forum section: electronics / projects

author: ALearningLad
author_rank: Contributor
timestamp: January 04, 2022, 03:57:21 am
content: Had a weird thought, but would it be possible to do a rough calibration based on someone else's? Like someone else takes a Arduino or something to the gpib and gets the cal data. Then I steal that data and shove it in my uncalibrated meter. Would that be possible, and if it is how accurate/inaccurate do you think it might be?Might be a really stupid question, but that is why I am asking.

author: bdunham7
author_rank: Super Contributor
timestamp: January 04, 2022, 04:02:17 am
content: I've heard of people trying that with oscilloscopes just to get them past the DIAGNOSTIC FAILED screen. But if you care about the accuracy of you meter at all, no it probably won't help. Unless the HP3478A is unusual, the default calibration data will be somewhere in the middle of the calibration adjustment range, so some other meter's data may adjust each range the right way or the wrong way, and most likely not by the right amount. You need to replace your battery and then find someone tocalibrateadjust it.

author: ALearningLad
author_rank: Contributor
timestamp: January 04, 2022, 04:23:19 am
content: Planning on sending it to a local calibration lab no need to worry! It was just a shower thought thanks for the answer, the more you know!
HP3968AZ reel to reel - Page 1
Forum section: electronics / projects

author: luthier
author_rank: Newbie
timestamp: March 06, 2019, 09:16:22 pm
content: I got a hold of this HP3968AZ reel to reel machine 20 years ago, which I was told was for instrumentation data. I'm trying to clear out these things, and was wondering if there is any interest in it, or if there is a better place to post that it is available. My email is luthier@epix.netThanks,Bob
HP6215A PS transformer problem - Page 1
Forum section: electronics / projects

author: electros6
author_rank: Regular Contributor
timestamp: June 08, 2014, 04:56:44 am
content: HI guys,I have a HP6215A power supply board without transformer. I have the service manual. the output of the power supply is 25V . I am having a 25V output transformer .If I connect the 25 volt ac to the board along with the biasing supply from another transformer of the prescribed rating will it work, will it get down to zero. I don't want to damage the board that's why I am asking you guys.
HP8903A Audio Analyzer Repair - Page 1
Forum section: electronics / projects

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: July 17, 2016, 12:30:01 am
content: Hi,This is a very quick repair that I just did on a HP8903A Audio Analyzer.The unit appeared to be dead when turned on.I removed the top and bottom covers, and measured the voltages on the main power supply electrolytic capacitors C1-C3.The voltages on C1 and C2 were normal, the voltage on C3 was low, around 1V.I found that pin 1 of the connector had over heated, melted the plastic and was not making proper contact.SchematicNote:HP marked the wire colours on the schematic. The numbers refer to the resistor colour code. The '7' indicates a purple wire. '92' is a white wire with a red tracer. This is useful if you are working on HP equipment and you forgot to record where the wires go.PhotographIt looks like the connector may have been changed before.You can see how the plastic on pin 1 is melted.RepairI replaced the connector on the transformer. I used Mode electronics 37-706-3. This is a Molex 0.156" connector packed for retail sale.I also replaced the connector on the board. I had to file the pins on the replacement connector slightly to get them to fit the holes in the PCB.WorkingHere is a picture of the unit measuring its own distortion:Similar RepairI have seen the same problem in HP1740A and HP1741A oscilloscopes. The root cause is the engineer under estimate the current in the transformer connections. With a capacitor input filter, the PF is about 0.65, so the RMS current is about 1.5x the d.c. current out capacitor.Regards,Jay_Diddy_B

author: valvedoctor
author_rank: Contributor
timestamp: July 17, 2016, 01:19:49 am
content: Nice instrument. I have the 8903B and still works a treat, knock on wood.
hp8904a function generator floating impedance? - Page 1
Forum section: electronics / projects

author: sarepairman2
author_rank: Frequent Contributor
timestamp: September 12, 2015, 09:05:16 pm
content: I have 2 HP8904A units.float measurements taken with 34401a, 10mohm input impedance settingSupposedly good unit:channel 1 to earth : 31k (functional light)channel 2 to earth ; 1k (functional light)supposedly bad unit (i think it just has a broken indicator light for float)channel 1 to earth: 45k (good light)channel 2 to earth : 16k (non functional light)I hooked up a DC supply to the float control relay and found that if I put enough DC into it I can get the impedance between chassis ground and the supposedly floating thing to read High Z on my 10Mohm input z ohm meter.Do these units both have faulty relays/relay controllers... or is floating >1Kohm considered good ? I figured float ment broken circuit, so a DC ohm meter should read infinity...

author: sarepairman2
author_rank: Frequent Contributor
timestamp: September 12, 2015, 09:06:56 pm
content: and when its not floating the impedance to earth ground/chassis is 50 ohms as it should be.SO WHAT is considered a reasonable DC impedance for a floating instrument?do these units have a common problem of the relay supply rail current being prone to fuck up?

author: tggzzz
author_rank: Super Contributor
timestamp: September 12, 2015, 09:32:37 pm
content: It isn't clear, but are you confusing "floating" with "isolated"?

author: sarepairman2
author_rank: Frequent Contributor
timestamp: September 12, 2015, 09:54:35 pm
content: Quote from: tggzzz on September 12, 2015, 09:32:37 pmeh, the front chassis says "float" and it has a little light that turns on when its floating. '

author: sarepairman2
author_rank: Frequent Contributor
timestamp: September 12, 2015, 10:04:05 pm
content: basically if the float is off the Low terminal center conductor reads like 0.5 ohms to chassis ground (shorted). when float is on it reads whatever I wrote (both my instruments are dual channel).the impedance between high and low center pins in float mode is ~50 ohms and I verified that it works as a fully differential amplifier output.im making a seperate thread for signal integrity of this instrument!
Hp8991a use cases - Page 1
Forum section: electronics / projects

author: Kraythorne
author_rank: Contributor
timestamp: January 15, 2022, 10:17:32 pm
content: Hi guysI landed myself a hp8991a peak power meter as part of a clearance and wondered what the difference is between this power meter and power meters like the 437b.Is this device an enhanced version of conventional power meters like the 437b, where it can do the same as those devices plus a bit more, or is it a totally different animal with limited use cases?RegardsSteve
HP/Agilent 34970A with error codes. How to fix? - Page 1
Forum section: electronics / projects

author: plazma
author_rank: Frequent Contributor
timestamp: January 21, 2013, 07:33:49 am
content: I got a 34970A with modules 34901A, 34902A and 34907A really cheap.The problem is the unit gives error codes 742-746.How can it be recalibrated/fixed?

author: free_electron
author_rank: Super Contributor
timestamp: January 21, 2013, 03:38:53 pm
content: Ouch. That's the multimeter module.Is that the full list or are there others ? Hold down the shift button and power up. Keep holding until the machine beeps ( a good 5 seconds ) then let go. That runs the full test ( takes about 30 seconds ).I have some experience fixing these but the multimeter module is very difficult to fix as the parts are unobtainium... If there are no other errors then those you give then the FRAM is dead.You can check that by going in the service menu and turning the multimeter off ( or by unplugging the multimeter cable to the motherboard ). If the errors go away then the fram is indeed dead.A lot of these machines are flogged on ebay with statement 'does not power up' or 'cal errors'. It's a crapshoot.
HPDL-1414 Display board - Page 1
Forum section: electronics / projects

author: Roeland_R
author_rank: Regular Contributor
timestamp: February 22, 2020, 08:52:06 pm
content: Hi everyone,I have created a small display board that uses 5 HPDL-1414 display modules. It uses I2C protocol (MCP23017-E/SP). The arduino code shows its simple to drive the display. The only problem I have is that the displayed strings are all in SRAM. I did try to store it in program memory using PROGMEM, but than all strings (character array[]) are corrupted, showing random characters. In my first attempt I used the String function instead of character array's. That was really horrible. It worked with one string, but after converting it to a function to send a string as parameter with it the arduino crashed because of memory problems. Now it works fine, but when I can use program memory there is more space for text to display. Next step is connecting an RTC module to the arduino showing the time. Sorry for the bad picture. Don't have a red filter.Hope you like it.You can watch a small demo here:https://youtu.be/2wIKiKhokB8

author: Roeland_R
author_rank: Regular Contributor
timestamp: February 29, 2020, 08:08:14 pm
content: Hi,I have uploaded this little project tohttps://github.com/RoelandR/HPDL-1414-boardwhere you can find the Kicad archive and arduino program for this display board. Software is for address 0x20, but you can modify it for other I2C addresses and chain to max 7 boards.
Mosfet data sheet shows different pin configurations? - Page 1
Forum section: electronics / projects

author: hal9001
author_rank: Regular Contributor
timestamp: November 21, 2021, 11:30:14 am
content: HSSK8811 is a dual P-channel from LCSC. The 2 pictures for pin configuration in the data sheet dont match each other. Is this a red flag to stay away from Huashuo brand? Any one has experience with Huashuo?

author: magic
author_rank: Super Contributor
timestamp: November 21, 2021, 11:55:59 am
content: I have noticed that bottom of the barrel Chinese transistor datasheets are copy-pasta collages of tables and figures ripped off from Western datasheets of equivalent parts.Seeing that kind of blunder isn't surprising too much.
HSTNS-PL22B to 13.8v mod? - Page 1
Forum section: electronics / projects

author: Fizfi
author_rank: Newbie
timestamp: December 21, 2022, 10:26:43 am
content: Hi,I recently got a (free) HP HSTNS-PL22B server power supply kit and I would like to repurpose it for a high current lab power supply as it can deliver 62A.The main problem is that I can't find any description of the pinout, so I tried to connect the shortest pins logically (the power supply should start after connecting other pins) and the power supply seems to turn on and voltage appears on the two large pins 12.37v.Who will tell me how to remake the power supply for 13.8 volts? I CAN PAY FOR HELP.Here is a photo more photos.https://ibb.co/m9VjSmvhttps://ibb.co/gy4MCLzhttps://ibb.co/FJsvJVJhttps://ibb.co/ChcFG03https://ibb.co/sQ8Rpgphttps://ibb.co/KhyM7tn

author: htcdmitriy
author_rank: Newbie
timestamp: February 22, 2024, 02:28:46 pm
content: I spent a long time looking for a way to change the output voltage (I needed to reduce it). Then, I replaced a resistor with the marking '221' (which means 220 Ohms) with a 200 Ohm one, and the voltage increased to approximately 13.8V. After that, I installed a 240 Ohm resistor and the voltage became 11.35V (meaning that a change of 20 Ohms results in approximately a 1 V change). I tested it with a 20A load at 11.35V. Overall, there's a fairly dense voltage divider in there, made up of 4 resistors, but the significant changes are provided by the '221' and '63B' resistors. I didn't test it for long, but I think if anything were wrong, the protection would have kicked in.
HSTNS-PL28 to 13.8v mod? - Page 1
Forum section: electronics / projects

author: Fizfi
author_rank: Newbie
timestamp: December 22, 2022, 06:30:04 am
content: HSTNS-PL28 Does anyone have knowledge about the voltage adjustment for this power supply?I couldn't find anything specific to this model online and the control PCB looks quite different to the many videos I have seen regarding adding or removing resistors for the other various models. There are only 2 potentiometers and the one to the right only gives minimal adjustment up to about 12.32v.Any advice or pointing to other resources much appreciated! This PSU seems to be made by LiteON and original p/n is PS-2461-7C-LF

author: pienari
author_rank: Regular Contributor
timestamp: January 08, 2023, 06:09:32 pm
content: Hi.I have found a way to rise voltage for PL28.https://aijaa.com/SesQtnJust replace 0ohm to 470ohm resistor or 1k trim pot.https://aijaa.com/VxUAjd470ohm resistor gives about 13.3v.Ovp kick in 13.5 - 13.6vIm still looking for how to get ovp higher and i think it can be found other board.Originally posted here..https://www.radiohullut.net/foorumi/viewforum.php?f=61&sid=855099355Greeting from Finland and happy new year 2023.

author: pienari
author_rank: Regular Contributor
timestamp: September 20, 2024, 08:39:54 am
content: Now i found a way to rise ovp for HSTNS PL-28.Mod works at least rev5 to rev14..I have tested psu and it works fine at 14.5v .I loaded psu with 22A current on/off without any ovp kickoff.I can make intructions soon.

author: pienari
author_rank: Regular Contributor
timestamp: September 25, 2024, 12:15:38 pm
content: Here is the instructions.https://youtu.be/KuOkziMm1gg
HSTNS-PL29 to 13.8v mod? - Page 1
Forum section: electronics / projects

author: jacke
author_rank: Newbie
timestamp: April 07, 2023, 06:44:10 pm
content: Does anyone have knowledge about the voltage adjustment for this power supply HSTNS-PL29?I couldn't find anything specific to this model online and the control PCB looks quite different to the many videos I have seen regarding adding or removing resistors for the other various models.There are only 2 potentiometers and the one on the right only provides a minimal adjustment up to about 12.32v but when I start turning it the power supply starts to squeak.Does anyone know what changes are needed to adjust the voltage?Follow some photos.Thank advanced

author: Electron-Pusher
author_rank: Newbie
timestamp: April 17, 2023, 03:24:47 pm
content: Hola jacke,I just figured this one out once I realized that PL29, PL30 and PL42 have the same controller board.I made a Document that explains it all.

author: Electron-Pusher
author_rank: Newbie
timestamp: April 17, 2023, 03:26:06 pm
content: Part 2Hope this helps you and others.

author: Electron-Pusher
author_rank: Newbie
timestamp: April 17, 2023, 03:31:37 pm
content: BTW:If you messed with the right pot, you can get it back to normal by adjusting it until the PS reads 12.31 Volts, that where mine was at the onset.Yes I also moved the potAlas I did mark it before hand.

author: lukkuch
author_rank: Newbie
timestamp: October 12, 2023, 08:28:23 am
content: Dear Electro-Pusher would you be so kind to post your tutorials in pdf? When I open them the descriptions and arrows are messed up and it is hard to know where to solder exactly.Thanks in advance.

author: Electron-Pusher
author_rank: Newbie
timestamp: October 13, 2023, 10:57:04 pm
content: Sure that's a reasonable request.Here they are:

author: emilio251e
author_rank: Newbie
timestamp: November 18, 2023, 10:02:59 am
content: did you desolder 221, how to solve it because I don't really understand this connection with the 1660 resistor? Friend from Poland, you've already done it, maybe you can take a photo because I don't want to burn anything

author: Trurl
author_rank: Regular Contributor
timestamp: November 18, 2023, 02:28:43 pm
content: For a more "thorough" perspective of the PL29 which is similar to the PL30 / PL33 / PL42, check out my post #14 of the following thread:https://www.eevblog.com/forum/projects/hp-hstns-pl33-1500w-psu-anyone-know-where-to-find-a-schematic/Cheers.

author: sp3rat
author_rank: Newbie
timestamp: January 04, 2024, 11:07:27 pm
content: HiIt is working.Thank you very much.I have a PL29 board.Jurek

author: Electron-Pusher
author_rank: Newbie
timestamp: October 20, 2024, 12:05:42 am
content: Glad some of you where able to use the info to mod their PS.Mine is running stable like that since March 2023.Running my radios stable even at ~40 A , that's when I use 2M and HF in the same contest.Most impressive: I normally do not hear the fan since these PS's are so efficient, so little heat is produced.Cheers
Power suply HSTNS-PL30 over voltage  - Page 1
Forum section: electronics / projects

author: shgatev
author_rank: Newbie
timestamp: February 07, 2023, 02:00:28 pm
content: Hi, I am trying to skip over voltage protection of this supply, make it 14v, there is no info anywhere in the net, can someone help me, please! It's a little different from pl33...Regards!
HSTNS-PL41 Looking for info explaining How to increase output voltage 13.5v-14v? - Page 1
Forum section: electronics / projects

author: Crunch69
author_rank: Newbie
timestamp: March 13, 2024, 08:27:06 pm
content: HSTNS-PL41 Looking for information to hack the power supply to produce a higher voltage than stock. This power supply has no pot's so it will need I believe a resistor placed on an op-amp to fool the supply to increase the higher output voltage. It may also require an override for the over voltage protection circuit OVP.Any help will be appreciated
HT396V & HT396R 0.156" (3.96mm) Connector 3D Models - Page 1
Forum section: electronics / projects

author: David_AVD
author_rank: Super Contributor
timestamp: June 06, 2016, 01:19:36 am
content: Does anyone have 3D models for HT396V & HT396R 0.156" (3.96mm) PCB connectors ?Preferably in AP214 format so I can use in Altium.They are board mounted sockets that pluggable terminal blocks fit into.
HT82K629A - Page 1
Forum section: electronics / projects

author: mr1979
author_rank: Contributor
timestamp: October 14, 2017, 05:27:43 am
content: Has someone used HT82K629A?Any problems?Does it work with Linux or Windows 7 , 10 or Embedded?Inviato dal mio PLK-L01 utilizzando Tapatalk
HT9032D Issues... Lost and Confused - Page 1
Forum section: electronics / projects

author: rfdes
author_rank: Regular Contributor
timestamp: November 13, 2018, 09:46:12 pm
content: Guys...Hopefully someone has some experience with the Holtek HT9032D CID decoder chip. I purchase 5 pieces off of eBay and threw together a quicky test jig. See image. Using a DDS set to 1200 Hz (or 2200 Hz, the CID FSK tones), I get no activity at the DOUT pin. I've tried several of the 4 ICs and no luck. This shouldn't be any easier. The input circuit is biased a 2.5V although I am seeing about 100 mV DC differential between the TIP/RING inputs. This seems high considering the datasheet details a sensitivity of something like -39 dBm. I've also swung the input FSK test signal +/- some 100 Hz or so. Nothing. All I was wanting to do is to manually swing the FSK tones back and forth to see if the decoder would work.Anyone have any first hand experience with this part?ThanksJimLargo, Florida
Hub dynamo Over Voltage Protection - Page 1
Forum section: electronics / projects

author: multifrag
author_rank: Contributor
timestamp: May 19, 2016, 01:34:40 pm
content: Bought an LM2596 AC to DC Buck converter. It's rated for 40V and I'm afraid of frying it when cycling down the hill.This is a project for long travel around Europe. I found dynamo to be most efficient to generate power for my phone. Should I build my own 1 amp ''apple'' usb connector or maybe someone is already selling them pre-built??
Hubbard Electrometer British MK V Electropsychometer E-meter Scientology - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: September 06, 2022, 08:35:46 am
content: here it is :-)I finally got one Hubbard Electrometer British MK V Electropsychometer E-meter Scientologyit was in poor condition, so i repaired it, and tested it..we now know i only tell the truth.https://youtu.be/lEzs3lmChTI

author: Terry Bites
author_rank: Super Contributor
timestamp: September 19, 2022, 07:13:01 pm
content: I hope you paid cash rather of getting caught up in a pyramid sales racket.Stay clear!

author: Benta
author_rank: Super Contributor
timestamp: September 19, 2022, 08:31:47 pm
content: This is hilarious. Especially the Scientology sticker on the lid that says it doesn't do anything at all, but is just a prop for the Scientology "priest".

author: daqq
author_rank: Super Contributor
timestamp: September 20, 2022, 03:44:17 pm
content: I'm amazed that actual bullshit did not start leaking out the moment you opened it.

author: magic
author_rank: Super Contributor
timestamp: September 21, 2022, 01:49:41 pm
content: Quote from: Benta on September 19, 2022, 08:31:47 pmThis is America, so it's probably legal CYA to prevent disgruntled "believers" from suing for psychiatric malpractice or whatever

author: Benta
author_rank: Super Contributor
timestamp: September 21, 2022, 02:26:01 pm
content: Since when is Denmark in America?

author: magic
author_rank: Super Contributor
timestamp: September 21, 2022, 02:41:56 pm
content: Quote from: Benta on September 21, 2022, 02:26:01 pmI hope it isn't yetBut the whole Co$ is an American thing. See the original text here:https://www.cs.cmu.edu/~dst/Secrets/E-Meter/Mark-VII/#dataplate
Huge GND plane -> prolblem? - Page 1
Forum section: electronics / projects

author: Manuel
author_rank: Newbie
timestamp: June 20, 2013, 12:00:27 am
content: Hi everyone!In my project I have got a copper filled PCB of 500x100mm size. The PCB carries only two lines which are isolation milled, the rest of the PCB ist still filled by copper which is only referenced to ground at one single point. Please see the attached image.As far as I know this will resolve in trouble within noisy environments, since the huge ground plane will act like an antenna and the single renference connection will never bring it completly down to the ground potential.Could you confirm my guess and maybe give me a literature resource to proove this?Cheers,Manuel

author: senso
author_rank: Frequent Contributor
timestamp: June 20, 2013, 12:40:16 am
content: 50cm of pcb for two single traces?Use a shielded cable for that ...

author: ConKbot
author_rank: Super Contributor
timestamp: June 20, 2013, 01:00:05 am
content: nice slot antenna you have there, depending on what exactly you mean by a "noisy" environment, it very well may make it worse as circulating currents from the slot antenna couple into the traces.

author: ejeffrey
author_rank: Super Contributor
timestamp: June 20, 2013, 06:56:44 am
content: Yes, this can cause problems at high frequency from slot modes. The size of the ground plane doesn't matter nearly as much as the size of the slot. The normal solution is to have a bottom side ground plane that is unbroken, and connect the top side to the ground plane with vias. As long as the vias are closely spaced they prevent any potential difference from forming between the opposite sides of the slot, and suppress radiative coupling. You can also add jumper wires across the slot, but the effectiveness is less due to the relatively high inductance.Whether this is any problem at all depends on what frequency you care about, what you mean by noisy, and how well your signal wire couples to the slot antenna.You can also have inductive coupling if you have low frequency magnetic fields, since what you have drawn is a wire loop with a large area. That would likely only be a problem if you had an inductor or transformer nearby.
Huge interference on 24V supply when AC connected - Page 1
Forum section: electronics / projects

author: Yaroooo
author_rank: Regular Contributor
timestamp: March 10, 2022, 12:33:09 pm
content: Hello,I've a problem on a revision of a custom board that drives stepper motors. This board originally had a single power supply source from an AC 110V . Internally there's a rectifier plus capacitance and DC result goes to power side (mosfets and stepper phases) and a switching regulator that powers logic at 12V. This board never had particular issues.After revision, power side and logic power side were separated. There's same AC that power mosfets but no longer the internal switching, now this one is powered by external DC at 24V. This two power supply sources have a common ground on PCB between rectifier low side output and 24V's gnd.What I encounter now is a huge noise on 24V and on outputs from devices that are powered from this 24V that generate several problems.Here's some images to explain:I'm trying to figure out how to reduce this noise. If I should filter and how the 24V input or place a filter between the joint point of this two grounds (AC and DC).Looking for any help.

author: penfold
author_rank: Frequent Contributor
timestamp: March 10, 2022, 02:50:56 pm
content: If you probe with a very short ground lead, (like the spring that often comes with probes) connected to the probe ground near the tip, is it still there? If you connect both the probe ground and probe tip to the circuit ground does it still register?

author: TheMG
author_rank: Frequent Contributor
timestamp: March 10, 2022, 03:37:59 pm
content: Is that 110V AC supply isolated? If not, then there's your problem! The negative side of the bridge rectifier is not at 0V with respect to AC ground, it's going to have quite some significant voltage there.To do this properly when running some circuitry off of non-isolated mains, the low voltage control circuit need to be galvanically isolated from the high voltage power circuitry. This would normally be done through the use of optocouplers.

author: Terry Bites
author_rank: Super Contributor
timestamp: March 10, 2022, 04:13:41 pm
content: Check for power loops. Close them off with CM chokes. I'm not sure anything you've added so far will help deal with the massive ground transients. Route/ wire all comons and gnd back to the transformer common.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 10, 2022, 07:55:00 pm
content: Zoom in on the noise. What does the waveform look like? Impulsive ringing? What risetime, frequency, amplitude, repeat rate?Tim
Huge scale, working model of a 555 timer chip using vacuum tubes - Page 1
Forum section: electronics / projects

author: nixxon
author_rank: Frequent Contributor
timestamp: October 27, 2021, 08:19:09 pm
content: I was impressed by this guy:https://youtu.be/bjAlzA4Cyys

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 28, 2021, 12:38:47 am
content: I am beyond impressed!Having said this, I once saw an analog TV sync generator made exclusively from tubes. It occupied a refrigerator sized rack.

author: daqq
author_rank: Super Contributor
timestamp: October 28, 2021, 10:15:16 am
content: Awesome build!Datasheet:Power consumption: YES

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 28, 2021, 04:04:02 pm
content: Quote from: daqq on October 28, 2021, 10:15:16 amA reminder that the WOM specified heater power.Another "misuse" of tubes, I did this a long ass time ago:https://www.seventransistorlabs.com/tmoranwms/Elec_Compound2.html(It's kind of serial and doesn't have a table of contents, just scroll down a few headings to see the final form, or read the background leading up to it if you like.)PWM in the low 100kHz range is quite feasible from tubes, and a final plate efficiency around 80% is achievable. Mind, overall efficiency still tops out around 50-60% from all the heater power, and bias drawn by everything else. Not having complementary devices really sucks for slew rate and power consumption (drivers and logic basically have to be "NMOS", as it were), but heaters consume about as much as bias so it's not like there's a whole lot to save either way.Note that the above is a sort of "class D-A". It has a load resistor to carry bias current to the output, so while the switching has high plate efficiency, the overall output efficiency is normal class A. "Neat", huh?More recently I made this,https://imgur.com/gallery/OF4jAxhSchematic:https://www.seventransistorlabs.com/Images/Tube_Shift_Register.pdfTim

author: TimFox
author_rank: Super Contributor
timestamp: October 28, 2021, 04:52:55 pm
content: In my entry years ago to the Signetics WOM design competition, I used 12AT7 triodes as a convenient interface from standard TTL (into the triode cathode) to a signal impossible to ignore.

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 28, 2021, 06:17:10 pm
content: One of the advantages of vacuum state electronics, is that they can be abused significantly without damage.You see the plate glowing cherry red? Unplug it, let it cool down, and then proceed to troubleshoot. There will be the usual discolored resistor, which can be easily replaced, but most times every thing else survives.
Huge solderless breadboard - Page 1
Forum section: electronics / projects

author: Tj138waterboy
author_rank: Regular Contributor
timestamp: January 23, 2021, 02:40:08 am
content: Building a ultra size breadboard due to getting tired of having many different types and sizes. Found a great setup at hobby lobby made of layered wood that will hide some componets in the bottom and possibly store odds and ends such as jumper wire containers and or small lipo usb backup battery. Im currently at a stand still due to using newer tp4056 modules and realized after continuity test found that the bat+ and out+ are connected full time but the bat- and out- are open circuit. I believe this is to prevent the module from draining the battery when not being used to charge.My goal was to be able to reconfigure most of the batteries/binding post/chargers depending on needs at the time. Ideally I would like to know the best way to utilize what I have pictured to use a split supply preferably using the tp4056 modules while connected to either seperate usb lipo backups or seperate ac to dc phone chargers, or best way to connect the buck modules for adjustable voltage. If needed I could substitute buck/boost for higher voltage. Also any input if I shoild cut out slot to add in the digital panel meter. My original idea was to use a on/off/on switch to toggle between the outputs of each buck module. There is a mini pushbutton switch at bottom of picture that is momentary on/on that would do same thing but would be drawing power full time. Which direction does the forum suggest ?
Humidity Control - Page 1
Forum section: electronics / projects

author: mclemens1969
author_rank: Contributor
timestamp: March 05, 2017, 10:24:36 pm
content: I like the results I am getting from 3D printers like Shapeways (pic of example enclosure attached). The thing I don't like is that the materials are not waterproof. I am not really concerned about liquids spilling on them, but outdoor exposure to constant normal humidity swings worries me.In astronomy, we prevent moisture from getting on optics by using small heaters.Is it possible to similarly keep condensation away from electronics by, for example, an array of 0806 resistors spread uniformly across the board, keeping the electronics at a proper temperature?
Humidity detector - Page 1
Forum section: electronics / projects

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 10, 2014, 10:15:32 pm
content: To counteract mould growth in a cupboard I've installed a small peltier based dehumidifier.Currently it is on full time (ok 24x7). I'd like to have it only activate if the the ambient humidity rises above a certain level and deactivates when the humidity falls to another set level. (adjustable hysteresis).Where I need help is advice on possible sensors as I've not found anything suitable.Any ideas ?Apologies if I've missed anything already covered. I have searched but

author: SArepairman
author_rank: Frequent Contributor
timestamp: March 11, 2014, 05:45:05 am
content: a analog humidity sensor connected to a bang bang controlleror a analog humidity sensor connected to a MCUhttp://www.linear.com/product/LTC1041https://www.sparkfun.com/products/9569should work together. read the ltc1041 datasheet

author: Stonent
author_rank: Super Contributor
timestamp: March 11, 2014, 06:27:54 am
content: There's always the chemical approach.http://www.damprid.com/

author: Kjelt
author_rank: Super Contributor
timestamp: March 11, 2014, 08:08:40 am
content: Search at Farnell for "humidity sensor" has a lot of hits even 27 digital ones but the good ones are quite expensive. If you are very comfortable with embedded hardware and software development that could be a way to go. If not do what all households in the world use: a mechanical hygrostat.Also be found at local shops or the real expensive ones at farnell for instance 1853714

author: PA4TIM
author_rank: Super Contributor
timestamp: March 11, 2014, 08:39:05 am
content: I use a Honeywell HIH-5031 humidity sensor (Farnell). In the datasheet are the formulas to calculate the temperature effect. I measure the temperature and that value is used by the software. The temp sensor is a LM335. Both are connected to the ADC of a Atmel328. I wrote the program on a Arduino but use the Atmell stand alone in this case.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: March 11, 2014, 05:38:15 pm
content: These aren't super cheap but work well-http://www.meas-spec.com/product/t_product.aspx?id=2466

author: Dave Turner
author_rank: Frequent Contributor
timestamp: March 12, 2014, 06:13:52 pm
content: Thank you all for the advice. I'll look at the suggestions and see what might work best for me.

author: kripton2035
author_rank: Super Contributor
timestamp: March 12, 2014, 06:30:55 pm
content: I have one of these for my heat exchanger - it works fine and everything is included.http://www.ebay.com/sch/i.html?_sacat=0&LH_BIN=1&_nkw=wh8040&_sop=15

author: Jibby
author_rank: Contributor
timestamp: April 21, 2014, 11:31:29 am
content: Humidity sensors are available.
Humidity sensor - Page 1
Forum section: electronics / projects

author: DavidDLC
author_rank: Frequent Contributor
timestamp: December 28, 2011, 02:52:02 am
content: What type of sensor is this ? Capacitive ? Resistive ? Other ?

author: gxti
author_rank: Frequent Contributor
timestamp: December 28, 2011, 03:15:41 am
content: I would assume that it is capacitiive, because the overlapping plate structure looks sort of like a capacitor. Multiple elements in parallel increases the capacitance for ease of measurement, smooths out errors from manufacturing tolerances, and exposes the sensor to more air. As I understand it most general-purpose hygrometer elements are of the capacitive type. You're going to need more information than that to interface to it though. A datasheet is a must.

author: johnmx
author_rank: Frequent Contributor
timestamp: December 28, 2011, 10:52:48 pm
content: The LDRs (light dependent resistors) have a similar structure and are resistive sensors....

author: qno
author_rank: Frequent Contributor
timestamp: December 29, 2011, 07:44:44 pm
content: they look like resistive humidity sensors.You can buy them at Conrad here in Europe.You can also roll your own by sticking 2 electrodes (copper wires) into gypsum.The response will be slow depending on size.Make them too small and they will easily break.
Hundreds of Graphic LCDs – What to do without the connector pinout? - Page 1
Forum section: electronics / projects

author: johnmx
author_rank: Frequent Contributor
timestamp: January 06, 2011, 12:55:53 am
content: Hi,I have a lot of TFT LCDs taken from 3 different types of PDAs and I would like to use them in my projects.The problem is that I cannot find the connector pinout of any LCD. There are many sellers in internet, but none of them have the datasheet.LCD type 1: From PDA HP 614c, 320x240, 64k color, part number: TX07D05VM0APALCD type 2: From PDA HP rw6815, 320x240, 64k color, part number: TX07D08VM1CABLCD type 3: From PDA HP hx2410, 320x240, 64k color, part number: TD035STEB3Is the garbage the final destiny?

author: mitpatterson
author_rank: Regular Contributor
timestamp: January 06, 2011, 12:58:28 am
content: If you can't figure it out, skip the trash and give them to me, lol, or someone who might actually use them, or try to figure it out(or in my case probably end up breaking them(in experimenting) before sending them to the trash, loL)

author: joelby
author_rank: Frequent Contributor
timestamp: January 06, 2011, 02:14:32 am
content: http://rossum.posterous.com/has some useful information for reverse engineering LCD protocols with a logic analyser. It is going to be a lot easier to do this if the LCDs are attached to a working PDA. If the LCD contains a controller chip, then searching for its data sheet is likely to be more helpful.

author: Jimmy
author_rank: Regular Contributor
timestamp: January 06, 2011, 02:49:14 am
content: Try thishttp://www.hitachi-displays-eu.com/doc/TX20D26VM0APA.pdf

author: johnmx
author_rank: Frequent Contributor
timestamp: January 07, 2011, 12:40:43 am
content: I found this web site which is a great source of LCD data sheets:http://www.beyondinfinite.com/library.htmlI can’t find the exact models I need, but there are some similar.Some PDAs are working well, so I might find out all connections with a logic analyzer.

author: veryevil
author_rank: Unknown
timestamp: January 07, 2011, 11:42:35 pm
content: If you have "Hundreds" you should definitely offer up some to the community to get multiple people working on solving them.I know I should have all the test equipment needed to work out the protocol / pin out if you had a working PDA.And I'm sure a few people on here would also be able to help.Steven

author: CafeLogic
author_rank: Regular Contributor
timestamp: January 17, 2011, 04:23:46 am
content: I had the same problem. I solved it using magnification, the datasheet for the column/row drivers, and photoshop. See here:http://www.cafelogic.com/articles-2/driving-a-controllerless-graphic-lcd-with-a-pic32/Keep in mind that a PDA LCD is not going to have an on-board controller (MCU interface), so you will have to deal with that after you get the pinout.
Huntron 1005 Oscillator  can we find the problem? - Page 1
Forum section: electronics / projects

author: sampler1
author_rank: Regular Contributor
timestamp: August 19, 2021, 07:56:33 pm
content: Hi All,like many the Oscillator died in my Huntron 1005B. as you know they are no where to be found. I came across the old kit schematic and figured I would try and build one. My 1st problem was IC1 and IC2 as they are not identified in the original schematic. I was told by some members to try LM336.At this point I have made the PCB but its a no go. I seem to be able to adjust the gain a bit but it seems to go into clipping very fast. The frequency does not adjust at all. So here I am bringing it to the pros. It should produce 80Hz at 10VPP.Any suggestions or see any errors?Best regards" alt="" class="bbc_img" />

author: kripton2035
author_rank: Super Contributor
timestamp: August 19, 2021, 08:08:04 pm
content: as I read the kit schematic, it seems to me that it is written 1/2 1458 beside the two aop ?so it should be a LM1458, obsolete, or its actual equivalent MC1458 ?and the LM336 is a voltage reference, not an AOP !even the LM356 is a single AOP ...

author: floobydust
author_rank: Super Contributor
timestamp: August 19, 2021, 08:32:05 pm
content: In your schematic, I see D4 backwards. Otherwise the circuit remake looks reasonable to me, assuming you are using 1458.

author: sampler1
author_rank: Regular Contributor
timestamp: August 19, 2021, 10:24:45 pm
content: Quote from: kripton2035 on August 19, 2021, 08:08:04 pmI have many LM1458's in stock and the Lm336 are for IC1 and Ic2

author: sampler1
author_rank: Regular Contributor
timestamp: August 19, 2021, 10:25:49 pm
content: Quote from: floobydust on August 19, 2021, 08:32:05 pmOMG D4 is backwards.. Ill check that out tomorrow and report. Thanks!

author: kripton2035
author_rank: Super Contributor
timestamp: August 20, 2021, 06:49:48 am
content: Quote from: sampler1 on August 19, 2021, 10:24:45 pmoups should have read better !
Huntron Tracker DIY – Can an MAX293 Elliptic Filter Chip be used? - Page 1
Forum section: electronics / projects

author: Chris56000
author_rank: Frequent Contributor
timestamp: December 25, 2020, 04:43:18 pm
content: Hi!I was looking thro' the design of the Russian "GO" RLC–2 RCL Meter and noticed this uses a MAX293 "8th Order Elliptic Filter" device to generate the two quadrature sinusoids for the test component, so this set me thinking – can the same approach be used in a D.I.Y. Huntron Design to generate the the 50Hz, 400Hz & 2kHz Component Test Voltage, then fed to a Power Amplifier and a small 100V Line Matching Transformer used in reverse then on to the rest of the Huntron Circuits that select the Test Voltage?Chris Williams
HUSB238A with CH334P enumeration? - Page 1
Forum section: electronics / projects

author: sslupsky
author_rank: Contributor
timestamp: June 18, 2025, 07:04:24 pm
content: Hello,I am working on a design that incorporates the HUSB238A USB PD controller. There is one USB Type C connector in my design that will be used for data and power. There are a couple RP2350 devices so I intend to use a USB hub controller (CH334P) to interface the USB DP and DN signals from the USB C connector to each RP2350. I have a question regarding the USB DP and DN connections to the PD controller. I am only intending on supporting PD only and at the moment do not intend to use BC or HVDCP. Am I overlooking something important by excluding BC and/or HVDCP? I am wondering if I need to connect the DP and DN signals to the PD controller if I do not intend to use BC or HVDCP? Also, does the HUSB238A enumerate as a USB device when connected? Should I connect the HUSB238A DP and DN to one of the downstream ports of the CH334P hub controller?

author: spostma
author_rank: Regular Contributor
timestamp: August 02, 2025, 10:33:18 am
content: a late reply, but a USB PD controller only uses one of the two CC pins of a Type-C connector.The D+ and D- are only for legacy BC1.2 charging mode, as the datasheet says.