hybridfree/eevblog-posts huggingface dataset:
Trying to understand how a Charger circuit works.  - Page 1
Forum section: electronics / beginners

author: mkvl
author_rank: Contributor
timestamp: June 29, 2023, 07:24:35 am
content: Hello everyone, I'm trying to understand the work of this Charger circuit, it's a Charger I have, I disassembled it and drew the circuit in the picture below to see how it works, but I could not fully understand it,I am aware of the principal working of transformerless circuit but this circuit seems to be working on half wave and this is what confuses me more, unless if it's a switching power supply which I still not aware of how it works, I can see that the circuit must be an oscillator to generate current in secondary coil, but there's two primary coils, so I can't figure it out what one is resonating and what's the role of the other one, also the role of transistor, does it part of oscillation circuit?.I appreciate any help to understand how this circuit works.The capacitors in the circuit are: two small ceramic capacitors, 102 is 1nf and 472 is 4.7nf.And one polarized capacitor: 400v/2.2uf.Two diodes.Two zener diodes.

author: magic
author_rank: Super Contributor
timestamp: June 29, 2023, 04:51:47 pm
content: It looks approximately like a ringing choke converter, a kind of SMPS. I suspect there are a few errors, for example the base shouldn't be connected only to AC neutral.I used to know a website with great description of how these things work and the various versions found in the wild, but I lost the link. Try to look something up, it should help with correcting mistakes and figuring out the circuit. The collector winding is the primary, and the other winding on the primary side should be feeding the base of the transistor, causing it to oscillate.

author: wasedadoc
author_rank: Super Contributor
timestamp: June 29, 2023, 05:00:20 pm
content: L2 is the primary. L1 is the feedback to make the circuit oscillate. You have the base and emitter of the transistor swapped over. D1 irectifies the incoming AC mains. D2 is the "flyback" diode.You should have written "principle", not "principal".

author: mkvl
author_rank: Contributor
timestamp: June 30, 2023, 02:34:13 am
content: This diagram in the picture is the same of the charger circuit I coped it exactly the same.

author: mkvl
author_rank: Contributor
timestamp: June 30, 2023, 02:36:23 am
content: The English is not my language.Thanks for your advices guys.
Trying to understand this load cell - Page 1
Forum section: electronics / beginners

author: jerryk
author_rank: Regular Contributor
timestamp: June 08, 2020, 08:09:32 pm
content: I have a load cell out of a crane scale MSI-4300. I am trying to find the datasheet on it but can't even find another cell that looks like this one.There are a couple of numbers on it - D00792 1 B and 30917 but no luck pulling anything up on via search. It's from a scale that I repaired (thanks to this forums help) but loaned it to a friend that killed it somehow. I may take another try at repairing it but before I do that I thought I might further my understand some of it's basic components before trudging forward.I have seem some interesting hacks with Arduino type boards, on sparfun and the like, using an amplification board for the sensor outputs that I might try. I think a look at a datasheet is necessary for such a project.Any help finding the datasheet would be great and ideas for learning projects with this thing would even be better.Jerry
Trying to understand this temperature sensor. - Page 1
Forum section: electronics / beginners

author: jerryk
author_rank: Regular Contributor
timestamp: March 31, 2018, 09:09:06 pm
content: I have a temperature sensor of a sauna that I want to read via MCP3008 and a raspberry pi. I am already using 4 LMT86 sensors on the MCP3008 with no issues. The sauna sensor consists of two unknown type ntc thermistors in parallel as shown in the attached photo.Temperature/resistance observations are as follows:Temp C Bead Glass7 71K 18K25 53K 10K50 31K 6KI have tried to understand how to use Steinhart Hart to figure this out but I'm a little bit stuck on the equation itself and how the two thermistors are being read by the existing microcontroller.Edit: added schematic to show the temp sensor connections to the MC.Any help or direction would be appreciated.Jerry

author: alexig
author_rank: Contributor
timestamp: April 01, 2018, 02:00:05 pm
content: Hi Jerry,I'm thinking that they might be using 2 different types of thermistors to average the results as one could be suited better for lower temperatures and the other for higher temperatures.There's a nice site that will calculate the co-efficients for you using the 3 data points you have provided -http://www.thinksrs.com/downloads/programs/Therm%20Calc/NTCCalibrator/NTCcalculator.htmAnd then it's just a matter of using the formula (https://www.ametherm.com/thermistor/ntc-thermistors-steinhart-and-hart-equation) and comparing both thermistors to see which one is better suited.

author: Wimberleytech
author_rank: Super Contributor
timestamp: April 01, 2018, 02:30:18 pm
content: It appears that one thermister bows downward and the other bows upward. If you plot the average of the two voltage-divided outputs you get something closer to linear (it appears from just a few data points).The top graph is the average of the two lower graphs.
trying to understand voltage reference circuit - Page 1
Forum section: electronics / beginners

author: hsn93
author_rank: Regular Contributor
timestamp: February 25, 2019, 09:31:00 am
content: hello, im tring to understand the circuit so i will try to explain what i understand. if i get somthing wrong and you can correct me i appreciate that.the circuit is for RTD 3 wire configuration from TI (http://www.ti.com/lit/an/snoa481b/snoa481b.pdf)as much as i understand:U1D / U1B / U1C are for voltage reference which is concerning this topic.i don't know about op amps and their types, drift, noise, common noise rejection, ...etc.its like black box for me so I'm trying to understand with idea of (these are ideal amplifiers).1- we have 1.25V fromLH4140ACH-1.25.2- I'm going to ignore that this 1.25V is connected toR19for now.3-U1Dpositive input has 1.25V.4-U1Dwill try to follow the input so its output will be 2.5V. becauseR21=R225- we have (the output going to the RTD (R6) with the resistors shown:(1636 / (1636 + 634)) * 2.5V = 1.802V is going to positive ofU1B6-U1Bis just buffer so its output is 1.802V.7- i assume that (R15, R16, C1, C2) is just filter and what is going toU1Cis just pure DC 1.802V8-U1Cis just buffer9- at top ofR19we have output of theU1Cwhich is 1.802, and at bottom ofR20we have 1.25V (difference = 0.55V)10- acrossR19, R20is 0.55V so that will be /2.11- input ofU1D= (1.25 + (0.55/2)) = 1.525V12- go tostep 4. except we have bigger voltagethis means it will keep increasing the voltage?

author: mikerj
author_rank: Super Contributor
timestamp: February 25, 2019, 10:17:00 am
content: U1D / U1B / U1C maintain a constant voltage drop over R18, i.e. it's a constant current source for the RTD.

author: Damianos
author_rank: Frequent Contributor
timestamp: February 25, 2019, 11:41:02 am
content: There is a reference on the first circuit presented in the mentioned application note.Because U1B and U1C are buffers (for DC), the output of the last is equal to the input of the first. Lets call it Vfb(feedback).At the input of U1D we have VinU1D=(Vref+Vfb)/2.As the gain of U1D is equal to 2, the output is VoutU1D=Vref+Vfb.The voltage across R18 isVR18=VoutU1D-Vfb=Vref+Vfb-Vfb=Vref.So the output current isIOUT=Vref/R18, independent of the output voltage (if the circuit works inside its limits).
Trying to use the CC2510 Debug Interface from RP2040 - Page 1
Forum section: electronics / beginners

author: Jaunedeau
author_rank: Regular Contributor
timestamp: December 17, 2023, 11:10:44 am
content: Hi,I am trying (just for the sake of learning) to use the CC2510 debug interface from an RP2040 (aliex clone Rp Pico). The documentation I use is mainly theCC1110/ CC2430/ CC2510 Debug and Programming Interface Specification Rev. 1.2.I see no response from the CC2510. I checked all the connections several time with a DMM.In the trace (see attachement) you can see :- I switch all pin from 0 to 1 one after the other to check that ecerything is fine on the breadboard (the 4.25µs is the shortest pulse I can have using the delay lib I currently use)- As in chapter 2.3 I put reset down, send two rising clock pulses, then reset high- I then send 0b01101000, hich should be GET_CHIP_ID according to table 2 in chapter 2.4- I switch the data pin to input (with pull up on the attached trace, but I also tried with pull down and floating)- I wait a bit then send a serie of clock pulses, hoping to see chip id and chip revision as stated in chapter 2.4.4 (the drawing on this chapter makes me think pull downs are expected)Can you help me debug this ?I join my (Rust) source code.Thank you,J.

author: Jaunedeau
author_rank: Regular Contributor
timestamp: December 19, 2023, 09:54:38 am
content: I made several changes and I don't know which ones were the good ones in the end, but I manage to make it work. I'll leave my hugly code here in case someone having the same problem finds this thread.trace :- two pulses to enter debug mode- sending 0x68 (ask for chip id)- answered "CC2510 rev 4"
Trying to work out how a DD1718PA works - Page 1
Forum section: electronics / beginners

author: tomoram
author_rank: Contributor
timestamp: June 19, 2022, 04:05:12 pm
content: I'm trying to understand how the DD1718PA boost converter works. It outputs an increased, dual-rail voltage from a lower voltage.https://www.amazon.co.uk/Precise-Converter-DD1718PA-Operational-Amplifier-Turn-plus-minus-9V/dp/B09K6HDDFJIt uses the XL6007E1 boost IC, but the configuration seems to be different to any schematic I can find. I've tried to reverse engineer the schematic from the pictures online I can't see enough detail.Some things I've noticed that confuse me:1. It looks like it's a single inductor - most dual-rail schematics use a transformer2. The input GND and output GND is the same - which suggests that it's not simply outputting double the voltage and dividing it to create a + and - voltage around the centre.Does anyone have any ideas on what this schematic might look like?

author: ledtester
author_rank: Super Contributor
timestamp: June 20, 2022, 04:38:26 am
content: Have a look at this thread:https://www.eevblog.com/forum/projects/challenge-a-buck-converter-providing-split-rail/where they discuss a similar design problem.

author: ledtester
author_rank: Super Contributor
timestamp: June 20, 2022, 07:59:17 pm
content: fwiw, the industry uses the acronym "SIMO" for "single inductor, multiple output" regulators. TI and Maxim seem to be the main players in this area.Some resources:A Maxim white paper on SIMO:https://www.maximintegrated.com/en/design/partners-and-technology/design-technology/single-inductor-multiple-output.htmlThe technical discussion in this UK patent *might* be easy to follow:UK Patent GB2441358A:https://patentimages.storage.googleapis.com/cf/c2/09/43fd6e12faa0d2/GB2441358A.pdf

author: tomoram
author_rank: Contributor
timestamp: June 22, 2022, 06:03:42 am
content: Thanks ledtester. I had seen the thread you linked but it still left some questions. The SIMO acronym is really useful to know, thanks!

author: Jeanious2011
author_rank: Newbie
timestamp: May 07, 2023, 05:46:16 pm
content: Thats the same chip as XL6007E1. I ordered the same unit and it came with that chip.
TS 100 Power Supply  - Page 1
Forum section: electronics / beginners

author: sorrycharlie
author_rank: Newbie
timestamp: July 09, 2020, 12:18:45 am
content: Hi there, sorry for the newbie question.I have a laptop power supply on the way for my TS100 but was wondering in the meantime if it's safe to use this old MacBook charger I have lying around.It is 16.5V @ 3.65AI also need to confirm that the centre wire that is shielded is the positive and the outside is ground?\Cheers

author: ledtester
author_rank: Super Contributor
timestamp: July 09, 2020, 04:15:40 am
content: 16.5V is fine for the TS-100 - i.e. it won't damage it.To avoid damaging the circuits you work on you want to verify that the ground is _grounded_ - i.e. the ground of the output is connected to earth ground.

author: sorrycharlie
author_rank: Newbie
timestamp: July 09, 2020, 10:31:44 am
content: Ok thanks, but how would I do that?And when I receive the laptop power supply I have coming, will I also have to do that with that?Cheers

author: ledtester
author_rank: Super Contributor
timestamp: July 10, 2020, 04:00:25 am
content: If the supply doesn't have three prongs then there's no way it can be grounded.If it does have three prongs you should check the continuity between the output GND and earth prong on the AC side. If there is continuity your power supply is grounded.Note that using a grounded power supply won't protect you against electrostatic discharge from the tip but it will eliminate the ghost voltage that switching power supplies generate. To be absolutely safe when soldering ESD sensitive components you should ground your tip using a grounding wire like shown here:https://www.rchelicopterfun.com/images/TS100-Grounding-525px.jpgAnother thing about TS100 power supplies... you should get as close to 24V as you can find. Using a higher voltage supply will dramatically decrease heating times. Here's a chart taken from the user manual:
TS100, ground and power supply.  - Page 1
Forum section: electronics / beginners

author: Leinard
author_rank: Newbie
timestamp: January 29, 2020, 08:25:34 pm
content: Premise: I'm a real beginner. Totally noob but curious and a quick learner.I'm beginning to practice this world and I needed a soldering station that is cheap (max 120€), safe (I have to work with caps, and other pcb stuff, so ESD safety is required) and T12 tip provided.So, my chances were: TS100 (often cited here and everywhere), T12 Ksger, and other chinese knockoffs. At the end I chose TS100 and today it's arrived but after a lot of reading online and here I met the earth/ground problem.For the ESD safety I know that the gnd screw has to be attached, through a cable, to something else. But I don't know how. After reading all the posts about here, I couldn't find a clear explanation on how to do the better solution. I read about the silicon cable, the shorting of capacitor, use of 1M resistor, gnd to negative, grounded and not grounded laptop PSU. I'm completely confused.The solution I thought are:1: Laptop grounded PSU + short of capacitor on GND screw of the iron or cable from screw to negative of power DC cable.2: Laptop grounded PSU + cable from GND screw to ESD mat3: Silicone wire 2 core to PSU bench + groung wire from screw to GND third output PSU bench.Can someone suggest me what is the best solution and explain me clearly how to do it?Thanks in advance!
TS100 issue. Inconsistent bit power? - Page 1
Forum section: electronics / beginners

author: Hughieandrolf
author_rank: Newbie
timestamp: November 01, 2019, 02:45:51 pm
content: Hi. has anyone any idea what may be going on here?I recently bought a TS100 soldering iron which came supplied with an angle cut pointed bit. I bought an 2 additional chisel bits but I can't always get the chisel bits to to work reliably :-When using my small "Portable" old HP laptop brick PSU rated 19V 1.58A (30W) The supplied angle bit works fine but when using the chisel bits, switching on from standby the iron "browns out" and reboots every second or so. I tried 3 x 18650s in series and the iron works with all bits as it does with a 24V 4A chassis supply but it's not really portable. I tried measuring the current on a boost buck CC/CV PSU module with integral meter and the meter display just randomly flashes.https://www.eevblog.com/forum/Smileys/default/confused0024.gifThanksSteve

author: Gyro
author_rank: Super Contributor
timestamp: November 01, 2019, 06:52:08 pm
content: It sounds as if your HP laptop brick is simply not up to the job and is going into an over-current protection /shutdown cycle. It is probably right on the limit with the original bit and just over with the new ones, especially when the tips are cold and it is running at 100% duty cycle.If you look at the TS100 manual, it specifies a PSU current rating of 2.1A for 19V supply (40W), so you're a fair bit short of that.I believe there has been to odd occurrence of a faulty, shorted element but the fact that they both work fine with Lithium cells and the 4A PSU seems to eliminate that.It would probably be best not to use it with a repeatedly browning out PSU, worst case it might cause damage to the switching FET or possibly even corrupt the firmware.P.S. You're probably having no luck with your current measurement because the element is controlled by PWM switching and the duty cycle will be changing as the tip warms up.

author: Hughieandrolf
author_rank: Newbie
timestamp: November 02, 2019, 02:36:25 am
content: Excellent. Thank you Chris. A case of RTFM.Steve.
TS100 Soldering Iron: Firmwares, Maintenance, Mods? - Page 1
Forum section: electronics / beginners

author: Mp3
author_rank: Frequent Contributor
timestamp: April 04, 2019, 02:43:31 am
content: Hey everyone, I got a mini TS100 soldering iron and it is honestly pretty cool. Just wondering if anyone's ever used any of the custom firmwares available for it. I've found at least one Github page with a fully open source firmware on it. Just curious if anyone has used any of these firmwares or other mods to it.By the way, I'm trying to learn how to measure a screw properly with digital calipers since i almost immediately lost one of the screws that holds either the soldering tip or the ground wire. If anyone happens to already know what size the screws are, let me know, it comes with 2 spares and it sucks to have to use one of the spares within a minute of trying to put it together!

author: Gyro
author_rank: Super Contributor
timestamp: April 04, 2019, 09:18:44 am
content: The main alternative firmware is Ralim's. The current RC4 pre-release is looking pretty good. Its PID controller is now optimized for the thermal characteristics of each individual tip type.https://github.com/Ralim/ts100/releasesIthinkthe screws are M2.
TS3702, what to do with unused pins ? - Page 1
Forum section: electronics / beginners

author: RacerX10
author_rank: Newbie
timestamp: April 03, 2013, 03:36:17 pm
content: I'm using a TS3702 comparator IC in a design, it has 2 comparators on board and I'm only using one of them. Any idea what I should do with the unused ins(2) and out(1) ? It has a push-pull CMOS output stage.Thanks !

author: amyk
author_rank: Super Contributor
timestamp: April 03, 2013, 07:51:00 pm
content: I'm surprised the datasheet doesn't have some variation of the standard warning about unused pins, which goes as follows:Quote(If you Google fragments of text from the above you'll find tons of different datasheets all containing the same warning.)

author: RacerX10
author_rank: Newbie
timestamp: April 04, 2013, 02:39:05 am
content: Found this :
TSC / Filter? Capacitors - Page 1
Forum section: electronics / beginners

author: Dipski
author_rank: Contributor
timestamp: September 23, 2013, 08:05:59 am
content: Hi folks, my first post here but long time follower and fan of the EEVblog.Just a (hopefully) quick question for someone familiar with CRT monitors or TSC capacitors in general. I've got a CRT monitor that has come with a bunch of equipment that has plenty of filter capacitors which have systematically blown and smoked up my workshop - my solution to this has been to replace the filter capacitors before plugging the equipment in to start with which has worked well. I'm looking at an old red capacitor which is marked 0.47K 250V PPN / TSC and Dr. Google tells me that TSC is a Thyristor Switched Capacitor which compensates reactive power, which sounds like what a filter capacitor does to me (please correct me if I'm wrong). Following that, my assumption would be that a regular 0.47uF 250V MKT Capacitor will be an ideal replacement for it. If anyone could confirm that I'm on the right track, or point me in the right direction it would be much appreciated.

author: Paul Price
author_rank: Super Contributor
timestamp: September 23, 2013, 09:54:37 am
content: The capacitor is a snubber capacitor and it is not really a filter capacitor in the energy storage business, just used to protect a SCR or TRIAC from excessive voltage transients during turn off.Chances are this capacitor is ok, this kinda cap is made to be extra rugged.Head due north.
TSOP4138 false triggering ??? - Page 1
Forum section: electronics / beginners

author: andybarrett1
author_rank: Regular Contributor
timestamp: December 07, 2018, 08:12:19 am
content: Hi and thanks for readingI have interfaced a Vishay TSOP4138 IR receiver with a Microchip PIC 16f648 all is good and works well.But all I am interested in is the first falling edge on the output of the 4138 when it sees the presence of a 38Khz source.*** I suspect I am getting false noise and this is triggering my Pic ****Circuit is a per datasheet*Looking at the datasheet the TSOP4138 does have a pullup (25k) but what I am wondering is if I put a harder pull up (22k maybe) in parallel then a 0.1uf cap to ground from the OP pin to the PIC.Would that act as a hardware filter.....Advice and help welcome thank you again for readingBRAndy

author: Buriedcode
author_rank: Super Contributor
timestamp: December 07, 2018, 09:45:11 am
content: These devices are very sensitive to noise on the power supply, as well as EMI. I recently used a similar device and ended up with 100 ohm resistor with a 47uF cap as a LPF for the Vsupply. I believe the application circuit in the datasheet also has this filter (but with no part values). A good start would be a 47ohm resistor with a 10uF cap.With that said, it will still probably get false triggers on the output, and your software should be able to cope with these. When a remote is sending a signal the AGC kicks in and reduces the gain, so you won't get false spikes in the middle of a transmission, only when its idle. Your software should be able to distinguish between a valid signal (NEC, sony, RC-5) and false triggers.
TSSOP breakout for SSOP chip - Page 1
Forum section: electronics / beginners

author: thefatmoop
author_rank: Contributor
timestamp: July 28, 2013, 10:08:48 pm
content: Would a 16 pin TSSOP breakout be compatible with a 16pin SSOP chip?http://www.adafruit.com/products/1207Looks so, but I'm not sure =[thanks!

author: Corporate666
author_rank: Unknown
timestamp: July 28, 2013, 10:12:17 pm
content: Quote from: thefatmoop on July 28, 2013, 10:08:48 pmYup, should work fine. I have a stack of those Adafruit adapters and have used TSSOP and SSOP's on them.Just check the pitch of your part leads... aren't some SSOP's 0.025" = 0.635mm and some TSSOP's are 0.65mm?
TTi CPX400DP - Page 1
Forum section: electronics / beginners

author: Andre Gopee
author_rank: Newbie
timestamp: November 08, 2022, 10:16:09 pm
content: Good day everyone, I am new here and I need some help. I have a TTI CPX400DP and the problem that I am having is when you first apply power to the unit and switch it on the unit will display (FAIL 4) and then switch to normal display. If I try to press the OP buttom is say FAIL4. I am not able to get any output but I can set the voltages from the from panel. I found a Zener Diode (D17) Damage and I replaced it with IC#2 (TNY254P) but the problem is still there. Can anyone point me in the right direction on what the FAIL4 Code is? Thank you and have a great day.
TTL Signal Conditioning - Page 1
Forum section: electronics / beginners

author: olsenn
author_rank: Frequent Contributor
timestamp: March 22, 2013, 04:57:36 pm
content: I currently have a frequency counter made up, sitting on my breadboard, but the input currently has to be a TTL signal (0v - 5v square wave) as it goes directly into my AVR microcontroller to be sampled.I would like to be able to input a wide range of signals, including for example, a -1v to +1v peak-to-peak sinusoid. I first tried a simple RF NPN (BF199) transistor as a switch, but that only worked up to about 100kHz (even though the datasheet says it has a current-gain product of 1100MHz and I tried various values of base/collector resistors). I then tried an op-amp comparator, but that had a performance that was about the same.I would like to be able to convert signals from 0.1Hz to 40MHz, and with p2p voltages (for sinusoids) of as low as 1.5v - 2v. If the input voltage goes above 5v I'm sure I can just use a clipper or a zener overvoltage protection circuit.

author: SeanB
author_rank: Super Contributor
timestamp: March 22, 2013, 05:05:59 pm
content: 74HC14 used as a linear amplifier, one stage driving the second as a clipper. Ac couple in via 100n capacitor.

author: MikeK
author_rank: Super Contributor
timestamp: March 23, 2013, 02:48:12 am
content: How about this:
TTP224 capacitive touch unreliable when using adapter - Page 1
Forum section: electronics / beginners

author: lutkeveld
author_rank: Regular Contributor
timestamp: January 14, 2021, 07:45:08 am
content: I am using a TTP224 chip for capacitive touch sensing through 3mm wood.If I run the chip via a LDO from battery, it works reliably.When I plug in a charger, the circuit starts to produce false positives.What would be the best way to combat this? Install an EMI (is this the problem?) filter between adapter and battery?Or use some filter before the capacitive touch chip?

author: janoc
author_rank: Super Contributor
timestamp: January 14, 2021, 12:57:25 pm
content: Change the adapter? Likely a cheapo switcher with a lot of ripple/noise upsetting the capacitive sensing. You can always put a common mode choke + some filtering capacitor or use higher voltage adapter with a local LDO to power the sensor, which will knock the ripple down as well.
Tube Specifications - Keep me honest! - Page 1
Forum section: electronics / beginners

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 07:05:18 pm
content: I'm working on trying to understand the Effective Load Resistance, THD, and Power Output of a power output tube as well as how it relates to an output transformer... stay with me.The screenshot below is taken from the schematics for a 50L6-GT tube. I'm simply trying to see if what I *think* I understand (i.e. what the schematic is trying to tell me) is correct."In general", the bottom portion is saying the  Load Resistance should be 2000 Ohms when the plate voltage equals 110V and the resistance should be 4000 Ohms when the plate voltage equals 200V. The total harmonic distortion should be 10% approximately. And, finally, the power output should be 2.1 and 3.8 watts respectively.Now, if we look at the top graph portion, the purple/pink horizontal line denotes 10% THD. The yellow section highlights 2000 to 4000 Ohms load resistance. The circles (1) and (2) are the points where the measured distortion intersects with 2000 ohms and 4000 ohms. The two red squares are where the power output intersects with 2000/4000 ohms. The wavy green line is simply highlighting the measured distortion. The large black arrow is a ballpark estimate of where the distortion is at its lowest point.Based on that, I *think* the graph is saying that the measured power output and distortion at 2000 ohms is roughly 3.4W and 12.75% AND at 4000 ohms, those values are 4.35W and 8.25% roughly.Now, IF I am reading all of this correctly, it appears that the optimal power output (4.2W) with the lowest THD (~8%) should be around 3600 ohms load resistance. So... am I reading all of this correctly?Thank you,- Wil

author: rsjsouza
author_rank: Super Contributor
timestamp: November 21, 2023, 07:20:02 pm
content: Wil, from where I see you seem to be correct. Just be mindful that the graph has a plate voltage fixed at 200V and a grid voltage of 110V, which is a setpoint that is not reflected at all by the table: the 2000 ohms sets plate and grid voltages to 110V and the 4000 ohms is set to 200/125V. Not much clear.

author: Wil_Bloodworth
author_rank: Regular Contributor
timestamp: November 21, 2023, 07:31:37 pm
content: Quote from: rsjsouza on November 21, 2023, 07:20:02 pmExcellent point! Mentally, I was trying to wrap my head around the clear differences between the "Typical Operating Conditions" specifications and the measured values... because the graph shows very different values than the table at the same input values.- Wil
Tube television diode split transformers - Page 1
Forum section: electronics / beginners

author: xwarp
author_rank: Frequent Contributor
timestamp: May 14, 2014, 02:25:15 am
content: Anyone successful in the dis-assembly of one?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 14, 2014, 03:29:40 am
content: !?? Please define?

author: SeanB
author_rank: Super Contributor
timestamp: May 14, 2014, 04:17:09 am
content: Difficult, as they are all well potted. You can use them as high voltage power supplies, look at the many online examples.
Tube tester shenanigans - Page 1
Forum section: electronics / beginners

author: CoopedUp
author_rank: Regular Contributor
timestamp: July 02, 2019, 05:30:32 pm
content: My tube tester works just fine with some tubes and others the needle just gets pinned in the wrong direction. Anyone know what this means? Is the tube on the inside of the tester cooked? Thanks

author: Cubdriver
author_rank: Unknown
timestamp: July 02, 2019, 09:02:45 pm
content: A bit of additional detail would help to get you an answer.Little things:What make/model of tube tester?What tubes does it work fine with?What tubes does it not work with?Does it sometimes work and not work with different specimens of the same tube type?-Pat

author: CoopedUp
author_rank: Regular Contributor
timestamp: July 03, 2019, 12:16:15 am
content: It's a mercury 1000 and it works with all the diodes I have put in it and I haven't tested a whole lot else but half of everything that is different like the all American fives I think the 50c 5and 35w4 work but none of the others 12ba6 12be6 or 12av6 at least that's the way I remember it not working

author: floobydust
author_rank: Super Contributor
timestamp: July 03, 2019, 03:08:03 am
content: When's the last time you calibrated it?I would see if the tester's bias supply is working and calibrated at -5.9V, along with setting thefourother cal trimpots. There are only four electrolytic caps, I would replace them given the age.

author: CoopedUp
author_rank: Regular Contributor
timestamp: July 04, 2019, 03:00:15 pm
content: I have replaced all of the capacitors already, and I don't know when it was last calibrated but I don't see how that would affect the pin going the incorrect direction
tungar charger and diodes - Page 1
Forum section: electronics / beginners

author: delta75
author_rank: Contributor
timestamp: January 18, 2012, 12:12:21 pm
content: Hi all,Recently my tungar valve battery charger's tungar rectifier died. I ordered a replacement from the states, but it arrived with a blown filament. High current diodes are expensive, so i had the idea of parrallel diodes to increase the current.Searching google i get two opinions some people say it would work as long as you use the exact same parts, but other say due one diode heating up more that would get more current and blow it, which is right , and how else can i increase the currentthanks delta75

author: amspire
author_rank: Super Contributor
timestamp: January 18, 2012, 12:29:02 pm
content: I had never heard of a Tungar Bulb before, so here is the manual for anyone else who is interested:http://www.radiomuseum.org/dsp_multipage_pdf.cfm?pdf=tungar_bulb_data_manual_52410.pdfIs the charger just the transformer and the Tungar rectifier? Which model rectifier does it use?

author: delta75
author_rank: Contributor
timestamp: January 18, 2012, 12:44:28 pm
content: the charger is basically a multitapped transformer going to a heavy duty rotary switch( made on a piece of absetos 6mm thick)then to the tungar rectifier,it was an ex raaf charger from the 40's .I have never had to change the valve till now, and their is no markings visible except 'L' anymore, the replacement from the states was a bit of a guess it looked right,

author: amspire
author_rank: Super Contributor
timestamp: January 18, 2012, 12:59:06 pm
content: And do you want to get it going again with valve rectifiers, or can you use semiconductor rectifiers?I guess to get the same voltage drop, you would need 10 or more silicon diodes in series, and perhaps a bit of resistance as well.

author: delta75
author_rank: Contributor
timestamp: January 18, 2012, 01:06:48 pm
content: I wanted to get it going with valves but couldn't find a suitable affordable valve. So i thought i would replace them with diodes but high current diodes are expensive,

author: amspire
author_rank: Super Contributor
timestamp: January 18, 2012, 01:17:05 pm
content: Quote from: delta75 on January 18, 2012, 01:06:48 pmYou are talking about vacuum tube diodes? I do not think you can use them as they will have a higher forward voltage. It has to be a gas/mercury type tube like the Tungar bulbs if you are going to use tube technology.If you want to go to semiconductor diodes, they could be economical, but it depends on the current. It sound like a half wave rectifier with only one Tungar bulb. And how much charging current ? 10A? What is the battery voltage?
tuning an fm transmitter - Page 1
Forum section: electronics / beginners

author: Adhith
author_rank: Frequent Contributor
timestamp: December 23, 2015, 08:08:29 am
content: hello everyone ..iam working on an fm transmitter & i have double checked the circuit but i can't tune the transmitter, could you please tell me how to do it or is there any other mistakes in my transmitter.iam attaching the transmitter and its connection diagram

author: VK5RC
author_rank: Unknown
timestamp: December 23, 2015, 08:13:34 am
content: Have you checked the pinout of the transistors? I have seen 3904s with varying pinouts.

author: VK5RC
author_rank: Unknown
timestamp: December 23, 2015, 08:18:18 am
content: Another 'slow' thought,Your board isn't vero strip board by chance? The stray capacitance can dampen oscillation esp at many MHz.PS was listening to 'solder smoke' podcast, JOO, joy of oscillation!

author: ataradov
author_rank: Super Contributor
timestamp: December 23, 2015, 08:24:19 am
content: There is no need to create new topics for the same project.What test equipment do you have?The circuit can be logically split into two parts. Everything before C2 is a low frequency amplifier and can be debugged by itself even with a cheap multimeter. Everything after C2 is a high frequency generator and it can be tricky to debug without a scope. But still doable.Can you attach a picture of the reverse side of the board and your test setup?

author: Shock
author_rank: Super Contributor
timestamp: December 23, 2015, 03:03:19 pm
content: Did you use 100 or 100K for R5?

author: brentab
author_rank: Newbie
timestamp: December 23, 2015, 03:59:42 pm
content: Judging from the above picture, that is a air core inductor (7 turns .4" in diameter and .6" long).L = n²?d²/(18d + 40h)If you do the math that is .250 uh. Over twice the inductance he needs

author: Audioguru
author_rank: Super Contributor
timestamp: December 24, 2015, 12:49:21 am
content: 10 years ago somebody posted that the circuit did not work so I tried it and yes it did not work:1) If the first transistor has high hFE and the battery is new then the transistor was saturated and does not work. If the first transistor has low hFE and the battery voltage is low then the transistor is cutoff and does not work. So I biased the transistor correctly and used a low-dropout 5V regulator.2) The frequency changed whenever something moved towards or away from the antenna (changing the capacitance). So I added an RF amplifier so the antenna was not connected to the oscillator.3) The frequency changed when the battery voltage was running down. So I fed the oscillator from the 5V regulator.I also added pre-emphasis with a small value for C4 (high audio frequencies boost) like real FM stations so it sounds perfect. It was built on stripboard with the strips cut as short as possible. it can be tuned over most of the FM broadcast band.
Tuning servo motors with a scope. Never used a scope before - Page 1
Forum section: electronics / beginners

author: golash
author_rank: Contributor
timestamp: February 19, 2015, 03:09:58 am
content: HiI have a project for my new oscilloscope and I`m a bit uncertain how to proceed. I have a 3 axiscnc machine that I've built and I`d like to tune the servos. I am totally new to the use of oscilloscopesand I`m very nervous about potentially shorting out the new scope.Here is a link to what I`d like to accomplish. Hoping for some guidance. This link has very detailed infothat I`m using for my testing.http://www.cnccookbook.com/CCServoTuning.htmI guess my real question is how easy is it to kill a scope.If anyone is interested I have a on-going thread at this location that details what I`m attempting to test.http://www.cnczone.com/forums/general-cnc-machine-related-electronics/243416-new-control-panel-build-looking-advice-layout-3.html

author: Mr.B
author_rank: Unknown
timestamp: February 19, 2015, 03:13:08 am
content: Have a watch of this very good tutorial...https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/
Turn a Buck converter into a Boost converter - Page 1
Forum section: electronics / beginners

author: EEVadam
author_rank: Newbie
timestamp: January 28, 2017, 10:01:14 pm
content: Hi this is my first post. Yesterday i bought a dc-dc converter , i thought it was a boost converter but it turned out it wasnt. So im curious if there is any way to convert the converter.Thank you

author: Ian.M
author_rank: Super Contributor
timestamp: January 28, 2017, 10:09:34 pm
content: First check the control IC datasheet to see if there's a boost mode application circuit, but the odds are not in your favour as the output transistor, diode and inductor will all need rewiring to rearrange the circuit, which will probably not be possible with the existing PCB layout.

author: EEVadam
author_rank: Newbie
timestamp: January 28, 2017, 10:14:41 pm
content: Thanks for you reply
Turn Digital Signal into Solid 12v Signal - Page 1
Forum section: electronics / beginners

author: Adam60
author_rank: Regular Contributor
timestamp: October 19, 2018, 10:24:52 pm
content: If one wanted to take a digital signal or sine wave signal crom a vehicle spped sensor and turn it into 12v dc, how would you go about it. So I would need a 100% solid 12v signal. I am thinking it would have to be something controlling a relay or some type of switch that would latch when it sees a signal, and unlatch when it does not. Any ideas appreciated. Diagrams??..

author: james_s
author_rank: Super Contributor
timestamp: October 20, 2018, 04:50:08 am
content: What you want is effectively a low pass filter, there are lots of ways to do this. A very simple way would be to use a R-C filter with the output of that feeding one input of a comparator. The other input of the comparator could go to the wiper of a pot connected between 12V and ground, or you could figure out the threshold you want and just use a divider made of fixed resistors.

author: Housedad
author_rank: Frequent Contributor
timestamp: October 20, 2018, 05:07:35 am
content: I don't know for sure, but I have a question about doing that. Would it not make a difference to the speed sensor circuit if the speed sensor detection is current based? Is it current or voltage based? They are hall effect sensors of some type on the tone rings. If current based sensing, would it not screw it up to use that signal directly for anything else?Someone around here would know the answer I hope.

author: Adam60
author_rank: Regular Contributor
timestamp: October 20, 2018, 01:43:21 pm
content: Vehicle speed could be Hall Effect or variable reluctance so I need a a way to change both if possible. I can't take away too much current from the circuit or I will run into more problems.

author: ArthurDent
author_rank: Super Contributor
timestamp: October 20, 2018, 02:56:15 pm
content: Use an opamp configured as a buffer so you don't load the driving circuit. The opamp output can drive a diode with a cap to rectify the output to get a D.C. voltage to turn a transistor on/off to control a larger relay or drive a sensitive relay directly.

author: Adam60
author_rank: Regular Contributor
timestamp: October 21, 2018, 12:54:55 pm
content: Would you have a diagram of such a circuit? That sounds like something that I am looking for. I was thinking if I could run the 12v through a relay, I would just need a low amp circuit to energize the relay coil. It takes roughly 100mA to do that.
Turn-off of constant current source using the reference voltage - Page 1
Forum section: electronics / beginners

author: brumbarchris
author_rank: Regular Contributor
timestamp: May 02, 2019, 02:38:04 pm
content: Hi all,I am currently studying this constant current source with opamp and P channel MOSFET. there is something I do not understand and that I would like to ask. The way I see it, the opamp will alwas drive the gate of the MOSFET so as to keep the negative input to the same voltage as the positive input. I would therefore expect that if I increase the reference voltage to 5V, the gate voltage will rise high enough to completely turn OFF the mosfet and to ensure the negative input also reaches 5V. I do not see this behaviour in simulation, though. If I rise the VREF voltage, the VGAT only increase so much, and the Vin voltage is clamped somewhere at 4.15V. So I guess the question is: why doesn't the opamp block the MOSFET when VREF=5V?

author: awallin
author_rank: Frequent Contributor
timestamp: May 02, 2019, 03:02:59 pm
content: try a higher supply-voltage for the op-amp. the output will go more or less close to the positive supply rail but not beyond..

author: brumbarchris
author_rank: Regular Contributor
timestamp: May 02, 2019, 04:45:43 pm
content: My intended goal was to turn off the mosfet by connecting the positive input of the opamp to the supply voltage. And I only have/want a single supply voltage in this circuit.Cristian

author: MarkF
author_rank: Super Contributor
timestamp: May 02, 2019, 05:39:04 pm
content: The LT1006 opamp output can only go to (V+) - 1.2V. Which will probably not completely turn off the MOSFET.Are you just trying to switch the output on/off or control the current?For just switching, this circuit for a solar panel charger may help.

author: brumbarchris
author_rank: Regular Contributor
timestamp: May 03, 2019, 09:11:06 am
content: Yep, it was the limited output capability of the opamp to swing to the upper rail. Changing the opamp solved it, thanks.I now ran in different problems, but I will post in the Projects and Technical stuff forum section, as it is not "beginners" stuff.Regards,Cristian
Turn on turn off circuit - Page 1
Forum section: electronics / beginners

author: abdurresitcan
author_rank: Newbie
timestamp: December 01, 2019, 06:33:22 pm
content: Hi, I'm high school 2nd grade student, my subject is Electic-Electronic. I'm new in Electric-Electronic. I need help about making turn on and turn off circuit in breadboard and proteus. I designed circuits but It did'nt work. What is my fault

author: MarkF
author_rank: Super Contributor
timestamp: December 01, 2019, 06:42:59 pm
content: Both of your circuits are momentary action. Not latching.Have a look at these two:https://www.eevblog.com/forum/beginners/push-button-power-circuit-for-arduino-trying-to-modify-it-for-12v-input/
turning a 0 - 1V DC signal to a 1 - 0V signal using op amp buffer? - Page 1
Forum section: electronics / beginners

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: September 04, 2021, 08:52:05 pm
content: an inverting amplifier with gain of 1 would do something like this but it would be offset by 1 Volt, which I don't want... but I can't seem to think of a way to do this...

author: TimFox
author_rank: Super Contributor
timestamp: September 04, 2021, 08:57:55 pm
content: It’s trivial with an inverting op amp circuit (assuming split supplies) to obtain any reasonable offset: just add the appropriate resistor from the inverting input (virtual ground) to a positive or negative voltage, as required.

author: magic
author_rank: Super Contributor
timestamp: September 04, 2021, 09:32:22 pm
content: That works given a sufficiently stable supply rail.If not, 0.5V for the noninverting input can be easily divided from any 1.25V bandgap reference using common resistor values.

author: TimFox
author_rank: Super Contributor
timestamp: September 04, 2021, 09:35:55 pm
content: Exactly. Note that I wrote “positive or negative voltage”, not “rail”. The last time I needed to do this in a precision application, I was very annoyed that nobody made three-terminal precision reference ICs with a negative output, and had to use a two-terminal device with resistor instead. Otherwise, I would have needed an extra op amp and two expensive resistors to obtain the stable negative voltage.

author: David Hess
author_rank: Super Contributor
timestamp: September 04, 2021, 11:43:07 pm
content: Quote from: ELS122 on September 04, 2021, 08:57:15 pmExactly, or you can leave the non-inverting input grounded and apply a suitable current to the inverting input. Since the inverting input is a virtual ground, this can be done with a resistor and voltage.

author: rstofer
author_rank: Super Contributor
timestamp: September 05, 2021, 01:48:40 am
content: Assuming the op amp will work down to 0V (or is dual supply), it looks like a subtractor will work. 1 - Vin is all you need because 1 - 0 => 1 and 1 - 1 => 0https://www.electronics-tutorial.net/analog-integrated-circuits/subtractordifference-amplifier/Note that when you wade through the math, R1 = R2 = Rf.
Turning a rotary knob with stepper motor - Page 1
Forum section: electronics / beginners

author: namlu
author_rank: Contributor
timestamp: July 12, 2014, 09:29:38 pm
content: Hello.I want to turn a rotary knob of a test equipment with a small stepper motor:https://www.google.co.il/search?q=rotary+knob&client=safari&hl=en&source=lnms&tbm=isch&sa=X&ei=HafBU_m_N6jG7Abu4ICADg&ved=0CAcQ_AUoAQIt is about 2 cm in diameter.My question is: how do I hold it with a stepper motor? How could it be attached?Any idea? Is there any known thing I can just put on top of a knob and attach it to the motor?Thank you.Sent from my iPhone using Tapatalk

author: BillWojo
author_rank: Regular Contributor
timestamp: July 12, 2014, 09:34:58 pm
content: Do a search for shaft couplers. You will need to know the diameter of each shaft.BillWojo

author: rob77
author_rank: Super Contributor
timestamp: July 12, 2014, 11:16:16 pm
content: +1don't even think about trying it without a shaft coupler ! you would kill the sensor (pot, encoder...) attached to the knob. the shaft coupler is a must to absorb any misalignment between the shafts. btw.. i'm talking about misalignment in orders is tenths of a degree or tenths of a millimeter off-center... so you have to "perfectly align" even when using a shaft coupler.

author: Stonent
author_rank: Super Contributor
timestamp: July 12, 2014, 11:19:50 pm
content: If the encoder clicks between positions you'll also need to make sure the stepper and encoder have the same number of clicks per rotation if you need to accurately set a position.Optical encoders like the ones used on ball mice do not click.

author: elliott
author_rank: Regular Contributor
timestamp: July 12, 2014, 11:24:11 pm
content: A piece of rubber hose works pretty well as a coupler for low torque applications.

author: namlu
author_rank: Contributor
timestamp: July 14, 2014, 09:11:49 pm
content: Hello guys.Thank you for your tips. After looking in ebay, I ordered rubber hose:http://www.ebay.com/itm/221234449225The size looks good and it actually may work.I will wait a bit with shaft couplers.Sent from my iPad using Tapatalk

author: DavidDLC
author_rank: Frequent Contributor
timestamp: July 14, 2014, 09:25:15 pm
content: Quote from: namlu on July 12, 2014, 09:29:38 pmI'm interested to know why do you want to do this. Can you explain ?David

author: namlu
author_rank: Contributor
timestamp: July 14, 2014, 11:19:20 pm
content: Hello.I need to go through the entire scale of an old test equipment, in order to debug a FPGA design. It takes about 10 minutes each time. I hope to do it automatically.Sent from my iPad using Tapatalk