hybridfree/eevblog-posts huggingface dataset:
Beginners DSO-138 assembly question - Page 1
Forum section: electronics / beginners

author: cepwin
author_rank: Unknown
timestamp: October 15, 2017, 08:35:54 pm
content: I'm putting together the DSO-138 and I ran into an issue. There are supposed to be 4 2-pin male jumper pins to install, two on the mail board, two on the LCD board. In the kit I instead found an 8 pin male jumper pin set. Are this somehow supposed to be broken up into 4 2-pin pieces?? Looking at the close up of the part it sure looks that way. If you are suppose to break up the 8-pin into 4-2pin pieces what is the best way to go about it?? I've attached a picture of the part in question

author: TK
author_rank: Super Contributor
timestamp: October 15, 2017, 08:40:09 pm
content: You can use a wire cutter to cut through the groves. If you don't have a wire cutter, then use a plier and hold 2 pins at a time to break or hold the other larger part, leave 2 pins out of the plier and apply force to break in pieces of 2 pins. If you need to cut them in larger pin counts, you can just use your fingers, but 1 or 2 pins is not that easy.

author: cepwin
author_rank: Unknown
timestamp: October 15, 2017, 09:01:49 pm
content: Thanks TK...that makes sense!

author: Brumby
author_rank: Unknown
timestamp: October 15, 2017, 10:28:18 pm
content: Before you start breaking anything, double check your requirements.My DSO138 has 2 x 2 pin, 1 x 3 pin and 1 x 4 pin headers - which adds up to the same 11 pins you have there.

author: cepwin
author_rank: Unknown
timestamp: October 17, 2017, 10:26:41 pm
content: Thanks and your're right and I misread thinking it was 2 1x3's....I ended up having two 1x1 rather than a 1 1x2 at the end...since there is only plastic between them and no connection I think it should still work ....I'm actually more concerned about the transistors

author: Brumby
author_rank: Unknown
timestamp: October 18, 2017, 01:45:42 am
content: Aside from being harder to install straight, two single pins will work just as well as a two pin piece - and once soldered properly, should not be a problem.The two 2 pin connections are primarily used as physical support for the "free" end of the display board. If I remember correctly, they do not have any electrical function.When installing a single row of pins, you have to be careful of vertical alignment in one direction - but when you have single pins, you have to worry about that for 360º. I would suggest that when you mount these 2 pins on the display board, you use the mating sockets on the main board to locate and align them. Justlightlyplug them together for this, as they are a very firm fit and if you want to check anything, the 40 pin connector is not easy to separate. (If you ever need to, be patient, take it gently and try to separate it evenly.)
beginners question about smu - Page 1
Forum section: electronics / beginners

author: jude_elec
author_rank: Newbie
timestamp: April 15, 2019, 08:00:41 am
content: HelloI am trying to understand about keithley 2450 smu and smu in general and write a python driver for itIn order to see how it works im connecting it once to a dmm and once to a source meterThe source meter im using is b2902a agilent smu, when im sourcing for example 1.5 v with a limit of 0.8 amper, the voltage that appears on the screen of the source much smaller(less than 1 mv) than what ive set, but on the keithley smu that im measuring with the voltage is 1.5v, what is the voltage that appears on the source?Ive read that it measures and source at the same time what does it mean? Does it mean that it switches between measure and source ?Ive done some reading but still don’t fully understand, because I have a few option on the instrument-voltmeter, ammeter, and 4 other measure and source options.thanks

author: HighVoltage
author_rank: Super Contributor
timestamp: April 15, 2019, 11:18:29 am
content: You really should read the manuals !!!You have set both the Keysight B2902A and the Keithley 2450 to source voltage and current.And then hook one up to the other? How?This is not a good setup !To start, just hook up a resistor (may be 1 Ohm) to the B2902A and apply the same voltage and current limit,to get a feeling for the instrument.Then do the same on the 2450 to get a feeling for this instrument.

author: Brad O
author_rank: Regular Contributor
timestamp: May 09, 2019, 07:16:53 pm
content: Did you figure this out? (you needed to press "Auto" on the B2902) I agree with HighVoltage's recommendation though, SMUs are very powerful but as a result they can seem more confusing than other instruments. Start with something simple before attaching instruments to each other.A point about hooking SMUs into each other. SMUs are generally designed to handle their own power envelope (look at the IV charts in the datasheets, see how they're symmetric?), so hooking two SMUs of the same type into each other is almost always fine. You have to be careful when connecting SMUs of different types to be sure one doesn't over-power and damage the other. In this case, the B2902A has the same max power output as the 2450 so the 2450shouldbe able to handle even any mistakes you make, but I would still avoid trying to force over 1A into the 2450.
Beginner's - removing diode - Page 1
Forum section: electronics / beginners

author: nForce
author_rank: Frequent Contributor
timestamp: October 03, 2019, 11:58:01 am
content: Hello, I have a simple question.Why do I have to remove a diode from the circuit if, I want to test if it's OK?Thanks.

author: xrunner
author_rank: Super Contributor
timestamp: October 03, 2019, 12:06:32 pm
content: It's possible that the stimulus applied to the diode in-circuit might be corrupted and flow around the diode because other components are connected to it. You can try to test it in-circuit but it might not give the correct reading.At most you could only de-solder one lead also and test like that.

author: Zero999
author_rank: Super Contributor
timestamp: October 03, 2019, 12:32:55 pm
content: Quote from: nForce on October 03, 2019, 11:58:01 amIt depends on the circuit. If the diode has other components in parallel with it, for example it's connected across the base-emitter junction of a BJT, it will read 0.6V in both directions, so will need to be removed from the circuit to be tested. If the diode is in series with the whole circuit, say for reverse polarity protection, it can be tested in circuit, as long as the connections to the power supply have been removed.

author: Kirill V.
author_rank: Regular Contributor
timestamp: October 03, 2019, 01:47:39 pm
content: It depends if you want to test the diode or the rest of the circuit.And if you are sure that the diode is not shunted, you can not remove it.

author: nForce
author_rank: Frequent Contributor
timestamp: October 05, 2019, 12:44:20 pm
content: What about other components: resistors, capacitors, inductors? I think, here you can leave the components in the circuit. Only if we plug out the power supply, right?

author: Zero999
author_rank: Super Contributor
timestamp: October 05, 2019, 04:16:52 pm
content: Quote from: blueskull on October 05, 2019, 02:22:56 pmThe ESR of capacitors can be quite often tested in circuit, because the capacitor should form the lowest impedance path at AC.

author: Zero999
author_rank: Super Contributor
timestamp: October 06, 2019, 08:54:29 am
content: Quote from: blueskull on October 05, 2019, 04:25:09 pmThat's true. I'm thinking more old school equipment such as linear power supplies, thermionic glassware and audio amplifiers.
Beginners Snap On Battery Charger Repair Project - Page 1
Forum section: electronics / beginners

author: Cactus
author_rank: Contributor
timestamp: January 04, 2019, 08:24:27 pm
content: For my next beginner's repair project I picked up a broken power tool battery charger. I have no idea of history other than it stopped working and the circumstances around that are unknown.On opening up the case, I saw that the mains +ve supply wire feeding the board had been nipped between the case top and bottom during assembly however it is not broken. I checked the board both sides and saw nothing obvious amiss other than a great big chunk missing from an opamp. For info I have attached some pics that lead to my questions.Is this usual to see this sort damage thing when an opamp fails and why would it fail this way?I have removed the opamp from the board but as it has no markings on it anymore how do I find out what to replace it with?I'm sure you will tell from my questions I am out of my comfort zone here so any thoughts members have would be really helpful.

author: ArthurDent
author_rank: Super Contributor
timestamp: January 04, 2019, 09:02:01 pm
content: The blown U1 is not an opamp but a SMPS controller chip that controls Q1 that is in series with the primary on the transformer covered in yellow. Q1 feeds a high frequency (50Khz?) signal to the transformer. There is probably more than just that chip blown.Here's a typical schematic that shows a similar chip in blue.https://img.bhs4.com/f8/6/f86356b388e38ed22898d1a074c700f5c88f92ba_large.jpg

author: Cactus
author_rank: Contributor
timestamp: January 04, 2019, 09:33:10 pm
content: Thanks Arthur, Im going to shuffle off for a bit to digest, research and learn. I will be back as soon as i get my head around things and understand bit more......... It looked a bit like an opamp
Beginners your not alone - Page 1
Forum section: electronics / beginners

author: M0BSW
author_rank: Frequent Contributor
timestamp: December 29, 2013, 04:21:11 pm
content: Some of us are still trying to get to grips with the search engine, it's a pity some of the more experienced members, were not a bit more understanding of this to beginner's isn't it

author: Simon
author_rank: Unknown
timestamp: December 29, 2013, 04:28:12 pm
content: Which beginner ?We have had a couple of complaints and yes "seasoned members" Should remember that there is a considerable variation in levels of experience of anyone on board be them a new user or someone who has been around for awhile.At the end of the day even I am not that experienced or knowledgeable and often ask basic questions it should not be assumed that post count or status on the forum equates to knowledge.On the other hand we have had some touchy people in the past, like somebody who got upset because he posted a schematic and got a debate rather than pats on the back when nobody asked for his schematic he just posted it because he felt like telling us all how to do it and got upset when he got an informed debate.
Beginning RF - Page 1
Forum section: electronics / beginners

author: Dan Moos
author_rank: Frequent Contributor
timestamp: November 25, 2016, 05:57:48 pm
content: I would like to start learning rf electronics, mostly because it is a branch of the hobby I haven't yet explored.Currently, I am reading the often recommended "RF circuit design", by Chris Bowick. I am enjoying it, and I'm pretty sure from a standpoint of acquiring knowledge on the matter, it has most of what I need.I also have "Build your own Transistor Radios" by Ronald Quan. It also seems like it will be useful, but doesn't start you off very simply.I'm looking for something that maybe starts with building simple crystal radios, explains the deficiencies, and slowly expands your knowledge, rather than springing fully functional super heterodyne receivers at you on chapter 2.My immediate goals in the field are simple. I'd be pleased as punch if I could understand the subject enough to build a set of walkie talkies similar to what I played with as a kid in the eighties. Or an AM receiver with which I could listen to the Seahawks on!.It seems in this world of Arduino, there is less interest in fundamental analog electronics, because I can't seem to find a good web resource for learning basic transistor radio design.Any resources to point to?

author: danadak
author_rank: Super Contributor
timestamp: November 26, 2016, 02:41:55 pm
content: Google "RF training", there is some free stuff out there. There are tons ofap notes, motorola early ones back in 70's/80's very good.The Radio Amateur Handbook has some receiver design training. The olderversions of handbook, 1990's would be less IC and more Transistor focused.Google "amateur radio handbook download", there are some free copies out there.https://archive.org/search.php?query=motorola%20rfRegards, Dana.

author: jonovid
author_rank: Super Contributor
timestamp: November 26, 2016, 04:22:15 pm
content: lots of radio projects here from 1970s to the 1990s ETI Magazine free pdf files.http://www.americanradiohistory.com/ETI_Magazine.htmtalking electronics has many radio projects too. see FM Bugs.http://www.talkingelectronics.com/te_interactive_index.htmlfor a cheap RF signal generator. be for starting receiving circuitsone transistor rf oscillator circuit then modulate it with audio from a greeting card Musical Box circuitif you live in a populated area. an old microwave oven case makes a good faraday cage for RF experiments.

author: danadak
author_rank: Super Contributor
timestamp: November 26, 2016, 04:47:23 pm
content: If you use Firefox and DownThemAll addon you can download all links on the pagewith essentially one click, eg. download all the magazine shown on the page.https://addons.mozilla.org/en-US/firefox/addon/downthemall/Also go to the home page, there are many more magazines for experimenters, etc..http://www.americanradiohistory.com/Regards, Dana.
Beginnings of a Lab - Page 1
Forum section: electronics / beginners

author: niftyfingers
author_rank: Newbie
timestamp: October 07, 2015, 10:00:01 am
content: Just wanted to post my progress online. There is much to be done

author: Cliff Matthews
author_rank: Unknown
timestamp: October 07, 2015, 10:57:19 am
content: How dare you! Clearly some of us envy, you are trying to Strat your stuff!

author: WN1X
author_rank: Unknown
timestamp: October 07, 2015, 12:21:42 pm
content: Your lab is too neat. Check out Dave Jones' lab (the live web cam) for the right way to do it

author: niftyfingers
author_rank: Newbie
timestamp: October 07, 2015, 02:06:43 pm
content: Quote from: Cliff Matthews on October 07, 2015, 10:57:19 amWell I did do 5 years of engineering school haha... to do work terms to get money to buy this stuff to learn how to do it the right way

author: Cliff Matthews
author_rank: Unknown
timestamp: October 07, 2015, 04:28:25 pm
content: Quote from: niftyfingers onTodayat 10:06:43 AM>Quote from: Cliff Matthews onTodayat 06:57:19 AMWell I did do 5 years of engineering school haha... to do work terms to get money to buy this stuff to learn how to do it the right wayIt might have been 4 years without those nicely distracting Stratocaster's.. Welcome and you may find novel stompbox ideas here too!

author: felixd
author_rank: Regular Contributor
timestamp: October 07, 2015, 05:19:26 pm
content: Ongoing process of cleaning my Labhttps://youtu.be/xhjkKhHQ0g8https://youtu.be/cPHZaZ6-hmo

author: niftyfingers
author_rank: Newbie
timestamp: October 13, 2015, 01:02:24 am
content: Got it cleaned up and can start doing some basic worksimple AC resistive divider to test my gear

author: xrunner
author_rank: Super Contributor
timestamp: October 13, 2015, 01:12:13 am
content: Nice strats.
Behaviour of an adjustable LDO if you leave of one ADJ resistor? - Page 1
Forum section: electronics / beginners

author: bryce1
author_rank: Regular Contributor
timestamp: March 14, 2015, 01:46:33 pm
content: Hi guys,as I dont have the part here with me, I can not test. Is there any defined behaviour for pulling the ADJ pin of an LDO completely low or to high (output level)?Take for example this part (TC1187):http://ww1.microchip.com/downloads/en/DeviceDoc/21353E.pdfMathematically, I guess without R2, R1 is unchanged. So no R2 means R2=1 :-D This would mean the the output is theoretically as high a voltage as possible, which should be Vin - 0.4V (worst case). No R1 on the other hand would really mean R1 = 0, so everything equals 0, even Vout.But what happens really? I guess the formula is not meant for these edge cases.Sorry for asking, I'd much rather try it.Thanks!Bryce

author: ConKbot
author_rank: Super Contributor
timestamp: March 14, 2015, 02:06:55 pm
content: No resistor is equal to infinity, not 0Imagine no resistor being equal the few gigaohms of resistance the PCB would provide.So as R2 goes to infinity, Vout = Vref * (R1/infinity +1) is Vref * 1, or it just outputs its reference voltage (1.2V)As R1 goes to infinity, the it will be Vout = Vref * (infinity/R2 + 1). But obviously it cant supply infinite voltage, so it just drops whatever its minimum dropout voltage is from the input (i.e. Vin- Vdo = Vout) . From the datasheet, talking about Vdo "typically 85 mV(TC1070), 180 mV (TC1071) and 270 mV (TC1187) at full load"The same goes for if you let R2 be zero. Obviously that makes the math blow up with the divide by 0, but if you call it 0.001 ohms (the lead will have resistance after all, and the solder joint, so close enough :p ) You get the same result as an open R1.If it helps you make sense of it, an LDO is an op-amp with a reference voltage (1.2V) applied internally to the + input, and the ADJ pin is the - input. On fixed voltage regulators the feedback pin has the feedback resistor divider built in internally.

author: bryce1
author_rank: Regular Contributor
timestamp: March 16, 2015, 04:36:43 am
content: Very helpful answer, thank you!

author: free_electron
author_rank: Super Contributor
timestamp: March 16, 2015, 04:47:31 am
content: Unknown.It depends on the regulator.There are regulators that can detect this and shut off their output.Others will drive vout equal to vinIf the bottom resistor is missing , some will drive vout to vref.It depends on how the regulator works internally.
Behaviour of DC and RY on a shugart interface - Page 1
Forum section: electronics / beginners

author: gkmaia
author_rank: Frequent Contributor
timestamp: May 04, 2020, 09:43:36 am
content: Im trying to learn more about how a shugart interface works.Does the disk change signal controls if a disk has been inserted and shorted the switch that detects if a disk is inside the drive?What does the ready, in use and direction selection signals covers then?
Behringer Europort EPA300 burning fuse  - Page 1
Forum section: electronics / beginners

author: landofshqiponja
author_rank: Newbie
timestamp: May 31, 2024, 01:42:08 pm
content: hello all!I have a Behringer EPA300 (europort) that the second it gets powered burns the fuse.Someone has repaired the system previously, unfortunately I don't remember what the problem was or what was repaired.The repair man I took it to now to figure out why the fuse keeps burning told me that without a schematic of the board, he cannot fix it as someone has previously repaired it in the wrong way.Does anyone know where I can download a schematic of the motherboard?Thanks so much!

author: darkspr1te
author_rank: Frequent Contributor
timestamp: June 01, 2024, 08:53:27 am
content: I've repaired quite a few behringer products so some tips.if primary fuse blowing then issue is in psu side of the system ,see the manual for epa 900 found here :-https://music-electronics-forum.com/forum/schematic-requests/42466-please-please-help-me-with-behringer-smpsu-19-power-supplyand here for epa300 i think (dont have one, cant confirm)https://www.electronica-pt.com/esquema/audio/behringer-audio/behriner-smpsu18-27413/it's a SMPS thats also used in the XENYX series mixers too but board layout is different i would guess.i often seen the psu to be on a connector so hope the techie did the first rule and check voltages.it is common for the IRF460 in the PSU to fail ,dont forget the isolator when replaced.check all caps for looseness , as a music equipment manufacturer they tend to not glue blob the large caps nor do they often glue connectors.input bridge rectifier also fails often as the designers cramp it in close to the heatsinks , in some units i've had multiple fails so we ended up remote mounting the diode pack and bolted to to metal (electrically isolated but heat sinked)cap failures from heat/drying up and bad solder joints also common, so if you hack crackles and pops then check the board for swelled caps or leakage, and also while running tap the equipment to test for the poor solder joint (very very common on portable tech)well good luckdarkspr1te
behringer x32 motor faders - decode the pcb  - Page 1
Forum section: electronics / beginners

author: darkspr1te
author_rank: Frequent Contributor
timestamp: June 11, 2025, 05:55:00 pm
content: So a long story short I recently saw a video online on using a behringer x32 motor fader in a midi fighter like situ and it stirred up a desire to build my own which i have been wanting to do for a while, my current setup is a Garage Band controller from M-Audio via midi out->esp32->art-net etc for my school hall lighting rig, it's position agnostic, works with QLCPlus+ and virtualdj either via artnet/OSL or usb-midi.so now i have 5 x32 faders and 5 L9110 h bridges, getting the motor running and detecting position was easy enough but my issue now is some docs say the x32 slider is cap sensitive and other say nothing ,i took one apart to see if there was any clues but am only staring and seeing nothing in my trade craft i know. so i ask anyone to have a look at the disassembled item and schematic from behringer to see if they can tell me is it touch sensitive ?the diagram/schematic included shows h-bridge at the top and what 'i' think is the connection to the faders 8 pins (not motor)for full x32 schematic google 'Behringer-X32-mix-sm' for those that want more info i may have missed.darkspr1te

author: themadhippy
author_rank: Super Contributor
timestamp: June 11, 2025, 07:05:27 pm
content: Don't recall the x32 having touch sensitive faders ,although even on the m32 and pro2 the so called touch sensitive controls did nothing whatever way i grabbed em so i could be wrong,

author: darkspr1te
author_rank: Frequent Contributor
timestamp: June 11, 2025, 08:19:34 pm
content: Quote from: themadhippy onTodayat 09:05:27 pmAs far as i know the touch is only there to disable any motor drive only, so you dont face "feed back/force" or do in case of Marks decks , which are both audio/visual decks so they added force feedback so when you tweak a light show you dont overshoot easily and have to rewind record again the light positions. i've used a few and they are magic

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 12, 2025, 06:53:12 am
content: I see no indication of capacitive touch detection capability in the disassembled parts, nor the schematic part you supplied.A simple way to detect if the knob is held by a user when the motor is running is to watch the change of the potentiometer reading. When it is not what is expected, just stop the motor.
Behzad Razavi Electronic Circuits 1 Video Tutorials - Page 1
Forum section: electronics / beginners

author: ramin110
author_rank: Contributor
timestamp: March 02, 2018, 10:00:56 am
content: American-Iranian professor Behzad Razavi free electronics video cources:https://www.youtube.com/channel/UClH7sqfyOoJ3jpeAqWZX7WA/videos

author: sibeen
author_rank: Frequent Contributor
timestamp: March 02, 2018, 10:13:20 am
content: I've come across his lectures before and they are very well done.

author: Wimberleytech
author_rank: Super Contributor
timestamp: March 02, 2018, 11:37:06 am
content: I have several of his books but was not aware of the lecture series. Thanks for sharing.

author: bmdaly
author_rank: Contributor
timestamp: March 02, 2018, 12:09:54 pm
content: I've watched all 45 lectures - each one a real "page-turner", if I can use that metaphor about videos. In the odd case where the material might seem a little boring, he cleverly cuts to real-world uses to keep the audience engaged.Can't recommend these highly enough for anyone starting out in solid state electronics, with an interest in gaining an understanding of what's going on under the hood and learning simple analysis techniques. The lectures cover the following areas:1. Diodes - PN junction2. BJTs3. MOSFETS4. Intro to OpAmpsDon't be put off by the fact that these are aimed at a 3rd level audience, as he avoids use of complex maths or physics.Would love to find more of his course lectures structured as these are (there appear to be some other of his lectures online, but not well structured into stand-alone courses like these ones).The only prerequisite is that you should be familiar with basic circuit analysis of linear circuits (Kirchhoff's laws, superposition theorem etc.).
BEMF zero crossing in BLDC motors? - Page 1
Forum section: electronics / beginners

author: ifonlyeverything
author_rank: Regular Contributor
timestamp: July 24, 2022, 02:29:57 am
content: From my understanding (which may be completely wrong), BEMF of a brushless DC motor is AC in nature i.e. it swings negative to positive. One common way of sensing zero crossing is forming a virtual ground between all 3 phases and then measuring BEMF of the undriven (floating) phase relative to this virtual ground. I've seen several schematics showing this, discrete implementations for hobbyists like to use the LM339. One such example is herehttps://simple-circuit.com/wp-content/uploads/2018/03/pic18f4550-sensorless-bldc-motor-controller-bemf-circuit.pngI've also seen motor controller implementations that measure phase voltage with an ADC.How is this possible when negative voltage inputs typically damages comparator and ADC inputs?LM339, for example, does not like negative inputs perhttps://www.ti.com/lit/an/snoaa35b/snoaa35b.pdand the ADCs on my STM32 have an absolute minimum of -0.3V relative to ground.

author: f36
author_rank: Contributor
timestamp: July 28, 2022, 04:55:51 am
content: The BEMF on each phase goes positive and negative with respect to the virtual ground (that you're trying to make with the resistor network),notyour circuit ground, so your comparator or ADCs will never see a negative voltage (ignoring any effects of parasitics in the circuit construction).The voltage on each phase will be pinned to ground or your bus voltage when one of the MOSFETs for the phase is on, and the BEMF will be between those two extremes when both MOSFETs are off. If the voltage on one phase tried for whatever reason to go above or below those limits, the body diodes on the FETs would start conducting and clamp the voltage.If you probe the phase outputs to your motor while it's running with the oscilloscope ground connected to your circuit ground, you'll see something like this. Note the position of the waveform relative to the baseline.
Ben eater 8-bit computer kit. - Page 1
Forum section: electronics / beginners

author: mjn2024
author_rank: Contributor
timestamp: July 15, 2021, 06:34:38 pm
content: Is the Ben eater 8-bit computer kit a good place to start for beginners who have experience with Arduino but want to move more towards regular electronics.

author: dcbrown73
author_rank: Regular Contributor
timestamp: July 15, 2021, 07:55:40 pm
content: I would think that it depends.Understanding basic electricity and simple circuits would be a good first step. I would think that kit would be more geared towards learning how computers work after you understand the basics.Obviously, I have no idea where you are at knowledge-wise. Ohms law, transistors, op-amps, 555 timers, etc. Once you see how the individual things work. Then put them together to build something bigger.It's like when troubleshooting devices. You break down the different areas one by one until you find the area causing the issue. (power supply, mid-circuit, output, etc)So, ask yourself what your current knowledge level is and go from there.That said, if you want to jump to building an 8-bit computer. No harm no foul. Go for it.

author: esepecesito
author_rank: Regular Contributor
timestamp: July 30, 2021, 05:14:21 pm
content: I was like 10 when I started myself building something like that with a z80. I took some years... and some smoked chips. At that time there was no internet. I had to make photocopies in the library of datasheets...It cannot be worst than that!Go for it! no doubt. Think it wiil not be as easy as seen in the videos, but you will make it!
Bench HV power supply voltage reduction - Page 1
Forum section: electronics / beginners

author: stellarsoundlabs
author_rank: Newbie
timestamp: November 19, 2021, 03:21:02 pm
content: Hi, I'd like to make a small breakout box along the lines ofthat will make it more convenient to check leakage of capacitors rated at up to 500V or so. (That design is quite different that what I need--but the intention of what I want to do is the same). Inputs would come from my HV bench power supply and outputs to an analog VOM and/or neon bulb as shown in the video.Using a bench supply as I am, and not the transformer approach in the video, is it feasible to add a switch to quickly drop from the full voltage coming in (which may be 0 to 500V let's say) to half and quarter voltage? this would save time in adjusting the power supply itself to charge/check caps at various voltage. I would add switch snubbers as needed to protect the switch.Since the input voltage is changeable, I'm not sure if transformers, high power resistors, or voltage regulators are indicated here. What is the best solution? Thanks for your patience with this question.
bench power supply - Page 1
Forum section: electronics / beginners

author: gmw666
author_rank: Newbie
timestamp: January 11, 2020, 03:43:13 pm
content: Hi alli am a complete newbie to electronics and have a question. I built a bench power supply (modular) and it works fine, however although it is cc cv there is no indicator led to tell me when it has gone in to cc mode. is it possible to add one and if so what would be involved. the unit consists of a 240v AC to 36V DC unit and a 36v dc to dc buck converter with a smaller buck converter 2A to supply the meter and fan.any help or advice would be much appreciatedGraeme

author: aheid
author_rank: Regular Contributor
timestamp: January 11, 2020, 04:03:09 pm
content: You've not told us how the thing works, so how can we tell you how to modify it?Show us some schematics of your circuit.

author: gmw666
author_rank: Newbie
timestamp: January 12, 2020, 09:00:34 am
content: hi Aheidsorry as i said i am new to this as i explained it is a modular unit so the design is not mine i found it on utube and followed the video on how to make it i have attached some pictures so you can see what i have done what i am trying to do is wire in an LED to let me know when the unit has gone in to CC mode hope the pics helpthanksGraeme

author: xavier60
author_rank: Super Contributor
timestamp: January 12, 2020, 09:15:26 am
content: CC indication needs to come from the Buck regulator's control circuitry. To do it with minimum risk, a schematic is needed.Look for pins or unoccupied holes that might be for an optional CC LED.

author: gmw666
author_rank: Newbie
timestamp: January 12, 2020, 09:16:26 am
content: here are a few close ups of the modules i used purchased from ebay of courseThe buck module is marked as an SZBK07 and the control chip on the back is an LM25116 i have tried to find a schematic for the module but the closest i got was a schematic for the control chip from the datasheet

author: xavier60
author_rank: Super Contributor
timestamp: January 12, 2020, 09:35:55 am
content: The 5 pin IC is likely to be the CS op-amp. Only if you are confident that you can take measurements without any probe slips, look for a pin that that has a large voltage swing as the regulator goes in and out of CC mode. Your probes need to be needle sharp. I use Silver Steel probes.

author: gmw666
author_rank: Newbie
timestamp: January 12, 2020, 10:02:06 am
content: I believe you are spot on the 5 pin IC is marked as an A63A which appears to be an LM321 op amp Am i looking for an increase in voltage when it goes in to cc mod eand a drop when it resorts back to cv mode

author: xavier60
author_rank: Super Contributor
timestamp: January 12, 2020, 10:07:44 am
content: Just look for a large voltage swing for now.

author: gmw666
author_rank: Newbie
timestamp: January 12, 2020, 10:16:03 am
content: ok will doi will get back to you with what i find. Also for info the small 3 pin IC above the op amp is a 5V regulator supplying the op amp and the inverting input of the op amp appears to be connected to the centre pin of the cc pot
Bench power supply - Page 1
Forum section: electronics / beginners

author: Suggy
author_rank: Newbie
timestamp: January 16, 2015, 03:11:29 pm
content: HI all, I have a dual channel power supply that supports series and parallel connections. Power supply maxes out at 31v and 5amp per channel am I wright in understanding that running in parallel mode I get 31v 10amp?and in series mode I get 62v 5amps?

author: KJDS
author_rank: Super Contributor
timestamp: January 16, 2015, 03:49:27 pm
content: You are right
Bench PSU functionality help needed.  - Page 1
Forum section: electronics / beginners

author: peps1
author_rank: Regular Contributor
timestamp: December 05, 2013, 01:04:05 am
content: Hey guys, the user manual for my dual bench PSU only has calibration information in it, so was wondering if I could get some advice on some functionality and abbreviations?The Buttons are: OCP, OVP, SER/INDEP, PARA/INDEPIts a Tenma 72-10495 (2 channel 0-32V 5A, 0-32V 5A)http://uk.farnell.com/tenma/72-10495/psu-bench-dual-5a-30v/dp/2251947

author: Fluxed Matter
author_rank: Regular Contributor
timestamp: December 05, 2013, 01:26:40 am
content: These abbreviations are common for power supplies and meanings/functions are:OCP = Over Current ProtectionOVP = Over Voltage ProtectionSER/INDEP = Both outputs can be connected in serial or independentPARA/INDEP = Both outputs can be connected in parallel or independentHope this helps.

author: peps1
author_rank: Regular Contributor
timestamp: December 05, 2013, 01:30:31 am
content: Thank you!Why is there the option to disable OCP/OVP?

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 05, 2013, 01:48:07 am
content: Quote from: peps1 on December 05, 2013, 01:30:31 amThere are times where you don't care about how much current something under testing pulls, just that it doesn't exceed the set voltage. Similarly, there are times where you worry more about the current through a system than a voltage that is too high.Sent from my EVO using Tapatalk

author: peps1
author_rank: Regular Contributor
timestamp: December 05, 2013, 01:55:37 am
content: OK, I get that for OCP, i dial in the max amps I want to be pulled and can bypass this with the button............But, how does that work with voltage? how could something pull more voltage then I have dialed in on the PSU?

author: Bored@Work
author_rank: Super Contributor
timestamp: December 05, 2013, 01:56:37 am
content: A rebadged Korad. A kind of manual is athttp://sra-solder.com/shopimages/products/instructions/KARAD%20user%20manual-multiple%20channel%20power%20supplies.pdf

author: peps1
author_rank: Regular Contributor
timestamp: December 05, 2013, 01:58:32 am
content: Quote from: Bored@Work on December 05, 2013, 01:56:37 amThank you

author: ConKbot
author_rank: Super Contributor
timestamp: December 05, 2013, 01:33:26 pm
content: Quote from: peps1 on December 05, 2013, 01:55:37 amThe only time Ive tripped OVP on a power supply when I was running a class D amplifier board with one, and we hit resonance on the seat shaker we were driving with the amp board. The power supply cant sink any current, but driving the highly inductive load, current was coming back into the power supply, and the voltage was shooting up. I added a load resistor drawing ~2A on each rail, and it started behaving.

author: peps1
author_rank: Regular Contributor
timestamp: December 05, 2013, 01:40:56 pm
content: Thanks for that ConKbot!Here to learn, so really appreciate you breaking that down for me with a real world example.
Bench PSU options?  - Page 1
Forum section: electronics / beginners

author: crashtest84
author_rank: Newbie
timestamp: February 22, 2018, 08:23:38 am
content: I'm taking an EE class this summer as a distance course and we're required to buy an Elenco XP581. I'd rather make sure to get a PSU that I'll want to use long after the course is over and I've seen positive reviews on the KORAD KA3305D. Any suggestions on what might make one better than the other? Other options?

author: Shock
author_rank: Super Contributor
timestamp: February 22, 2018, 11:12:49 am
content: The Elenco is a quad supply but very limited features and three of the outputs fixed.The Korad is a triple supply and looks digitally controlled with one output fixed. It also seems to have parallel and series mode plus should be able to be configured for combined positive and negative voltages. There is a usb and serial interface on the rear. So quite a few more features, and from reading seriously small manual the current can be set and also configured to turn off the output if a specific current is exceeded.You're only really going to get caught out if you're asked to supply +5 +12 -12 and some other voltage all at once. I would say if you have a spare PC power supply handy and the Korad you could account for most situations.

author: grifftech
author_rank: Frequent Contributor
timestamp: February 22, 2018, 03:49:43 pm
content: how about this?

author: mikerj
author_rank: Super Contributor
timestamp: February 22, 2018, 04:09:44 pm
content: You really ought to sleeve all those soldered connections. It currently looks like a loosely assembled pile of future short circuits.

author: crashtest84
author_rank: Newbie
timestamp: February 23, 2018, 02:14:21 am
content: Awesome. I do have one or two PC power supplies laying around somewhere so that shouldn't be a problem. Thanks!
Bench supply remote sense - Page 1
Forum section: electronics / beginners

author: ratio
author_rank: Regular Contributor
timestamp: April 12, 2017, 10:43:06 pm
content: Why would one need a remote sense on a benchtop power supply?

author: langwadt
author_rank: Super Contributor
timestamp: April 12, 2017, 11:11:38 pm
content: Remote sense compensate for the current dependent voltage drop on the wires.With thick wires, low currents and no need for super accuracy you don't need itI'm sure I remember Dave had a video that nicely illustrated it but I can't find it

author: ratio
author_rank: Regular Contributor
timestamp: April 13, 2017, 12:10:59 am
content: Quote from: langwadt on April 12, 2017, 11:11:38 pmThe only use I could come up with on my own was to compensate for undersized leads. I'd imagine there must be some other uses, but I just don't know what they might be.

author: sleemanj
author_rank: Super Contributor
timestamp: April 13, 2017, 05:58:25 am
content: Quote from: ratio on April 13, 2017, 12:10:59 amWhen you want to deliver a constant voltage to the device under test (DUT) under various load conditions.Very common example is testing dc-dc converter efficiency, you want to test their characteristic at different current draws, but in order to have useful data you need to ensure that the input voltage is the same for each series of tests (ie you want to test input yV, output zV at various different currents so you can see how the efficiency or other characteristics vary with current). If you don't have a remote sense power supply, you have to measure and tweak the voltage each time.

author: BravoV
author_rank: Super Contributor
timestamp: April 13, 2017, 06:59:53 am
content: Quote from: sleemanj on April 13, 2017, 05:58:25 amAdded for completeness sake.(highlighted in red)

author: dimkasta
author_rank: Regular Contributor
timestamp: April 13, 2017, 08:05:46 am
content: for quick testing and prototyping, It can also eliminate or at least moderate the effects of incomplete or non-finalized local decoupling.

author: Avacee
author_rank: Unknown
timestamp: April 13, 2017, 08:49:22 am
content: Quote from: langwadt on April 12, 2017, 11:11:38 pmOP: This video demonstrates how with the voltage drop from the Power Supply to the Device Under Test the actual voltage at the DUT is not what you think it is.It also shows how using the remote sense terminals shows the actual voltage at the DUT.If you see the same YouTube image as I do below you can see one Multimeter reads 4.691V yet the Power Supply reads 5.000V.There's a drop of 0.309V across the wires. The Remote Sense would let the PSU set itself to have 5V at the DUT.Dave later has to set more than 5V on his PSU to get 5V at the DUT.
Bench top DC power supply recommendation (10 mV resolution, single output) - Page 1
Forum section: electronics / beginners

author: dpinho
author_rank: Newbie
timestamp: August 30, 2015, 04:09:06 pm
content: Hi,Can anyone recommend a good DC bench top power supply in the range of 50-75 GBP?I've been looking into chinese ones (YIHUA, Mastech) but not really sure.Tks,David

author: rolycat
author_rank: Super Contributor
timestamp: August 30, 2015, 04:49:18 pm
content: TheTenma 72-10480isn't bad, and can be had for around £50. It's a rebranded Korad KA3005D.TopLoser on the forum has returns for sale at around half price from time to time. May be UK only, though.

author: dpinho
author_rank: Newbie
timestamp: August 30, 2015, 09:23:07 pm
content: Tks,What about the YH-305DA (http://www.ebay.co.uk/itm/YH-305DA-VARIABLE-REGULATED-DC-POWER-SUPPLY-FOR-LAB-30V-5AUK-BLUE-LED-DISPLAY-/181680649017)?I'm having trouble actually comparing the output regulation:The YIHUA has a Load Stability: 0.01% + 3mV and a Setting Accuracy: 0.1%The Tenma quotes Setup Accuracy: <0.05% +20 mV and Read back Accuracy: 10 mVPlus the YIHUA is an extra 20 15 GBP. And it has a weird pot f without knob for current adjustment...

author: rolycat
author_rank: Super Contributor
timestamp: August 30, 2015, 09:57:15 pm
content: I don't have personal experience of either PSU, but based on threads likethis, I wouldn't trust the Yihua to meet its specs. Nor does it inspire confidence that the pictured item in your eBay link has the "CURRENT ADJ" label printed upside-downThe Korad/Tenma unit is a fairly popular choice with other forum members. There's a discussionhere. The programmable version is available from a Germanvendorfor just 89 Euros, which seems like a good deal.
Benchtop supply replacement cables - Page 1
Forum section: electronics / beginners

author: Jay112
author_rank: Regular Contributor
timestamp: May 14, 2016, 02:25:05 pm
content: I have one of these cheap Chinese benchtop power supplies (http://www.ebay.com/itm/15V-1A-DC-Power-Supply-Precision-Variable-Adjustable-Regulated-Cell-Phone-Repair-/321105942440), which I know isn't ideal.So far it's working well for my purposes, with the only problem being that the probe connectors keep falling out of the unit, since there doesn't seem to be a good connection there.I remember vaguely that a few months ago I had read on this forum that it's common to replace the cables on those cheap supplies, and that the new cables fit better into the sockets. I tried searching for that information but couldn't find it.Do you have any suggestions for replacement cables for a power supply?

author: Ian.M
author_rank: Super Contributor
timestamp: May 14, 2016, 02:35:40 pm
content: They look like screw down terminals with a central 4mm socket. If its critical to avoid accidental disconnections, use crimp on fork terminals on whatever leads you make up. Alternatively most unshielded banana plugs should be fine.The probe leads illustrated have half-length safety shields and aren't compatible with those terminals unless you trim the shields off and even then may be too short for reliable retention - check the socket depth with a matchstick and compare to the plug pin length before you butcher them. (Not that you want probe tipped leads on a bench PSU - croc clip ended ones are far more practical, or make dedicated leads with fork terminals for each project)
Benjamin Franklin, conducted Kite Experiment? - Page 1
Forum section: electronics / beginners

author: 1Mperios
author_rank: Newbie
timestamp: December 23, 2013, 10:32:25 am
content: Hello all,did Ben Franklin actually conduct the Kite Experiment? In a documentary here:http://youtu.be/uhgo9fAlAQQit claims he proposed it but never conducted it, the French later conducted his experiment and confirmed his theory.Regards
BenQ W1070 projector: Help with screen position and angle - Page 1
Forum section: electronics / beginners

author: TRAPTRAP
author_rank: Regular Contributor
timestamp: August 10, 2015, 08:39:41 pm
content: I'm trying to set up my BenQ W1070 projector from the corner of the room, because I can't position it on the opposite wall from where I want the screen. But, because of the way it's positioned, the image looks crooked, and isn't a perfect square/rectangle. Is there some setting or something that I can use to adjust the screen that will fix this?Also, I'm trying to adjust the position of the screen (not the projector itself) but the option called "position" in the "display" tab of the menu is grayed out, and I can't select it. What can I do about this?

author: dacman
author_rank: Frequent Contributor
timestamp: August 10, 2015, 11:11:13 pm
content: According to the W1070 specifications, it has neither horizontal keystone nor lens shift (only vertical for both). The projector needs to be placed on the vertical center-line. (Note that some manufacturers use Left/Right or L/R vice Horizontal.)As far as position goes, it is not something that can be done from the remote. There is a manually operated lever on the unit that can lens shift it from 110% to 130% in the vertical only (which means that the lens will point 10% to 30% below the bottom of the image, or above it if mounted upside down).
Beryllia - Page 1
Forum section: electronics / beginners

author: Daxxin
author_rank: Regular Contributor
timestamp: November 01, 2017, 06:16:30 pm
content: How safe is open this module ? there is berillium chemical inside ? i need to check some transistors inside

author: dmills
author_rank: Super Contributor
timestamp: November 01, 2017, 06:22:32 pm
content: Just do not break the power transistors (Usually BeO is used as the insulator between the die and the mounting base), not generally a problem unless you start crushing or grinding the power sand.The stuff is genuinely nasty, and you really do not want it getting into an open wound or your lungs, but as long as it is contained in the transistors it is not a problem.Regards, Dan.

author: daqq
author_rank: Super Contributor
timestamp: November 01, 2017, 06:23:00 pm
content: There is probably some beryllium based ceramic inside - popular for HF stuff.To the best of my knowledge: The ceramic should be stable and as such safe, but if it cracks, chips or otherwise produces particles, the particles can be dangerous when inhaled/ingested. As such you should be careful when disassembling the module to avoid scratching or breaking of the ceramics.See:https://en.wikipedia.org/wiki/Beryllium_oxide#Safety

author: Kire Pûdsje
author_rank: Regular Contributor
timestamp: November 01, 2017, 07:39:32 pm
content: BeO is typically used in RF power components, such as transistors and loads/attenuators.Just do not break these ones, otherwise, nothing to worry about.