hybridfree/eevblog-posts huggingface dataset:
Device tester for Photocoupler - Page 1
Forum section: electronics / beginners

author: firas
author_rank: Contributor
timestamp: July 01, 2019, 05:48:19 pm
content: Hello. Is there a tester device to check photocoupler (moc3023.TLP250.TLP3023.IL420.4n35.....etc)

author: Zero999
author_rank: Super Contributor
timestamp: July 01, 2019, 07:40:56 pm
content: As far as I'm aware, there's no off the shelf device to test all of those opto-couplers, but it should be trivial to build a test circuit.

author: Stray Electron
author_rank: Super Contributor
timestamp: July 01, 2019, 07:56:14 pm
content: I'm not familiar with those numbers (and I'm not going to take time to look them up) but I've seen Tektronix curve tracers used to test opto-couplers. I think Tektronix covered testing them in either one of the user's manuals for one of their curve tracers (probably the 575 manual) or in one of the series of small books that they printed regarding different types of test equipment and electronic measurements.

author: Zero999
author_rank: Super Contributor
timestamp: July 01, 2019, 08:26:33 pm
content: Quote from: Stray Electron on July 01, 2019, 07:56:14 pmThe original poster listed a wide range of opto-couplers with: basic BJT, TRIAC and MOSFET driver outputs. I've never used a curve tracer, but I imagine it's most suited to diode and BJT output varieties.

author: Jwillis
author_rank: Super Contributor
timestamp: July 02, 2019, 03:17:08 am
content: There are IC testers available for checking opto couplers for around 30 dollars.I can`t tell you how good they are but what do you want for 30 bucks.The IC tester demonstrated is at around 17:55. Check it out.

author: firas
author_rank: Contributor
timestamp: July 02, 2019, 05:06:52 pm
content: This device does not work

author: Seekonk
author_rank: Super Contributor
timestamp: July 02, 2019, 05:51:37 pm
content: I should try this with my cheap $10 component tester. Wire up a socket so the LED looks like a base (1). The other end of the LED (2) ties to emitter (3). Collector (4) is the collector. It will look like a funky transistor with Vf and some gain.

author: wraper
author_rank: Unknown
timestamp: July 02, 2019, 06:01:36 pm
content: Quote from: Seekonk on July 02, 2019, 05:51:37 pmIt can work as sort of BJT if it has transistor output but very poor gain, usually below 1.

author: David Hess
author_rank: Super Contributor
timestamp: July 03, 2019, 03:19:48 am
content: Quote from: Stray Electron on July 01, 2019, 07:56:14 pmIt would not be difficult to use any bipolar transistor curve tracer to test an transistor optocoupler. Wire the cathode to the emitter/source and you have a three pin bipolar transistor equivalent with a current gain from about 0.1 to 1 depending on the current transfer ratio.
DFplayer audio question - Page 1
Forum section: electronics / beginners

author: skerdzius
author_rank: Contributor
timestamp: April 27, 2015, 08:18:18 am
content: I have DFplayer mini mp3 audio player powered from 5V supply. I output sound via DAC_R, DAC_l pins.And it works like this1. DFplayer connected directly to speakers plays audio just fine.2. DFplayer connected to these exact speakers just with 20 meters audio cable this time. Doesn't play a sound. (why?)3. I connect my phone to these speakers with 20 meters audio cable and it works and plays fine.Can you give me any suggestions why 2. doesn't work?
DFPLayer Mini - Page 1
Forum section: electronics / beginners

author: PerranOak
author_rank: Frequent Contributor
timestamp: January 10, 2020, 08:55:13 pm
content: I've bought a DFPLayer Mini and it seems to work well on speaker.However, on earphones it has an audible 38.7Hz hum in "quiet bits".Any ideas how I can investigate this please?Cheers.
DI-770 Series - Page 1
Forum section: electronics / beginners

author: Dat Tran
author_rank: Contributor
timestamp: August 17, 2015, 09:13:36 am
content: I have a DATAQ product. It is DI-770 Series. But i can't find it's driver. Every starting, i alway see a notification as below:any ideas, i needed, Thank you so much!

author: Dat Tran
author_rank: Contributor
timestamp: August 17, 2015, 02:17:25 pm
content: Any Ideas for me, help me

author: Dat Tran
author_rank: Contributor
timestamp: August 17, 2015, 04:30:32 pm
content: Hi, Dave. Can you help me?
DIA60 as a HAP? - Page 1
Forum section: electronics / beginners

author: Noidzoid
author_rank: Regular Contributor
timestamp: July 12, 2018, 11:24:50 am
content: I have a DIA60 desoldering tool connected to my Xytronic 968 which I intend to buy new nozzles for as the one it came with is bad.Thinking at first I would have no further use for the old nozzle, I thought again.I have been trying to find a HAP60 hot air pencil to connect to the 968 to no avail and although I can find a HAP80 quite easily here in the UK I can not be sure it is suitable for my machine.As I am just a budding hobbyist, switching things around every now and then is not a problem, I have no deadlines or time constraints.Is there any reason why I shouldn't remove the filters from the DIA60 desoldering tool, connect the vacuum tube on the 968 to the HAP outlet and use the DIA60 with the old nozzle dry as a temporary HAP60?

author: stj
author_rank: Super Contributor
timestamp: July 12, 2018, 05:40:50 pm
content: one thing i can see is the fact that your monitoring the temperature of the head and not the air.that's also a very focussed airstream - not sure how you use it without blowing bits off the board.

author: Noidzoid
author_rank: Regular Contributor
timestamp: July 12, 2018, 09:48:29 pm
content: Yes I see what you mean............
Diagnosing a 12V 5A power supply - Page 1
Forum section: electronics / beginners

author: varias
author_rank: Newbie
timestamp: September 23, 2024, 01:05:47 pm
content: Hello, everyone. I've been using this 12V 5A power supply for a few years. Today, it fell to the floor with a good whack. Sadly, it stopped working. I would like pointers to where to start looking for what could be wrong. I've opened it and there's nothing indicative of a fault except a plasticky, chemical smell. I have a multimeter to probe around. Thanks for any help.

author: Phil1977
author_rank: Frequent Contributor
timestamp: September 23, 2024, 01:27:41 pm
content: In many cases a whack like this cracks a PCB trace around the solder joint of some heavy component or a mechanically stressed part like the AC connector.These cracks can be so fine that they are not recognizable in your pictures. You should carefully inspect with magnifiers or take the multimeter to measure continuity. A first step would be testing continuity from the AC connector to the bridge rectifier, from the rectifier to the buffer cap, etc. If you can't find anything on the primary side, you can try the same from the DC output on the secondary site.PS: Please discharge the primary buffer capacitor before doing any tests. If you don't know what that means, then ask someone for help. The charge in this cap can be dangerous.

author: Manul
author_rank: Super Contributor
timestamp: September 23, 2024, 03:48:11 pm
content: Appart from what Phil1977 said, take a multimeter and check all SMD ceramic capacitors on the bottom side for shorts. Possibly under the white goo too. Ceramic capacitors often crack and get short circuited, they hate flexing and impacts.

author: floobydust
author_rank: Super Contributor
timestamp: September 23, 2024, 06:35:56 pm
content: This is a cheap power supply. Quite a few parts deleted to save money.Danger- there are no bleeder resistors R1-R4 so the main filter capacitor can bite. Always make sure it's discharged before going in.Usually the electrolytic capacitors fail, the 10uF 50V part is critical. Check the two other green ones, they are undersized and would not last long.Solder joint looks fractured on the jumper.
diagnosing and modifying timer circuit with op-amps - Page 1
Forum section: electronics / beginners

author: Jbates58
author_rank: Regular Contributor
timestamp: January 02, 2017, 08:51:58 am
content: hi all,the purpose of the timer is a glow plug controller for my diesel motor. it controls the glow relay turning the plugs on and off. it also controls an indicator light on the dash, and thats where my issue lies. i did think about by passing it and using a SPDT relay to trigger the LED, (easy as) but as the unit continues to cycle the glow plugs on and off after the motor has started, i dont want the light to keep comming on an off. it didnt do it in the original car and i dont want it to in the new one either.long shot, but i am trying to adapt a timer into my car from my old car, and get it to work. i have nearly everything going, except the light on the dash. it pulses on for a split second and then its off. but the unit, as far as i can test & tell continues to operate correctly.at first i though that it was because there may not be a limiting resistor on the dash, been that the original was a fillament globe and the new one is LED, so i put in a 330 ohm and same results, so i tried the filament globe, and still the same result.then i traced back the pcb a bit, and found that the ground lead of the led was connected to a d1698 transistor (on the collector pin), so i traced out the transistor, and the emiter pin runs to ground through a few possible options, but i measure no resistance between them.looking at the base resistor, i thought that the value may be wrong for the led vs the fillament, so it played around with it using my decade box, and no go. (trying again with the fillamant globe also confirmed this). the base is controlled by a TA7590 IC (quad op-amp) and i am out of my league now. i looked into op-amps to work it out, but it still a bit past my current understanding.i am hoping that there is someone on here, that lives in brisbane, australia, that has a good understanding on how op-amps work, that i can bring the unit to and can go through it with me. aswell as assist me in working out why its not working the way it should. (it worked correctly in the last vehicle, and as far as i can tell, all the wiring is correct [checked it a few times]).i have attached pics of the pcb.as far as i can tell, Q5 is the transistor that controls the LED, and its base resistor is R35. it is driven by pin 1 of the OP-AMP, and from there im out of my depth.cheersJasonsorry, stupid sh1t a55 photobuchet wont let me rotate the pic.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 02, 2017, 09:15:36 am
content: Quote from: Jbates58 on January 02, 2017, 08:51:58 amIf you operated the unit without a resistor there is a chance that you will have blown the transistor. Do you have a schematic of the device?

author: Jbates58
author_rank: Regular Contributor
timestamp: January 02, 2017, 09:40:49 am
content: Quote from: Andy Watson on January 02, 2017, 09:15:36 amsorry no, i dont have a wiring diagram. and i didnt go to far below the resistor value (r35 [3.3K]) as i sisnt want to do any damage, i went as low as 3k.Jason
Diagnosing car radio that won't power on via button - Page 1
Forum section: electronics / beginners

author: Fritzoid26
author_rank: Newbie
timestamp: October 01, 2025, 11:04:00 pm
content: I am trying to fix a vintage car radio that won't turn on, I have isolated the problem back to the power and buzzer daughterboard. The power button does not turn the radio on. The power button goes from OL to ~300 Ohms when depressed to ground (150 if I push harder)When I ground the button at the red x (see schematic) directly with a screwdriver, bypassing the button, the radio turns on and works perfectly. Similarly, when I just so much as touch the multimeter at the blue x's in the schematic, I can turn the radio on and off. It's as if the power button isn't being pulled down to ground enough, but my understanding is that transistors just require a flow of current, so it shouldn't matter that the resistance to ground via the button is 300 Ohms, all the other buttons are a similar resistance and work fine?I have desoldered and measured all transistors, resistors, and zener diodes on the board and all checks out, I have also reflowed the board, checked and replaced most of the caps. IC601 also receives +5 V and GND. There is also a voltage drop from 0.5 V to 0 V before the diode, I can't measure after the diode as measuring it turns the radio on. What is the problem? Any help appreciated.

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: October 02, 2025, 01:16:55 am
content: Replace or clean power switch.Jeff
Diagnosing failure of charger - Page 1
Forum section: electronics / beginners

author: fixit7
author_rank: Regular Contributor
timestamp: May 30, 2019, 07:54:00 pm
content: This phone charger failed and I would like to diagnose why it failed.It was running quite warm before it failed.https://www.dropbox.com/s/7d9hztgdfp9znr3/CellPhoneCharger1.JPG?dl=0https://www.dropbox.com/s/0cmemsca888ttv2/CellPhoneCharger2.JPG?dl=0https://www.dropbox.com/s/lhomejqgem4wffw/CellPhoneCharger3.JPG?dl=0The one pic looks like some component melted and spread that yellowish-brown residue.That yellowish plastic board with components on it....is that a cost saving item?It looks pretty cheap.

author: Achu
author_rank: Contributor
timestamp: May 31, 2019, 01:26:58 am
content: I think its a resistor burned due to heating.SMD components are not that common in regular spare parts stores.you could try online.
Diagnosing Power rail faults/ LTC1435 switching regulator - Page 1
Forum section: electronics / beginners

author: johndon2000
author_rank: Contributor
timestamp: July 03, 2013, 08:17:44 am
content: Hi, I'm looking for a simple way to determine if a switching regulator is faulty (specifically the LTC1435)... there aren't clearly defined inputs & outputs as there is a lot of feedback, so comparing inputs & outputs with a KTBG device doesn't seem to help.Basically, a 3.3V rail is showing as 2.9V and I suspect the LTC1435... obviously I can just swap it out but is there a more technical method for determining faulty devices for future reference?Many thanks,John.

author: Paul Price
author_rank: Super Contributor
timestamp: July 03, 2013, 11:50:24 am
content: From what you are describing, and while you are not offering a schematic to clarify your situation, I would not suspect the regulator IC as the cause of the low 2.9V rail reading. Rather I would expect some filter capacitor feeding the voltage to be regulated by the switcher chip has developed ESR or has opened up and needs replacing.

author: digsys
author_rank: Unknown
timestamp: July 03, 2013, 12:05:56 pm
content: If it's part of a system, you'd first assume it's been designed ok (in most cases), so all that leaves you with is a good ol' DSO (or CRO).Check V_level coming in and noise, check V_level going out and noise and finally current, which you can do with a current probe.

author: dfmischler
author_rank: Frequent Contributor
timestamp: July 03, 2013, 12:19:12 pm
content: Do you have a schematic?

author: johndon2000
author_rank: Contributor
timestamp: July 03, 2013, 02:38:50 pm
content: No schematic but I'll upload a "typical application" diagram from the pdf...

author: Paul Price
author_rank: Super Contributor
timestamp: July 03, 2013, 02:45:50 pm
content: Have you scoped Vin to see if it is a clean D.C. >4.5V ?

author: johndon2000
author_rank: Contributor
timestamp: July 05, 2013, 07:13:33 am
content: Yes, looks like a good level approx 5V.

author: Paul Price
author_rank: Super Contributor
timestamp: July 05, 2013, 08:21:18 am
content: Can you take a look with your scope at the "Switch" pin on the control IC and just a take a picture of what you see on your scope with your cellphone or else just hand sketch a picture of a single pulse interval. The pulses should be periodic. And show with voltage levels by penning them on the picture. You can scan your hand-drawn or transfer your cellphone picture into your computer and post it as a .jpg file here. I can tell from a picture that is looking at this point and tell you what is wrong if your picture shows the upper and lower voltage levels of the pulse with your help, if necessary.As far a advice goes, a picture is worth a thousand nerds.
Diagram Doofus - Page 1
Forum section: electronics / beginners

author: TechJeff
author_rank: Contributor
timestamp: July 01, 2024, 09:53:27 pm
content: Hello Ladies & Gents,So I am trying to get this drone together for the kids on the 4th of July. But I am working off a diagram somebody put on the internet. Trying to learn more about electronics by using an Arduino too.Everything is close, but the problem is that the drawing... seems to be wrong. I don't have enough experience to call a ball from a strike- I am a diagram doofus, lol. I would greatly appreciate your help deciphering this diagram.Referring to the first attached diagram, everything makes sense- save for the black arrow I have placed. If you look, it seems to me that he has the negative side of the voltage divider, going into the positive voltage in... Short circuit city to my eyes.Granted, there is no dot showing the downwind side of the voltage divider to indicate a connection- but why show that path at all? It seems to me that he forgot to send that to wherever it is supposed to go.And the red arrow shows a connection from the battery to the voltage in pin on the Arduino. That looks right to me, but please let me know if that's not right. FYI, battery is 11 volts, well within the tolerance of the Arduino.The second drawing shows the full diagram.Two questions.1. Does that voltage divider really connect there?2. If it does not, where does it go? Does it go to a ground pin? Will any ground pin work?Refer to the second drawing for the entire diagram.Thanks guys. Really want to show the kids that Grandpa is still "Hip and relevant" lol. In reality, trying to spur an early interests in technology.TJ

author: Ian.M
author_rank: Super Contributor
timestamp: July 01, 2024, 10:19:27 pm
content: Looks sane, assuming the right end of R2 goes to Gnd. It feeds A0 with 40% of Vin, allowing the ADC to measure battery voltages up to 12.5V (+ 1 diode drop). You'll see another dodgy junction dot on the 5V net going to the gyro and receiver power - someone was lazy with their schematic entry and went pin to pin rather than taking the time to get a wire end where the junction should be.

author: TechJeff
author_rank: Contributor
timestamp: July 02, 2024, 02:46:42 am
content: It works!Well by works I mean it did not blow up and the Arduino gave an all good. I still need to hook up the antenna and the ESC controllers, but so far it is awesome!Thank you!TJ
Dial for 3296W potentiometers - Page 1
Forum section: electronics / beginners

author: JoeP
author_rank: Contributor
timestamp: November 11, 2018, 04:21:11 pm
content: I've bought a set of 3296W potentiometers for use in various electronics projects, however they aren't the easiest to turn. It seems obvious that they are intended to be used with a screwdriver, but I was wondering whether anyone's made a dial that just clips on?Thanks,Joe

author: ArthurDent
author_rank: Super Contributor
timestamp: November 11, 2018, 04:40:51 pm
content: Unless you want to replace them with panel mount pots with counter dials at $$$ then what I do is use an alignment tool (see photo) designed to not slip off the tiny adjustment screw and use a Sharpie to place a mark on the tool so I can keep track of where I've turned the screw.

author: Richard Crowley
author_rank: Super Contributor
timestamp: November 11, 2018, 05:00:18 pm
content: That is a 10-turn trim pot. The photo shows the style with screwdriver adjust.Nobody makes after-market knobs for that style pot because there is not enough shaft to connect to.There are OTHER styles of trim pots with knobs. Here is a style with an extended, knurled shaft that can be turned with your fingers (or with a screwdriver).And here is a single-turn pot with built-in knob.

author: Wimberleytech
author_rank: Super Contributor
timestamp: November 11, 2018, 06:46:39 pm
content: Just for kicks, I drew this up and printed it. It works, but a screwdriver is probably a better solution.

author: JoeP
author_rank: Contributor
timestamp: November 11, 2018, 09:42:20 pm
content: Nice one! I was thinking something like that would be possible. I've managed a much more crude solution - soldering the leg of a resistor into the groove. It works okay, but bends quite easily and isn't exactly the most comfortable to use.

author: not1xor1
author_rank: Frequent Contributor
timestamp: November 12, 2018, 07:58:22 am
content: Quote from: JoeP on November 11, 2018, 04:21:11 pmthat doesn't make any sense since that kind of trimmer is specified for a quitelimited amount of rotational life, i.e. 200 cycles
Dickson charge pump from a microcontroler and current drawn - Page 1
Forum section: electronics / beginners

author: Jaunedeau
author_rank: Regular Contributor
timestamp: April 09, 2025, 07:26:42 am
content: Hi,I need to send a 9.5-12V constant signal into a SCART connector (apprently 1KOhm min, 10kOhm nominal). Since I have only 5V on the board I tried to simulate a Dickson charge pump using the timer on the microcontroller inspired by Dave's Microcontroller Voltage Doubler video (I4ED_8cuVTUon youtube).I made asimulationto find proper capacitors values before testing on breaboard, and though I found that 1 to 10uF and 1k to 1MHz give the proper output after 1 to 10ms, the current drawn on the pin is very high. I set the ESR to 5Ohm (is this a realistic value for lcsc / aliexpress 0603 1 or 10uF ceramic capacitors ?) and it dropped to a couple hundred mA (for about 20ųs only).Should I be concerned with the initial current drawn during the first few cycles ? Do I need to add a serie resistor on the clock outputs ?Thank you,j.

author: jwet
author_rank: Frequent Contributor
timestamp: April 09, 2025, 05:11:27 pm
content: Most Port pins on uP's can only source about 20 mA. I cap looks like a short when first charge. I would add a resistor to reduce the short circuit to about 20 mA- this would be about 250 ohms. You'd like to run at a high frequency and use moderate sized caps perhaps 1 uF. What you is a tripler. If you feed start at 5v and put 5v minus a diode drop above it, you'll get 9V. You also want a output cap. You shouldn't have such high droop on each cycle.There are small parts that do this job for a dollar- the old faithful is the ICL7660. Its data sheet might give you some tips too.

author: Jaunedeau
author_rank: Regular Contributor
timestamp: April 09, 2025, 09:33:08 pm
content: I wanted to avoid using a 7660 (for space issue) but it is apparently not the best choice here !
DICKY JUMPER WIRES - Page 1
Forum section: electronics / beginners

author: neko efecktz
author_rank: Regular Contributor
timestamp: November 14, 2016, 12:20:46 am
content: Good morning all,Has anyone used these jumper wires form JAYCAR.https://www.jaycar.com.au/150mm-plug-to-plug-jumper-leads-40-piece/p/WC6024https://www.jaycar.com.au/150mm-plug-to-socket-jumper-leads-40-pieces/p/WC6028https://www.jaycar.com.au/150mm-socket-to-socket-jumper-leads-40-piece/p/WC6026Plus others that they stock.I have, and I found that the plug / socket breaks off quite often.Two pieces this morning.You may not know why until you realize that the wires inside are7 strands of 0.09mm copper coated steelCrimping to the plastic sheath of the wire is not very good so a lot of strain is applied to the thin steel wires.If I had a choice I would avoid them but there is no guarantee that buying them on line will have any better resultsThat's my rant.a good bit shorter than Daves.Thank you for listening.BILL.

author: Whales
author_rank: Super Contributor
timestamp: November 14, 2016, 01:25:05 am
content: Indeed these are thin, they're only designed for signal levels (eg less then a few hundred mA). When I need thicker ones I crimp them up myself.Rule of thumb: never expect there to be copper in anything unless you can cut it open before buying it.

author: Bryan
author_rank: Frequent Contributor
timestamp: November 14, 2016, 10:33:58 am
content: Ya, most are junk nowadays, add these crappy jump wires to sub par breadboards that are everywhere and it is surprising one can get a breadboard project to work properly. Scratched my head for days trying to get a Jupiter receiver to work properly on a breadboard. Probed around and the supply line was dropping to 4.2 volts on the breadboard. The jumper wires and the breadboard could barely pass 100ma. Was thinking of dropping some dollars on a quality 3M breadboard. Interesting on the SparkFun jumpers, will have a look.

author: station240
author_rank: Unknown
timestamp: November 14, 2016, 11:29:35 am
content: If you buy enough of these cheap jumper wires, you'll get one that is open circuit from the box. Of course no one expects that when breadboarding a circuit, so fun and games ensure.
Did BigClive hack of LED bulb, now warmer - Page 1
Forum section: electronics / beginners

author: Peabody
author_rank: Super Contributor
timestamp: November 26, 2023, 10:13:27 pm
content: I needed to gently light a walkway alongside my condo garage which comes on automatically at night. I decided to hack a 60W equivalent bulb to be closer to 15W, all as described many times on the bigclivedotcom Youtube channel. The current control chip had two sense resistors in parallel, 75R and 10R, for a parallel resistance of 8.8R. I removed the 10R, so the resistance went from 8.8R to 75R, and the bulb went from 8.6W to 1.5W per my Kill-a-Watt.So that went fine, and the brightness looks about right, but to my eye the color seems to be a bit warmer. The bulb was 2700K to start with. Anyway, can someone explain what determines the color of an LED bulb? Does it have anything to do with the frosted plastic globe that the light goes through, or is it different phosphors in the LED itself? And does color vary with current, or am I just imagining that difference?

author: Zero999
author_rank: Super Contributor
timestamp: November 26, 2023, 10:52:38 pm
content: The colour temperature is only specified under a range of drive currents. It's quite likely that at lower currents, a greater proportion of blue is absorbed by the phosphor, creating a warmer light.Is this a problem? I would have thought it a lower colour temperature would be better, since it won't affect night vision as much, compared to a higher temperature, which has more blue.

author: Peabody
author_rank: Super Contributor
timestamp: November 26, 2023, 11:22:12 pm
content: Thanks. No, I think it looks ok. Just a little warmer than I was expecting. And I guess now it will last forever, or at least as long as the capacitor lasts. I was just curious how the manufacturer sets the color.

author: Whales
author_rank: Super Contributor
timestamp: November 27, 2023, 05:49:15 am
content: Yes drive power affects the colour temperature of white LEDs.The manufacturer controls the colour temp by the composition (chemistry) and construction (thickness & possibly other attributes) of their phosphor layers. Inside a white LED there is actually a blue LED, then (at least) a mix of two phosphors on top to convert the blue into other colours. Together when mixed they appear white.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: November 27, 2023, 01:34:16 pm
content: It is a guess:These are usually blue LED's, combined with different phosphors, and the guess is that some of the phosphors are driven into saturation at the top brightness, or at least they are not linear with energy input.

author: Peabody
author_rank: Super Contributor
timestamp: November 27, 2023, 03:18:35 pm
content: Ok, so if I wanted cooler light after the hack, I could just start with a 5000K bulb.
Did I buy the wrong eprom programmer? - Page 1
Forum section: electronics / beginners

author: cypher007
author_rank: Contributor
timestamp: May 09, 2020, 06:17:11 pm
content: i recently bought a tl866a. i then began to regret this decision as it seems the tl866ii plus is better? i will use mine for laptop bios repair so 1.8v, 27c400 for my amigas, and some other older 8bit roms.have i bought the wrong one?

author: james_s
author_rank: Super Contributor
timestamp: May 09, 2020, 06:28:55 pm
content: The II is newer, it's possible that it's better, but the older model is just fine. If it supports the chips you need to program then there's no reason to regret it. I have an older TL866 that I've been very happy with.

author: cypher007
author_rank: Contributor
timestamp: May 09, 2020, 09:32:51 pm
content: ive bought this to hopefully flash newer 1.8v bioseshttps://www.ebay.co.uk/itm/1-8v-ADAPTER-v2-0-MOTHERBOARD-MX25U1635-MX25U6435-MINIPRO-TL866-SKYPRO/114021334031?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649i did notice a youtuber who bought a tl866ii plus and it had an extra square chip adapter with it. i might try and dump some early 90's gals that i have on an accelerator. im not sure if the 4 i have will be the right size. i guess i can maybe buy it separately.im just looking for the widest compatibility. i suppose the fact the tl866a does 21v compared to the tl866ii 18v.

author: Shock
author_rank: Super Contributor
timestamp: May 10, 2020, 02:05:38 am
content: Ideally get both just for compatibility and programming voltage, but you can hold off on the newer model until you need it.You probably also brought a lookalike clone as they stopped making the original a while back. You may need to flash a valid serial into it if it complains on the latest firmware that it's not genuine,discussed in this thread.The good news is since the original has been reverse engineered they can easily be repaired and recovered if they fail.

author: james_s
author_rank: Super Contributor
timestamp: May 10, 2020, 03:42:14 am
content: The list of supported chips is published, and you can also download the software and load it without the programmer to see what's there. If the chips you want to flash are in the list then it will do the job.
Did I fry my MAX3485 3.3v Because I used 5vdc Supply? - Page 1
Forum section: electronics / beginners

author: K1JOS
author_rank: Regular Contributor
timestamp: August 21, 2014, 03:52:59 am
content: I needed to set up a RS485 2-wire for 3.3vdc MPU I/O to the RX/TX pins. I bought the MAX3485 but inadvertently powered up Vcc at 5vdc instead of 3.3v. Now I see 2.6Vp-p signals on one of the differential lines but only 400mVp-p on the other differential. The datasheet says the chip can take a max of 7vdc supply. I have changed (and removed) the bias and termination resistors but no change in the very low differential line. Like an idiot I only bought the pair I needed (another week wasted) ... could this be anything other than a bad chip?

author: bobcat
author_rank: Regular Contributor
timestamp: August 21, 2014, 12:17:32 pm
content: Most likely the chip is bad. The 7volt maximum rating is for static operation (no signals) or very short time duration. On the order of milliseconds.To test just the output, you can remove the transmission line and terminator. Put a 330 ohm resistor on each output to ground. Then test again. If it seems to work, then maybe there is a problem with the terminator or cable or other component.

author: K1JOS
author_rank: Regular Contributor
timestamp: August 21, 2014, 12:35:47 pm
content: Thanks for the tip. One chip worked fine on both differential lines and the other was completely dead.
Did I get the layout of this step-up converter right? (LT3478) - Page 1
Forum section: electronics / beginners

author: klausde
author_rank: Newbie
timestamp: June 02, 2025, 09:58:42 am
content: Hi folks,I designed a LED driver circuit to control 1) a single high-power led (using a constant current step-up converter, the Linear Technology LT3478) and 2) a logic level converter (TI 74AHCT125) for controlling an external APA102 led strip. The input voltage is 5V, the desired constant current for the high-power led is 1A - I use a 10 µH inductor with a switching frequency of 300kHz.I’m new to PCB design so would appreciate it if experienced eyes could have a second look.The datasheet states that the ground path for the RT resistor and VC capacitor should be taken from nearby the analog ground connection to the exposed pad (near Pin 9 - see attached image),separate from the power ground near Pin 16. The figure in the datasheet that shows this is also attached.Tapping the ground at separate points for the power path and for logic capacitors is to reduce interference, right?I created separate filled zones as a ground plane so that no direct path exists between the VC cap and RT resistor and the power ground. Will this do the job?I thought this construction feels a bit counterintuitive, since the power ground and acoustic ground are still just separated by a mere 5 mm (Pin 9 to Pin 16). Does the slight detour make a real difference?I tried to take into account theother pitfallsthat one can run into when designing a step-up converter:- Minimising the area of the 'hot loop' between the switching pins, input capacitor and inductor to reduce noise- An adequate trace width for this loop (I filled the zones beneath the inductor with copper pours), taking into account current spikes beyond 1A- As many as possible thermal reliefs between the ground plane on the top and bottom layers- Since the logic level converter is on the same board I added two decoupling capacitors (10 µF and 0.1 µF) and a ferrite bead to avoid interferenceDid I implement these requirements more or less correctly? Do you see any room for optimisations?Thanks in advance!
Agilent E3633A, Gain out of range for gain error correction - Page 1
Forum section: electronics / beginners

author: somlioy
author_rank: Regular Contributor
timestamp: February 05, 2013, 05:08:43 pm
content: Hi, My E3633A started to act weird (error 632 and 718). I got a tip from free_electron on the forums that one of the op-apms in the adc-circuit would be defect and suggested me to replace all four (U25, U28, U35, U41). So I did. After reassembled the unit and tried to power it on. I immediately knew something was wrong when it took a few seconds for the display to turn on so I turned it off again quickly. I smelt magic smoke and saw a burnt resistor. R148. See the attached schematic on page 22 (129).Does anyone know why I smoked this resistor and possible other stuff? And maybe explain the circuitry around R148?Finally got around and replace those parts and everything seems alright except that I still got the err 718 (Gain out of range for gain error correction) when turning on the output. Display shows -0.014V/0.055A. DMM shows a climbing voltage. Output is climbing whether its on or off. It has been powered for a while now and its outputting about 22volts atm.No errors when I'm doing a self test at boot.Are there still some faulty components or do I just need an calibration?Schematics attached.

author: amspire
author_rank: Super Contributor
timestamp: February 06, 2013, 01:17:30 am
content: Without wading through the full circuit, it looks like something tripped the overvoltage crowbar thyristor that should short the output, but it looks like something is still providing considerable power to the output.There is a good chance that the Optocoupler (U46) is now damaged, and the crowbar thyristor (CR39) could be fused.I would remove R148 until the supply is fully working again, and then put it back and check that the crowbar circuit is working.Read the manual on how to configure the crowbar - a wrongly set crowbar can easily give the impression that a supply does not work.

author: somlioy
author_rank: Regular Contributor
timestamp: February 06, 2013, 08:18:52 pm
content: Thanks for your response.I think I found the fault. When replacing those op-amp I managed to get a bridge beneath U25 (pin 6 and 7) and U35 (3 and 4).Also found two other chips that I fried (visually); CR24 BAV99 diode and U24 74HC4051 mux/demuxer. Muxer died because its output was shorted to the -17.4V rail. CR27 I dont know why. U25 could be damaged aswell since its output was shorted to the 15V rail if I'm not misstaken.Hopefully I didnt kill too much due to my stupidity.

author: somlioy
author_rank: Regular Contributor
timestamp: March 05, 2013, 05:03:36 pm
content: Finally got around and replace those parts and everything seems alright except that I still got the err 718 (Gain out of range for gain error correction) when turning on the output. Display shows -0.014V/0.055A. DMM shows a climbing voltage. Output is climbing whether its on or off. It has been powered for a while now and its outputting about 22volts atm.No errors when I'm doing a self test at boot.Are there still some faulty components or do I just need an calibration?
Did I kill my voltage regulator? - Page 1
Forum section: electronics / beginners

author: MGaddict
author_rank: Contributor
timestamp: March 29, 2025, 10:30:56 pm
content: I'm trying to get an old power supply working. It's outputting a wopping .2v on the 5v rail. There are 2 voltage regulators, lm7912ct and an lm7905ct.I was trying to figure out how to test them and i found some examples for 7805 regulators and they demonstrated putting 7-27v into the input and you should get 5v on the output.Seems simple enough.Being a negative voltage regulator, I made some assumptions and I'm trying trying to figure out if killed this thing or it was already dead and likely the cause of my issue....I used an ATX power supply to supply -12v to the 7905. The thing got hotter than heck immediately and had nothing on the output.So... Did I screw up using -12v or was that right and this thing was already dead?I'm going to order a replacement but before I try to test the 7912, I'd like to know if I screwed that up.

author: langwadt
author_rank: Super Contributor
timestamp: March 29, 2025, 10:42:03 pm
content: Beware that the pinout of 78xx and 79xx is not the same

author: MGaddict
author_rank: Contributor
timestamp: March 29, 2025, 11:05:59 pm
content: DOPE!!!So, um, ya. About that...I can still hope that it was already the problem i guess.Stupid, stupid, stupid. I guess this is how we learn right?

author: Zenith
author_rank: Frequent Contributor
timestamp: March 30, 2025, 12:19:00 pm
content: You also need a load on the output when testing those three terminal regulators. It need not be much, just enough to draw a few mA, but I've found that just using only a DMM (typically 10MegOhm input resistance) can produce strange results, especially if the regulator is faulty.
Did I kill this PCB? - Page 1
Forum section: electronics / beginners

author: boguesuser
author_rank: Newbie
timestamp: May 13, 2025, 10:09:23 pm
content: I put the solder paste, placed it on the hot plate, and let it heat to temp (my hotplate has no ramp function).Now all my vias are clearly visible. Is this normal or did I screw it up by heating it too quickly?I haven't added components yet, just some solder on the back for extra current capacity.This is an 8 layer board with epoxy filled and capped vias.

author: boguesuser
author_rank: Newbie
timestamp: May 14, 2025, 01:21:37 am
content: I'll note that these vias were unnoticable before I did this so this is a pretty big change.I know that one of the weaknesses of this type of via is that it is prone to breakge due to thermal cycling. I just want to make sure that I've not supercharged that before I start adding components.

author: wraper
author_rank: Unknown
timestamp: May 14, 2025, 01:58:03 am
content: Via filler compound has popped out of the vias. PCB should still work but it's somewhat damaged.

author: radiolistener
author_rank: Super Contributor
timestamp: May 14, 2025, 02:31:37 am
content: you can cover the damage to the layer with a protective varnish. In general, even without a mask, this does not affect the work. But it makes the board more vulnerable to rotting and oxidation, and if a bare wire touches the surface, a short circuit may occur

author: boguesuser
author_rank: Newbie
timestamp: May 14, 2025, 08:30:18 am
content: Ok. Good to know.I was worried there might be a risk of the vias snapping because of this but it's just that the via epoxy fill came out, I can work with that.Most are under pads anyway and the few that aren't I'll cover with some conformal coating.Thanks for the help!
Did I order the right caps ? - Page 1
Forum section: electronics / beginners

author: cosmicray
author_rank: Frequent Contributor
timestamp: January 30, 2015, 03:42:50 am
content: I ordered some caps, to build the Simple Negative Voltage Converter as shown in the ICL7660A data sheet (same basic circuit in most any 7660 data sheet). It calls for two 10uf caps (polarized electrolytic) for the charge pump.In ordering the caps, I was more focused on the ESR, voltage, and uF, and totally blitzed out to other specs (that now I am waking up to). What I ordered was a 1210 MLCC 10uF 16V X5R ceramic cap (Samsung). The datasheet shows an ESR of about 0.03 ohms at 10 kHz.But now it dawns on me that these are not polarized. In researching this, I noted several threads talking about MLCC caps, and how they present quite different capacitance values depending on the DC bias voltage. The Vcc for the 7660 will be +5V, so that I can generate a -5V rail. Current draw will be negligible, likely less than 5 mA.Will these caps work, or do I need to go back and get real polarized electrolytic type ?

author: helius
author_rank: Super Contributor
timestamp: January 30, 2015, 04:03:07 am
content: I don't know if it will work (X5R can present a capacitance of 40% less than nominal with 5V bias), but you can either overrate the capacitor, or use a type that doesn't suffer that effect. SMD tantalums are very good for that application.

author: wraper
author_rank: Unknown
timestamp: January 30, 2015, 04:11:53 am
content: There is no obvious reason why they would not work. About capacitance drop under voltage, As they are 1206, likely it is not so horrible like if they would be 0805. Anyway, there is no reason why IC would not work with half of the capacitance.

author: c4757p
author_rank: Super Contributor
timestamp: January 30, 2015, 04:18:41 am
content: Nothing requires polarized types, they were just emphasizing that they don't have to benon-polarized (a fact that might not be obvious to someone unfamiliar with charge pumps).They're pretty big (physically) caps and X5R, so they'll probably be fine. You might be able to find a capacitance-vs-voltage plot for them (Samsung had them, but they seem to have fucked up their website and I can't get it to produce the characteristics sheets anymore; DigiKey appears to be caching them though) if you're concerned.

author: cosmicray
author_rank: Frequent Contributor
timestamp: January 30, 2015, 04:36:33 am
content: Quote from: c4757p on January 30, 2015, 04:18:41 amI have the characteristic sheet, which I found via DigiKey. The part # is CL32A106KOJNNNE. I suspect the chart is the marked "DC Bias characteristics". My impression was around 5-10% down at 5v.
Did Not Connect: Potential Security Issue - Page 1
Forum section: electronics / beginners

author: markav2
author_rank: Contributor
timestamp: January 22, 2023, 01:06:58 pm
content: I'm a long-time Firefox user and I don't remember seeing this on the top of the website.Does anyone else see this?The problem looks like possibly a banner ad is not being supplied by HTTPS.

author: Terry Bites
author_rank: Super Contributor
timestamp: January 22, 2023, 02:08:03 pm
content: Siemens no?
Did some old IC’s come with solder on their leads/pins? - Page 1
Forum section: electronics / beginners

author: [Chrille]
author_rank: Contributor
timestamp: September 17, 2024, 09:23:48 pm
content: I have acquired some old TTL IC’s (New Old Stock) and on some of them they have solder on their leads (not all brands or series). Most of the time they do not have any solder on them like you would expect from a new IC. They look new/unused and the leads have the original angle/bend so they don’t look used otherwise.So the question is: Did some manufacturers apply solder to their brand new factory IC’s? We are talking very late 70’s/early 80’s 74xx TTL chips.

author: indeterminate
author_rank: Regular Contributor
timestamp: September 17, 2024, 09:59:03 pm
content: Pre tinned leads where fairly common

author: coromonadalix
author_rank: Super Contributor
timestamp: September 17, 2024, 10:11:13 pm
content: photos would be nice ... yes there was pre-tinned ones, but evenly put, not blob when you desolder / salvage ic's or unless you solder wick them

author: Stray Electron
author_rank: Super Contributor
timestamp: September 18, 2024, 12:24:36 am
content: Quote from: indeterminate on September 17, 2024, 09:59:03 pmTin plated yes, solder no! What you have are probably what are called "solder pulls". Those are used chips that are unsoldered from a circuit board vs "socket pulls" which are used ICs that are taken from sockets. Both types are very common in the surplus/ used IC market.If you want to be certain, then look up the manufacturer's data sheet for the part. I THINK a few manufacturers offered pre (solder) tinned parts but I have used probably over 100,000 ICs of that vintage and I've never seen a pre-soldered part.

author: wraper
author_rank: Unknown
timestamp: September 18, 2024, 01:14:44 am
content: Quote from: Stray Electron on September 18, 2024, 12:24:36 amYou speak bollocks. For TH parts factory tinned terminals are almost as common as tin plated. More so on older parts. Currently it became way less common for DIP ICs but still very widespread for other parts.

author: wraper
author_rank: Unknown
timestamp: September 18, 2024, 01:21:52 am
content: Here you go, brand new IRF740PBF from Vishayhttps://www.lcsc.com/product-detail/MOSFETs_Vishay-Intertech-IRF740PBF_C2570.html
Did Xilinx ever make a DIP CPLD? - Page 1
Forum section: electronics / beginners

author: CaptDon
author_rank: Super Contributor
timestamp: December 26, 2024, 01:33:24 am
content: I have the full Xilinx ISE client and the JTAG cable (both USB and the parallel port version. I am looking for a 5 volt DIP CPLD or possibly a 5 volt SMD CPLD already attached to a DIP carrier. CPLD doesn't have to be very sophisticated, something simple is o.k. 2XC64?

author: Andy Watson
author_rank: Super Contributor
timestamp: December 26, 2024, 01:52:15 am
content: I doubt it.Didn't Xilinx buy the CPLD designs from Philips? (about two decades ago). Even then, DIPs were essentially obselete for new chips. I don't recally any Philips CPLDs in DIP format.

author: oPossum
author_rank: Super Contributor
timestamp: December 26, 2024, 02:26:08 am
content: Microchip (Atmel) does:https://www.microchip.com/en-us/product/atf2500c

author: eeproks
author_rank: Newbie
timestamp: December 30, 2024, 04:32:43 am
content: There was a DIP version of the smaller XC2000s, but that's a 40 year old chip. Doubt your tools support it, and it's a couple of orders less featureful than the 2XC64. You'll have much better luck finding a recent-ish SMD chip bonded to a DIP breakout board; they're everywhere. The problem is 5V I/O is increasingly uncommon.
Die cast shielding - Page 1
Forum section: electronics / beginners

author: Tantalum
author_rank: Regular Contributor
timestamp: April 10, 2017, 09:29:43 am
content: HelloI wanted to understand how such shielding actually works.https://youtu.be/EY0acWrCYjw?t=754Since the aluminum plate are connected to the ground a little bit everywhere on the PCB, how is it possible that it doesn't create ground loops???Thanks

author: The Soulman
author_rank: Super Contributor
timestamp: April 10, 2017, 09:48:24 am
content: Quote from: Tantalum on April 10, 2017, 09:29:43 amThere are some ground loops but because of the short physical distance and the thickness of the shield parasitic properties are slim to none.I.E, there isn't much capacitance, inductance or resistance between any given two points.