hybridfree/eevblog-posts huggingface dataset:
Official website for Dekko Soldering Stuff - Page 1
Forum section: electronics / beginners

author: erniarrow
author_rank: Newbie
timestamp: July 18, 2023, 06:12:01 am
content: Hello, is there anyone who can help me provide a link to the official catalog or website of Dekko Soldering products? I have come across many Dekko Soldering products in the market, but some of them are counterfeit. It's difficult for me to verify their authenticity because so far, I haven't found any official catalog or website that contains original Dekko Soldering products.

author: liaifat85
author_rank: Regular Contributor
timestamp: July 18, 2023, 08:29:18 am
content: could not find any website. I do not think it's a dependable, well-known brand. Try goot or hakko instead.

author: erniarrow
author_rank: Newbie
timestamp: July 18, 2023, 10:03:33 am
content: Thak for reply the post. In my country, the Dekko brand of soldering tools is quite well-known and has been in production for a long time. These Korean products are known for their durability and come in various variations, as far as I know, all of which are portable soldering irons. I feel the need to inquire about this because I have come across some Soldering Stations claimed to be Dekko products, but I found them on Aliexpress as unbranded Soldering Stations. If I can find the official website of Dekko and their production catalog, it would be easier for me to verify the authenticity of these products.

author: erniarrow
author_rank: Newbie
timestamp: July 18, 2023, 10:05:40 am
content: Interestingly, I found that all the reviews on YouTube for Dekko soldering tools come from a single country, leading me to suspect that these products might not be available in other countries.

author: erniarrow
author_rank: Newbie
timestamp: July 18, 2023, 10:10:08 am
content: Here are some examples of Soldering Stations claimed to be Dekko products, but I found similar unbranded products on Aliexpress.

author: tooki
author_rank: Super Contributor
timestamp: July 19, 2023, 11:33:47 am
content: Quote from: erniarrow on July 18, 2023, 10:10:08 amGiven that the Dekko logo is clearly a knockoff of the Hakko logo, it’s quite obvious that Dekko is simply a Hakko clone, not a serious brand.
Offline Flyback SMDesign Help - Page 1
Forum section: electronics / beginners

author: Reckless Maker
author_rank: Newbie
timestamp: March 11, 2021, 11:28:16 pm
content: Howdy All,I'm trying to design a 35-45W offline flyback supply but am having trouble verifying the design. The final product will be very low run (<100 units), so I chose an off-the-shelf transformer
Offset Current simulation in pspice - Page 1
Forum section: electronics / beginners

author: roogadget
author_rank: Contributor
timestamp: March 28, 2019, 10:49:44 am
content: I am trying to figure out why the pspice output is -82.04mV when the theoretical calculations are 95mV.I am using the formula:R1||RF * Ios = 10k||200k * -200nA = -0.0019mVOpen-loop Gain = 50k-0.0019mV * 50k = -95mVI am following the guides from this document:http://www.zapstudio.com/Assets_Publish/OAC%20CH2%20Simulation%20Offset%20I_V%20Noise.pdf

author: iMo
author_rank: Super Contributor
timestamp: March 28, 2019, 12:05:22 pm
content: Afaik, the R13 should be the parallel combination of R1 and R4.
Offset signal from AWG with DC power supply in series, OK? - Page 1
Forum section: electronics / beginners

author: Aldo22
author_rank: Super Contributor
timestamp: March 26, 2025, 10:38:05 am
content: HiI'm sure this question has been asked many times before, but I haven't found what I was looking for.Is it OK to offset a signal from the AWG with a battery-powered DC power supply in series?I have basically tried it with low voltage and no load.It seems to work (photo).But can it be dangerous for these devices if I apply e.g. 20Vpp + 10VDC?What happens under load (e.g. 50Ω)?My question: Can I try it out or can something go wrong?Thank you!

author: benj38
author_rank: Frequent Contributor
timestamp: March 26, 2025, 07:42:08 pm
content: Think about it for a second: the battery will be connected to the output of the signal generator in series with the load resistance. Thus, if the load resistance is low enough, you can certainly damage the generator if you exceed the voltage you are allowed to feed into its output (don't look for a spec of what this maximum voltage is, it is almost never specified by the manufacturer).The solution is very simple: connect a blocking capacitor in series with the output of the AWG, thus preventing the DC voltage from feeding into it.The value of the capacitor depends on the frequency of the waveform, and the load resistance: it should present a small enough impedance at this frequency compared to the load.Two important points to keep in mind:The capacitor will obviously also block the average dc value of the generator's output waveform, so if this is not zero you will have to compensate for it by adjusting your DC voltage supply accordingly to supply this as well.You want to avoid switching the DC supply into the circuit abruptly since (if this DC voltage is high enough, the capacitor big enough, and the load resistance low enough) the resulting inrush current charging the capacitor that will pass through the generator may damage it. Instead, bring the DC voltage up gradually.

author: benj38
author_rank: Frequent Contributor
timestamp: March 26, 2025, 08:49:01 pm
content: I will add the following clarification to my previous reply:Note that in that reply I was focusing on protecting the generator from the DC supply, but not the DC supply from the generator.The reason is that it is quite common for the generator to present to the DC supply a similar or even higher impedance than the load (e.g., both may be 50ohms) and thus, a substantial portion of the DC supply voltage will fall on the generator's output and may jeopardize it.In contrast, unless one has a good reason to suspect otherwise, it is usually a safe bet to assume that the DC supply will present to the generator a substantially lower impedance than the load, and thus only a small portion of the generator's AC voltage will fall on the DC supply.

author: Aldo22
author_rank: Super Contributor
timestamp: March 26, 2025, 09:00:44 pm
content: Thanks for the answers!That makes sense.I just wanted to ask about the protection of the battery-powered DC supply, but you answered that already in the second post.
offtopic: is it worth to wait till black friday with scope purchase? - Page 1
Forum section: electronics / beginners

author: tester43
author_rank: Regular Contributor
timestamp: September 15, 2018, 07:00:28 pm
content: well.... i am checking on net, but maybe somebody remembers if there was anything like price significant drop in oscilloscopes price last year black friday?Today I see 1054z for 350, and SDS1104 for around ... 500

author: admiralk
author_rank: Regular Contributor
timestamp: September 16, 2018, 12:22:41 am
content: Black Friday is a gimmick to stimulate the sales ofconsumergoods.

author: Stray Electron
author_rank: Super Contributor
timestamp: September 16, 2018, 12:29:13 am
content: It might be worth asking for a "Black Friday"discount though. In this county we have the general expression that "you don't get it unless you ask for it for it first". I've asked for discounts in many places and usually get them.

author: t1d
author_rank: Super Contributor
timestamp: September 16, 2018, 06:24:06 am
content: Call the company. Asked for the sales department. Ask for a salesperson that is on commissions. Ask if there will be a sale. Why a salesperson on commissions? Because, whether the company has allowed that person to announce the sale, before the press release, they are v-e-r-y likely to give you a clue, if you ask how to make sure they will get the credit, for your sale, should you make a purchase. Ask about Cyber Day, too... Is that Monday? For the internet sale...

author: tester43
author_rank: Regular Contributor
timestamp: September 16, 2018, 01:55:03 pm
content: good - thanks all

author: tszaboo
author_rank: Super Contributor
timestamp: September 16, 2018, 07:26:44 pm
content: We obviously need "Test equipment Tuesday".

author: Bud
author_rank: Super Contributor
timestamp: September 16, 2018, 07:38:51 pm
content: I found that life is too short to wait for sale.On the other hand i discoverd if you wait long enough you find that you do not want it anymore when the thing finally goes on sale. So waiting may actually save you money.

author: 2N3055
author_rank: Super Contributor
timestamp: September 16, 2018, 07:53:27 pm
content: I agree with Bud..If you need it, you need it...That being said, I did get very nice discount on a Picoscope last year's Black Friday...But that was pure coincidence.So it is pretty much luck, if you happen to need something, and you have money and it is Black Friday and you happen to get a deal on what you need...Not something you can count on and make plans around it...
Ohmic PN junction - Page 1
Forum section: electronics / beginners

author: blueskull
author_rank: Unknown
timestamp: September 16, 2016, 05:54:11 am
content: Hi all,Is it possible to create Ohmic or tunnel contact between N+ and P+ layers?I'm trying to build a stacked diode (PN/PN/PN/PN) structure, and I, apparently, can not do it that way since the reverse biased PN junction will prevent current from flowing through.Therefore, I'm thinking if I can build P+/P/N/N+/P+/P/N/N+/... structure, so that the boundary highly doped P+/N+ layers can form Ohmic contact instead of diode contact.Theoretically I can use triple well process and series connect devices laterally, but I only have (cheap) access to MOCVD process, not patterning process. So I would really like to vertically stack devices instead.Thanks in advance.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 16, 2016, 07:36:33 am
content: You probably want metal barrier layers inbetween. Except you don't...I'm thinking HV diodes (a single part, containing a stack of matched single diodes, to achieve the required rating) are common dies simply soldered together. You could shorten the process one step by using aluminum layers between N/P layers. But, then your crystal structure gets screwed up, and you can't keep growing single crystal. So, obviously that's not a useful method.I think a heavily doped layer will work, to a point: you get a tunnel junction, with a very low breakdown voltage. It's not ohmic, but you probably don't care at this point. But there's nothing to stop carrier diffusion, so the result is a huge stack of DIACs, which I don't think will work very well.Maybe you can grow the heavily-doped regions very thick (10s of um), so diffusion and recombination kills off the thyristor gain?Stacked single junctions also can be tested individually before assembly.(It's been some years since I've practiced theoretical semiconductors, so this is probably stuff you already know better about.)Tim
Ohms and static electricity grounding - Page 1
Forum section: electronics / beginners

author: gildasd
author_rank: Frequent Contributor
timestamp: July 14, 2014, 08:31:44 pm
content: Hello,I'm currently temp-working for a firm that makes plastic extrusions. Mostly high end cable guides and the such.What intrigues me is that certain synthetic rubber covered profiles (sound dampening) apparently pick up dust via static build up.The dust that is not large fragments of plastic but of very fine "charcoal" appearance that is probably dragged through (dust is sucked off in two stages and the actual extrusion takes place in water, so there is very little airborne plastic dust).This morning I raised some eyebrows as I came early to measure continuity of different parts the machines.Overall, it seems pretty good as each entire process in mounted on two steel rails.However, I did measure resistance between the "trap door" trays that receive the finished profiles and the packing surface below it (50cm drop).This resistance varies from 25 Ohms 450 Ohms depending on the machines.A what level of resistance will the static buildup be affected?Must i measure something else?Thanks!(disclaimer, I'm only working there two more days as a student job, I have no interest other than my general electrical culture)

author: tautech
author_rank: Super Contributor
timestamp: July 14, 2014, 08:44:44 pm
content: I wouldn't think that little would be a problem, though if they are both powered machines there might be an earthing problem.Resistance above true ground would be my concern, not just for static discharge, for electrical safety also.

author: Rerouter
author_rank: Super Contributor
timestamp: July 14, 2014, 08:49:36 pm
content: as there is a water bath nearby, the plastic dust has likely picked up some dirty water with minerals / other process stuff which after evaporating increase the conductivity of the plastic making it a very crude resistor,what is actually holding the plastic powder to the (synthetic rubber if i read right) trap door would need to only be the tiniest trace of oil, from there plastic will happily cling to plastic,

author: gildasd
author_rank: Frequent Contributor
timestamp: July 14, 2014, 08:59:53 pm
content: The water is distilled, filtered and replaced in a continuous loop... In fact the profile is rectified 2 to 3 times submerged before being "strained"...It the water had any dust, the profiles would be scratched and would go straight to recycling ( done partly in house - another story).There is no oil anywhere as it could affect the "pulling" part of the machine and make the day very miserable!!!Every electrical motor and transformer is connected directly to the grounding in the general supply 380/420V system.All the structural and mechanical parts are all connected to two rails and grounded separately.(As per EU regulations)
Ohms Law? - Page 1
Forum section: electronics / beginners

author: ckuhn1
author_rank: Newbie
timestamp: October 15, 2013, 12:57:03 am
content: I am a newbie in the electronics world and I was wondering if someone would be able to explain Ohms Law to me. If you could think of an example or two to help explain Ohms Law it would be much appreciated.

author: Kryoclasm
author_rank: Regular Contributor
timestamp: October 15, 2013, 01:11:54 am
content: Some Links:http://en.wikipedia.org/wiki/Ohm's_lawhttp://www.physicsclassroom.com/class/circuits/u9l3c.cfmHere is a great intro video of it.If after reading up on it you have anyspecificquestions, feel free to ask away.

author: ckuhn1
author_rank: Newbie
timestamp: October 15, 2013, 01:54:43 am
content: Thanks! This will definitely come in handy.
Ohms Law, Calculating resistance - Page 1
Forum section: electronics / beginners

author: ploppity
author_rank: Newbie
timestamp: February 23, 2018, 11:40:38 am
content: In a project I'm currently working on I thought this would be a nice debug style message, but I can't actually work out what I'm trying to do!To make everything simple and hopefully easy for anyone to understand, I have shrunk down the problem to this:(don't know how to upload image, so I'll try some ascii art)3.3V supply into 560 ohm resistor used a pullup into both a processor pin (ADC) and a 1K resistor to ground. The 1K resister can be anything between 1K and 10K (pot). I want to measure the resistance and display that value.I can create a table in the software and use analog windows using this equation: Resistance / (Resistance + Pullup) * 3.3 (VIN) which gives me voltage and then converting that voltage to an ADC value is easy as I can just divide the voltages and multiply by my ADC resolution.What I can't do and trying to do is to do this without tables.I can convert the ADC result to a voltage quite easily (divide by my ADC resolution and multiply by VIN).So this makes the question easy:1K resistor to ground and 560 ohm pullup: 1000/(560+1000)*3.3 = 2.115VTo work out resistance we must work out currant, so I=V/R, so 3.3 / 560 = 0.005892857142857.So R=V/I, so 2.115V / 0.005892857142857 = 358. Not what I was expecting!How do I get 1000 ?

author: danadak
author_rank: Super Contributor
timestamp: February 23, 2018, 12:27:57 pm
content: Let R1 = 560R2 = 1000Vdd = 3.3VmeasVmeas = (R2 * Vdd)/ (R1 + R2) or Vmeas * R1 + Vmeas * R2 = R2 * VddorR2 (Vdd - Vmeas) = Vmeas * R1or R2 = (Vmeas * R1) / (Vdd - Vmeas)= (2.115* 560) / (3.3 - 2.115) = 1184.4 / 1.185 = 999.5 ohmsRegards, Dana.

author: Nusa
author_rank: Super Contributor
timestamp: February 23, 2018, 12:57:27 pm
content: This is basically your voltage divider circuit as I understand it:http://www.ohmslawcalculator.com/voltage-divider-calculatorYour mistake was in calculating the current. It's not 3.3/560, since the voltage drop over the 560 ohm resistor is only 3.3-2.115 = 1.185 Volts. Which means the current is 1.185/560 = 0.002116 AmpsCurrent is the same through all components in series, so the current through the other resistor that drops the other 2.115 V will also be 0.002116 Amps. Which means R = V/I = 2.115/0.002116 = 999.5 ohms, which is close enough given ADC precision and rounding.Which is pretty much what the other respondent said, but with less explanation.

author: ploppity
author_rank: Newbie
timestamp: February 23, 2018, 01:07:55 pm
content: Thanks Nusa, danadak equation was useful, but your explanation and telling me why and how I messed up was a far better response. Now I know why and not just how
OHMS LAW - the lighter side. - Page 1
Forum section: electronics / beginners

author: SL4P
author_rank: Super Contributor
timestamp: April 27, 2016, 02:04:52 am
content: I spotted this on another forum recently.Thought it may get a laugh here!

author: Ampere
author_rank: Regular Contributor
timestamp: April 27, 2016, 05:07:45 am
content: There's a printout of this tacked to one of the cork boards in my school's lab. Somebody in the faculty has a sense of humor.
Ok I screwed up YH305DV6-2-1 older power supply I don't want to throw away - Page 1
Forum section: electronics / beginners

author: Paulw56
author_rank: Newbie
timestamp: November 12, 2024, 05:50:14 pm
content: I made a large blunder and connected the positive lead to negative post with 3.2 battery pack heard pop unit reads volts no current. Iremoved board shows no damage 6800uf cap looks ok. Any suggestion would be apricated.

author: MathWizard
author_rank: Super Contributor
timestamp: November 17, 2024, 11:23:03 am
content: So are you saying you hooked up a 3.2V battery, backwards to the PSU, was it turned on, if so to what ? How big of a battery was it, and for how long ?If it was unpowered, a lot of current would flow into the reverse protection diode, D6 in the schematic below. The 4700uF would have the reverse diode voltage across it. IDK how bad -3.2 volts would be for the cap, not good tho, but sooner or later that diode would probably cook, a full 3.2V would make for a huge current. However higher the current that passed from the battery, the more voltage would be lost internally in the battery, so that would lower the voltage the diode and cap would see.Past that, -3.2V shouldn't matter to that power transistor, if it was turned off. If it was turned on, the output BJT might pass a lot more current, like in a little sim I just tried. The BJT went from passing 10mA into a 3.2V source, to passing ~8Amps, and the diode was passing ~10A.Yeah so check that output cap, diode and power transistor too.
Old analog oscilloscope question - Page 1
Forum section: electronics / beginners

author: zvonex66x
author_rank: Contributor
timestamp: January 19, 2018, 03:15:26 pm
content: Hi all. I'm new here so if I do some mistakes please just tell me....So, I have today trying to find some parts in my old collection of stuffs and there I see my old analog oscilloscope which I have used few years ago.Now I figured out that I still don't know what is this two inputs/outputs and i will be glad to find it out...Someone here know it for sure... so let's see..Marks RED

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 19, 2018, 03:22:19 pm
content: Z is "Z modulation" or intensity of the beam (input).The other one I guess is the time base output (sawtooth).

author: zvonex66x
author_rank: Contributor
timestamp: January 19, 2018, 03:28:51 pm
content: Thx, you are right with other one. i hooked up to my oscilloscope and it is sawtooth.Thanks

author: zvonex66x
author_rank: Contributor
timestamp: January 19, 2018, 03:41:49 pm
content: Nice

author: w2aew
author_rank: Super Contributor
timestamp: January 19, 2018, 04:31:59 pm
content: Quote from: PA0PBZ on January 19, 2018, 03:22:19 pmThe Z in an input, so you can use an external signal to change the trace brightness. You can do interesting things with this with creative external circuits - such as placing markers on the waveforms, or even turning the scope into a video monitor (like my avatar). The biggest downside to this scope is that it appears to be a recurrent sweep scope, not a triggered sweep, so it is more difficult to get stabilized traces, and the horizontal is not really calibrated.

author: james_s
author_rank: Super Contributor
timestamp: January 19, 2018, 07:39:38 pm
content: The Z input is handy for vector displays too, you can play games like Asteroids on a scope, or use one of the various scope clock circuits.

author: Tony_G
author_rank: Super Contributor
timestamp: January 19, 2018, 10:26:57 pm
content: I did a short video to show an example of how a HP 8340B used the Z axis:https://youtu.be/9nBKTJnEuSUHope you find it interesting.TonyG
Old Analog Osciloscope with wrong voltage values on one channel - Page 1
Forum section: electronics / beginners

author: augustol
author_rank: Contributor
timestamp: June 29, 2021, 11:47:27 pm
content: Hi, everyone,I'm a beginer in electronics, have made a couple of projects by myself and decided to stop, study and dig a little deeper. Not much long ago I dicovered the EEVBlog on youtube and eventually the actual forum. This is actually my first post here But I've been reading a lot of the posts even before actually signing in and stuff.So, I decided to get mysel an osciloscope. I was almost buying a Hantek usb osciloscope when I saw this old Minipa MO-1222 for sale. I decided to abandon the Hantek and get the old analog osciloscope.It's a two channel osciloscope and i just received it. It came with two probes (wich I'll probably substitute latter). I decided then to do the basic testing using the 1kHz 2V pk-pk signal built in the osciloscope. Channel 1 shows the right horizontal scale but the vertical scale is off (it shows aproximately 1.4V).Everything else seems to work fine, math function works ok, holdoff, trggering, level, coupling, etc. At least the things that I know how to check.Channel 2 is also perfect.Tried switching probes to check if the problem wasn't the probes and it's not.What should I do?

author: tunk
author_rank: Super Contributor
timestamp: June 29, 2021, 11:59:29 pm
content: Below volts/div there's another rotary knob - is it turned all the way up?

author: augustol
author_rank: Contributor
timestamp: June 30, 2021, 12:06:54 am
content: Oops hahaIt wasn't. Good thing I posted to the beginners begginers section.Thank you very much!And yes, I will do a little research on what does that knob do.
Old Circuit Boards as art? - Page 1
Forum section: electronics / beginners

author: Josephur
author_rank: Newbie
timestamp: December 27, 2013, 02:14:52 am
content: Let me explain what I would like to do. I have collected a large amount of old circuit boards that I want to use in the bottom of a 5ft glass case in my computer shop. These boards are from lots of different devices and some of them have LEDs.. I wanted to activate some of the LEDs via an Arduino, however I am worried that interfacing surface mounts and other LEDs mounted on the existing boards may cause a safety issue. Am I over worried that perhaps powering them might leave residual power in the board and perhaps cause overheating or fire?

author: Rerouter
author_rank: Super Contributor
timestamp: December 27, 2013, 02:28:32 am
content: take a scalpel and trim the traces so power only goes where you want it to, even better, poly-fuse your outputs, you cant really blow anything up if it cannot get enough wattage into it,for the most part those older boards leds will be driven by an npn low side switch, so some voltage can leak into the board on the high side, but limited by the current limiting resistor of the led.
Old converter +5V to +6v/-6v  circuit to replace - Page 1
Forum section: electronics / beginners

author: Daxxin
author_rank: Regular Contributor
timestamp: April 24, 2019, 07:32:08 am
content: just looking for some input how to replace this old part of schematic with something more actualand using less space . thats an UART circuit rs232 side +/- supply.

author: Yansi
author_rank: Super Contributor
timestamp: April 24, 2019, 07:37:43 am
content: ST232 (or, if you feel you have too much money, then MAX232).

author: capt bullshot
author_rank: Super Contributor
timestamp: April 24, 2019, 08:56:47 am
content: You might look for one of these 1W DC/DC modules:https://www.mouser.de/ProductDetail/CUI/PCN1-S5-D12-S?qs=sGAEpiMZZMvGsmoEFRKS8LplFs206tN2zFuLlXCrk2SUcLZoXUgtXA%3D%3DThey've got basically the same circuit inside.Edit: The link points to a +/- 12V model, but other voltages are also available with these. Although +/- 6V is quite uncommon, I doubt you'll find one. +/- 5V, +/- 12V and +/- 15V are more common with these. Otherwise, for a RS232, +/- 12V is the usual voltage specification, not +/- 6V (though it'll work).

author: mariush
author_rank: Super Contributor
timestamp: April 24, 2019, 09:15:41 am
content: If you don't need isolation and can live with ~+/- 10v (should be perfectly fine for rs232) , you could also use a couple of voltage doubler/inverting ICsex. seehttps://www.digikey.com/product-detail/en/microchip-technology/TC7660SCPA/TC7660SCPA-ND/418702use one for 5v->~2x5v and 2nd one for 10v -> -10vAll you need is bunch of ceramic caps and diodes around these DIP ICs.edit: the circuit in your picture seems like it takes 5v and makes+/- 6v .. but isn't rs232 +/-12v? I think the minimum threshold was +/- 8v that's why i said +/- 10v should be fine.for +/-5v you'd only need one chip in inverter mode and theres cheaper ICs for that with max 5.5v input voltage, like max1720 for exampleA more flexible (adjustable output voltage, so could have +/- 6v or +/-12v) would be to use two *33063 *34063 switching regulator... super cheap, available in DIP, can use lower switching frequencies to make circuit on stripboard, online calculators and freeware software on sourceforge to tell you component vales if you don't want to use formulas in datasheet.Requires inductor, diode and a bunch of ceramic caps and resistors but for 10-50mA you would possibly need for rs232 these should be super cheap. Probably less than 1-1.5$ for two , one in step-up mode and one inverting mode (neg. voltage)
Old Digital Experimenter XK 200  Is there any documentation anywhere? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: August 16, 2013, 12:30:16 am
content: I got this Digital Experimenter XK 200 with a bunch of other stuff when I went to buy an oscilloscope from someone but he wanted to get rid of everything in the room.https://app.box.com/s/uhsvv4er59dais02lb8sIt has a little breadboard that screws into the middle but I removed it just because I wanted another breadboard for something.I've found a black version of it on eBay that comes in a little carrying case but I haven't found out much about it.I'm assuming it came with documentation?Would anyone know where to find the documentation?

author: edavid
author_rank: Super Contributor
timestamp: August 16, 2013, 02:15:16 am
content: You might try asking Elenco, seems like their model number.

author: dentaku
author_rank: Frequent Contributor
timestamp: August 16, 2013, 02:39:35 am
content: I does seem to be a battery powered ICS branded version of the fancier Elenco XK 200.I found the manuals for the XK 150, XK 500 etc. on the Elenco website but unfortunately not the XK 200.Looking at the specs of the XK 500 I see it has a XR 2206 in it for the function generator. That would have been nice to salvage from itQuote from: edavid on August 16, 2013, 02:15:16 am

author: edavid
author_rank: Super Contributor
timestamp: August 16, 2013, 04:22:15 am
content: Quote from: dentaku on August 16, 2013, 02:39:35 amThat's why you shouldaskthem.

author: CharlieWorton
author_rank: Regular Contributor
timestamp: November 01, 2019, 04:59:15 am
content: The Elenco XK-200 Analog/digital trainer is supplied by Penn Foster (in the US) and International Correspondence Schools (in Canada) as a learning tool, used in completing some of the final lessons in their electronics technician course (described at this link:https://www.pennfoster.edu/programs-and-degrees/electronics/electronics-technician-career-diploma). The trainer includes a (very modest) power supply, a rudimentary function generator, a breadboard, a bunch of jumper wires, and some logic switches. I think Elenco valued it at around $200, but its capabilities could be obtained from various AliEpress kits for much less than that. If you enjoy breadboarding circuits, I guess it could be convenient to have the power supply right there with the breadboard. But it is intended primarily as a teaching/learning tool for students learning electronics, and its capabilities are reflected by this. >Charlie
Old Digital TV receivers & other stuff - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: August 22, 2017, 08:35:34 am
content: Hello all,I have a bunch of old Digital Video receiver boxes and a bunch of old ADSL modems. Do you guys keep this stuff? Can it be repurposed into something useful? Or do you just strip them for parts (ie power supplies and what not).Thanks,

author: dmills
author_rank: Super Contributor
timestamp: August 22, 2017, 09:31:35 am
content: That sort of thing usually just goes in the trash here, life is too short.I mean on a good day you might manage to salvage an impressively cheap power supply (But that will be the only impressive thing about it), or maybe a used hard disk, everything else in a mass market consumer box like that will be on some sort of undocumented SOC. Occasionally a modem will have a usable pulse transformer or something but they are cheap enough I would rather just add them to the next Mouser order then spend the time to rip one out of some old junk.No, good junk is usually industrial rather then consumer, much more prone to quality parts, and often the parts have actual datasheets.Regards, Dan.

author: made2hack
author_rank: Frequent Contributor
timestamp: August 24, 2017, 07:15:20 am
content: You are probably right Dan. There is no way to make millions of something for cheap comes with good components.
Old electrolytic capacitor markings - Page 1
Forum section: electronics / beginners

author: michalism
author_rank: Regular Contributor
timestamp: November 14, 2018, 08:01:40 pm
content: Hello all.I need to replace some leaky electrolytic capacitors in an old sound system made by SANYO. I think it's from the early 70's.Unfortunately, some small electrolytic capacitors use a marking that is not known to me.For example, in the attached picture the capacitor is marked as "M307" and has 1/25 printed on the other side (not visible in the photo).I would assume that 1/25 may mean 1uF/25V, but then what M307 means? in some cases letters are used to declare tolerance, but then what 307 means?Any help or reading material would be much appreciated!Best regardsMichalis

author: wraper
author_rank: Unknown
timestamp: November 14, 2018, 08:18:12 pm
content: QuoteMight be date code, batch number. Nothing useful to worry about.

author: michalism
author_rank: Regular Contributor
timestamp: November 14, 2018, 08:22:57 pm
content: Great, thanks. So, is my assumption for 1uF/25V correct?Sent from my SM-A600FN using Tapatalk

author: wraper
author_rank: Unknown
timestamp: November 14, 2018, 08:32:28 pm
content: Yes

author: Benta
author_rank: Super Contributor
timestamp: November 14, 2018, 08:50:53 pm
content: ^ This1 uF, 25 V. The size is also right.

author: Sudo_apt-get_install_yum
author_rank: Regular Contributor
timestamp: November 15, 2018, 12:42:23 pm
content: Ahh the good old days when PCB's were brown and had strange markings.
Old Fluke DMM got sticky... - Page 1
Forum section: electronics / beginners

author: umkumiut
author_rank: Contributor
timestamp: May 31, 2018, 06:11:09 pm
content: Hello.I was searching for a similar topic but could not find one. My apologies if there is one...I bought a nice old (20 years old or so) Fluke handheld DMM recently. It is in 'like new' condition, however, its yellow rubbery parts (the holster) are sticky. The holster is integrated into the housing, so it is not a separate part. I took the meter apart and tried to gently wash the housing with soap, dish wash and water, but once it dries up, the stickiness comes back.The plastic parts are fine, it is not hardened, no cracks or something.Has anyone saw something like this so far? Is there a solution to get rid of the stickyness?I learnt, that silicone gets sticky over time, but this material isn't silicone, or is it?Thanks

author: retiredcaps
author_rank: Super Contributor
timestamp: June 01, 2018, 12:11:40 am
content: Which model? A Fluke 70 series III?

author: helius
author_rank: Super Contributor
timestamp: June 01, 2018, 12:53:58 am
content: Natural rubber (latex) can break down over time into a viscous liquid. Aside from replacing the rubber part, I'm not sure there is any way to reverse the damage. One thing you can try is soaking it in a mixture of methyl salicylate (oil of wintergreen) and xylene. This is what is used to preserve rubber typewriter platens.

author: Cliff Matthews
author_rank: Unknown
timestamp: June 01, 2018, 01:20:14 am
content: Same happened to my model-77 in the 90's, so I brushed on blue silicone liquid meant to waterproof boots and it's been fine and dry since then. Some people say using talc powder works too.

author: umkumiut
author_rank: Contributor
timestamp: June 01, 2018, 08:25:23 pm
content: Quote from: retiredcaps on June 01, 2018, 12:11:40 amIt is a 89 IV.Thank you for your suggestions. After letting it dry overnight, it feels a little bit better now. I rubbed some talc powder on it, became a bit better.I'll make photos over the weekend if anyone interested.

author: retiredcaps
author_rank: Super Contributor
timestamp: June 02, 2018, 04:14:31 am
content: Quote from: umkumiut on June 01, 2018, 08:25:23 pmSee if your 89IV has the slow settle problem likehttps://www.eevblog.com/forum/testgear/fluke-89-iv-slow-settle-in-5v-range/

author: umkumiut
author_rank: Contributor
timestamp: June 02, 2018, 06:56:30 pm
content: Quote from: retiredcaps on June 02, 2018, 04:14:31 amYes, it is a bit slow, compared to a 287 and a 87V. It has FW1.00No big deal for me.

author: james_s
author_rank: Super Contributor
timestamp: June 02, 2018, 07:07:51 pm
content: I hate that soft touch coating that turns to sticky goo as it ages. I have an old 486 laptop that did that and cleaning it off is a real pain, maybe I should try the talcum powder approach. My current laptop has the same sort of finish so I'm sure it will also turn gooey eventually.
Old Gakken Kit restoration - Electronicraft - Page 1
Forum section: electronics / beginners

author: Quantumplate
author_rank: Regular Contributor
timestamp: October 14, 2021, 03:49:41 pm
content: Not quite a beginner here - three years in on the self-taught journey, and a few dark nights of the soul-dering irons down; plenty more to go I expect. Anyway at the start of my quest to understand the art of domesticated lightning ie electronics, I bought this lovely old 50-in-1 projects kit, and have been doing it up ever since. So far I've had to replace all the rusty spring terminals, all tin can caps, the solar cell, aerial and a transistor. Next up it's the relay: the contacts seem shot, probably not helped by my enthusiastic sanding early on. The coil resistance is about 480 ohms, it's a SPDT of course and energises at around 2.5v. The projects all use it in a circuit with a germanium tranny providing the current which I've measured at a maximum of 18mA.So is it an idea to try adding solder to the contacts? (i don't know a lot about relays...) In both positions I measure 0.3ohm IF they align properly, which being cheap and cheerful it doesn't do most of the time - especially in the energised position.Does anyone know a source for these old ice cube low volatge relays?And would any 500 ohm, 2.5 - 3.5v rmodern day relay do the job? Am I missing anything knowledgewise?Thankyou light sheddersps was going to add a pic, but too large. I'm sure you know the clear plastic relays I'm talking about though.

author: Quantumplate
author_rank: Regular Contributor
timestamp: November 14, 2021, 10:55:45 am
content: Just in case anyone else is ever seeking a replacement relay I found it! After a long search there's a reed relay equivalent made by Pickering - excellent helpful company. The serial number is 105-1-C-5/3D. It's 500ohms, near enough and 5v nominal operating. Works a treat. Phew...

author: tkamiya
author_rank: Super Contributor
timestamp: November 26, 2021, 03:26:13 am
content: I remember those! In fact, I had a few myself. Gakken was big in educational markets in Japan. Name itself translates to "schools and researches". Along with those kits, they had monthly publication that came with different projects. Fun time!

author: TERRA Operative
author_rank: Super Contributor
timestamp: November 26, 2021, 07:20:48 am
content: 'Otona no Kagaku' is the periodical magazine by Gakken, it translates to 'Science for Adults'. I've done a few for fun. Good times.
Old GE radio - Page 1
Forum section: electronics / beginners

author: CoopedUp
author_rank: Regular Contributor
timestamp: July 02, 2019, 04:35:18 am
content: I would like help to identify the vintage of this radio. all I know is it's somewhere between 1930-49. If anyone know something I'd appreciate it. Also is the circle with the 17 and other illegible text the date code. Thanks

author: CoopedUp
author_rank: Regular Contributor
timestamp: July 02, 2019, 04:41:37 am
content: I'm having problems with attachments

author: CoopedUp
author_rank: Regular Contributor
timestamp: July 02, 2019, 04:48:22 am
content: I would also like to know how much people think it would sell for, I plan on cleaning it up and recapping it to get it working. I saw one on eBay sell for around $300

author: Circlotron
author_rank: Super Contributor
timestamp: July 02, 2019, 05:08:26 am
content: 1937-1938https://www.radiomuseum.org/r/general_el_f74.html

author: CoopedUp
author_rank: Regular Contributor
timestamp: July 02, 2019, 01:17:39 pm
content: Oh thanks that didn't take long.

author: Wimberleytech
author_rank: Super Contributor
timestamp: July 02, 2019, 03:58:39 pm
content: You have your answer but I will add this.One of the images listed patents covering this unit. It was produced no earlier than the issue date of the last patent (the one with the highest number). Could be a lot later, of course.
Old Laptop CCFL Repair - Page 1
Forum section: electronics / beginners

author: Richard4432
author_rank: Newbie
timestamp: December 04, 2020, 02:53:33 am
content: Hi Everyone, I have been watching some videos on YouTube and practicing my electronics skills. I wanted to try and fix an old Sony laptop I have. I think the LCD Inverter is bad from the original machine. I have been unable to locate an exact replacement so I thought I would try a generic inverter and this is where I am at.The laptop works with an external VGA screen. It is a Sony Vaio PCG-F690 from around the year 2000. It is a P3 850, 128MB RAM, with an ATI Rage mobility. I though it would be a fun Windows 98 machine and would make for a good project to move up in my beginner status.The laptop screen just died one day. As a result this system has been sitting in storage for years. If the original inverter is installed the screen shows no signs of life. Using my meter I can measure the input voltages at the inverter.My original inverter has 5 pins. Voltage In (16 V), Drive (5V), Contrast, Brightness, Ground. The new board has 4 pins. Voltage In (5-28VDC), Drive (0-1 volt off, 2-5 volts on), Brightness, Ground. I soldered the wires from the laptop lcd cable to the inverter. My monitor will now turn on white but I can't see anything else. During the laptop boot the screen will go dark for a second before it redraws to white. Originally I had VCC, Drive, Brightness, Ground. I moved the Brightness wire to contrast. That made the layout VCC, Drive, Contrast, Ground. Both results are the same. If I do not connect either brightness or contrast the screen remains dark.1 - Can a generic inverter be used?2 - Am I going about this project the wrong way?3 - Does anyone know where I might get another generic CCFL driver that has 5 inputs?I need to know what to research or read to get me moving on the right path.Edit - I found the forum post for some good beginner materials and will start looking there.
Old Modem AC 9v Power Supply. - Page 1
Forum section: electronics / beginners

author: mwd
author_rank: Newbie
timestamp: January 17, 2022, 06:48:00 am
content: Hey Guys,Hope this is ok to post.I have an old external 56k modem I want to get working. I don't have the power adapter.It says it takes 9volt AC but I feel a 9volt DC adapter may work, something about old modems had AC adapters because it was cheaper but they still run DC internally.I can open up the modem and attach photos.Thanks

author: Buriedcode
author_rank: Super Contributor
timestamp: January 17, 2022, 07:09:25 am
content: Yeah, post a quick photo of the board - preferably where the power connector is. A bunch of power diodes and caps, or an integrated rectifier would pretty much answer this. There are some cases with AC input is preferable - such as generating higher voltages from diode multipliers, but its certainly not common.

author: SeanB
author_rank: Super Contributor
timestamp: January 17, 2022, 07:43:32 am
content: 9VAC because it half wave rectifies it inside, to get the higher positive and negative voltages to drive the RS232 interface. Then a regular bridge rectifier, that is then regulated down to 5V with a 7805 regulator or two in parallel. The AC is needed to operate. Look inside you will find the AC input, the power switch, then a bridge rectifier and a 1000uF 16V capacitor, plus another 4 470uF 25V capacitors and diodes, used to do a doubling of the voltage, and a negative doubling, to get a pair of 18V rails, that are regulated to + and - 15VDC rails with another pair of voltage regulators, or in some a pair of zener diodes and transistors.

author: mwd
author_rank: Newbie
timestamp: January 17, 2022, 09:17:02 am
content: Hey guys,Thanks for the replies! I haven't worked out how to get into it yet but I've found these docs:https://fcc.report/FCC-ID/H52PT-3020/80190.pdf- Block Diagramhttps://fcc.report/FCC-ID/H52PT-3020/80188.pdf- Inside Photos (bad quality)https://fcc.report/FCC-ID/H52PT-3020EDIT: I've ordered an HT802 ATA with the plan to setup 2 modems to communicate with each other. The other modem I have is a Netcomm MyModem (previously Banksia MyModem) which is very similar to the first modem I ever had, so that is cool.

author: Zero999
author_rank: Super Contributor
timestamp: January 17, 2022, 10:46:40 am
content: It'll probably work from a 9VAC or 12VAC square wave. Use a 12VDC power supply and an a self-oscillating circuit made with a few BJTs.Here's a circuit origionaly designed for 24V, but it will work with 12V.

author: magic
author_rank: Super Contributor
timestamp: January 17, 2022, 10:53:29 am
content: Sometimes a low power audio amp can be used to power such devices in absence of a suitable transformerAt least on the bench. For long term use, it shouldn't be hard to find a suitable wall wart.
old oscilloscope trouble shooting - Page 1
Forum section: electronics / beginners

author: woodyunreal
author_rank: Newbie
timestamp: October 24, 2013, 11:44:57 pm
content: I have a telequipment S54A oscilloscope pretty old. ( it was sitting around from long ago) I remember it was put away cause it tryed to test Mains frequency (*cough) unisolated. The unit still turns on but no trace on the screen If you turn it off the trace dot will scan from its left to the center of the screen as it fades away. Even the poor old Prob base has been broken (ill worry about that when i can get a possable useful display trace). So i was wondering what would be the best place to start checking circuits. i havent done anything but to take off the cover and look for burnt traces and scored components.I did find a Basic schematic for it. Its vague at best. Anyway any thoughtsmaybe the timebase circuits... thoughts , suggestions or direction of travel would be greatly appreciated.

author: Unknown
author_rank: Unknown
timestamp: October 25, 2013, 12:25:07 am
content: This document may be helpful:http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

author: woodyunreal
author_rank: Newbie
timestamp: October 25, 2013, 01:22:58 am
content: i shall loook it over
old osscilloscope - Page 1
Forum section: electronics / beginners

author: ethhanners
author_rank: Contributor
timestamp: January 31, 2015, 04:31:59 am
content: I have an old analog oscilloscope that is still surprisingly almost in spec. I am wondering if it would be a good idea to open it up and clean out the internal dust to clean it. Would this be recommended or should I just leave it?

author: radiomog
author_rank: Regular Contributor
timestamp: January 31, 2015, 04:34:21 am
content: clean it. helps keep the temps down.disconnect from mains first

author: ethhanners
author_rank: Contributor
timestamp: January 31, 2015, 04:44:54 am
content: thank you I had been told by some that I could break solder connections -thank you

author: radiomog
author_rank: Regular Contributor
timestamp: January 31, 2015, 06:11:09 am
content: just how do you intend to clean it?just blowing it out with air or ?let it cool down to room temp first

author: devanno
author_rank: Regular Contributor
timestamp: January 31, 2015, 06:42:01 am
content: If you blow it out with air, and if there's a muffin fan for cooling, before blowing on the fan, hold the blade still with your finger. Easy to overspeed these fans with a blast of compressed air, and they often die after that due to the stress on the bearings... at least that's been my experience working on PCs.

author: tggzzz
author_rank: Super Contributor
timestamp: January 31, 2015, 09:36:41 am
content: Quote from: radiomog on January 31, 2015, 04:34:21 amAnd leave disconnected for several hours, to ensure any capactors near the CRT have completely discharged. Think "dielectric soakage", and be wary

author: tautech
author_rank: Super Contributor
timestamp: January 31, 2015, 11:05:31 am
content: Quote from: ethhanners on January 31, 2015, 04:31:59 amHave a look inside and if it's clean...leave it.

author: lapm
author_rank: Frequent Contributor
timestamp: January 31, 2015, 04:33:07 pm
content: Personally at home i just use can of compressed air out at balkony... Dont want that dust cloud anywhere inside...Cleaning old instrument from dust shuld be ok as long as you dont use vacuum cleaner for it and just stick that tube everywhere... Vacuum cleaners generate some nasty esd braking voltages easily...