hybridfree/eevblog-posts huggingface dataset:
DP832 Rigol power supply question. (Sharing a common) - Page 1
Forum section: electronics / beginners

author: Plasmateur
author_rank: Regular Contributor
timestamp: August 11, 2019, 03:38:53 am
content: My question is in regard to channel 2 and channel 3 of the power supply found here:https://www.tequipment.net/RigolDP832A.htmlIn the bottom right corner you can see the negative terminals of ch.2 and ch.3 of the power supply share a common - and in another thread on here someone had said they share the same ground.But I didn't think these channels were referenced to ground until those terminals were physically connected to ground.So if ch.2 was set to 10V, that should be the potential difference between the terminals of ch.2 - and if the positive terminal of ch.2 was measured with a an oscilloscope probe tip, there would be some oscillating voltage measured until the negative terminal was connected to earth ground - at which point the scope should read 10V flat.Is this correct?

author: ledtester
author_rank: Super Contributor
timestamp: August 11, 2019, 04:05:36 am
content: QuoteI think they were saying the same thing. Often "ground" is used to refer to the negative terminal of a power supply, and it doesn't necessarily mean it is connected to earth ground. Channel 2 and 3 share the same negative terminal.The point is that ch 2 and ch 3 are floating but not isolated from each other. Ch 1 is isolated from the others, so you can put, for instance, ch 1 and 2 in series by connecting ch 1's + terminal to ch 2's - terminal. However, if you connect ch 2's + to ch 3's - you'll short circuit the supply.Since they are floating, ch 2 and 3 are not reference to ground by the supply. But once you ground, say, ch 2 you are also grounding ch 3.

author: Plasmateur
author_rank: Regular Contributor
timestamp: August 11, 2019, 04:14:51 am
content: Quote from: ledtester on August 11, 2019, 04:05:36 amOkay, that's exactly how I thought it worked. Thanks for taking the time to reply.

author: rstofer
author_rank: Super Contributor
timestamp: August 11, 2019, 04:34:12 pm
content: Which means that when you need +15V, -15V and +5V, Ch2 MUST be the +15V output. There a wiring diagram for this in the User Manual.This might be used for some dual rail op amps feeding into a single rail low voltage op amp before feeding into a uC ADC input.
dp832 spurious no load reading - Page 1
Forum section: electronics / beginners

author: gb243
author_rank: Contributor
timestamp: April 03, 2015, 11:55:02 am
content: After a long wait my new DP832 arrived yesterday but there is an issue. Channel 1 shows 40ma of current 20 seconds after startup (and channel turned on) even when there is no load. If I put a resistor accross the terminals sufficient for 1ma current flow the spurious reading goes away. If I put a proper load onto channel 1 or 2 they both read the same. The 40ma reading just vanishes. My resolution is only 10ma so should I just keep a high value resistor accross the terminals or send it back?I guess sending it back is a no brainer but that means doing without for many more weeks as I know the distributer has no stock. Has anyone seen this before?

author: saturation
author_rank: Super Contributor
timestamp: April 03, 2015, 04:39:31 pm
content: What current does it read when you short circuit channel 1?Can you short CH1 output with a DMM set to current mode and confirm the current readout?

author: gb243
author_rank: Contributor
timestamp: April 04, 2015, 06:08:52 pm
content: With no load it shows the 40ma any load as small as 1ma and the reading vanishes. If I set 8ma CC then my DMM reads about 9ma and the display shows 10 as that is the display resolution. From cold start up the 40ma reading takes about 90s to display. After warm up it appears rapidly from a full power down and restart.So the reading is more of an annoyance. Switzerland has the customer service of the UK in the 1970s. Something has to be on fire and the dealer will still tell you to send it back to the manufacturer. This current does not seem to be real and normally I can ignore these things it is just I can imagine this getting worse over time.
DPDT on/on switch replacement - Page 1
Forum section: electronics / beginners

author: breadhead124
author_rank: Newbie
timestamp: November 27, 2023, 12:26:15 pm
content: Hello everyone. Definitely a newbie here! I am attempting to replace a DPDT on/on switch in the attached circuit. It appears from the schematic that only three connections are used. I broke apart the switch to remove it and as you can see in the attached picture, only three connections were soldered. The other three had lengthened pins soldered onto the DPDT connections but these just passed through the board, no solder. I just want to make sure I am thinking right. Any help appreciated. Sorry, the switch in question is "S7" on the schematic.Thank you,Jim

author: Ian.M
author_rank: Super Contributor
timestamp: November 27, 2023, 12:42:02 pm
content: There is evidence of crystallized solder in two of the supposedly unsoldered holes and the third (top right) looks like it may have had an annular pad topside which pulled away together with most of the hole's plating, so I believe the original switch had dry joints on three of its pins, with insufficient solder to form a topside fillet on two of them. Its not unusual to find dry joint on components subject to mechanical stress in normal operation.The schematic shows all six pins connected and the pins that stayed in the PCB appear to be from different poles of the switch, so solder all the pins when you fit the replacement, as it doesn't make sense to leave any unconnected.

author: breadhead124
author_rank: Newbie
timestamp: November 27, 2023, 12:46:57 pm
content: I see three connections but fail to see the other three for S7?Thank you,Jim

author: Ian.M
author_rank: Super Contributor
timestamp: November 27, 2023, 01:00:21 pm
content: Sorry, I was confusing it with S3. You are correct, the schematic shows S7 as SPDT, with three connections. However it is very common to use a DPDT switch with one pole either not connected or wired in parallel with the other, in place of a PCB mount SPDT switch as with six legs in a rectangle it is more stable than with three legs inline.Look at the other side of the PCB as its tracks and pads should help clarify the actual connections to S7. You should see evidence of previous solder joints on the pads for the pins that pulled out.

author: breadhead124
author_rank: Newbie
timestamp: November 27, 2023, 01:32:35 pm
content: Thank you so much for your help!Best,Jim
DPDT switch trouble - Page 1
Forum section: electronics / beginners

author: r00n
author_rank: Contributor
timestamp: May 03, 2024, 11:44:02 pm
content: Hello there.I am having trouble with the DPDT switch in this schematic.In the position of the switch labelled fast it appears that one switch is routed to nothing while the other switch in fast position goes through the 1u cap. In the slow position of the switch we have a loop around R14 and R15 and the second switch routes down through the 10u cap. The 10u cap discharging slower than the 1u cap I understand, but the loop around the r14 and r15 has me confused. Perhaps I misunderstand the DPDT switch wiring or the schematic.Thanks again for your help.

author: BeBuLamar
author_rank: Super Contributor
timestamp: May 04, 2024, 12:02:29 am
content: In the FAST postition the top switch doesn't do anything. In the SLOW position the top switch put R14 in parallel with R15.

author: themadhippy
author_rank: Super Contributor
timestamp: May 04, 2024, 12:03:49 am
content: the switch puts r14 in parralel with r15 when in slow.

author: r00n
author_rank: Contributor
timestamp: May 04, 2024, 12:24:15 am
content: that's so embarrassing. can't believe I didn't see that.Thanks for not belittling me
DPDT switches and PCBs - Page 1
Forum section: electronics / beginners

author: frasdoge
author_rank: Contributor
timestamp: March 19, 2019, 07:29:39 am
content: Hello,I'm making my first PCB design and I can't find a decent price on a DPDT switch. More specifically I can, but only in panel form factors or with outrageous shipping costs ($20 shipping, 7+ days for a $3 component on DigiKey, Mouser, Element14).I've picked up a switch that's perfect but in a panel form factor (the rectangle pins with holes in them). Is there any way to connect and mount that to my PCB? Ideally I'd just grab the version with the through hole pins, but no hobbyist stores sell them and I'm not keen on the wait or bs shipping costs when I've got a bit of a deadline.Advice would be appreciated.Cheers

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 19, 2019, 07:51:38 am
content: Solder lug is the term you're looking for.I mean, you can still solder that to a board if you don't mind a chintzy butt joint (i.e., the lugs just butt up against the PCB, and a generous solder fillet is all that's holding it down). If you have enough space to form the terminals, you can get more of a gull wing or flat lead joint, still SMT.Better is using slot shape thru pads, and soldering the terminals into the board that way. You probably can't use round holes (like you can with round or square pins), because they'd have to be way too large. (Most fabs don't complain if you use slotted pads, it's pretty standard.)Best? Idunno, giving up and panel mounting it (and using wrapped and soldered wires, heat shrink -- a whole harness assembly) is way too much effort, plus it takes up space that you might not have, to begin with. Maybe "better" should be changed to "best" above?And yeah, good switches are stupid expensive, at least in small quantities. Hard to find in good styles too. It bothers all of us.You could always risk it on some Ali Express junk, maybe it'll turn out alright -- if not, you're only out a couple of bucks, equivalent to as much time you've already spent writing and reading in this thread already! (Never lose your perspective on this sort of thing. Unless you're doing it a thousand times over, it simply doesn't add up, to keep searching for something truly competitive!)Tim

author: Jeroen3
author_rank: Super Contributor
timestamp: March 19, 2019, 07:52:57 am
content: Quote from: frasdoge on March 19, 2019, 07:29:39 amLarger holes, more solder. Just like the rectangular power jack connectors.

author: frasdoge
author_rank: Contributor
timestamp: March 19, 2019, 10:23:22 am
content: Yeah I figured I was using the wrong term, will know for the future!I'm new to soldering so will have a chat with some technicians at uni about how they'd go about bodging my connector on.Originally tried to make my own footprint but the max diameter was 1 mm (the lug is 1x2) and didn't think to make a slotted pad.Found that RS Components has stock of the through hole version so sent in an order for that. They've not given an estimated delivery date but they don't charge shipping. Worst case scenario I'm out $2.50 and they'll arrive too late. Ah well.Cheers guys.
DPT design - Page 1
Forum section: electronics / beginners

author: ngalanos
author_rank: Newbie
timestamp: September 27, 2014, 10:48:03 pm
content: Hi,I am trying to design a Double Pulse Tester to investigate the switching losses of a MOSFET, but I'm having trouble with my Capacitor bank. Most of the designs that I found, are using bulk electrolytic caps, film and ceramic capacitors but i don't really understand the use of each one and how they pick their values. Is there any "guide" how to choose them or is it based on experience? Can someone explain ?Thank you

author: Paul Price
author_rank: Super Contributor
timestamp: September 28, 2014, 06:20:35 am
content: If you want to talk about a circuit..show your schematic.

author: ngalanos
author_rank: Newbie
timestamp: September 28, 2014, 09:27:57 am
content: my apologies...the schematic looks like the one in the photo attached.
Drag Soldering tip for Aoyue 968a+ soldering station - Page 1
Forum section: electronics / beginners

author: djd_oz
author_rank: Contributor
timestamp: December 02, 2020, 12:14:55 pm
content: Hey there,Was wondering if you are able to assist me with some recommendations on which tip to use for drag soldering with the Aoyue 968a+ soldering station.Many thanks!

author: rstofer
author_rank: Super Contributor
timestamp: December 03, 2020, 03:17:34 am
content: I use a 1/8" chisel tip. That is what I use but it isn't right.https://www.hakko.com/english/tip_selection/work_drag.html

author: uli12us
author_rank: Contributor
timestamp: December 03, 2020, 04:34:04 am
content: The recommended type for drag soldering is the type BCM or CM. The BC or C will work as well. The type with a small hole in it should be better, because you have a small reservoir of solder, with that you can remove too much solder from bridged pins, because the solder flows back to the hole. Or at least should flow, I haven't tested it until now.
Drain Voltage vs Drain-Source Voltage. Difference? - Page 1
Forum section: electronics / beginners

author: fourierpwn
author_rank: Regular Contributor
timestamp: December 13, 2018, 11:21:51 am
content: I think the title is pretty self-explanatory. For any FET or FET-like (MESFET, JFET, HEMT, etc) device, is Vd the same as Vds?I was once told that they're not the same thing but I do not understand why. I would say that this has to do with the point of reference but to say that Vd is not the same as Vds then what is Vd referenced to? If we say that it is referenced to some other terminal, then it would become VdX where X is gate (Vdg), body (Vdb), source (Vds). Right?Perhaps this is something which is only considered on the intrinsic level?

author: mikerj
author_rank: Super Contributor
timestamp: December 13, 2018, 11:30:54 am
content: You are correct, this is simply down to the reference voltage you use. Vd would typically mean the drain voltage w.r.t 0v, but the source terminal may not be tied to 0v so Vds would be different.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 13, 2018, 09:00:37 pm
content: Source is generally considered the common terminal. But do check if they're referring to a standard test circuit/fixture that they're using, and if the source voltage is nonzero, that will matter!Speaking of RF types, mind that Vds(max) is usually rated as the DC figure, while assuming an inductive load (RFC, bias tee, whatever) in a conventional common-source amplifier -- the peak rating (beyond which breakdown can be expected) may be 2 or 3 times higher!Or maybe it's not. The only way to tell is to waste $50+ by blowing one up.RF parts...Tim
Draining Coil/inductor magnetic fields. - Page 1
Forum section: electronics / beginners

author: MrZwing
author_rank: Regular Contributor
timestamp: February 01, 2015, 09:04:22 am
content: Is there a way to drain away the magnetic field in an coil/inductor faster in an oscillating circuit?I'm thinking more or less in a standard "on-off" where as soon as the power is cut is there a way in circuit to remove the magnetic charge faster?Or is it all in the material of the coil that determine that?/MrZ

author: MrZwing
author_rank: Regular Contributor
timestamp: February 01, 2015, 09:34:12 am
content: My plans is that I want to build a Tattoo (super stable) power supply and the faster the oils of the machine is drained the better "flow" the needle gets. so I though that not only by using better materials also have something in circuit that helps the drainage of the coils.Since i am completely new to electronics i see this as a long term project. is there a possibility to use a Transistor that turns on and open up a drain circuit the coil when the power is off and then shut off that circuit when power is back on? of am I taking unnecessary steps for something that can easily be done some other way?

author: MrZwing
author_rank: Regular Contributor
timestamp: February 01, 2015, 10:13:00 am
content: I would say this is the most simple setup, not what I'm planing on building but it shows the principle how the circuit works and is configured.

author: Seekonk
author_rank: Super Contributor
timestamp: February 01, 2015, 10:16:24 am
content: Shorting the coils seems obvious, but that actually slows down the mechanical action. Anything (capacitor, resistor, diode, MOV) placed across the coil slows it down.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 01, 2015, 12:19:22 pm
content: Since V = -dPhi/dt, you simply allow the voltage to spike as high as possible.It's not usually a big deal, as the magnetic field can decay in microseconds, while it takes milliseconds for the mechanical action to begin to move again.Tim

author: MrZwing
author_rank: Regular Contributor
timestamp: February 01, 2015, 12:48:15 pm
content: Thank you for the answers I will look into what you said and see how to implement it in my final design.
Drake W4 sticky meter - Page 1
Forum section: electronics / beginners

author: TUSHIN
author_rank: Newbie
timestamp: May 22, 2024, 07:35:19 am
content: I have an old Drake W4 wattmeter with a sticky meter. Before I try a small amount of machine oil on the meter bearing, has anyone seen the same problem and what was the fix?

author: Gyro
author_rank: Super Contributor
timestamp: May 22, 2024, 08:27:39 am
content: Welcome.Just a quick reply as I need to move. I've had a quick look on the web and all (there were lots of) the Drake (RF?) wattmeters I saw had traditional moving coil meters.Do notgo anywhere near the meter with machine oil, you will ruin it!Now please provide more detail - the model of the meter, a photo, more detail of exactly how the meter is behaving - is it in particular locations on the dial etc. You need to provide a decent level of information if you expect a reasonable level of help.Edit: sorry, I missed the W4, but as I mentioned, the nature of the sticking, whether you've had it for years and it's slowly / suddenly come on. Whether you've just received it from ebay etc. are all relevant.

author: jonpaul
author_rank: Super Contributor
timestamp: May 22, 2024, 10:59:04 am
content: A D'Arsonvol : meter movement is a PRECISION device with springs and bearing and tiny tolerances like a fine mechanical watchNEVER APPY OIL OR COMPRESSED AIRThis is typical of a Flake of scale paint or metal particle falls into the movement.General drill: Hold instrument with meter face, down,Tap sides repeatedly, see if any tiny flakes or particles fall on face.Snap face off, shake out particles.Test.No result, repeat.Jon
DRAM nodes + chip size calculation - Page 1
Forum section: electronics / beginners

author: tec5c
author_rank: Frequent Contributor
timestamp: September 03, 2015, 03:01:50 pm
content: I have come across a question that is beginning to consume me. The question stems for previous years take home exams at my University. I have spoken to quite a few people who did the exam with this question in it and not one managed to get it correct, most did not even attempt it.I have left out some of the details, as they are not significant to the question (though I can post everything up if anybody wants to see it)The question says. "For the 1 um node, calculate the chip size as a function of density (in powers of 2) if the constants of proportionality for the row and column addressing logic are both 20. Plot from 2^8 to 2^24."I can also post up my working so far, though I am not too sure if I'm even on the right track as I have been unable to find too much information online about this.Any ideas?
Drawing a potentiostat circuit! - Page 1
Forum section: electronics / beginners

author: Henry_90
author_rank: Newbie
timestamp: November 29, 2019, 01:04:16 pm
content: Hello everyone, I am new here!I am doing an exercise for a course and I really need some input. I have to draw a potentiostat design, 3-electrode with op amps. No current should flow through the RE. For this, I have the following drawing for now, which I am attaching.Please note I have VERY LITTLE knowledge on this topic, but I still need to understand the basics on how to draw this. Does the drawing look correct for the things I have written?After that I will also have to add a battery to apply different voltages (Where can I put that in the circuit?) and then another op amp with a rotary switch to vary the gain. How to draw the switch? Is that just a lever that opens and closes the line? Where to put it??Any advice?I really want to make this kind of correct, but I also don´t have all the time that it would be needed to learn the whole topic properly. It is not really my field either so I don´t even need that. But I still have to solve this exercise. So I´d just need to be pointed towards the right direction to solve this quickly, understanding something, but also without the need to become an expert on how to draw potentiostat circuitsIf anyone can offer a reply I will be very grateful!H
Dreambox 500HD rebboting whenever I change channel which involves switching LNB  - Page 1
Forum section: electronics / beginners

author: martin271260
author_rank: Newbie
timestamp: January 17, 2018, 02:09:26 pm
content: I have a Dreambox 500HD, and whenever I change channels which involves a satellite switch (I have dysec and 3 LNBs) the box switches off and reboots. Has anybody come across this problem? All other things are fine - switch LNBs configuration etc.

author: cvanc
author_rank: Frequent Contributor
timestamp: January 17, 2018, 02:56:32 pm
content: Hi Martin and welcome.I do not know anything about your specific equipment, but here are a couple of generic suggestions for troubleshooting pretty much anything:1- Always verify your power supplies are working correctlyFrom your description it seems possible that the switching between LNBs is related to your fault. And this switching is the kind of thing that might need "just a little more power, for just a moment" from your power supply. If your power supply was marginal, it might stumble during that moment. You will need some simple test equipment for this - a multimeter is the minimum, and an oscilloscope is really handy. But at least a multimeter.2- If possible, open up the unit and perform a visual inspectionIt does not work 100% of the time, but often you can SEE a problem inside a failing unit. And as step 1 suggests, you typically want to start by examining the power supply. (Is your power supply an external unit - i.e., a "wall wart"?) You want to look for things like this:Evidence of burning/overheating/discoloring (get your nose in there as well, sniff around)Examine electrolytic capacitors for signs of overheating/bulging/leakingLook closely at all the soldering - try to find any bad solder jointsAll three of these potential problems are common and represent a good start at understanding what's going wrong. With a little luck you can find something simple and obvious to take care of.Also, a really good idea is to 'get more eyes on the problem'... in other words POST PICTURES here on the forum of what you're looking at. There are a lot of folks here who will be willing to look at them and offer suggestions.Good luck with your repair.

author: stj
author_rank: Super Contributor
timestamp: January 18, 2018, 05:03:22 pm
content: test without the lnb's or switches.if it stops resetting, test one lnb at a time, and then add one switch at a time.it could be poor caps in the box/psu,but it could also be a problem in one of the switches or lnb'si used to be in this game, although the kit is generally very good, there are times water can get into a switch or lnb and do strange things.

author: Bicurico
author_rank: Super Contributor
timestamp: January 18, 2018, 06:23:06 pm
content: I had similar issues on a VU+ Duo. After replacing the Elkos it is working OK again.Satellite receivers have typically a high internal temperature, which harms the Elkos.If this does not fix the problem, get a new tuner.Regards,Vitor
Whats the component in my Dremal 800. - Page 1
Forum section: electronics / beginners

author: Strada916
author_rank: Frequent Contributor
timestamp: June 18, 2013, 12:32:38 pm
content: I am looking for a replacement part. From what I can gather its a schottky diode. But further googling has lead me to believe its possibly a MOSFET with out the gate connected and using the parasitic diode inherent in MOSFETS. Anyone else have any ideas as to what it is as mine has blown off and I have replaced the MOSFET but the until is no where nearly as powerful. Would this diode improve performance ? I am thinking the B-EMF from the motor is shuting the MOSFET down or the MOSFET I replaced the original with may not be up to spec. I think the replacement was a IRZ44Anyone got some ideas.The first picture shows the part circled in red.the other picture shows the original driver MOSFET.PS These pictures are from the following websitehttp://messageboard.dremel.com/Topic5273-28-1.aspx

author: Unknown
author_rank: Unknown
timestamp: June 18, 2013, 04:13:30 pm
content: Not able to tell you the exact replacement or actual number ! funny Chinese numbers; most likely a standard IRF840 MOSFET would do,or higher current ?... seeing they have gone to SMD without heat-sink, leads me to think it's not much more than a standard device.Pin-outs might be an issue, best to back engineer motor to device for information... the three pins are used, centre tag I expect is the d=drain, due the device base soldered directly onto the PCB.UPDATE: it's a... N-CHANNEL 30V - 0.0034 ohm - 80A TO-220 STripFET POWER MOSFETHTML View:http://html.alldatasheet.com/html-pdf/24512/STMICROELECTRONICS/STP80NF03L-04/1627/1/STP80NF03L-04.html

author: Strada916
author_rank: Frequent Contributor
timestamp: June 18, 2013, 08:08:41 pm
content: Quote from: vlf3 on June 18, 2013, 04:13:30 pmI know the main TO220 mosfet is a STP80NF03L, I can get a replacement however the circled device looks like some sort of mosfet used as a diode. Unless its actually a double package schottky diode?

author: Unknown
author_rank: Unknown
timestamp: June 18, 2013, 09:10:40 pm
content: Okay SorryI missed the detail, and now see what your getting at; well sadly I have no answer to this ? the numbers on the device don't provide any useful info, to help you.

author: sleemanj
author_rank: Super Contributor
timestamp: June 19, 2013, 02:50:28 am
content: Circled component is an ST LS 30 diode.Datasheet attached.

author: Strada916
author_rank: Frequent Contributor
timestamp: June 19, 2013, 08:12:38 am
content: Quote from: sleemanj on June 19, 2013, 02:50:28 amthank you will purchase and install.
Dremel main board: puzzled about AC dark magic - Page 1
Forum section: electronics / beginners

author: Erwin Ried
author_rank: Regular Contributor
timestamp: December 14, 2019, 11:43:01 pm
content: I have a broken Dremel 398 (with a small digital display that is always ON) and I am quite puzzled about 3 things (I am thinking maybe I could recreate the PCB with an Attiny, if I could understand about AC magic).1) How they convert 230V AC to 5VCC for the PIC with so little components?2) How do they detect the RPMs in the microcontroller only with 1 wire around the stator?3) The microcontroller and LCD are always powered on, but there is a switch that turn the Dremel ON and OFF (with a soft start), how does the uC knows WHEN to do the soft start/stop?PCB:Thanks a lot for your time

author: Zero999
author_rank: Super Contributor
timestamp: December 14, 2019, 11:56:21 pm
content: I think you properly need to reverse engineer the PCB, to answer all your questions.1) The microcontroller is probably powered using a capacitive dropper.https://www.google.com/search?client=firefox-b-d&q=capacitive+dropper.2) It might not use sensing at all and could be completely open loop.3) I don't knwo, there isn't enough information about how the switch is wired up.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: December 15, 2019, 12:01:56 am
content: Quote from: Zero999 on December 14, 2019, 11:56:21 pmGreat! probably yes, Ill try to reverse engineer the PCB. I removed most of the parts to test them but they are all fine (caps, triac, inductors, resistors). So the PIC or the small NPN transistor is one of the damaged parts.Quote from: Zero999 on December 14, 2019, 11:56:21 pmIt has:Code:Electronic feedback controller. Enchances overall torque and performance at low and mid-speed ranges.But as you see in the pcb, there is only 2 wires going to the brushes and 1 going to the stator armature

author: Zero999
author_rank: Super Contributor
timestamp: December 15, 2019, 12:06:23 am
content: Quote from: Erwin Ried on December 15, 2019, 12:01:56 amThere are ways to get the speed of a motor without two wire feedback such as: detecting the back EMF, or that wire could be picking up the electrical noise generated by the commutator, but it's possible there is no feedback at all and what you've read is just marketing BS.

author: schmitt trigger
author_rank: Super Contributor
timestamp: December 15, 2019, 12:08:37 am
content: Dremel motors are (or at least the one I got) universal motors.Meaning: series wound.Perhaps this single wire is a stator (field) tap, where the motor current can be indirectly read?As 0-999 mentioned, a full reverse engineering may be required.

author: Erwin Ried
author_rank: Regular Contributor
timestamp: December 15, 2019, 12:13:19 am
content: Quote from: Zero999 on December 15, 2019, 12:06:23 amBefore it was broken, you could feel the electronic feedback working (if you tried to stall it on low RPMs for example).Anyhow, I will try to explore the pcb on monday. The problem is I have a hard time finding logic on circuits dealing with AC stuff
drill bit Standard through hole lead size - Page 1
Forum section: electronics / beginners

author: amateur_25
author_rank: Regular Contributor
timestamp: May 18, 2014, 11:54:25 am
content: Am I correct in saying the standard hole for through hole components is 0.7mm ?I need to know because I need to buy more hss drill bits since they're very easy to snap when you're drilling free hand with a dremel.I been using the wrong size drill bit so my components wobble

author: Kjelt
author_rank: Super Contributor
timestamp: May 18, 2014, 12:02:41 pm
content: Make a very tiny hole first in the pcb with an ultra sharp punchiron. The bit will grab directly instead of wondering around and snap. Also fix the pcb tightly to prevent horizontal motion.

author: andtfoot
author_rank: Unknown
timestamp: May 18, 2014, 12:06:19 pm
content: I usually use 0.8mm for standard stuff, and 1mm for larger stuff.Seems to work for me so far.

author: sleemanj
author_rank: Super Contributor
timestamp: May 18, 2014, 12:43:37 pm
content: I use 0.8mm for almost everything, 1.1mm for slightly larger stuff, 1.4mm for very large stuff

author: woodchips
author_rank: Frequent Contributor
timestamp: May 18, 2014, 07:44:09 pm
content: Don't use twist drills. They are too long and flexible. Use the correct spade point carbide drills which have a 0.8mm bit only 3-4mm long in a 3mm shank. Also run them at 10,000rpm, or as fast as possible but less than 3,000 rpm and they don't cut too well.

author: ampdoctor
author_rank: Frequent Contributor
timestamp: May 18, 2014, 10:41:15 pm
content: When I roll my own boards I fully expect the fit and finish to be a little ugly. If you want pretty, farm it out! That said, if I'm working on building a prototype I tend to use the 3/64" bit you find in the common 7 piece dremel index. It's a little big but it's not horrible at least for the 1/2w resistors and more common TH caps I use. For 1/4 or 1/8w components you might want to go down to the 1/32" bit depending on the lead size. If you want the hole size bang on exactly right, then you'll probably want to invest in a set of precision bits and a drill press.Here's my personal slick trick for those "off the shelf" bits. I use that broken bit you speak of! When I secure it in the chuck there's only a small nub poking out and it doesn't flex or wobble even with a fair amount of downward pressure. It's just long enough to get through about 3-4 mm worth of FR-4 stock.

author: sleemanj
author_rank: Super Contributor
timestamp: May 18, 2014, 11:48:22 pm
content: Translated for the metric.Quote from: ampdoctor on May 18, 2014, 10:41:15 pm

author: ampdoctor
author_rank: Frequent Contributor
timestamp: May 19, 2014, 01:20:32 am
content: Quote from: sleemanj on May 18, 2014, 11:48:22 pmThat's fine. Just saying though that those 7 bit dremel indexes are labeled imperial and not metric.http://www.amazon.com/Dremel-628-01-Piece-Drill-Bit/dp/B0000302Z3
Drive current for led 0 to 100% - Page 1
Forum section: electronics / beginners

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: June 02, 2019, 07:24:53 am
content: 1. Need to drive a single white led, part no: 2ES103CW06000001 , datasheet:http://www.edison-opto.com/en/product/es_s_white_seriesDatasheet says it has Vf=3.4V & If=700mA, Peak pulse current: 1AIntensity needs to be varied from 0 to 100%.2. Want to know, suppose I want to glow led at 100%, should I give maxium 3.4V/700mA or I can increase voltage or current further for high intensity? If yes, how to calcualte maximum recommended values for safe operation

author: hamster_nz
author_rank: Super Contributor
timestamp: June 02, 2019, 07:56:02 am
content: In general for LEDs the average current is the important parameter, as the light is generated as the elections move through the device. Each electron that moves through the LED emits a little bit of heat and light, and in doing so will lose around 3.4V of energy.For this LED you need to design such the the average current is less than 700mA, and the peak current is less than 1A.A 1A current that is on 70% of the time, and quick enough you can't see it flash is also acceptable.Any more current than this risks breaking the device.

author: tggzzz
author_rank: Super Contributor
timestamp: June 02, 2019, 08:17:36 am
content: Since you are interested in intensity, you should alsomeasurethe light output as a function of current.It won't be linear.

author: digsys
author_rank: Unknown
timestamp: June 02, 2019, 08:55:00 am
content: If it is a good quality brand, you can often push them 2x or even 3x their max ratings, BUT with greatly reduced life.If you can get rid of the heat, then they will survive longer. Usually 150% w/heatsink is what most push to.A much better deal, is to use a higher op/efficient led and run it below ratings.

author: Vindhyachal.takniki
author_rank: Frequent Contributor
timestamp: June 06, 2019, 12:01:36 pm
content: I have been driving it at 700mAh with ease at good brigtness & able to vary to 0% also
drive gnd with attiny... possible? - Page 1
Forum section: electronics / beginners

author: Halford
author_rank: Contributor
timestamp: March 25, 2015, 10:20:10 am
content: Hello everyone,I'm a real beginner and I'm building an adapter for a video receiver.to select the channel you have to short gnd output (see picture).I do that with a dip switch, but for the project I have I would like to do it with a simple button.Can I drive that with an ATTiny?I mean replace the dip with the ATTiny85?ThanksHal.

author: Psi
author_rank: Super Contributor
timestamp: March 25, 2015, 10:43:43 am
content: yes, you can drive those channel pins with an ATTiny and make your own pushbutton controls in code.One issue you need to be aware of is voltage. I suspect those dip switch inputs are 3.3V.If you feed 5V into them from a ATTiny you will probably damage it.What you can do is change the ATTiny outputs between output mode (with logic low) and input mode (floating).This will be the same as what the DIP switch does.In one state the pin will pull to ground and in the other state it will be floating. No 5V is ever produced so there is no damage to the chip.However this is risky because you could make a mistake while coding and accidentally set the output to high.So i recommend you put some resistors between the attiny and the IC. 1K in each connection should be fine.For your codingDDRx sets input vs outputPORTx changes function depending on if DDRx is set for input or outputIf it's an output PORTx sets if the output is GND or 5V (0=low and 1=high)If it's an input PORTx enables/disables the internal pullupSo you want to set the bits in PORTx to 0 (so its always GND when set as an output)Then you can write code to change DDRx bits between 0 or 1 (0=switch off 1=switch off)

author: Halford
author_rank: Contributor
timestamp: March 25, 2015, 10:50:18 am
content: great news ! thank you!I saw that the operating voltage for an ATTiny85 is from 2.7v to 5.5v.... couldn't I run the whole board with 3.3v so no issues will happen?Thanks again for the helpHal.

author: rs20
author_rank: Super Contributor
timestamp: March 25, 2015, 10:54:04 am
content: Quote from: Halford on March 25, 2015, 10:50:18 amExcellent idea

author: Psi
author_rank: Super Contributor
timestamp: March 25, 2015, 10:54:30 am
content: Yes, if you run the attiny from 3.3V you never have to worry about it.You could forget about switching i/o between input and output state and just drive them as outputs.

author: Halford
author_rank: Contributor
timestamp: March 25, 2015, 10:58:09 am
content: yess!great news!Thank you for the inputs, this weekend I'll try to do a sketch for the codethanks againHal.
Driver for IGBT G40N60UFD - Page 1
Forum section: electronics / beginners

author: upeguiborja
author_rank: Newbie
timestamp: July 25, 2019, 10:06:05 pm
content: Hi,I'm currently building my first Tesla Coil, A SSTC based on the design this guide (https://www.loneoceans.com/labs/sstc2/), It has been a little hard for me to source the IGBTs and the ICs locally but finally today i was able to buy a couple of G40N60UFD IGBTs for the coil.The issue is i cannot find the Driver which is recommended in the guide (UCC27425) nor the (IC DS1233D-5+) IC, any of you have any recommendation for replacement components?.I've seen IR2110, MIC4425YN and MD1810K6 on local stores, but i don't know which suits the guide topology and characteristics better.and for the DS1233D i have no hope.Any tips would be helpful. Thanks
Driver for LED PCB - Page 1
Forum section: electronics / beginners

author: CHBowman
author_rank: Newbie
timestamp: August 30, 2022, 08:55:22 pm
content: Hi,I’m building a series circuit of four 500mA LEDs. I will be using a 25 Watt 500mA constant current driver. The question I have: is the amount of total watts used for the circuit calculated as the (Forward Voltage of each LED * # of LEDS) * (500mA)? If so the the total circuit will be 14W. Will 25W be too much for the circuit or will the constant current driver self adjust in this situation?This is my shopping list:4 series MCPCBhttps://www.cutter.com.au/product/mcpcb-xp120quad-lin/HYF38P40F290AG-S1 500 mA @ 5-7Vhttps://m.alibaba.com/product/62029092676/3535-SMD-300nm-308nm-305nm-310.html?LED Driverhttps://www.trcelectronics.com/View/Mean-Well/APC-25-500.shtml

author: mariush
author_rank: Super Contributor
timestamp: August 30, 2022, 09:07:18 pm
content: Leds in series : min voltage = number of leds x forward voltage of each led, current remains the sameleds in parallel : min voltage = forward voltage of one led, current = number of leds x current of single ledYeah the meanwell led driver in theory will work, it can do 15v..50v , so 4 leds in series at 5..7v would be 20-28v and that works out well.
driver to 12v LED strip??? - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: January 14, 2019, 05:41:34 pm
content: Hello!Im planning on installing some LEDs in my mothers kitchen.I already have the LED strips (5630).It will be about 3-4 m long.My question is what i should do for driver?How good r the cheap ones on ebay?Thanks in advance.

author: Zero999
author_rank: Super Contributor
timestamp: January 14, 2019, 09:00:16 pm
content: All that's needed is a 12V power supply. Buy a decent brand, from a reputable store.

author: Zero999
author_rank: Super Contributor
timestamp: January 17, 2019, 11:49:37 am
content: You didn't specify how many Amps the LED strip needs.LED strip has built-in current limiting resistors, so requires a constant voltage supply. Choose a 12V power supply with an equal or higher current rating, than the LED strip requires. There's no need to worry about fire, so long as you use a decent branded power supply, with over-current protection and suitable cable for the current rating.
Driving 110vdc load with mosfet - Page 1
Forum section: electronics / beginners

author: iceisfun
author_rank: Regular Contributor
timestamp: September 13, 2016, 09:49:00 pm
content: HelloI need help finding the correct mosfet to drive this load. I have a bunch of these and I want to drive them with a TTL output.The ones I have tried seem to have some leakage when gate is pulled down to ground.https://www.amazon.com/dp/B00LVP267S

author: Zero999
author_rank: Super Contributor
timestamp: September 13, 2016, 10:09:58 pm
content: All MOSFETs leak some current when off.You could try using a BJT instead, as it will have a lower cut-off current.

author: iceisfun
author_rank: Regular Contributor
timestamp: September 13, 2016, 11:08:10 pm
content: I ordered one up to test it out.Will getting a much bigger mosfet help?

author: Zero999
author_rank: Super Contributor
timestamp: September 14, 2016, 08:20:50 am
content: Quote from: iceisfun on September 13, 2016, 11:08:10 pmNo, if anything I would suspect a larger MOSFET would make it worse, not better, since it will have a larger die. A higher voltage, lower current rating may help though.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 14, 2016, 08:23:48 am
content: Think dumber. Put a resistor across the LED load!Or slightly less dumb -- more usefully -- use an incandescent bulb instead of a resistor? Might be useful, even if it's just as a pilot light? Idunno.Sometimes it's simple things.Tim

author: Zero999
author_rank: Super Contributor
timestamp: September 14, 2016, 08:35:44 am
content: Quote from: T3sl4co1l on September 14, 2016, 08:23:48 amDuh I don't know why I didn't think of that. lolIt can be a very high value resistor, to minimise the power dissipation, even 1M would probably do.

author: macboy
author_rank: Super Contributor
timestamp: September 14, 2016, 04:32:26 pm
content: Quote from: T3sl4co1l on September 14, 2016, 08:23:48 amA small incandescent bulb is a very clever idea, Tim. They have a much lower resistance when off/cold, so would be very effective at shunting the leakage current. Then when fully energized, the resistance goes way up and limits the power consumption. A bulb intended for a small plug-in 120 V nightlight would probably work very well.

author: tatus1969
author_rank: Super Contributor
timestamp: September 14, 2016, 06:31:31 pm
content: why are you worried about leakage current? Your 110V LED stripe will be perfectly dark when switched with any suitable MOSFET.

author: Zero999
author_rank: Super Contributor
timestamp: September 14, 2016, 06:42:07 pm
content: Quote from: tatus1969 on September 14, 2016, 06:31:31 pmMOSFETs generally have a leakage current of 1µA or more, which is enough to dimly light white LEDs.All that's needed is a resistor in parallel with the LED rope to reduce the voltage to below the LED strings' forward voltage. An incandescent lamp would do but I suspect it's overkill. A 1M resistor will draw 110µA when the LEDs are on and have <1V across it due to the MOSFET's leakage current.
Driving a 555 from another 555 - Page 1
Forum section: electronics / beginners

author: bitman
author_rank: Unknown
timestamp: August 07, 2018, 10:46:34 pm
content: I have a (to me) strange issue. I have a small circuit that needs to send out a set of small pulses from a push of a button. I have created two 555 timer circuits (using a LM556) where one is a momentary switch with about 1 sec hold time, and the other is approx 100Hz which is supposed to turn on ONLY when the output signal from the first timer is high. See the attached diagram.First of, this setup works albeit it took quite a bit of experimentation with the Control Voltage.Problem: When I don't use the switch, after a bit of time (5-10 seconds) I get a pulse about every second from the second timer - even though there's no signal coming out from the first timer (U1A). I found that adding a small resister in parallel with the D1 LED would fix this (not sure why) but if there's another circuit that turns on an LED for instance, somehow that triggers a single pulse from this circuit too.I'm sure I'm overlooking the obvious? I just cannot see it.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: August 07, 2018, 11:23:48 pm
content: HiPull Resistor 33K to ground, connect pin 5 to reset of second 556 and its CV pin using a 10nF capacitor to ground.

author: mikerj
author_rank: Super Contributor
timestamp: August 08, 2018, 08:17:07 am
content: I agree with with the above, use the reset pin to gate the second 555, not the CV pin.

author: Gyro
author_rank: Super Contributor
timestamp: August 08, 2018, 08:52:36 am
content: Looking at your schematic, I don't see a supply decoupling capacitor. With LM555/556 it's important to have a 100nF capacitor between supply and ground, close to the package. Without this, false triggering is possible (particularly in a dual configuration) - the output stages take a large supply current spike when they switch.While it isn't the problem in this instance, it's an important thing to remember.

author: malagas_on_fire
author_rank: Frequent Contributor
timestamp: August 08, 2018, 11:08:42 am
content: Quote from: malagas_on_fire on August 07, 2018, 11:23:48 pmHere is a quick drawing of the purpose connection, plus the bypass cap sugested by Gyro . It was added a 220 Ohm in series between output of first 556 to second 556 reset to protect pin of overcurrent spikes.

author: bitman
author_rank: Unknown
timestamp: August 08, 2018, 01:26:47 pm
content: Hello malagas_on_fire,Just a quick followup - your design was pretty much where I started except for the pull DOWN resistor. That change made it work. I've got some sources (books etc) that states what I did should work (and it actually did) so I'm now trying to figure out why yours is so much betterAnyway, thanks for the post - it was very helpful.
Driving a dual Anode LED  - Page 1
Forum section: electronics / beginners

author: made2hack
author_rank: Frequent Contributor
timestamp: June 23, 2017, 02:03:21 pm
content: Hello all,So I have a dual color LED (Red + Green) that share a common GND. So it is essentially 2 anodes (1 for each colour) and the common GND.I want to use the 2 pins from the TP4056 (Pin 6 STBY & 7 CHRG) to drive the dual anode LED. Right now, the charge board has 2 separate LEDs. When the system is charging, pin 7 (CHRG) is pulled to GND. A RED LED connected from VCC to Pin 7 through a resistor is turned on.When charging is done, STBY is pulled low, CHRG goes High-Impedance and a Blue LED turns on (connected from VCC to Pin 6 through a Resistor).How would I use my dual Anode LED with common GND since both status pins go low to GND?

author: MosherIV
author_rank: Super Contributor
timestamp: June 23, 2017, 03:26:58 pm
content: QuoteI do not think you can unless :a) you can change what Pin 6 & 7 do orb) you need extra components to invert pins 6 & 7

author: rstofer
author_rank: Super Contributor
timestamp: June 23, 2017, 04:52:57 pm
content: Google for 'common cathode pnp'You can use PNP transistors to drive the anodeshttps://www.reddit.com/r/electronics/comments/1b8mrr/pnp_transistors_for_common_cathode_rgb_leds/The fact that the existing signal pulls to ground makes the PNP approach fairly attractive.Or, buy the right LEDs...

author: StillTrying
author_rank: Super Contributor
timestamp: June 23, 2017, 05:09:42 pm
content: My first thought was that it can't be done without more components, my second thought is the'maybe'below.If the outputs are open collector you don't need the 1n914s, unfortunately its no-battery indication would now be both leds on instead of both off.

author: made2hack
author_rank: Frequent Contributor
timestamp: June 23, 2017, 07:01:58 pm
content: Quote from: rstofer on June 23, 2017, 04:52:57 pmAhh, I was using the search phrase 'driving leds from pnp' but that one makes sense.