hybridfree/eevblog-posts huggingface dataset:
Driving multiple logic mosfets and cmos inputs from 7555 timer? - Page 1
Forum section: electronics / beginners

author: rmdr
author_rank: Newbie
timestamp: August 20, 2021, 08:15:03 pm
content: I'm designing a 12-hr CMOS clock and using a 7555 timer as a PWM generator (1.4kHz) for brightness control. The PWM output drives 8 loads, four of which are logic compatible 2n7002ps NMOS gates (30pF at 0.6nc) and the other four are CMOS inputs (three 7-segment decoder blanking inputs and one AND gate input). I may have gone overboard with the load resistors at 7.5k each. My reasoning was that the 7555 output source current is limited to 10mA before the output voltage drops significantly. At 8 loads, the total current is limited to 8*(5/7.5k) = 5.3mA. If the gate capacitance was large enough, this would for a very brief insignificant period of time during the transient on the gate, make the 7555 output voltage equal to 2V.Now I don't think I really need these gate resistors because the capacitance is so small, and I calculated that with 7.5k gate resistors, the gate voltage would reach 5V in 5*RC = 5*7.5k*30pF = 1.125 us, 0.315% of my PWM switching time (0.157% of the period), so 7.5k would suffice. I believe without the resistors, the current should not be a big issue, but I still added them due to multiple loads.Do I really need gate resistors to limit the current, even for 8 loads (highlighted in red in attached schematic), since the input capacitances are so small? The same applies for the gate resistors coming from the second counter bit 0, AM/PM indicator flip-flop, and second reset indicator from the XOR (all highlighted in green in attached schematic) since they all at <1Hz.

author: Zero999
author_rank: Super Contributor
timestamp: August 20, 2021, 08:26:11 pm
content: The problem is the switching speed will be low. Reduce the 7k5 resistors to something like 100R for a start. You could add an emitter followed, with a diode between the base (cathode) and emitter (anode) to speed up the on time, but it will reduce the output voltage by 0.6V.

author: David Hess
author_rank: Super Contributor
timestamp: August 21, 2021, 01:16:01 am
content: At such a low speed, the 7555 should drive that set of loads just fine.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 21, 2021, 02:31:06 am
content: You could use a second quad AND to avoid the discrete NANDs (and half as many 2N7002s), or really the gate will drive LEDs just fine by itself, then no transistors needed at all.I'd avoid 74AHC, regular HC is fine here. No need for anything faster. (Is AHC faster, or just unclamped input? I forget.)Also could use a second '3G14 to buffer the 555 output, or a hex (HC14) to do both in one chip.Tim

author: David Hess
author_rank: Super Contributor
timestamp: August 21, 2021, 09:03:36 pm
content: Quote from: T3sl4co1l on August 21, 2021, 02:31:06 amAHC is about 50% faster than HC.
Driving N channel high-side gate from external PSU. - Page 1
Forum section: electronics / beginners

author: step_s
author_rank: Regular Contributor
timestamp: September 11, 2016, 04:43:57 pm
content: Hi.I'm currently sitting with a small buck converter project, and have used P-channels, which works all fine and good, but would rather have an N-channel, due to the lower on resistance.The problem is now, that the N channel will need a higher voltage on the gate. So I made a setup with a small boost converter to drive a higher voltage from the normal input.I have 5V in, and 11V on the boost.The question is now: Wont I risk overvolting the gate of the output N channel when the gate goes high? Wont I risk going into negative voltages when the gate goes low? (Using a 20V MOSFET with 8V gate max)The point here is, that the difference in gate and source voltage is important, so if the MOSFET reacts with a delay, the gate can already have been driven high or low, before the source pin has started to react, and this can cause damage?Would a slight skew rate on the gate help to negate the voltage difference maybe?Hope this makes sense, and that you have some ideas

author: step_s
author_rank: Regular Contributor
timestamp: September 11, 2016, 05:47:22 pm
content: Thanks for the suggestion Blue. Seems easy to just use the CiS530, will have a look at it in the futureThe problem is here though, that the bootstrapping only allows for 80%, maybe 85% duty cycles, due to the capacitor recharge time.The point here was to try and charge LiPo's from 5V, which will require a very high duty cycle.With the current 3A N channel MOSFET I'm using, I see the gate and source voltage are very close (gapped by maybe 3V max). My concern was just with a bigger MOSFET with higher delay times. Just don't want to blow one up as soon as a start testing

author: step_s
author_rank: Regular Contributor
timestamp: September 11, 2016, 07:01:05 pm
content: I see.The speed is nowhere near that high. Running at 500kHz right nowI've just noticed alot of premade buck IC's, in the cheaper range, to have these duty cycle limitations. Although the SiC530 is not at all expensive, getting driver, and MOSFETS in one packageI will look into this some more!

author: arlipscomb
author_rank: Contributor
timestamp: September 11, 2016, 07:55:11 pm
content: For a small power supply does the difference between the N and P channel make that much of a difference?

author: Ammar
author_rank: Regular Contributor
timestamp: September 12, 2016, 01:38:13 am
content: There are chips designed for driving high side switches that take into account your concerns. Have a look on Digikey
Driving numitrons with PCF8574? - Page 1
Forum section: electronics / beginners

author: psycho0815
author_rank: Regular Contributor
timestamp: February 14, 2014, 08:04:38 am
content: Hi all,Yesterday i got a nicely packed package from the ukraine containing some numitrons i got off of ebay.So obviously i want to play with them a little. I don't have a proper driver chip though.What i do have in my parts bin is a couple PCF8574 I²C port expanders. Now i've seen projects where people use those to drive 8 leds but a couple of things have me confused.1) in the datasheet it says max Io is 25 mA which is fine since according to the IV-9 datasheet the numitrons only take about 20. But it also says Iss max is 100mA. Now doesn't that mean that while i can sink 20mA per i/o-pin i can only turn on max 5 at a time?2) in some of the howtos i've seen, they hook the leds directly to the pins, claiming that the chip will limit the current, but isn't that a bit risky? also wouldn't that mean that the chip has to dissipate the excess power? What resistor value would you recommend given a 5V supply? I was thinking 100 ohms, and decrease that to a min of 56 Ohms if it's too dim.Thanks in advance.

author: sync
author_rank: Frequent Contributor
timestamp: February 14, 2014, 12:35:36 pm
content: Have a look at this thread:https://www.eevblog.com/forum/projects/multiplexing-iv-9-numitrons/
Driving relays with Arduino and UNL2003 darlington array - Page 1
Forum section: electronics / beginners

author: sean87
author_rank: Regular Contributor
timestamp: August 23, 2017, 06:41:40 pm
content: Hi guys,I want to drive up to 3 relays using Arduino Due (3.3) digital output pins. There are three signals "REL_MASTER, REL_CH_A and REL_CH_B" coming out of the Arduino. I think UNL2003 has protection diodes but I added my own as well. Is the following wiring schematic looks ok? Can you please check before I blow up something

author: vk2amv
author_rank: Unknown
timestamp: August 24, 2017, 12:55:16 pm
content: Make sure you have current limiting resistors in series between the microcontroller and each UL2003 input.The value is not overly important for a basic project like this, anywhere between 2 to 10k should be fine I would think.Other than that as far as I can tell your schematic looks fine to me.

author: Ian.M
author_rank: Super Contributor
timestamp: August 24, 2017, 01:24:59 pm
content: ItsULN2003A, not UNL2003 or UL2003.The internal clamp diodes are rated for the full collector current so as long as the COM terminal is connected to the highest positive voltage ral supplying the relay coils your extra diodes are superfluous.You do NOT need extra resistors - the ULN2003A has integral 2.7K base resistors for operation from 5V logic levels. It needs at least 2.4V in to guarantee to pass 200mA load current, and if you use more than about 5K as an external resistor you wont get enough input voltage. If you expect to blow up the ULN2003 badly, 1K resistors *MAY* save your MCU.
5char - Page 1
Forum section: electronics / beginners

author: Thompson11k
author_rank: Newbie
timestamp: November 07, 2017, 06:00:32 pm
content: 5char

author: kjr18
author_rank: Regular Contributor
timestamp: November 08, 2017, 11:56:59 am
content: Try probing that ribbon cable and some of the leds for continuity and write down results. Probably they are powered in serial/parallel configuration, probably in groups of 5 or something like that. This way you should be able to make something out of it.

author: CJay
author_rank: Super Contributor
timestamp: November 08, 2017, 12:08:25 pm
content: Six contacts on the edge connector, that'll be five groups of LEDs so divide the number of LEDs by five and then multiply the result by 3 which will give you a rough figure for the voltage you need to drive them.I reckon roughly 25-30V, I've salvaged a few of those strips.Limit the current to 10mA at first.

author: mariush
author_rank: Super Contributor
timestamp: November 08, 2017, 12:28:58 pm
content: Those leds typically have a forward voltage of 6v , since there's two diodes in each package. Then you have several of them in series, usually 5 to 8 or something like that... basically you need 30 to 45v like the people above me say to get them working.The current is probably 100 mA for each led or something that would make them use around 1w at most (1w/6v = ~ 166mA) but to be on the safe side, limit the current to 10-20mA .If you don't have a power supply that can limit current, you can build something quickly with any lm317 linear regulator or some other fixed voltage linear regulator, just look in the datasheets at example circuits.

author: CJay
author_rank: Super Contributor
timestamp: November 08, 2017, 01:01:15 pm
content: Quote from: mariush on November 08, 2017, 12:28:58 pmWell spotted, I hadn't noticed that and haven't seen them like that before either

author: mariush
author_rank: Super Contributor
timestamp: November 08, 2017, 02:55:57 pm
content: To be more precise they look like they're the 6v 7030 variety.You can find them by searching for led backlight 6v 7030 (or some mix of these keywords) ... basically like i said 6v ~140mA (1w)Here's some examples :1.https://www.alibaba.com/product-detail/LG-Innotek-LED-LED-Backlight-1W_60673030140.html2.https://www.aliexpress.com/store/product/SEOUL-LED-Backlight-1W-7030-6V-Cool-white-90-100LM-TV-Application-STWRX2S1E/936602_32222537428.html
driving several high power LED - Page 1
Forum section: electronics / beginners

author: edmundopt
author_rank: Regular Contributor
timestamp: January 28, 2015, 04:26:22 pm
content: Hello everyone,I have a project with 4 LED, after some searching on my usual supplier(mouser), I found just what I wanted, the CREE CXA1512-0000-000N00M40E5, problem is, they are only available with the 37v, the 18v ones are out of stock.I choose this model because of size/lumens/angle and because I allready have the expensive connector with heat sink for it so I'll stick with it.Problem is the usual driving method was ONE switched managed boost converter --> FOUR switch managed buck constant current, but my design does not reach 37v on the output.. so I need a new one..I want sugestions for two things, first, are there any options to this :[SM BOOST CONVERTER] (from 11v~14v to 40volts out 2AMPS )--> [SM BUCK CONSTANT CURRENT] --> LED (must reach 350mA @ 37v )--> [SM BUCK CONSTANT CURRENT] --> LED (must reach 350mA @ 37v )--> [SM BUCK CONSTANT CURRENT] --> LED (must reach 350mA @ 37v )--> [SM BUCK CONSTANT CURRENT] --> LED (must reach 350mA @ 37v )sugestions for the boost and constant current regulators, many thanks

author: katzohki
author_rank: Frequent Contributor
timestamp: January 28, 2015, 05:15:48 pm
content: Not to skip your question, but did you try calling and ask when they are in stock?The part number you gave is for 37V unit. Apparently no one has 18V unit.

author: edmundopt
author_rank: Regular Contributor
timestamp: January 28, 2015, 05:18:07 pm
content: yes, they will have the 18v part available in June

author: edmundopt
author_rank: Regular Contributor
timestamp: January 28, 2015, 10:36:30 pm
content: I found the MeanWell LDD-350HS wich costs 7€ and looks perfect...So any other sugestions for wiring the LED's ??

author: theatrus
author_rank: Frequent Contributor
timestamp: January 29, 2015, 05:41:14 am
content: The Meanwell LDD units are perfect for a drop-in design like this.Otherwise, you need a buck and/or boost constant current controller. At 350mA there are a ton of options (NCP3066?)
Driving tons of small incandescent light bulbs - Page 1
Forum section: electronics / beginners

author: jimon
author_rank: Regular Contributor
timestamp: August 21, 2016, 10:53:21 am
content: So, let's say I have 72 light bulbs like thishttps://www.grainger.com/product/GE-LIGHTING-Miniature-Lamp-6VF02they are 5w 28v little monsters and I want to drive them digitally. There will be max 18 bulbs turned on simultaneously, and 6 turned on bulbs will be an average load. (PS. if anyone knows bulbs with smaller working voltage in #313 case - I'm listening)There is primer for driving them :http://www.allegromicro.com/~/media/Files/Technical-Documents/an295012-A-Primer-On-Driving-Incandescent-Lamps.ashx?la=enwhich basically says using current limiting resistor or warming up resistor, or just use current limiting driver and be done with it.So can I just use LED driver IC's and be done with it? Though I would like to avoid any PWM stuff if possible, to make it more "vintage" of sorts ..Or what would be the best way to drive them for one-off device? Cost doesn't matter much.

author: jimon
author_rank: Regular Contributor
timestamp: August 21, 2016, 11:07:39 am
content: 0402 would be quite a challengeI more looking for something that can provide multiple channels in one package ... otherwise indeed mosfet+resistor per channel is "a way to go"

author: jimon
author_rank: Regular Contributor
timestamp: August 21, 2016, 09:29:11 pm
content: Hm, so I guess instead of just #313 bulbs I can get any BA9s T3.25 bulbs ... which enables me to get 5v or even 2v bulbs!Than something like thishttp://www.ti.com/product/tlc59116-q1which is 16 ch LED driver start to make sense! I can cover 72 bulbs with only 5 IC's!
driving two LMZ14201 by using LM3880 with Mosfet  - Page 1
Forum section: electronics / beginners

author: BeO
author_rank: Contributor
timestamp: July 07, 2018, 10:46:40 am
content: HelloI need to drive two LMZ14201 in sequenceI will try to test this schematic updated with two Mosfet to drive the EN pin and one p Chanel to put the EN pin to the groundP Mosfet will ground through a resistor to force LMZ14201 to 0 V outputN Mosfet will power the EN pin to 5 Vand vise versa following flag level ( flag is in 5 V )can someone can give an advice on this schematicI will set one circuit per LMZ14201RegardsBeO
Driving/sensing signals through a magnetostrictive rod (mechanical filter) - Page 1
Forum section: electronics / beginners

author: cadr
author_rank: Contributor
timestamp: July 31, 2024, 09:05:13 pm
content: Hi,I got a nickel rod, and I would like to try to make it into some sort of mechanical filter (just for fun). Put a coil on each side, put a signal on one side, read it out the other, see what the frequency response is.Would like to use my nanoVNA to do this.What amplifiers on either side should I use? Any pointers to how to go about doing this? (I'm finding various articles from magazine reprints from the 50s, but nothing that has been super helpful yet.)Cheers!-Ben
Drok regulator -  LM2596 - Page 1
Forum section: electronics / beginners

author: Stuartambient
author_rank: Regular Contributor
timestamp: June 08, 2016, 10:35:49 am
content: I'm looking at using this type of regulatorhttps://www.amazon.com/DROK-Numerical-Regulator-Converter-Adjustable/dp/B01CE5P33M/ref=sr_1_5?srs=9119938011&ie=UTF8&qid=1465381625&sr=8-5&keywords=regulatorI like the fact that it has the ammeter and voltmeter built in but what I can't tell is if I'd be able to flush mount it to a front panel so the meters and pots are accessible. From the picture it looks like the caps tower over the depth of the meter.Edit - should have read through the feedback before posting. It can't be flush mounted.

author: mikerj
author_rank: Super Contributor
timestamp: June 08, 2016, 10:56:52 pm
content: Also there are no "pots". It's all controlled by push buttons, a particularly poor feature for a bench supply IMO.

author: Stuartambient
author_rank: Regular Contributor
timestamp: June 09, 2016, 12:21:24 am
content: Quote from: mikerj on June 08, 2016, 10:56:52 pmPush buttons and a screw driver, but those can easily be replaced by a regular pot. Once I get the board going I'll be changing over.

author: Stuartambient
author_rank: Regular Contributor
timestamp: June 09, 2016, 06:07:15 pm
content: Okay, I've been looking at the datasheet on the 2596 so I'm wondering about two things. The lm2596 is rated for output current of 3a, yet the specs on the Amazon site show rating of "5A MAX(Please use within 4.5A)". This just another case of tricky advertising?I was considering making one on my own but of course a ready made board is way easier. Anyway, the datasheet also recommends a 1N5823 diode. Hard to tell in the pic if they used one or not.http://www.amazon.com/DROK-Regulator-Converters-Step-down-Voltmeter/dp/B00S7YK8KS?ie=UTF8&psc=1&redirect=true&ref_=ox_sc_act_title_2&smid=AFHAE9RJVUMBEdit- so looking at another 2596 board (same maker) is rated for 3A. Seems that because they throw on some heat sinks and bigger caps the chip gets a higher rating. Some boards with bigger heat sinks have higher output current. Isn't this driving the device way beyond its recommended parameters?

author: eetech00
author_rank: Regular Contributor
timestamp: June 12, 2016, 04:44:11 am
content: HIThe LM2596 can provide 3A output but will go into current limit at 4.5A, so you don't want to run it greater than 3A.Also, don't rely on vendor specs, always check the manufactures datasheet. TI makes the LM2596.

author: Stuartambient
author_rank: Regular Contributor
timestamp: June 12, 2016, 01:54:23 pm
content: Thanks and yes I did read the data sheet. Actually the sheet is more like a bookI was just pointing out that they are trying to push the board with higher ratings by adding more heat sink. My designated power supply has a 3.3a max output so no worries about pushing it.I was digging around mouser and digikey to find vc's that have a higher current rating but the list is amazingly long.
Drop across AGW cable - Page 1
Forum section: electronics / beginners

author: joniengr081
author_rank: Regular Contributor
timestamp: February 26, 2024, 03:33:40 pm
content: I was searching a table for AWG cable resistance and found the following.https://www.powerstream.com/Wire_Size.htmThe cable AWG 12 is rated up to 9.3 A and having a resistance 5.20864 Ohm/km.I wanted to calculate the voltage drop for 8 meter long cable which is carrying 6 A current. There is a voltage at source 3.3 V at one end of the cable and the voltage sink ICs on the other end of the cable.V_drop = I x RV_drop = (6 A) x (5.20864 Ohm/km x 8 /1000)V_drop = 0.250 VThe calculation shows 250 mV drop across the cable. Is there anything I am missing ?

author: RoGeorge
author_rank: Super Contributor
timestamp: February 26, 2024, 03:59:09 pm
content: If the resistance is for one wire, an 8 meter cable has 2 wires, so 16 meters in total. 250mV drop on one wire, and the same drop on the other wire, total 0.5V drop on the cable. If the power supply gives 3.3V, at the other end of the 8m cable, it will be only 2.8V for a 6A load. And that is if the wires are made of Copper. Other materials will be worst.https://www.rapidtables.com/calc/wire/wire-gauge-chart.htmlSame website has a calculator for the voltage drop, too:https://www.rapidtables.com/calc/wire/voltage-drop-calculator.html

author: MarkT
author_rank: Frequent Contributor
timestamp: February 26, 2024, 08:36:08 pm
content: QuoteWell just that you don't need tables if you use cross-sectional area for these calculations. Resistivity of copper = 1.78 * 10^-8, resistance = resistivity * length / area (all in ohms and metres).Or a rough and ready method: 18 milliohms * (length in m) / (area in square mm)Use 35mohm for there-and-back.

author: JXstaystonight
author_rank: Contributor
timestamp: February 27, 2024, 03:03:57 am
content: Your calculation is correct, but it seems like you've converted the cable's resistance per kilometer to ohms for the given length of 8 meters, which is why you divided by 1000. However, since the resistance value you have is already given in ohms per kilometer, you don't need to divide by 1000 again.So, the correct calculation for the voltage drop would be:V_drop = I x RWhere:I=6 A (current)R=5.20864 ohm/km (resistance per kilometer)V_drop = 6×(5.20864×8)V_drop = 6×41.66912V_drop = 250.01472 mVSo, the corrected voltage drop across the cable would be approximately 250.01472 mV. Your initial calculation was correct; you just unnecessarily divided by 1000.
Drop in replacement for SN74LS123D with non-inverting input at 1A and 2A pins - Page 1
Forum section: electronics / beginners

author: muthukural001
author_rank: Regular Contributor
timestamp: November 23, 2019, 12:13:37 pm
content: Hi,I am looking for SN74LS123D replacement IC that should have non-inverting input at pin 1 (1A) and pin 9 (2A) where as in SN74LS123D those pins are inverting inputs.If the replacement is available, I don't have to do the rework.Please suggest.Thanks and Regards,Muthu
dropped my compartment box with many parts on the floor, should I worry? - Page 1
Forum section: electronics / beginners

author: exe
author_rank: Unknown
timestamp: December 30, 2018, 08:44:02 pm
content: Hi!I was removing my lab and accidentally dropped my box with LDOs, refs, opamps, etc from about 1.5m height on a concreted floor. Do you think something bad could happened to components? I'm not really worried if something died as I can replace it. I'm worried about long-term reliability. The box is a typical AideTek ESD-safe box.

author: Zero999
author_rank: Super Contributor
timestamp: December 30, 2018, 09:07:43 pm
content: They should be fine. I've dropped boxes of components like that numerous times and nothing has been damaged. The components are so light that won't hit the floor with enough force to damage them. If you're very unlucky the package could be damaged, in which case it's possible a wire bond inside has become weakened, in which case you should discard the component, if you're worried about reliability, otherwise it should be fine.

author: Brumby
author_rank: Unknown
timestamp: December 31, 2018, 01:55:11 am
content: I agree.To get any significant impulse force imparted to a component it would need to be solidly mounted to the toolbox case itself. If you've got components on reels, cut tape or in tubes or loose in bags, they might get a bit shaken, but the forces that matter will not be all that high.I would suggest that any component mortality that did occur because of this event will be unlikely and indistinguishable from a random failure.

author: james_s
author_rank: Super Contributor
timestamp: December 31, 2018, 05:45:50 am
content: I wouldn't worry about it. I've had RAM chips damaged by ESD but most jellybean parts are reasonably robust. If they parts were going into a satellite or missile or something I'd say write them off but otherwise don't sweat it.

author: exe
author_rank: Unknown
timestamp: December 31, 2018, 08:52:30 am
content: Thank you very much, guys! I'll report if something weird happened to the parts.

author: GreyWoolfe
author_rank: Unknown
timestamp: December 31, 2018, 10:33:51 pm
content: You should worry. You will miss picking up 1 IC land legs up that you will step on whilst barefoot.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: January 01, 2019, 01:49:44 am
content: Quote from: GreyWoolfe on December 31, 2018, 10:33:51 pmYep - BTDT

author: Brumby
author_rank: Unknown
timestamp: January 01, 2019, 03:58:21 am
content: Quote from: basinstreetdesign on January 01, 2019, 01:49:44 amI admit to nothing .....

author: james_s
author_rank: Super Contributor
timestamp: January 01, 2019, 06:48:57 am
content: I stepped on a TO3 once while wearing only socks on my feet. Ouch.
DRV8825 motor controller driver power on issues - Page 1
Forum section: electronics / beginners

author: newtekuser
author_rank: Frequent Contributor
timestamp: March 31, 2024, 05:41:22 pm
content: Hello All,I'm putting together a motor controller board using the DRV8825 IC and having some issues with power on. I'm measuring 12.2V at the input cap C5 as well as on C1, C3 and C4, but the internal regulator V3P3OUT does not produce anything. None of the IC pins are shorted and no motor is connected to VMA and VMB pins. nReset and nSleep pins are tied to VP3OUT via 10K pull-ups and the enable pin is floating. Per the data sheet, this configuration should enable the IC.Attached my schematic and board layout (2 layer with solid GND on bottom). The IC was purchased from DigiKey and should be good.I know that the calculation for Vref is now slightly off because I designed it for 12V not 12.2V but my understanding it is that if it affects anything that would be the current limitation.Is there anything that stands out as an issue with the schematic, or board layout that would cause this?

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 31, 2024, 06:39:51 pm
content: Maybe adding a 100nF cap between nRST and gnd so it resets at power-on?

author: newtekuser
author_rank: Frequent Contributor
timestamp: March 31, 2024, 08:14:58 pm
content: Quote from: DavidAlfa on March 31, 2024, 06:39:51 pmThat did not do it unfortunately.I found an article describing how to use the DRV8825 controller and they're tying reset and sleep pins to 5V instead of 3.3V. However, in my case I do not connect to the MCU (PIC) just yet which operates on 5V logic anyways.QuoteWould this be the issue?https://www.makerguides.com/drv8825-stepper-motor-driver-arduino-tutorial/Or is it a catch 22 issue because I'm connecting it to 3.3V when there's no 3.3V voltage because the regulator is not enabled? If that's the case reasoning tells me I should drive these pins (RST, SLEEP) high from the MCU.

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 31, 2024, 09:09:35 pm
content: Your problem is nSleep, it turns off V3P3OUT, so trying to get power from that pin will never work.nRST and nSleep have a 100K pulldowns, connect 12V to each pin through a 330K resistor.This will make a voltage of (12/(330+100))*100 = 2.8V.

author: newtekuser
author_rank: Frequent Contributor
timestamp: March 31, 2024, 11:58:54 pm
content: Quote from: DavidAlfa on March 31, 2024, 09:09:35 pmThank you! I ended up tying sleep and reset pins to another 5V rail I have in the circuit and it now works. Motor also spins fine in both directions
DRV8825 motor driver - motor winding pins polarity - Page 1
Forum section: electronics / beginners

author: newtekuser
author_rank: Frequent Contributor
timestamp: March 30, 2024, 04:07:51 pm
content: Very noob question:Per the data sheet of this IC, positive current for the motor winding pins goes from AOUT1 -> AOUT2 and BOUT1 to BOUT2.Does this mean BOUT1/AOUT1 are positive and BOUT2/AOUT1 are negative, or is it backwards? I know electron flow is from negative to positive, but convention is backwards. However, I do not want to blow up my motorIf this goes by convention rather than actual electron flow, then it should be A1 is +, A2 is - and similar for channel B, correct?

author: DavidAlfa
author_rank: Super Contributor
timestamp: March 30, 2024, 05:10:36 pm
content: You can't blow a DC motor with the wrong polarity, it will just run backwards.

author: newtekuser
author_rank: Frequent Contributor
timestamp: March 30, 2024, 05:33:24 pm
content: Quote from: DavidAlfa on March 30, 2024, 05:10:36 pmThat’s what I thought too, but got confused when some folks left negative reviews on amazon that wires were labeled incorrectly and blew their motors.

author: aliarifat794
author_rank: Regular Contributor
timestamp: April 03, 2024, 03:04:05 pm
content: AOUT1 and BOUT1 are typically connected to the positive terminal of the motor windings.AOUT2 and BOUT2 are typically connected to the negative terminal of the motor windings.Here is also the datasheet of DRV8825:https://www.ti.com/lit/ds/symlink/drv8825.pdf

author: pcprogrammer
author_rank: Super Contributor
timestamp: April 03, 2024, 06:42:23 pm
content: The DRV8825 is a somewhat dedicated stepper motor driver, and normally is connected to a single stepper motor that has two windings. The stepper motor has to be properly connected to be turning.The outputs are not labeled + or - because they can be either. Internally there is a H-bridge per winding, that can connect one output to the + and the other to the -, or the other way round, or have them both floating, or short a winding to apply break.Based on the DIR input the stepper motor will move in either forward or backward direction when step is pulsed.So it is not so much that the outputs need to be polarity correct but more phase correct. Look into how a stepper motor works to see what I mean with that.For driving a normal DC motor there are better motor drivers out there. Either with a single H-bridge for one motor or multiple bridges to drive more motors.
Dry bones - Page 1
Forum section: electronics / beginners

author: PerranOak
author_rank: Frequent Contributor
timestamp: August 29, 2019, 09:44:34 am
content: I was soldering a board yesterday and everything was going fine. Then, for no reason I could see, one joint would not solder! All the joints before it were OK as were all the joints after it.It was a manufactured PCB and the component was a through-hole T092 tranny - this happened on only one lead - with quality multicore solder and a Hakko FX-888D.The solder simply "climbed-up" the lead, away from the pad as if allergic to it! Neither flux nor masses of solder helped.Eventually, it worked after trying time and time again.Why on Earth does this happen and what should one do about it?

author: taydin
author_rank: Frequent Contributor
timestamp: August 29, 2019, 09:51:45 am
content: Must have been covered with some kind of oxidation. Those will be really hard to remove with heat, because oxides have a very high melting point. There are acid based fluxes for this type of situation, but those do cause corrosion themselves if the copper traces are exposed.

author: amyk
author_rank: Super Contributor
timestamp: August 29, 2019, 11:46:13 am
content: Was the pad connected to a large ground plane or similar?

author: PerranOak
author_rank: Frequent Contributor
timestamp: August 29, 2019, 12:33:06 pm
content: taydin: ah, I see.amyk: no but the lead was quite long.

author: MosherIV
author_rank: Super Contributor
timestamp: August 29, 2019, 03:22:28 pm
content: Hi. I agree with amyk. Most likely a pad with high thermal mass.You mentioned you eventually did it.It just takes a long time to get enough heat into the pad to get the solder to melt onto it.Even the best brand irons will take time.My personel preference is for Metcal irons, they handle high thermal mass the best, easily out perform other brands.Just look up the Metcal penny trick. Not many irons can solder together pennies or 2 nuts!

author: PerranOak
author_rank: Frequent Contributor
timestamp: August 29, 2019, 04:32:09 pm
content: They sound excellent.There is no tendency to damage components with them though is there?

author: MosherIV
author_rank: Super Contributor
timestamp: August 29, 2019, 05:51:39 pm
content: Yes, it is possible to damage components by over heating them.Do not worry to much about it, you are probably ok.

author: Brumby
author_rank: Unknown
timestamp: August 30, 2019, 01:55:05 am
content: In addition to oxides, you may have had other contamination, such as oils from fingerprints or any one of a bucket of other things.If these are not cleaned off before soldering, you will have a hard time and overheating components - and tracks/pads - becomes a much greater risk.Some can be cleaned with IPA while others may require other means - including physical scraping. But if you do scrape, be careful to only attack the contaminants. Be kind to the pads!
Drying wet pcb without wasting a heap of electtricity = problem solved? - Page 1
Forum section: electronics / beginners

author: bobbydazzler
author_rank: Regular Contributor
timestamp: March 20, 2021, 01:46:05 pm
content: I'm soldering a mini buck convertor to a bit of strip board to beef it up slightly and after I soldered in the diode I realized I hadn't cut one of the tracks properly. For safety from fiberglass particles I always like to cut stripboard while it's wet so it's much harder for the particles to float around in the air.After this I like to dry the pcb in the oven at low temperature but of course this wastes lots of power so this time I thought to just use a dummy load which works great, I sat the pcb on top of the 5w 10r resistor and powered it with 4v which is about 1.5w of heat and it only took 5-10min to completely dry.
DS1052E CH1 voltage scale strange once off reading..  - Page 1
Forum section: electronics / beginners

author: gjh
author_rank: Contributor
timestamp: June 17, 2012, 07:26:40 am
content: Im measuring TTL Signal "T1 IN" on a RS232 driver (Using SP3232 for a custom car OBD to RS232 adapter). I normally expect a signal not really higher than 5v, but on one of my readings I've got a voltage scale of 20V dc on CH1 which would translate on the graph to a little just above 40v.. When showing the display for Vmax, Vmin, Vpp, etc. it shows Vmax = 252mV, Vmin= 20.0mV, Vpp = 232mV, Vavg=130mV, etc..On my other readings (6 in total) the scale matches up to around 5v with full display (Vmax, Vmin, etc) showing similar ranges for whats mentioned above..Just wondering if its just a once off strange reading which I can ignore as long as other multiple readings show what Im expecting or is there something more happening here.?

author: bingo600
author_rank: Super Contributor
timestamp: June 17, 2012, 08:01:26 am
content: Did you by accident switch your probe from x10 to x1 , on that reading ?/Bingo

author: gjh
author_rank: Contributor
timestamp: June 17, 2012, 09:27:54 am
content: I may have accidently switched it between x10 to x1 or something like. I remember switching backwards and forwards with x10 to x1 since I couldn't believe my reading.. I didn't get a good reading until I hit AUTO again. Then I never obtained that reading again, even when I tried to reproduce it switching probe x1 to x10 setting.So I guess this can be put down just to interference from switching between x1 to x10 while taking the reading just on one instance.
DS1054Z 3v+3v=4v? - Page 1
Forum section: electronics / beginners

author: swgertsch
author_rank: Contributor
timestamp: January 14, 2016, 06:42:17 pm
content: New to oscilloscopes. Just bought a DS1054Z and I have been playing around with it to familiarize myself with its capabilities. Did a Math (A+B) operation against two signals feed from the probe calibration source. The individual source (CH1 and CH2) signals are identical (no surprise) but when I add them together the (A+B) resultant voltage appears to be 4Vpp. See attached picture.Note: The two input signals are superimposed on each other.No sure what is going on here. Can anyone explain this phenomenon?Also, there appears to be excessive noise at the 0V level (A+B) signal plot.

author: rrinker
author_rank: Super Contributor
timestamp: January 14, 2016, 06:49:09 pm
content: You didn't have one probe on 10X, did you?

author: Monkeh
author_rank: Super Contributor
timestamp: January 14, 2016, 06:52:57 pm
content: You have the math trace set to 1V per division. It's clipped.

author: swgertsch
author_rank: Contributor
timestamp: January 15, 2016, 06:55:58 am
content: Your absolutely right, the math A+B trace is clipped with the vertical scale set at 1v/div. I did not suspect the clip because the top of the A+B trace appears to be visible (it should not be there is the signal is "off" the screen).Anyway, I changed the vertical scale of A+B to 2v/div and "magically" the resultant is what I expected to see.I would have thought there would be some flag/message for the user (me) that the displayed section of a trace was being vertically clipped.So what did I learn? If the signal touches the top/bottom of the display assume the signal trace is being clipped from the display.

author: bitshift
author_rank: Regular Contributor
timestamp: January 15, 2016, 07:23:12 am
content: Quote from: swgertsch on January 15, 2016, 06:55:58 amYes, I usually have a rough idea of the level of the signal and then start with a larger V/div and then trim it down to fit the signal.Just for interest, you could guess that the signal was being clipped. No real world signal would be so perfectly clean and noise free on the edge of the scope display (look at the existing waves, the sum has to be as noisy as both combined).

author: Mechatrommer
author_rank: Super Contributor
timestamp: January 15, 2016, 10:22:08 am
content: Quote from: swgertsch on January 15, 2016, 06:55:58 ami agree clipped signal should not be visible. this is software bug that we have to live with $399 china made scope.. dont expect too much perfection

author: Jeroen3
author_rank: Super Contributor
timestamp: January 15, 2016, 10:36:38 am
content: Clipping is expected behavior, even for analog scopes. That it exactly matched the top of your screen is your bad luck.
DS1054Z mains input voltage - Page 1
Forum section: electronics / beginners

author: mammut89
author_rank: Newbie
timestamp: July 14, 2018, 05:16:42 pm
content: HelloAnyone knows if the DS1054Z has a Active PFC or some way accepts both 110 and 220v ?The reason I am asking is because I live in Norway (220v outlets) , I am visiting the US and can get the DS1054Z for much cheaper than I get here. Will the US bought DS1054Z switch to 220v automatically for me ?

author: ataradov
author_rank: Super Contributor
timestamp: July 14, 2018, 05:54:13 pm
content: Would not it be faster to just google and download the user manual?Or just google the images:

author: rstofer
author_rank: Super Contributor
timestamp: July 14, 2018, 06:22:56 pm
content: The label on my US version says 100-240V 45-440 HzChanged to 240V, I originally typed 250V...

author: mammut89
author_rank: Newbie
timestamp: July 14, 2018, 06:24:22 pm
content: thank you

author: rstofer
author_rank: Super Contributor
timestamp: July 14, 2018, 06:46:03 pm
content: Quote from: mammut89 on July 14, 2018, 06:24:22 pmPlease note that I made a typo in the original answer, 240V not 250V...
DS1054Z screen capture via USB - Page 1
Forum section: electronics / beginners

author: int2str
author_rank: Regular Contributor
timestamp: April 04, 2015, 08:14:23 am
content: Is there a way to capture a screenshot from the DS1054Z via USB to a PC (not using a flash drive)?I tried the "Print screen" function from "Ultra Sigma", but it gives me an error:"Error ! (Possible causes)1. Screen printing not supported by this unit.2. Communication error"I can talk to the device using commands, so I don't think it's 2.Any advise?Thanks!

author: int2str
author_rank: Regular Contributor
timestamp: April 04, 2015, 09:07:01 am
content: Might have jumped the gun with my post a littleUsing Marmad's tool, I was able to capture a trace.No freq counter in the display unfortunately.Will try the Rigol software next.
DS1307 max readings? - Page 1
Forum section: electronics / beginners

author: alecto
author_rank: Contributor
timestamp: June 11, 2017, 11:40:21 am
content: Well the question is in the subject...couldn't find the info in the datasheet...or the internet...currentlyI am reading the ds1307 memory every 10th of a second...wich means 36000 reads/1 houris it too much?

author: ggchab
author_rank: Frequent Contributor
timestamp: June 11, 2017, 03:25:50 pm
content: No problem. I made a clock based on the DS1307 and I read it 10 times per second.I could also have used the SQW/OUT signal programmed at 1Hz to read the chip once per second.

author: alecto
author_rank: Contributor
timestamp: June 11, 2017, 05:07:10 pm
content: thank youbelgian solidarity then...
DS1307 RTC WITH PIC16F877A  - Page 1
Forum section: electronics / beginners

author: neko efecktz
author_rank: Regular Contributor
timestamp: July 08, 2017, 02:51:57 am
content: Good afternoon every one.For a couple of weeks now I have been trying to download a workable code for PIC16F877A and LCD to set and display a DS1307 RTC.I'm using PIC16F877A because that is what I have.Not working at it full time.I am using MPLAB and am still basically a beginner.A lot of code on line is written in micro C or some other language called ASSY. Actually I know what ASSY is but I don't want to learn that as well as C.I use MPLAB because it works with PicKit 3I use Pickit 3 Because it works with MPLAB,I use PIC's because they work with MPLAB and Pickit 3if you get the way I've drifted so far. Quote Henry Blake (M*A*S*H)I managed to find some code written in MPLAB C and looked like it might get me started.I downloaded the code that included i2c.h RTC.h & RTC.CI added my own LCD Display Code.As can be seen i2c.h has Processor: PIC32MXDoes that mean this version is no good for PIC16F877A or just has some features that are not available in PIC16F877A but should still work.Where can I find the file i2c_legacyI'm not sure where I found the code.I have tried to find it again to add links to this post but it eludes me for now.i2c.h has/*******************************************************************************FileName: i2c.hProcessor: PIC32MXCompiler: Microchip MPLAB XC32 v1.00 or higherCopyright © 2008-2009 released Microchip Technology Inc. All rightsreserved.*/#ifndef _I2C_H_#define _I2C_H_#include <xc.h>#include <GenericTypeDefs.h>#ifndef _PLIB_DISABLE_LEGACY#include <peripheral/legacy/i2c_legacy.h> // Legacy definitions, do not use#endifRTC.h has/** File: RTC.h* Author: B.BINDU* ST Number: 206017553* Created on 03 May 2013, 1:26 PM*/#include <xc.h>RTC.C has/** File: RTC.c* Author: Student Companion SA:www.studentcompanion.co.za* Real Time Clock Using DS1307 on I2C Bus* To simulate in Proteus, The I2C debugger must be connected on the I2C Bus.*/#include <xc.h>#include "LCD_PORTS_V2.h" my own LCD Display code#include "RTC.h"#include <stdio.h>#include <stdlib.h>#include "i2c.h"I am unable to find i2c_legacy.h online.I have tried to find it in MPLABs download site but nothing obvious comes up.If anyone can help me out It would be appreciated.Thank you.BILL.
DS2072 dead, Help me!  - Page 1
Forum section: electronics / beginners

author: adaleju
author_rank: Newbie
timestamp: November 03, 2013, 02:40:28 pm
content: Hello friends please helpme, while updating my ds2072 shutdown power...it is possible to save? thx in advance

author: ivan747
author_rank: Super Contributor
timestamp: November 03, 2013, 02:58:30 pm
content: Is it new? If everything else doesn't work, you can try sending it to Rigol so they replace it under the warranty.

author: metalphreak
author_rank: Frequent Contributor
timestamp: November 03, 2013, 03:14:38 pm
content: Pretty sure there is a recovery method, where you hold down a button and have the update file on the usb drive inserted. Have a search through the big DS2000 thread on here.
DS2072 I2C DECODE HELP - Page 1
Forum section: electronics / beginners

author: bambam
author_rank: Contributor
timestamp: June 10, 2013, 09:48:37 am
content: Hi allDoes any one know of any good instructional/tutorial sites for hobbyists, on digital decode using the scope. im new to the hobby and only just getting into digital/mcu stuff and would like to try and make use of the features of my scope, im just not sure where to beginthanks in advancematt

author: Harvs
author_rank: Super Contributor
timestamp: June 10, 2013, 12:45:54 pm
content: By far the most important part of knowing how to use any decoder, is first knowing how to decode the bus data by hand, so that you understand what each of the bus states mean and can identify when the scopes decoder has got it wrong (or it throws up its hands to say there's something wrong with the data.)So if you haven't tried it yet, get some scope grabs of some I2C data to a device you know, print it out on paper, then go through the I2C bus transactions in the devices datasheet. You should be able to identify who is sending what. You'll quickly get the hang of it.Once you've got that down, when you open the decode menu on your scope, all the options will probably make a lot of sense. The actual scope operation is quite easy, as long as you know what all the bus transactions mean.

author: bambam
author_rank: Contributor
timestamp: June 10, 2013, 03:09:25 pm
content: Thanks for that, ill get straight into it although i sense some brain ache to come

author: Circuitous
author_rank: Unknown
timestamp: June 10, 2013, 05:46:32 pm
content: If you're looking for a book on it, here's one by forum member free_electron:http://www.elektor.com/products/books/electronics/en-mastering-the-i-c-bus.35.1855876.lynkx
DSO-213 - Page 1
Forum section: electronics / beginners

author: m3vuv
author_rank: Super Contributor
timestamp: January 07, 2022, 11:14:29 am
content: HI,can anyone tell me if these can do xy mode,if so i have the idea of using one with an oscillator to cobble together a sort of poor mans huntron tracker component tester,would be handy for off site work and could be pocket sized and battery powered.

author: rpiloverbd
author_rank: Regular Contributor
timestamp: January 07, 2022, 11:34:52 am
content: Is it DSO-213 or DS213? Are you talking about this one?Or something else?

author: m3vuv
author_rank: Super Contributor
timestamp: January 07, 2022, 11:42:15 am
content: im talking about this:https://www.facebook.com/marketplace/item/425558938930374?ref=search&referral_code=marketplace_search&referral_story_type=post&tracking=browse_serp%3A9d1b72dd-a819-445b-98be-5dd081ab15ed

author: HB9EVI
author_rank: Frequent Contributor
timestamp: January 07, 2022, 12:56:56 pm
content: had it, sold itit's not worth the time, it's just a toy

author: Gyro
author_rank: Super Contributor
timestamp: January 08, 2022, 12:11:41 pm
content: The DSO-213 and DS-213 appear to be the same thing. The DS-213 was developed by Miniware (same people as TS100 / TS80 / ? Screwdriver). The DSO-213 is the same model sold by SainSmart. From the pictures I've seen, so far it still bears the Miniware logo (SainSmart often pirate stuff).Here's a very brief summary by Ben Brown (Ralim) - author of the alternative TSxx IronOS f/w)...https://ralimtek.com/posts/2019/ds213/
dso 5202B display background - Page 1
Forum section: electronics / beginners

author: YaakovK
author_rank: Newbie
timestamp: June 18, 2023, 01:18:42 pm
content: Hello,Any idea how to change the scope black background to white background?It is critical for printing recorded oscillogram. The black background absorbs a lot of ink!Thanks,Yaakov

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 18, 2023, 02:15:47 pm
content: Try ImageMagick:https://stackoverflow.com/questions/9155377/set-transparent-background-using-imagemagick-and-commandline-prompt-or-If you scope has a network attachment, just find some software that captures through the network port.

author: YaakovK
author_rank: Newbie
timestamp: June 20, 2023, 01:40:03 pm
content: Thanks for idea! Based on it, I have used ACDSee photo-editor and found the solution.Yaakov