hybridfree/eevblog-posts huggingface dataset:
Using protected 18650 if circuit already has protection - Page 1
Forum section: electronics / projects

author: Peabody
author_rank: Super Contributor
timestamp: May 25, 2020, 03:08:51 pm
content: I'll be using one of these:https://www.aliexpress.com/item/32870411748.htmland it already has the usual DW01 protection circuit. I just wondered what difference it would make if the 18650 used in this module is a protected cell. I assume at low current it wouldn't make any difference, but if your load is something like an amp, it seems you would be going through four mosfets, and that might make a noticeable difference. I don't have an unprotected cell at the moment to experiment with, but wondered if anyone has already looked into this. Basically, if you had to buy a battery for this device, would you make a point of buying an unprotected one, or does it just not matter?A related question. If I wanted to use a protected cell, but didn't want double protection, it seems I could bypass the protection on the module by just connecting the negative battery terminal directly to ground. Is that right?

author: tunk
author_rank: Super Contributor
timestamp: May 25, 2020, 03:35:52 pm
content: I don't know about the protection, but a protected cellmay not fit as it is 3-4mm longer than an unprotected cell.

author: KL27x
author_rank: Super Contributor
timestamp: May 25, 2020, 09:43:55 pm
content: I think almost all 18650 cells have a fuse in there. If you burn the fuse, the cell is dead. Some sellers might call this fuse "protection."I have used polymer batteries with an internal circuit that cuts out at overcurrent and have to be reset. That's annoying, because you have to put 4V on it to wake it up, again, and the protection acts like a fast fuse, and it should really be a slow-blow, IMO. I haven't seen that yet, on an 18650, but apparently they exist (^ and it adds 3-4 mm). Yeah, you will lose a tiny bit of power to the internal FET, but that will be very little. I wouldn't worry about it.All li ion chargers regulate charge current and max voltage. The circuit you linked also prevents overdischarge. The protection on the cell itself is often just for max current (for discharge. I dunno if it also works for charging, but the charger should take care of that). If your cell has extra goodies on the protection, then it might be redundant. That would be unusual, though, to have undervoltage protection on a cell, itself. The cutout voltage depends on the load, so it's not typical to add that to a generic cell. The board you linked decided that for you, but the optimal cutout will depend on the draw at the time, and is typically up to the designer/engineer to decide where that should cutout.
Using random scavenged ferrite bead on HDMI cable? - Page 1
Forum section: electronics / projects

author: lpc32
author_rank: Frequent Contributor
timestamp: October 15, 2014, 09:44:23 pm
content: I've an HDMI cable that appears to add noise to a coax antenna cable connected next to it. Will putting a random scavenged ferrite bead on the HDMI cable fix the problem?

author: wraper
author_rank: Unknown
timestamp: October 15, 2014, 09:54:05 pm
content: I depends. Definitely worth to try, if just putting it on does not help enough, make a turn through it. It might be that putting it on coax will give a better result or putting on both.

author: lpc32
author_rank: Frequent Contributor
timestamp: October 15, 2014, 11:03:02 pm
content: Anything specific to look for?I think I may have a beaded VGA cable somewhere, but not sure if the bead can be opened easily.

author: wraper
author_rank: Unknown
timestamp: October 15, 2014, 11:16:02 pm
content: If you have any toroid ferrite or iron powder core lying around it would also do.

author: lpc32
author_rank: Frequent Contributor
timestamp: October 16, 2014, 05:41:27 pm
content: Nice idea, thanks. Maybe I can find some in old PSUs, but not sure if large enough to go over the antenna connector.

author: SeanB
author_rank: Super Contributor
timestamp: October 16, 2014, 06:21:55 pm
content: The beads on cables typically are moulded on, and will probably not be openable to slip over the cable end. You can probably fit them to the coax though after taking the F connector end off. The ferrite toroids in PC power supplies will fit over a HDMI plug though, but will not be as effective, you might need both and to use 2 or 3 stacked on the HDMI cable at both ends to provide better attenuation. Both types are cheap or free if you have old electronics around.

author: macboy
author_rank: Super Contributor
timestamp: October 16, 2014, 06:53:38 pm
content: Try asnap-on ferrite.
Using regular DPDT relay to convert delay-on relay to delay-off relay - Page 1
Forum section: electronics / projects

author: calzap
author_rank: Frequent Contributor
timestamp: February 02, 2020, 05:30:54 pm
content: This is largely a mental exercise and probably not original. I would never use such a circuit except in an emergency or maybe a proto-prototype if a delay-off relay wasn't available. If a delay-off relay was needed in a design, that's what would be specified. However, I recently received a batch of nice delay-on relays and wondered if there was a way they could be used as delay-off relays. Because they are double throw relays, it's possible with the addition of a regular (aka instant or no-delay) DPDT relay. And to be safe in most situations, a SPST-NO relay would be needed too.The basic design is pictured below. Some items that would normally be used, like coil TVS devices, have been omitted. The circuit is shown with electromechanical relays, but would work with SSRs.To see how it would work, we'll step through use of the control switch.1. Imagine the control switch is open and has been for at least the delay time of the delay relay. The instant relay coil is not activated, so there will be no power to the load via the instant relay. However, there will be signal power from the instant relay to the coil of the delay relay, so there will also be no power to the load via the delay relay.2. Now imagine the control switch is closed. The coil of the instant relay will be activated and the instant relay will send power to the load and stop sending signal power to the delay relay. Because the delay relay is no longer be receiving signal power, its coil will be deactivated and it will also start sending power to the load.3. Next imagine the control switch is opened. The coil of the instant relay is deactivated, and it will no longer be sending power to the load. However, the instant relay is now sending signal power to the delay relay. The delay relay will continue to send power to the load until the delay time has expired, at which point, its coil will be activated and power will no longer be sent to the load.If unplanned power to the load would be harmful (often the case), then the safety relay should be used. Without the safety relay, if the signal power source fails, but the load power supply is active, then the load would be energized. The safety relay eliminates this scenario. No safety relay would be needed if signal and load use the same power source.This circuit has disadvantages compared to a single delay-off relay:a. more complex; so, more ways to fail.b. more expensive in most cases.c. requires more space.d. at least one relay will always be powered.
Using Rigol DS815-TG for RS-485 analysis? - Page 1
Forum section: electronics / projects

author: w3amd
author_rank: Regular Contributor
timestamp: January 24, 2016, 01:25:27 am
content: Hi guys,Would it be better to use a scope or spectrum analyzer for RS-485 analysis? I may have some noise problem but need to investigate. I'm getting a combination of additional unexpected data on the bus, alignment issues and CRC errors. Some times an extra character appears in front of the data packet.If it would be the spectrum and the spectrum expects 50 ohms load what would I need to add externally to measure with the spectrum.Load on the ends of each RS-485 side should be about 120 ohms so this in parallel I expect would be half. However, currently the line lead on the RS-485 bus is less than a meter long so it isn't terminated at either end.Cheers,John

author: TheSteve
author_rank: Unknown
timestamp: January 24, 2016, 05:52:12 am
content: No idea how you'd use a spectrum analyzer for that unless you're experiencing some RF interference. A scope is your best bet, especially if it has a serial decoder built into it.

author: w3amd
author_rank: Regular Contributor
timestamp: January 24, 2016, 08:20:31 pm
content: Hi Steve,Thanks for your response. I was going to look for the offending frequency. I have further development on this from testing so I'll add a post because the subject is now different.John

author: georges80
author_rank: Frequent Contributor
timestamp: January 24, 2016, 09:01:07 pm
content: Scope. If the interference is large enough to affect the differential nature of RS485 you should EASILY be able to see it with a scope. With 2 channels you can look at the input and output of the RS485 transceiver.cheers,george.

author: w3amd
author_rank: Regular Contributor
timestamp: January 24, 2016, 09:02:59 pm
content: Thanks George,If I can get up the hill tomorrow to get into the office I'll give it a look. We got a meter here on the East Coast yesterday.John
Using Samsung SmartTV for distributed stream around build. - Page 1
Forum section: electronics / projects

author: mrpackethead
author_rank: Super Contributor
timestamp: April 24, 2018, 08:28:35 am
content: I want to be able to place a number ( > 20 ) Samsung Smart TVs ( or other brand possibly ) around a building to display the same video source. I'd like to connect them via either wifi or wired ethernet. It just seems to me that theres no reason why i shoudl have to use an external box such as a raspberry PI, or similar.. theres enough brains in those TV's that in theory i shoudl just be able to find the right app to listen to a suitable multicast IP Source.Any ideas>
Using SD power switch to switch the power supply for 1.8 V signaling in SD card - Page 1
Forum section: electronics / projects

author: PRI@123
author_rank: Newbie
timestamp: January 03, 2023, 03:37:07 am
content: I am planning to use the SDSDUN4-128G-GN6IN SD card in my design. As higher bus speeds require low-level signaling, UHS-1 adopts a 1.8 V signaling level for SDCLK, CMD and data lines [3:0].To change to 1.8 V signaling, the microcontroller (MIMXRT1024CAG4B) NVCC_SDD power pin has to be changed from 3.3 V to 1.8 V. To switch the voltage from 3.3 V to 1.8 V, I am planning to use the SD power switch BD2204GUL-E2, which has a continuous load current of 0.5 A and an absolute maximum current of 1 A. The maximum current consumption of SD card in UHS104 mode is 800 mA and I'm planning to operate the SD card at 60 MB/s.Can I use this SD power switch, as my continuous load current of this switch is only 0.5 A, but my SD card current consumption could be 800 mA (as per physical layer simplified specification V9.00 on sdcard.org)?enter image description here

author: thm_w
author_rank: Super Contributor
timestamp: January 04, 2023, 10:15:11 pm
content: The Vdd to the SD card should be constant at 3.3V. The switch to 1.8V is for the IO only, and current requirements there would be fairly low.https://media.digikey.com/pdf/Data%20Sheets/Viking%20PDFs/VTUSDzzzGCCxMTLC.pdf

author: PRI@123
author_rank: Newbie
timestamp: January 05, 2023, 05:01:56 am
content: Thanks for the response. Can you explain how and when the signaling voltage switch occurs?
Using Sealed USB-C Connector in High Humidity Environment - Page 1
Forum section: electronics / projects

author: elefurtronik
author_rank: Regular Contributor
timestamp: January 16, 2023, 09:42:26 pm
content: Hello,I would like to make a power connection with a USB-C connector in high humidity area. Is it possible to make it happen? I don't want any battery drainage and also short circuits on my electronics. My control circuit has already been sealed. I will also design a battery cap with USB-C male head.If you know, a sealed USB-C male-female match which has been used before, please let me know.

author: thm_w
author_rank: Super Contributor
timestamp: January 17, 2023, 12:29:14 am
content: Cell phones.They have wet port detection, if they detect a short/water then they will not charge.You can also get the screw cap style, not sure if that is what you are talking about:https://www.mouser.ca/new/amphenol/amphenol-ltw-waterproof-usb-3-a/What voltage and power are we talking about?

author: elefurtronik
author_rank: Regular Contributor
timestamp: January 17, 2023, 07:55:02 am
content: Hi,Here, the issue is if I put wet protection, how much does it cost to me minimum?My battery is 6v and load pulls max around 1A6V, 3W-6W

author: jonpaul
author_rank: Super Contributor
timestamp: January 22, 2023, 05:26:00 am
content: Neutrik professionnel USB portj
Using SMPS for PWM motor controller - input filtering? - Page 1
Forum section: electronics / projects

author: Buriedcode
author_rank: Super Contributor
timestamp: April 24, 2025, 05:37:36 pm
content: Hi,I have a proxxon micromot 50, along with several other "Minicraft" drills. I have the power supply for the Minicraft - 24VA 9-16V SCR speed control - that works well but I was thinking about making a dedicated supply for the slightly more powerful (40W) proxxon.The original supplies for these typically use a large iron transformer with SCR speed control. Simple and effective. But I don't have a large 50Hz transformer, got plenty of 12-18V, and laptop power supplies that can supply >3A. So I have two related questions:1) Given a PWM control is effectively on/off, should I put a large filter (caps + inductor) between the SMPS and the PWM controller, or do you think the power supply won't be too bothered by rapid changes in loads?2) I have limited experience in motor control, but I have read that one sohuld choose a PWM frequency so that the current ripple through the motor is <10%. I have no need for absolute speed control (no feedback), nor any need for high torque at very low speeds. The drill claims max 20k RPM, so a control from 30-100% power would be just fine. Any ballpark figures of what PWM frequency I should use? And is that 10% figure correct?If the above is more-or-less correct, then I guess that SMPS will see just a 10% variation in load, and so, will probably behave. Given I am building this from scratch, would sensing the current to the motor be wise? Simple is good, but I thought this would be a good excuse to make something a bit better than "just a 555 and MOSFET" job - perhaps using a PIC/AVR PWM module spefically designed for motor control.Aside from simplicity, the only other advantage I can see of the original iron transformer + SCR is its weight - a heavy solid box sits nicely on the bench
Using solder resist instead of silkscreen to get black text and graphics? - Page 1
Forum section: electronics / projects

author: kasbah
author_rank: Contributor
timestamp: November 20, 2016, 07:35:35 pm
content: I am making a weird looking PCB as promotional item and just got the first boards back. It's a light following bristle bot inspired bythis one by Facelesstech.I don't know if my version works yet but before even assembling it I realised I shouldn't have made the back completely black. It seems wrong when you hold it in your hands as the edges on the front are without resist. I want to make it bare board (so the light can shine through) and make everything currently on the back in white silkscreen in black instead. The last picture is a rendering close to what I would like to do.1. Can I use the black solder resist to make detailed graphics on the back like I have on the silkscreen or do I need to use black silkscreen?2. If I need to use silkscreen, can I even put silkscreen on bare board without resist?The design is Creative Commons (CC-BY), made with Inkscape,svg2modand KiCAD andavailable on GitHub.

author: RobK_NL
author_rank: Frequent Contributor
timestamp: November 21, 2016, 11:59:47 am
content: Several PCB manufacturers offer black silkscreen (on either side of the board). As long as you do not intend to solder the boards in a machine, you'll be fine without a soldermask.

author: kasbah
author_rank: Contributor
timestamp: November 21, 2016, 12:13:03 pm
content: Thanks, but if I use the resist layer to try and draw the things that are currently on the silkscreen layer it won't turn out so well, no? The reason would be to have white on the front and black on the back without adding cost for doing a special order.

author: wraper
author_rank: Unknown
timestamp: November 21, 2016, 01:24:19 pm
content: Quote from: kasbah on November 20, 2016, 07:35:35 pmNo, if it won't be rejected, fab will just remove it.

author: wraper
author_rank: Unknown
timestamp: November 21, 2016, 01:33:30 pm
content: Quote from: kasbah on November 21, 2016, 12:13:03 pmIt will be fine, but you need to be sure that solder resist is according to fab design rules. if it is too narrow, those areas will be either removed by the fab or if they don't remove it, some narrow areas still might be randomly missing.Some PCB art:
using SR flip flop to transform a pulse - Page 1
Forum section: electronics / projects

author: john23
author_rank: Frequent Contributor
timestamp: October 21, 2024, 11:25:51 am
content: Hello ,I have two pulses which are very slow and have different rates shown bellowThe schematics of SR flip flop with the two switches.I have tried to build and simulate as shown below.But there is this switches issue you shown in the schematcs bellow.how can i represent these switches in my simulation?Thanks.

author: john23
author_rank: Frequent Contributor
timestamp: October 22, 2024, 09:02:16 am
content: UPDATE:Hello We can look at the situation as logical 1 is +12V and logical zero is -12V.I dont know why S-R fits this.As i see it a D flip flop fits more for the dask.my data is +12V pulse and clock will be -12V.So if the clock is low(-12V) the D-flip flop passes the data from input to output.I think the state which points to the red arrow is the best.In the web site below i have found a schematics shown below.In this article logical 0 is 0V and logical 1 is 5V.So i want to test the d-flip flop truth table:CLK -5V and data 5V so V_base<V_emiter and Q3 is closedHow can i know what is Q1 base voltag in such situation?Thanks.https://0creativeengineering0.blogspot.com/2019/03/what-is-d-flip-flop-using-discrete.html
Using switching LED driver as a regulator - Page 1
Forum section: electronics / projects

author: 8086
author_rank: Super Contributor
timestamp: December 09, 2016, 11:44:07 am
content: Hi all,Have a bit of a problem and I immediately knew where to turn!I'm working on a super low cost design and it needs a boost regulator.I've found this part:http://www.dioo.com/attachments/files/20161031115726_129.pdfIt's calling itself an LED driver but what I want to know is, if I place feedback resistors to provide 200mV to the FB pin at the desired output voltage, is there anything stopping me from just using this to power whatever I want (within reason) like a normal boost regulator?
using tactile switch to turn ON and turn OFF a circuit - Page 1
Forum section: electronics / projects

author: tapasxplore
author_rank: Contributor
timestamp: November 15, 2017, 07:29:37 pm
content: Hi,I am planning to use tactile switch to turn ON and turn OFF a circuit (see attachment for schematic), I don't want to use slide switch for turning ON-OFF the circuit. I have narrowed down to SRC0 (Smart push-button on/off controller) from STmicroelectronics, is this right choice, or there are other more feasible alternatives available.Regards,Tapas

author: Mr.B
author_rank: Unknown
timestamp: November 15, 2017, 07:39:25 pm
content: If I understand your requirements correctly...Have a watch of Daves video:EEVblog #262 - World's Simplest Soft Latching Power Switch CircuitFurther information here:https://www.eevblog.com/forum/beginners/world%27s-simplest-soft-latching-power-switch-circuit-%28modification%29/msg121811/#msg121811https://www.eevblog.com/forum/projects/two-mosfet-soft-latching-startup-switch/msg167730/#msg167730https://www.eevblog.com/forum/projects/characteristics-of-a-soft-latch-power-switch/msg152164/#msg152164https://www.eevblog.com/forum/projects/yet-another-self-latching-mosfet-switch/msg171647/#msg171647https://www.eevblog.com/forum/beginners/world%27s-simplest-soft-latching-power-switch-circuit-%28modification-2%29/msg121872/#msg121872https://www.eevblog.com/forum/projects/an-improvement-on-the-soft-latching-power-switch/msg171112/#msg171112https://www.eevblog.com/forum/projects/mosfet-power-switch-with-auto-off/15/
Using tantalum polymer capacitors for capacitor bank? - Page 1
Forum section: electronics / projects

author: daqq
author_rank: Super Contributor
timestamp: July 19, 2018, 12:06:32 pm
content: Hi guys,In a project I'm using a 4000 uF bank of (currently) 100u/10V ceramic caps to store a small voltage (adjustable up to 3.5V) and discharge when needed. The RMS current is around 10 Amps, with a peak value of 35Amps during (partial) discharge and 15 Amps max during charging. The ceramic caps have pretty much no ESR, so there's no problem with heating or anything.There is a problem though, it's pretty costly, and I'm afraid a bit that the ceramics might crack under mechanical stress (steps have been taken to avoid this, but still, 40 ceramic caps in one place). I'm OK with the capacitance change with temperature and DC bias.I've been looking into alternative.Electrolytes will not be used (bad previous experience, higher, 70 deg temperatures will be present etc.). Staying with ceramics would work, but they are fairly pricey.I've been looking into tantalum polymer caps, such as this one:https://www.mouser.sk/ProductDetail/Vishay-Polytech/T55D227M010C0050?qs=YCcZ0GhAU2rddC%252bsxopTHA==@20pcs, they should have the same capacitance, while taking up a bit less space, and being cheaper in general.I've never worked with tantalum polymer caps. Do you think that it's a good application for these caps, or should I stick with my current solution?Thanks,David

author: Siwastaja
author_rank: Super Contributor
timestamp: July 19, 2018, 03:44:02 pm
content: Quote from: daqq on July 19, 2018, 12:06:32 pmWant to elaborate on that "bad previous experience"? This soundsexactlylike a job for electrolytics, since high temperatures are not present, and the ESR doesn't seem to be too important since the current is fairly low.The whole world runs on electrolytic caps no problem. 70 degrees is not much at all. After about 90, you start running out of derating margin, bringing you back into the not-unlimited-lifetime-territory.Badly designed or crappy products do fail, but they do fail due to ceramic capacitors failing as well. Elcaps are fairly easy to design in correctly: pick a Japanese brand capacitor with 5000+ h lifetime, derate temperature, ripple current and voltage ratings a bit, and glue large caps down if installed in enviroment with vibration. Products designed like this work for decades.Tantalums are classically notorious for failing, although tantalum polymers should be less suspectible.Another option is aluminimum polymer electrolytic, longer life compared to traditional alu elcaps, but this is a fairly new product segment compared to tried-and-tested basic alu elcaps which are super robust when used correctly.
Using Tektronix TM5000 Modules without mainframe - Page 1
Forum section: electronics / projects

author: bborisov567
author_rank: Regular Contributor
timestamp: January 22, 2023, 11:23:00 am
content: I got some modules from the dumpster yesterday. They appear to be from a Tektronix TM5000 sysytem. I am mainly interested in using the powers supply and the distortion analyzer. I am not interested in the GPIB functionality. Is there somebody more familiar with the system to shed some light?Links to the TekWiki:https://w140.com/tekwiki/wiki/PS5010https://w140.com/tekwiki/wiki/AA501

author: srb1954
author_rank: Super Contributor
timestamp: January 22, 2023, 12:46:30 pm
content: Quote from: bborisov567 on January 22, 2023, 11:23:00 amYou have stumbled onto quite a treasure trove there. If the AA501 and SG505 are in good working condition or can be easily fixed you should be able to sell them for at least US$800 for the pair. The other two modules are not nearly as valuable.Rather trying to put together a substitute system to power them it will be far easier, and cheaper, to just go out and buy a TM5006 mainframe The mainframe provides multiple voltages, both AC and DC, to each module slot and it would not be simple job to replicate that with external power supplies for each module. You could also use a TM5003 mainframe but these seem to be quite rare to find.Do not buy a TM503, TM504 or TM506 mainframe as these will not physically accommodate the GPIB equipped modules. However, you can house the SG502 and SG505 in a TM50x mainframe as well as a TM500x mainframe.

author: alm
author_rank: Super Contributor
timestamp: January 23, 2023, 12:48:03 pm
content: You can find the pinout of the rear interface here:here. It contains some unregulated AC and regulated DC voltage rails, and two bipolar power transistors (PNP and NPN). Not all plugins will use all pins. Check the individual plugin schematics for details.But like srb1954, I think acquiring a TM5000 mainframe, probably TM5006 given the number of plugins and given that the smaller mainframes are often more expensive, is the easiest solution.

author: anotherlin
author_rank: Frequent Contributor
timestamp: January 25, 2023, 05:36:27 pm
content: As already mentioned, it is almost for sure more efficient and economically cheaper to just go buy a TM5003 (3 plug-ins) or TM5006 (6 plug-ins, one of which can be high power) rack. You have the AA5001, which is the programmable version of the AA501.There are a lot of various plug-ins available from Tektronix for rather cheap, even oscilloscopes (SC502, SC503, SC504).I can only recommend you to buy such a rack.
Using TFT LCD with Raspberry PI Zero using custom board - Page 1
Forum section: electronics / projects

author: aiq25
author_rank: Regular Contributor
timestamp: March 10, 2019, 07:19:25 pm
content: Hi. I would like to use a 2.8" screen with a Raspberry PI Zero using SPI. I'm creating my own custom PCB that the PI will be mounted on. The pre-made LCD boards from eBay are too large, as I would like a slimmer board. I'm not sure how the TFT screens work, I never used one. Can I buy one off eBay and use it without their PCB? Seems like I would need the ILI9341 IC on my board to interface with the screen (via ribbon cable), is this true?

author: jayeye
author_rank: Contributor
timestamp: March 23, 2019, 03:18:40 am
content: Without more information, I assume you mean the all-too-common TJC-028-9341SPI-based boards, which usually also have a touch screen interface chip and an SDcard connector, all for under USD10. The carrier boards just bring the FFC wires out to the .1'' header; the better ones may have bypass capacitors or a 5V to 3V3 LDO.My approach would be to get a board, carefully desolder the FFC connector edge from the pcb, separate the mounting plate (it's just held in place with double-sided tape), use google to find the pinout (or just use a multimeter!)Tell us how it goes/ji

author: jayeye
author_rank: Contributor
timestamp: March 23, 2019, 03:20:31 am
content: You can also get a version of the same LCD module without the 9341 controller, just one that brings out all the data and control pins, but you won't save more than a dollar, if that, and you need to be a lot more accurate with the timing of your signals, which would require real-time-priority processes and/or a kernel module. In short, way too much effort.

author: aiq25
author_rank: Regular Contributor
timestamp: March 23, 2019, 05:57:04 am
content: Quote from: jayeye on March 23, 2019, 03:20:31 amI'm not really trying to save cost, just space and thickness of my board. I also don't need a touch or SD card (I think). I'll try to disassemble one like how you suggested and see how it goes.
Using the ADF4157/ADF4156 DDS - Page 1
Forum section: electronics / projects

author: Dajgoro
author_rank: Frequent Contributor
timestamp: December 09, 2014, 11:49:45 am
content: I recently found about the ADF4157/ADF4156 DDS signal generator that can go up to 6GHz.It seems like a nice little inexpensive ic, but the problem is how to handle such a frequency range.Supposing that ic is properly controlled, how would it be possible to amplify/buffer such a signal, and get it to a bnc connector?Can this be done on a regular double sided pcb?

author: Dajgoro
author_rank: Frequent Contributor
timestamp: December 10, 2014, 05:04:21 am
content: Is this such a impossible task that nobody won't even touch it?

author: marshallh
author_rank: Unknown
timestamp: December 10, 2014, 05:32:39 am
content: People already sell RF gens based around that chip... check ebay.Devil is in the details.

author: awallin
author_rank: Frequent Contributor
timestamp: December 10, 2014, 06:03:11 am
content: check the evaluation board for PCB design/layout:http://www.analog.com/en/evaluation/eval-adf4156/eb.htmlmini-circuits has amplifiers that go to 6 GHz and above, e.g.http://194.75.38.69/products/amplifiers_smt_gpw.shtmltest-gear to look at the harmonics of a 6 GHz signal isn't going to be cheap..

author: photon
author_rank: Frequent Contributor
timestamp: December 10, 2014, 06:49:16 am
content: Note that the part is not a DDS. Note that it is not a complete PLL. You need to add an external loop filter and an external VCO to generate a sine wave since the output is a voltage from its charge pump intended to control the external VCO frequency.So even though the part is cheap, the cost of the additional parts will add up.

author: Dajgoro
author_rank: Frequent Contributor
timestamp: December 10, 2014, 07:06:17 am
content: Quote from: photon on December 10, 2014, 06:49:16 amYes, I know. I can use a 0-30MHz DDS for generating that sine wave.The demo boards are a bit expensive, I was hoping to have just a small pcb with this ic + other required components to get it working, without a control mcu. The mcu could be on a separate board.The evaluation board is a 4 layer pcb, I wonder if would it work on two, even if the signal suffers a bit?Edit:Even if I build it, how can I test if it works(if i have no other such source to mix with)?
using the DRV8816 2x 1/2 bridge as high or low side switch - Page 1
Forum section: electronics / projects

author: Simon
author_rank: Unknown
timestamp: January 29, 2020, 11:29:45 am
content: i am looking at the following:http://www.ti.com/lit/ds/symlink/drv8816.pdfIf I pul the input to the side I want to operate and instead PWM the enable pin would this effectively allow me to select and control the highside or low side only?
Using the eZ430-Chronos Hands Free - Page 1
Forum section: electronics / projects

author: hornm
author_rank: Newbie
timestamp: March 05, 2015, 09:59:59 pm
content: Hey guys,I had an idea for using the eZ430-Chronos as a hands free device as it has a built in accelerometer. This allows for the use of tilt axis for navigation and other operations. I was wondering if anyone had any ideas on how to get the watch to stay in standby mode until it is activated to use the watch. What could be used to awaken the watch from sleep mode and do this without too many false positives.I plan on using the supplied normal operation code and modifying it to just add in the capability to use it hands free.Thanks!
Using the LM1881 to detect the start of a new video frame - Page 1
Forum section: electronics / projects

author: TimB100
author_rank: Contributor
timestamp: September 16, 2019, 10:16:13 pm
content: Hi every one, sorry this may be obvious to others but its not for me.I'm working on a project that will use the LM1881 sync separator. One of the tasks I need to do is count the horizontal lines to know what line I'm on.There is a signal generated for every H scan which is great but the Vsync line is not at the start of the first H line. Its in the middle of a load of other Hsync pulses.I'm going to be using a Pic to do some analysis of the video signal so can obviously do some timing. Perhaps after the Vsync count the Hsync pulses to get to the first Hsync of the new frame scan. Or time it for x us then wait for the next Hsync and that will be the start of the first line etc etc.Its obviously not rocket science as even a 12mhz pic can generate text overlays in the same place every time.Can anyone tell me the best method?Many thanksTim
Using TL084 or TL074?   - Page 1
Forum section: electronics / projects

author: gbowne1
author_rank: Contributor
timestamp: May 17, 2010, 02:05:20 am
content: Hi all! What would help me figure out which TL074 or TL084 to use?Looking at the data there is a lot to choose from to narrow it down. But I got a little lost in the datasheets. I've used other TL0** type IC's but this pair is a little confusing.They are opamp IC's of course.. so they have a +4v/-4v input rail and seem to be a 70 to 80db Common Mode Rejection Ration (CMRR).Voltage and Bias current @ 15v w/ different values.The application needs a 14pin package.They both come from STMicro or TI.Greg

author: allanw
author_rank: Frequent Contributor
timestamp: May 17, 2010, 02:59:13 am
content: Dunno if you saw this, but TI's site says "TL081 - Similar parts, where TL08x is a general purpose family and TL07x is a low noise family"

author: gbowne1
author_rank: Contributor
timestamp: May 17, 2010, 03:21:06 am
content: No. I didn't see that. Low noise would be nice. It's an RF Application.

author: tecman
author_rank: Frequent Contributor
timestamp: May 19, 2010, 11:20:32 pm
content: Quote from: gbowne1 on May 17, 2010, 03:21:06 amRF should mostly not be related to the op-amp. The low noise refers to internally generated noise in the op-amp. The op-amp noise will be much lower in spectrum than RF.If you are working in mV signals, lo noise can be a benefit.Paul

author: Zad
author_rank: Super Contributor
timestamp: May 20, 2010, 12:35:16 am
content: The gain-bandwidth product on the TL08x is only 4MHz anyway. That is to say at 4MHz, max gain is 1, 2MHz it is 2, 1MHz it is 4 etc. There are RF op-amps, but that isn't one.

author: gbowne1
author_rank: Contributor
timestamp: May 22, 2010, 01:45:13 am
content: Project: RF Power Amplfier for 87MHZ - 108MHz FMOutput Min.: 500w ERPOutput Max : 700w ERPRF Input @ drive: 7wThinking about using a BLF278 by NXP Semiconductors they are about $150.Or maybe one of the MRF transistors.GReg
Using transformer with 10% higher input voltage - Page 1
Forum section: electronics / projects

author: Jester
author_rank: Frequent Contributor
timestamp: December 29, 2023, 07:57:52 pm
content: Thoughts at using this transformer with 240V in at 220V terminal, and ~220V out at 200V terminal. Concern is over-excitationLoad is intermittent perhaps 20% duty cycle max. but will be near 1kVA at times.

author: Zero999
author_rank: Super Contributor
timestamp: December 29, 2023, 08:07:53 pm
content: It should be fine, especially given the low duty cycle.Did you get it from Europe i.e. a 50Hz region? If so, then it's even better, since the slightly higher frequency will reduce the flux, reducing the chance of saturation.

author: BrokenYugo
author_rank: Super Contributor
timestamp: December 29, 2023, 08:34:02 pm
content: Japanese name and voltages make me think this is some sort of old boost transformer for using 220V (now 240) equipment on Japanese 200V power or vice versa, half of Japan is 50Hz so I wouldn't doubt it if it's happy on 240V 60Hz power. I'm no transformer expert but I would think checking the idle current at 240V would give a good idea. EDIT: idle power, not current.

author: johansen
author_rank: Super Contributor
timestamp: December 30, 2023, 02:18:20 am
content: What are you worried about?It will just warm up quicker.Idle current is meaningless, you need a watt meter. or just weigh it, then put it in a well insulated box, leave it on for 1000 seconds (to make the math easier) and measure the temperature rise.
Using transmission line effects to measure soil moisture - will this idea work? - Page 1
Forum section: electronics / projects

author: miceuz
author_rank: Frequent Contributor
timestamp: January 17, 2013, 02:56:08 pm
content: I'm working on this idea - oscillator drives a transmission line which is burried in a soil and XOR gate measures the phase shift between the driving signal and reflection that comes back.I've build a prototype which uses xor gates as inverters to make an oscillator - it kinda works, but I want to go higher frequency and I want a more stable frequency.So, I want to use a ready made oscillator (something likehttp://www.ctscorp.com/components/Datasheets/008-0256-0_F.pdf), but I'm not sure if it will be able to drive a transmission line. Could anybody comment on this idea?

author: jerry507
author_rank: Regular Contributor
timestamp: January 17, 2013, 07:58:34 pm
content: Done in most quality sensors:http://www.decagon.com/products/sensors/soil-moisture-sensors/ec-5-soil-moisture-small-area-of-influence/

author: Daving
author_rank: Contributor
timestamp: January 18, 2013, 01:53:32 am
content: If you're not worried about spacial variation of moisture, you could just measure the capacitance.It's difficult to give advice without more specifics, but if we assume that you are using 1mm wire and the wires are spaced 1cm apart, then you can expect to see your capacitance range between 30pF to 250pF / meter, and the wavelength of your signal is going to vary from (at 50Mhz) 1-3 meters. These are just rough numbers. You can reduce the capacitance by spreading the wires apart, and that will also increase the characteristic impedance, so make sure that you're series resistor matches to minimize unwanted reflections. Could work, just make sure to balance everything out.You might look into TDR, if you want to know how the soil changes with depth or distance, for example.
Using triac as AC power line switch - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: June 17, 2018, 05:53:14 pm
content: Hi,I attach a circuit where I pretend to control the AC input to a bridge rectifier. I usually see that triacs are used in AC switching and phase control applications such as motor speed and temperature modulation controls, lighting controls, and static switching relays. In this case I just want to control the moment when the bridge is going to be fed. The Triac that I will use is 1-3 quadrant triac. I've seen 4 quadrant triacs, but not so common. Do you think that it could work the way I have arranged the circuit?

author: james_s
author_rank: Super Contributor
timestamp: June 17, 2018, 06:00:12 pm
content: It looks reasonable. It's certainly not unheard of to use a triac based SSR to control the power of something.

author: Yansi
author_rank: Super Contributor
timestamp: June 17, 2018, 06:04:25 pm
content: You know... you have just invented a SSR.//EDIT: And btw, you circuit lacks inrush current limiting. Add at least a suitable NTC in series with the input.
using TWO Sanyo LB1641 Bidirectional motor drivers to drive bipolar stepper? - Page 1
Forum section: electronics / projects

author: dentaku
author_rank: Frequent Contributor
timestamp: January 31, 2015, 03:15:55 am
content: I have these two old Sanyo LB1641 Bidirectional motor drivers I found somewhere.http://pdf.datasheetcatalog.com/datasheet/sanyo/ds_pdf_e/LB1641.pdfI was wondering if it would be possible to drive a 4 wire Bipolar stepper motor using TWO of these to create the correct sequence (one for each winding).I tested them both and they can run a little DC motor in both directions depending on which of the two IN pins is high and low. I know everyone uses the L297 or something similar but I just though this was in interesting experiment.question regarding the datasheet: On page two it says...Input level1 : 2.0V or greater0 : 0.7V or lessThat's fine, I'm assuming that IN1 and IN2 register a HIGH if you give them 2V or higher and LOW if lower than 0.7V.QUESTION: What tells me the maximumvoltage and currentthat IN1 and IN2 (pins 5 and 6) can withstand?
Using uCurrent circuit to measure power - Page 1
Forum section: electronics / projects

author: jmag999
author_rank: Contributor
timestamp: January 02, 2013, 08:32:28 pm
content: I'd like to adapter the uCurrent circuit to also measure voltage (and therefore power). What I am trying to figure out is how to tie in the ground from the circuit to be measured. Obviously I need this in order to measure the circuit voltage. But how do I connect this with the power supply in the uCurrent. I don't think I should tie the virtual ground to the circuit ground. What about connecting the battery negative with the circuit ground? Any ideas?

author: IanB
author_rank: Super Contributor
timestamp: January 02, 2013, 10:36:27 pm
content: You just need two DMMs. Use one to measure the current through the uCurrent, use the other to measure the voltage across the device under test, multiply the two measurements to give power. It will just work, no modifications needed anywhere.

author: jmag999
author_rank: Contributor
timestamp: January 03, 2013, 01:03:20 pm
content: In my circuit, I have 2 current measurement circuits (same as ucurrent) plus an additional opamp circuit ( same as ucurrent with no shunt ). This will get hooked up to 3 DMM inputs. However, all the opamps are powered from the coin cell. When I introduce the system ground, the input to the voltage reading opamp will not have a common ground with the system. There could be a potential across it that exceeds the limits of the opamp. How do I connect the grounds to prevent this from happening in this system.
Using UF4007 as pull-down - Page 1
Forum section: electronics / projects

author: Neukyhm
author_rank: Contributor
timestamp: March 02, 2018, 10:07:45 am
content: Hi there, I have a positive voltage that can be from 0v to +150v. I would like to measure when it's 0v, so the attached circuit is what I was thinking about.The IC is a TC4468. The idea is that when the voltage is >0v, the diode blocks and the 12v goes to the TC4468.When the voltage is 0v, the diode pulls down the TC4468 input. However, the UF4007 has a voltage drop of 0.8v, just the upper limit for a logic0 input. The question is, is this a good idea? Is there a better method to do this?

author: capt bullshot
author_rank: Super Contributor
timestamp: March 02, 2018, 10:21:52 am
content: That's a pretty usual way to do this - should work

author: Gyro
author_rank: Super Contributor
timestamp: March 02, 2018, 11:08:08 am
content: The circuit looks more sensible when you draw so that the resistor is a pullup to the +12V supply to the TC4468 (I assume).Yes, it should just about work but the guaranteed logic low input to the TC4468 is 0.8V, so you might be a bit close depending on how close to 0V your 0-150V rail gets (ie. it actually needs to get within 100mV or so of 0V). A suitably voltage rated schottky would give you just a little more leeway but not much.You need to consider what happens when your 0-150V supply is in the 0.5-3V range.

author: Gyro
author_rank: Super Contributor
timestamp: March 02, 2018, 08:57:00 pm
content: Without knowing more about your application and the varying 150V rail, I think you would be far better to use a proper analogue comparator, with hysteresis, to ensure a clean and predictable transition. Without that, the logic level that the TC4468 'sees' is going to transition several times due to noise as the voltage passes through its undefined logic transition region. Probably not what you want in a power mosfet driver!http://www.ti.com/lit/ug/tidu020a/tidu020a.pdf
Using USB data pins for device identification in battery charging application? - Page 1
Forum section: electronics / projects

author: clem
author_rank: Newbie
timestamp: April 22, 2013, 08:09:50 am
content: I'm working on my first battery powered project and I'm using USB for charging (no data). As part of the user interface for the device I need to be able to tell the difference between two different charging bases. The UI changes when the device is plugged into 'base A' and a different behavior when it is plugged into 'base B'. The device needs to be able to identify the two different bases even if the base is unplugged. This isn't for something like setting the charging rate, it is purely a UI behavior specific to the device.My initial plan was to use the ID pin for this, but it seems that using D+ and D- are preferred. However the USB battery charger spec says that Dedicated Charging Port should short D+ to D-.My current idea is to pull D+ to 3v3 though a 4k7, D- to ground with a 4k7 and connect D- to an ADC pin. In one base I'll put a 4k7 and the other a 10k across D+/D-. This way I'll be able to tell if the device is connected to the base even if the base itself is not plugged in (the 3v3 comes from the battery). Most chargers seem to leave D+ and D- open others short D+ to D-. If D+/D- is open I'll get 0V on the ADC and 1.65V if it is shorted. However, I'm not sure how a PC handle having D+ at 3v3 and D- at GND.I realize this is non-standard, but any ideas how non-compatible it will be? Any ideas for a better way to implement this?

author: kxenos
author_rank: Frequent Contributor
timestamp: April 22, 2013, 09:19:24 am
content: In the charging base you can short D+ with D- and connect these pins with a, say, 100k to GND and 200k to Vcc. In the other charging base do the opposite: 200k to GND and 100k to Vcc. At the mobile just compare D+ or D- with Vcc/2.

author: amyk
author_rank: Super Contributor
timestamp: April 22, 2013, 10:11:51 am
content: Quote from: clem on April 22, 2013, 08:09:50 amThat's how a full-speed/high-speed device is detected when plugged in. The host will have its own 15k pulldown resistors on D+ and D-.http://www.beyondlogic.org/usbnutshell/usb2.shtml

author: Memphis
author_rank: Contributor
timestamp: April 22, 2013, 10:52:59 am
content: Would be better to review the USB 3.0 and USB 2.0 specification for thishttp://www.usb.org/developers/docs/
Using USB SiK radio as USB host instead of client - Page 1
Forum section: electronics / projects

author: PP3331
author_rank: Contributor
timestamp: March 21, 2020, 04:56:00 pm
content: Hi all. I have a device that is normally connected to a PC for relatively low speed data transmission via a USB cable. So, USB host on the PC side, USB client on the device side. I would like to replace the cable with a pair of SiK USB radios. The problem of course is that the radios are USB clients, and I need some way to use one as a host to connect on the device (USB client) side. The device is *not* OTG capable.Does anyone make a chip or other inexpensive purpose-built (and small) unit for this purpose? Thanks. Stay well.

author: PP3331
author_rank: Contributor
timestamp: March 22, 2020, 08:27:37 pm
content: I'll be solving this with a Raspberry Pi Zero W. I can use its Wi-Fi interface instead of the radios initially. If I need to add the radios later, I have compatible versions that can connect to the Zero W's serial connections. The board includes integral USB OTG master that should drive the client device.